CA1299647C

CA1299647C - Control system for an electronically commutated motor, electronically commutated motor system, laundry apparatus and methods for controlling same

Info

Publication number: CA1299647C
Application number: CA000615743A
Authority: CA
Inventors: John Henry Boyd, Jr.; Alexander Muller
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1990-05-24
Filing date: 1990-05-24
Publication date: 1992-04-28
Anticipated expiration: 2005-04-18

Abstract

CONTROL SYSTEM FOR AN ELECTRONICALLY COMMUTATED
MOTOR, ELECTRONICALLY COMMUTATED MOTOR SYSTEM, LAUNDRY APPARATUS AND METHODS FOR CONTROLLING SAME

Abstract of the Invention Control system for an electronically commutated motor (ECM). The ECM includes a stationary assembly having a plurality of winding stages adapted to be selectively commu-tated, and rotatable means associated with the stationary as-sembly in selective magnetic coupling relation with the wind-ing stages. A circuit commutates the winding stages by selec-tively supplying power thereto in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered. The control system includes a circuit coupled to the winding stages for simultaneously converting the voltages across the winding stages to digital form thereby to digitize the voltages, and a circuit for producing successive patterns of digital signals in at least one preselected sequence, for selecting the digitized voltage across the at least one unpowered winding stage depending on the digital signal pat-tern produced, and for producing a following pattern in se-quence after at least one predetermined logic level of the selected digitized voltage has occurred. Another circuit responds to the successive patterns of the digital signals for generating the successive patterns of the control signals for the commutating circuit. Other control systems, electronical-ly commutated motor systems, laundry apparatus, and methods for controlling them are also described.

Description

~ 03AM ~938 CONTROL SYSTEM FOR AN ELECTRONICALL~ COMMUTATED
MOTOR, ELECTRONICA~LY COMMUTATED MOTOR SYSTEM, LAUNDRY APPARATUS AND METHODS FOR CONTROLLING SAME
This application is a division of Canadian application Serial No. 479,501, filed April 18, 1985.
Field of the InvQntion This invention relates in general to dynamoelectric machines and domestic appliances and more particularly to control systems with special applicability to electronically commutated motors, electronically commutated motor systems, laundry apparatus and other appliances, and methods for operating them.
Back~round of the Invention While conventional brush-commutated DC motors may have numerous advantageous characteristics such as convenience of changing operational speeds and direction of rotation, it is believed that there may be disadvantages, such as brush wear, electrical noise, and radio frequency interference caused by sparking between the brushes and the segmented commutator, that may limit the applicability of such brush-commutated DC
motors in some fields such as the domestic appliance field including the laundry apparatus field.
Electronically commutated motors, such as brushless DC
motors and permanent magnet motors with electronic commutation, have now been developed and generally are believed to have the above-discussed advantageous characteristics of the brush-commutated DC motors without many of the disadvantages thereof while also having other important advantages. Such electronically commutated motors are disclosed in the David M. Erdman U.S. patents 4,005,347 and 4,169,990 and Floyd H.
Wright U.S. Patent 4,162,435, all of which are commonly assigned with the present application. These electronically commutated motors may be advantageous ~`

03AM 5g3~
~2~ 7 employed in many dlfferent fields or motor appLications among which are domestic appliances, e.g., automatic washing or laundry machines such as disclosed in commonly assigned Canadian Patents No. 1,193,651 - Boyd, Jr.,issued September 17, 1985; No. 1,140,658 - Erdman et al, issued February 1, 1983; No. 1,150,962 - ~ersh~erger, issued August 2, 19~3;
and ~o. 1,199,997 - ~rdman, issued January 28, 19~6.
Laundry machines as disclosed in the above pa~ents are believed to have many significant advantages over the prior art laundry machines which employ various types of transmissions and mechanisms to convert rotary motion into oscillatory motion to selectively actuate the machine in its agitation washing mode and iA its spin extraction mode. Such prior art laundry machines are l~ believed to be more costly and more complicated to manufacture, consume more energy, and require more servicing. Laundry machines with electronically commutated motorS require no mechanical means, other than mere speed reducing means, to effect oscillatory action of the agitator or tumbler, and in some applications, it is believed that the spin basket might be directly driven by such a motor.
While the past control systems, such as those disclosed in the aforementioned coassigned patents for instance, undoubtedly illustrated many features, it is believed that the control systems for electronically commutated motors in general, and for such motors utilized in laundry machines, could be improved, as well as the methods of control utilized therein.
In some of the known control systems, the pOsition of the rotatable assembly (i.e., the rotor) of the electronically commutated motor was located by sensing the back emf of one of the winding stages on the stationary assembly (i.e., the s~ator) thereof. More particularly the back emf of an unenergized winding stage was sensed and integrated to determine rotor position during aAy one commutation period in a ~ 7 sequence of commutation. IJith the advent or inex~ensive microprocessor chips, controlling an electronically commutated motor with a microprocessor and discrete element controL
svste~ has been described. Coassigned U.S. Patent ~,250,544, "Combination Microprocessor and Discrete FL~men~ Control System for a Clock Rate Controlled Electronicalley Commutated Motor" issued February 10, 1981 to R.P. Alley discloses such an arrangement. It is believed t;-at further i~prove-ments and other departures can be made in methods and systems for controlling electronically commutated motors and for domestic appliance applications including laundering apparatus ap~licatlons.
Summarv of the Invention -Among the objects of the present invention are to provide improved control systems for an electronically commutated motor, improved electronically commutatec motor systems, improved laundry apparatus, and improved methods for controlling them which do not require position sensing by integration during a co~mutation period; to provide such improved control systems for an electronically commuta~ed motor, electronically commutated motor systems, laundry apparatus and other appliances, and methods for controllirg them wnich can screen out unexpected or accidentally produced signals and transients from a micro-processor or digital computer to maintain proper operationof the system, the motor, or the appliance; to provide such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry appara~us, and methods for controlling them which can relia~ly start an electronically commutated motor and insure its operation in a selected direction o~ rotation:
to provide such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry apparatus, and methods in which the motor is protected from excessive current; to provide such improved control systems for an electronically commutated mo~or, ' ~3~ 03AM 5938 electronically com~utated r,otor s~stems, launcry a~paratus, and methods in which the s~ee~ of the motor is adjus~ably controlled; to provice such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry a~aratus, and methods for controlling them in which the rotor position is sensed from the bac~ emfs or the winding stages when the rotor is coasting and there are no commutation periods; to provide such improved control systems for anelectronically commutated motor, electronically commutated motor systems, laundry apparatus, and methods for controlling them which are resistant to error in determining the rotor position from the back emrs or the winding s~ages when ~he rotor is coasting and there are r.o commutation periods; to provide such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry apparatus, and methods for controlling them which can commutate an electronically commutated motor in a preselected sequence, discontinue the co~mutating, ana then resume commutating at a proper point in the sequence to keep the motor running smoothly determined from the back emfs of the winding stages when the commutating was discontinued;
to provide such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry apparatus, and methods for controlling them which accelerate the motor in a low speed connection arrangement of the winding stages, change from the low speed connectiOn arrangement to a higher speed connection arrangement of the winding stages and sense the rotor position to smoothly resume accelerating the motor in the high speed connection arrangement; to provide such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry apparatus, and methods for controlling them which brake the motor; to provide such improved control systems for an elect~onically ~ 7 03AM 5938 commutated moto~, electronically commutated motor systems, laundry apparatus, and methods for controlling them which smoothly and rapidly reverse the motor; to provide such im-proved control systems for an electronically commutated ~otor, electronical1y commutated motor systems, laundry apparatus, and methods for controlling them which periodically reverse the motor; and to provide such improved control systems for an electronically commutated motor, electronically commutated motor systems, laundry apparatus, and methods for controlling them which power at least some of the winding stages and ro-tate the rotor~ and then leave all the winding stages tempo~
rarily unpowered and provide a current path for the previously powered winding stages to facilitate rotor position monitoring and accomplish other purposes.
Other objects and features will be in part apparent and in part pointed out hereinafter.
In general and in one form of the invention, a con-trol system for an electronically commutated motor including a stationary assembly having a plurality of winding stages adap-ted to be selectively commutated, and rotatable means associ-ated with the stationary assembly in selective magnetic cou-pling relation with the winding stages, and means for commu-` tating the winding stages by selectively supplying powerthereto in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered, comprises cir-cuitry coupled to the winding stages for simultaneously con-verting the voltages across the winding stages to digital form thereby to digitize the voltages. The cir~uitry for digitizing the voltages is combined with circuitry for producing succes-sive patterns of digital signals in at least one preselected sequence, for selecting the digitized voltage across the at least one unpowered winding stage depending on the digital signal pattern produced, and for producing a following pattern in sequence after at least one predetermined logic level of ~ 6~ 03AM 5938 the selected digitized voltage has occurred; and also combined with circuitry responsive to the successive patterns of the digital signals for generating the successive patterns of the control signals for the commutating means.
In general and in another form of the invention, a control system for an electronically commutated motor includ-ing a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable rneans associated with the stationary assembly in selective magnetic coupling relation with the winding stages, and means for com-mutating the winding stages by selectively supplying power thereto in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered, comprises cir-cuitry coupled to the winding stages for digitizing the volt-ages across the winding stages and circuitry responsive to successive patterns of digital signals for generating succes-sive patterns of the control signals for the commutating means. A digital computer operating under stored program con-trol has inputs for the digitized voltages. The computer hasmemory elements for storing data representing at least one preselected sequence of the patterns of the digital signals and for storing data, corresponding to each pattern of the digital signals, identifying the respective input for the ~5 digitized voltage for the at least one unpowered winding stage. The computer successively produces one of the patterns of the digital signals, senses only the digitized voltage at the identified input corresponding to the one pattern and pro-duces the following pattern in se~uence after at least one predetermined logic level of the digitized voltage at the identified input has occurred.
In general, and in a further form of the invention, an electronically commutated motor system comprises an elec-tronically commutated motor including a stationary assembly having a plurality of ~inding stages adapted to be selectively ~ 7 03AM 5938 commutated, and rotatable means associated ~ith the stationary assembly in selective magnetic coupling relation with the winding stages, first and second conductors for supplyin~
power, and a circuit for commutating the winding stages by selectively switching the winding stages to the supply conduc-tors in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered. A circuit is cou-pled to the winding stages for digitizing the voltages across the winding stages, and another circuit responds to successive patterns of digital signals for generating successive patterns of the control signals for the commutating circuit. The sys~
tem has a digital computer operating under stored program con-trol and having inputs for the digitized voltages. The com-puter has memory elements for storing data representing atleast one preselected sequence of the patterns of the digital signals and for storing data, corresponding to each pattern of the digital signals, identifying the respective input for the diyitized voltage for the at least one unpowered winding stage. The computer successively produces one of the patterns of the digital signals, senses only the digitized voltage at the identified input corresponding to the one pattern and pro-duces the following pattern in sequence after at least one predetermined logic level of the digitized voltage at the ~5 identified input has occurred.
In general, and in still another form of the inven-tion, laundry apparatus comprises means operable generally in a washing mode for agitating water and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of water from the fabrics, an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages for driving the agitating and spinning means in the washing mode operation and in the spin mode operation ~hereof upon the commutation of said winding stages. First and second conductors are provided for supplying power. The laundry apparatus also includes a circuit for commutating the winding stages by selectively switching the winding stages to the supply conductors in response to a pattern of control signals leaving at. least one of the winding stages unpo~ered at any one time while the other winding stages are powered. A circuit is coupled to the winding stages for digitizing the voltages across the winding stages. A circuit responds to successive patterns of digital signals for generating successive patterns of the control sig-nals for the commutating means. The laundry apparatus has a digital computer operating under stored program control and having inputs for the digitized voltages. The computer has memory elements for storing data representing at least one - preselected sequence of the patterns of the digital signals and for storing data, corresponding to each pattern of the digital signals, identifying the respective input for the digitized volta~e for the at least one unpowered winding stage. The co~)uter successively produces one of the patterns of the digital signals, senses only the digitized voltage at the identified input corresponding to the one pattern and pro-duces the following pattern in sequence after at least one predetermined logic level of the digitized voltage at the identified input has occurred.
In general, and in a method form of the invention, a method for controlling a system having an electronically com-mutated motor including a stationary assembly having a plural-ity of winding stages adapted to be selectively commutated,and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, and means for commutating the winding stages by selectively supplyin9 power thereto in response to a pattern of control signals leaving at least one of the winding stages unpowered 03AM 5g3~
*7 at any one time while the other winding stages are powered, comprises the steps of digitizing the voltages across the winding stages and ger.erating successive patterns of the con-trol signals for the commutating means in response to succes-sive patterns of di9ital signals. Data is prestored represent-ing at least one preselected sequence o~ the patterns of the digital signals. Data is also prestored corresponding to each pattern of the digital signals, identifying the respective digitized voltage for the at least one unpowPred winding stage. One of the patterns of the digital signals is succes-sively produced and only the identified digitized voltage cor-responding to the one pattern is sensed. The following pat-tern in sequence is produced after at least one predetermined logic level of the identified digitized voltage has occurred.
Generally, and in another method form of the inven-tion, a method for controlling a system having an electronic-ally commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commu-tated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, first and second conductors for supplying power, and means for commutating the winding stages and pro-ducing a current in the winding stages by selectively switch-ing the winding stages to the supply conductors in response to a pattern of control signals, comprises the steps of producing successive patterns of digital signals in at least one prese-lected sequence and generating patterns of the control signals for the commutating means in response to the successive pat-terns of the digital signals. The current in the winding stages of the electronically commutated motor is compared with a predetermined level, and a preestablished pattern of the digital signals is produced for a predetermined period of time to reduce the current in the winding stages, whenever the pre-determined level is exceeded. The current reducing pattern of ~ 6~7 03~M 5938 the digital signals is periodically produced at an adjustable rate when the predete~mined level is not exceeded.
Generally, and in a still further form o~ the inven-tion, a control system for an electronicallY commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assem~ly in selective magnetic coupling relation with the winding stages, first and second conductors for supplying power, and a circuit for com-mutating the winding stages and producing a current in thewinding stages by selectively switching the winding stages to the supply conductors in response to a pattern of control sig-nals, comprises a circuit for generating patterns of the con-trol signals ~or the commutating circuit in response to the lS successive patterns of the digital signals and a circuit for comparing the current in the winding stages of the electronic-ally commutated motor with a predetermined level. A further circuit is provided for producing the successive patterns of digital signals in at least one preselected sequence for the generating circuit, for producing in response to the comparing circuit a preestablished pattern of the digital signals to reduce the current in the winding stages upon the predeter-mined level being exceeded, for monitoring the voltage across the winding stages to monitor the position of the rotatable means when the current is being reduced, and for resuming pro-ducing the successive patterns of digital signals in sequence after a predetermined time intervalO
Generally, and in yet a further form of the inven-tion, a control system for an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, and means for commutating the winding stages by selectively supplying power thereto in response to a pattern of control signals ~ 03AM 5938 leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered, comprises a circuit coupled to the winding stages for converting the voltages across the winding stages to digital form thereby to digitize the voltages. The circuit for digitizing the vol-tages is combined with a circuit ~or producing successive pat-terns of the control signals in at least one preselected sequence to rotate the rotatable means, for subsequently pro-ducing a pattern of the control signals which causes the com-mutating means to leave all of the winding stages temporarilyunpowered, for sensing the digitized voltages while the wind-ing stages are temporarily unpowered and then resuming produc-ing the successive patterns of the control signals in sequence beginning with a pattern of the control signals determined from the sensed digitized voltages.
Generally, and in an even further form of the inven-tion, laundry apparatus comprises means operable generally in a washing mode for agitating water and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fatrics to effect centrifugal displacement of water from the fabrics and an electronically commutated motor including a stationary assembly having a plurality of winding ` ~ ` stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages for driving the agitating and spinning means in the washing mode operation and in the spin mode operation thereof upon the commutation of the winding stages. First and second conductors are provided for supplying power. The laundry apparatus has a circuit for commutating the winding stages by selectively switching the winding stages to the supply conductors in response to a pat-tern of control signals and a circuit coupled to the winding stages for converting the voltages across the winding stages to digital form thereby to digitize the voltages. In the ~ J~ ~ O~M 593~

laundry apparatus is a circuit operable generally for switch-ing the winding stages from a first connectiOn arrangement to a second connection arrangement, and a circuit for producing successive patterns of the control signals in at least one preselected sequence to rotate the rotatable means, for sub-sequently producing a pattern of the control signals which causes the commutating means to leave all of the winding stages temporarily unpowered during switching of the winding stages from the first connection arrangement to the second connection arrangement, for sensing the digitized voltages while the winding stages are temporarily unpowered and then resuming producing the successive patterns of the control sig-nals in sequence beginning with a pattern of the control sig-nals determined from the sensed digitized voltages.
In general, and in an additional form of the inven-tion, a control system for an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic couplirg relation ~ith the winding stages, comprises a circuit for ccmmutating the winding stages by selectively supplying power thereto in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered.
Another circuit responds to successive patterns of digital signals for generating the successive patterns of the control signals for the commutating circuit. Still another circuit is provided for producing the successive patterns of the digital signals in at least one preselected sequence, and for subse-quently producing a different pattern of the digital signalswhich causes the commutating means to connect all of the wind-ing stages together, thereby braking the motor.
In general, and in a further method form of the invention, a method for controlling an electronically commu-tated motor including a stationary assembly having a plurality 03AM ~938 of winding stages adapted to be selectively commutated, androtatable means associated with the stationarY assembly in selective magnetic coupling relation with the winding stages, and means ~or commutating the winding stages by selectively supplying power thereto in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered, comprises the steps of producing successive patterns of the control signals in at least one preselected sequence ~or com-mutating the winding stages in a first connection ~rrangementand producing a pattern of the control signals which causes the commutating means to leave all of the winding stages tem-porarily unpowered. The winding stages are switched to a second connection arrangement, and the position of the rotat-ing means is sensed while the winding stages are temporarilyunpowered. Production of the successive patterns of the con-trol signals in sequence is resumed beginning with a pattern of the control signals determined from the position of the rotating means sensed while the winding stages are temporarily unpowered.
Generllly~ and in still another method form of the invention, a method for controlling an electronically commu-tated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation wi~h the winding stages, and a circuit for commutating the winding s~ages by selective-ly supplying power thereto in response to a pattern of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered, comprise~ the steps o~ converting the voltages across the winding stages to digital form thereby to digitize the vol-tages and producing successive patterns of the control signals in at least one preselected se~uence to commutate the winding ~ 7 03AM 5938 stages and rotate the rotatable means. A pattern of the con-trol signals is subse~uently produced which causes the commu-tating circuit to leave all of the winding stages temporarily unpowered. The digitized voltages are sensed while the wind-ing stages are temporarily unpowered. A patter~ of the con-trol signals is determined from the sensed digitized voltages.
Production of the successive patterns of the control signals in sequence is resumed beginning with the pattern so determined.
Generally, and in yet a further method form of the invention, a method of controlling laundry apparatus compris-ing means operable generally in a washing mode for agitatiny water and fabrics to be laundered therein and operable gener-ally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of water from the fabrics, an electronically commutated motor including a stationary assem-bly having a plurality of winding stages adapted to be selec-tively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the windinq stages for driving the agitating and spinning means in the washing mode operation and in the spin mode oper-ation ~hereof upon the commutation of the winding stages, and first and second conductors for supplying power. The method comprises steps of converting the voltages across the winding stages to digital form thereby to digitize the voltages and commutating the winding stages by selectively switching the winding stages to the supply conductors in at least one prese lected sequence. The commutating is temporarily interrupted to leave the winding stages temporarily unpowered, and the winding stages are switched from a first connection arrange-ment to a second connection arrangement~ The digitized vol-tages are sensed while the winding stages are temporarily unpowered, and the commutating is resumed beginning at a point in the sequence determined from the sensed digitized voltages.

03AM ~938 ?.~;;'; ' ' ' )~'~7 In gene~al, and in an even ~rther method form of the invention, a method for controlling an electronically com-mutateà motor including a stationary assembly having a plural-ity o~ winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, and means for commutating the winding stages by selectively supplying power thereto in response to a pattern of control signals leaving at least;of the winding s~ages unpowered at any one time while the other winding stages are powered, com-prises the steps of generating successive patterns of the con-trol signals for the commutating means in response to succes-sive patterns of digital signals and producing the successive patterns of the digital signals in at least one preselected sequence. A different pattern of the digital signals is pro-duced which causes the commutating means to connect all of the winding stages together, thereby braking the motor.
In general, and in a yet additional form of the invention, a control system for an electronically commutated motor including a stationary assembly having a plurality of winding stages -Idapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, and first and second conductors ~or supplying power, comprises a circuit for commutating the winding stages in response to successive patterns of control signals leaving at least one of the winding stages unpowered at any one time while the other winding stages are powered. The commutating circuit includes sets of electronic devices connected across the supply conduc-tors, each set having a junction point connected to a respective one of the winding stages. Each o~ the electronic devices is respectively able to be switched by a corresponding one of the control signals in each pattern of control signals.

~ t~ 7 03AM 5938 The control system includes a circuit for producing the suc-cessive patterns of the control signals in at least one prese~
lected sequence to switch on only one electronic device in each of at least two of the sets of the electronic devices at once and cause a current to flow in the winding stages to rotate the rotatable ~eans, and for subsequently producing a pattern of the control signals to switch off one of the elec-tronic switching devices which was previously switched on so that the commutating means leaves all of the winding stages temporarily unpowered and also provides a current path for the previously-powered winding stages.
Generally, and in a yet further additional form of the invention, a control system for an electronically commu-tated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, and a circuit for commutating the winding stages by selective-ly supplying power thereto in response to a pattern of control signals leaving lt least one of the winding stages unpowered at any one time while the other winding stages are powered, comprises a circuit coupled to the winding stages or simul-taneously converting the voltages across the winding stages to digital form thereby to digitize the voltages and a circuit 2S responsive to successive patterns o digital signals for sen-erating successive patterns of the control signals for the commutating circuit. The control system includes a circuit for producing successive patterns of the digital signals in a first preselected sequence, producing a different pattern of the digital signals for causing the commutating circuit to remove power from all of the winding stages, sensing the digi-tized voltages while the power is so removed, and producing successive patterns of the digital signals in a second prese-lected sequence to rotate the rotatable means in the reverse ~ ~3~ 6'~7 03AM 5938 direction after a predetermined time pe~iod has elaps~d subse-quent to the last occurrence o~ a predetermined logic level in any of the digitized vnltages.

3rief Description of the Drawin~s FIG. 1 is a block diagram showing a control system having a high-low speed switching circuit, a commutating cir-cuit, a power supply, a control signal generator, a microcom-puter, a voltage digitizing circuit, and a current interrupt and speed controlling circuit with an electronically commu-tated motor in a laundry machine according to the invention;
FIG. 2. is an exploded, perspective view of the main elements of an electronically commutated DC motor which is controllable by the control system of FIG. l;
FIG. 3 is a schematic diagram of the high-low speed switching circuit, the commutating circuit, the power supply and the motor of FIG. l;
FIG. 4 is a schematic diagram of the control signal generator with the microcomputer of FIG. l;
FIG. 4A is a diagram of current flowing in the motor as a result of commutation in a preselected sequence:
FIG. 4B is four schematic diagrams of circuits effectively resulting in the commutating circuit of FIG. 1 Çrom different digital signal patterns and corresp~nding con-trol signal patterns produced in accordance with the invention;
FIG. 5 is a voltage versus time diagram of a wave-~orm of voltage across an unpowered winding stage of the motor during a commutation period FIG. 6 is a schematic diagram of the voltage digi-tizing circuit and of switches for providing commands to the microcomputer of FIG. 1 according to the invention;
FIG. 6A is a voltage versus time diagram of a digi-tized voltage to which the voltage of FIG. 5 is converted in accordance with the invention;

:

. . ~' , ~ iJ~ 03~ 5938 FIG. 7 is a schematic diagram of current interrupt and speed controllin~ circuit of FIG. 1 ir.
accordance with the invention;
FIG. /~ is a voltage versus t me diagram of outputs Q and Q-bar o~ a latch or flipf1op in the circ~it of FIG. 7 for interrupting t~e microcomputer and causing the control signal ge~erator of FIG. 1 to generate a pattern of control signals to reduce the current flowing in tne winding s~ages of the motor;
FIG. 8 is part of a flow diagram of operations of t~e microcomputer of FIG. 1 in accoraance with the invention;
FIG. 9 is an additional part of the flow d_agram of operations performed bv the microcomputer of FIG. 1 l~ in accordance with the invention in accomplishing a washing mode selected in the opera~ions of FIG. ;
FIG. 10 is a flow diagram of operations performed by the microcomputer of FIG. l in accordance with the invention in a low speed back emf routine of FIG. 9;
FIG. ll is a flow diagram of operations performed by the microcomputer of FIG. l in accordance with the invention in a reversing routine of FIG. 9;
FIG. llA is a flow diagram of operations performed by the microcomputer of FIG. 1 in accordance with the inven-tion for braking the motor as during a reversing routine;
FIG. 12 (appearir.g on the same sheet of drawings as FIG. 8) is a flow diagram of operations performed by the microcomputer of FIG. l in accordance with the inventiOn upon interruption by output Q-bar of FIG. 7A;
FIG. 13 (appearing on the same sheet of drawings as FIG. 8) is a flow diagram of operations performed by the microcomputer of FIG. 1 in accordance with the inven~ion for varying a duty cycle for the circuit of FIG. 7;
FIG. 14 is a flow diagram of operations performed by the microcomputer of FIG. 1 in accordance with theinvention in accomplishing a spin mode selected in the o~erations of FIG. 8;

~ ~,,sri~*~7 03~M 5938 FIG. 15 (apDearing on the same sheet or drawings as FIG. 10) is a flow diagram of operations performed by the microcom?uter or FIG. 1 in accordance with t:~e inven-tion in a high s?eed back e~r routine or FIG. 1~;
FIG. 16 is a flow diagram of o~erations perrormed by t~e microcom?uter or FIG. 1 in accorance with the invention in advancing in a se~uence of commutation and turning off the motor on command;
FIG. 17 (appearing on the same sheet of drawings as FIG. ll) is a flow diagram of operations performea by the microcomputer or FIG. 1 in accordance with the invention in a relaying routine of FIG. 14;
FIG. 18 (appearina on the same sheet of drawings as FIG. 8) shows voltage versus time diagrams of wave~orms of the digitized voltages of all of the winding stages when the rotor of the motor is coasting clockwise or counter-cloc~wise as during the relaying routine of FIG. 17;
FIG. 19 is a flow diagram of operations performed by the microcomputer of FIG. 1 in accordance with the invention for determining a proper point in sequence to begin or resume commutation when the rotor of the motor is turning, as in the relaying routine of FIG. 17.
Corresponding reference characters rerer to corresponding parts throuanout the several views of the drawings.
~he exemplifications set out herein illustrate preferred embodiments of the invention in one form therof, such exemplifica~ions are not to be construed as limiting the scope of the invention in any manner.
Detailed Descriptlon of Preferred Embodiments Referring now to the drawings and more particularly to FIG. 1 a laundry apparatus 11 includes an electronically co~mutated motor (EC~ ~ adapted to be energized from a DC
power supply 12 and having (see FIG. 2) a stationary assembly inclllding a stator 13 and a rotatable assembly including a permanent magnet rotor 15 and a shaft 17. Stator 13 includes a plurality ~e.g., three) oî winding stages Sl, S2 and S3 . ~ ,, .

~ 7 03~M 59~z (~IG. 3). i~1inding s~ages Sl, s2 ana C3 have c~ii s ~s or sections Sl~ and Sl~, S2A and S2B and S33 recpecti-Jely.
Winding s.ages Sl, ~2 and S3 are adapted to be elect-onicaily com~utatea in at least one preselected s~quence. ~ach ~inding stage has an e~d terminal ~ 2, and T3, res~ectively, and an intermediate tap Il, I2, ana I3, respec~i~Jely. The winding stages Sl, S2, and S3 are adapted to be elec~;onically coDmutated at end terminals Tl, T2, and T3, so that both coil sets or sections in each winding s~age are commutated, for turning the rotor 15 at a low speed. It is noted that sections SlA, S2A, and S3A define tapped sections of the winding stages whic~ are adapted to be electronically commutated at interrediate taps Il, I2, and I3 respectively for turning rotor l; at a higher speed. When t~.e winding 1~ stages Sl, S2, and S3 are energized or ~owered in a temporal seauence, three sets of eight magnetic poles are established that provide a radial magnetic field that moves clock-~ise or countercloc~wise around the bore of stator 13 depending on the preselected seauence or order in which the stages are powered. mhis moving field intersects with the flux field of the permanent magnet rotor to cause the rotor 15 to rotate relative to the stator 13 in the desired direction to develop a torque which is a direct flnction or the intensities or strengths or the magnetic fields. If a more detailed description of the construction of electronically commutated motor ~ is desired, reference may be had to the aforementioned Canadian Patent ,~o. 1,193,651 to John E. Boyd, Jr.
ECM M thus constitutes an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding s~ages.

~ J~,7 03~ 5938 Further, while electronically commutated motor M is illu5-trated herein for purposes of disclosure, it is contempLated that other such motors of different constructions, having 2, 4, 6, etc. poles and having 2, 3, 4 or more winding stages and/or different winding arrangements may be utilized in one or another form of the invention so as to meet at least some of the objects thereof.
The winding stages o motor M as explained for instance in the aforementioned Alley U.S. patent 4,250,544 are commutated without brushes by sensing the rotational position of the rotatable assembly or rotor 15 as it rotates within the bore of stator 13 and utilizing electrical signals generated as a function of the rotational position of the rotor to sequentially apply a DC voltage to each of the winding stages in different preselected orders or sequences that determine the direction of the rotation of the rotor. Position ~ensing may be accomplished by a position detecting circuit responsive to the back emf of the ECM to provide a simulated signal indicative of the rotational position of the ECM rotor to con-trol the ~imed -aequential application of voltage to the wind-ing stages of the motor.
Referring back to FIG. l, laundry apparatus ll also ` has a basket 23 which is rotatable within a tub tnot shown) which holds the water for washing the fabrics to be laundered, and a coaxially mounted agitator 25, both of which are rotat-able independently or jointly about their common axis. Agi-tator 25 and basket 23 together comprise means operable gener-ally in a washing mode for agitating water and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal dis-placement of water from the fabrics. However, it is contem-plated that such means may also include only a basket which is mounted on a horizontal or inclined axis and there is no sepa-rate finned agitator but the basket is operated in an oscilla-tory mode to agitate the wash water and fabrics to launder ~Z~ 6 ~7 03AM 593Z

them ~pon the commutation of the winding stages, the rotat-able assembly ~f motor M drives the agitating and spinning means and is coupled selectively to the agitator alone during the washing mode operation and to both the basket and the agi-tator in the spin mode operation through a connection mecha-nism 27 which suitably comprises a fixed ratio speed reducer, such as a gear box or a pulley arrangement, for instance, or in some applications, the shaft 17 of motor M can be directly coupled to the agitator and the basket. The rotatable assem-bly of motor M and any such fixed ratio speed reducer consti-tute means for driving the agitating and spinning means in the washing mode operation and in the spin mode operation thereof upon the commutation of the winding stages.
Commutating circuit 31 is provided with power from power supply 12 and constitutes means for commutating the winding stages by selectively supplying or switching power thereto in response to a pattern of control signals 32 leaving at least one of the winding stages unpowered at any one time while ~he other winding stages are powered. Commutating cir-cuit 31 also constitutes means for controlling the applicationof DC voltage t~ the winding stages to provide a resultant effective voltage thereto.
A high-low speed switching circuit 41 couples commu-tating circuit 31 to motor M, and constitutes means operable generally for switching the winding stages from a first con-nection arrangement (connecting each of winding stages Sl, S2, S3 as a whole through terminals Tl, T2, and T3 to commutating circuit 31) to a second connection arrangement (connecting the coil sections SlA, S2A, and S3A of the winding stages Sl, S2, and S3 through terminals I1, I2, and 13 to commuta~ing circuit 31). In the present embodiment the first connection arrange-ment is a low speed connection arrangement and the second con-nection arrangement is a higher speed connection arrangement.
I~ is to be understood that other connection arrangements ~6 ~7 03AM 593~

involving t~o or more speeds, or not invoLving speed consideration5 at all are contemplated in the practice of the in~ention for accomplishing the objects thereof. ~igh-low s?eed s~itching circuit 41 is responsive to a High on line ~ for relaying the winding stages from the low s?eed connection arrangement to the high speed connection arrange-ment and responsive to a Low on line H for relaying the wincing stages from the high speed connection arrangement to the low speed connection arrangement.
Commutating circuit 31 responds to a set or six control signals, collectively designated 32 and individually designated A+, A-, B+, B-, C+, and C-, from a control signal generator 51. Since each or thecontrol signals A+, r.~~ B+, B-, C+, and C- can be high or low, there are 26 or 6~
permutations or patterns of the control signals. Control signal generator 51 constit~tes means responsive to succes-sive patterns of digital signals 52 for generating successive patterns of thecontrol signaLs 32 for the commutating circuit 31.
A microcomputer 61 in FIG. l produces successive patterns of the digital signals 52 in at least one preselec-ted sequence, which causes the control signal generator 51 to produce successive patterns of the control signals 3Z in the at least one preselected sequence and in turn cause the motor M to be commutated in the at least one preselected sequence by the commutating circuit 31 to make the rotor 15 turn. The direction of rotation which results is clockwise when a first preselected sequence is used, and counter-cloc~wise when a second preselected sequence is used.
In the preferred embodiment disclosed herein, microcomputer 61 is an Intel 8748 microcomputer having lK
bytes of user program~able and erasable read only memory (EPROM), an 8 bit central processing unit (CPU), 27 input/output (I/O) lines, an 8-bit timer counter, reset and interrupt capability, and an on-board oscillator and cloc~. The instruction set for . ~ .
.

~ ~r~ 03AM 5938 .
the 8748 is set forth in MCS-48(R~ Familv of Sl~nq~l~e~Chio ~licrocom~uterS User~s Manual, Intel Corpo~ation, Santa Clara, California, September, 1981, pages 4-5, in addition to other technical information. Since the implement1on and use of microcomputerS as a general matter is well known to the person skilled in the art, the details of the 8748 are omitted for brevity. The microcomputer 61 is shown as a rectangle in several of the Figures with only those pin designations for the 8748 shown for connections involved in the operations and circuits of any given Figure, all other pins in a given Figure being suppressed ~or clarity. It is to be understood that the 8748 is but one example of a digital computer which can be utilized in the practice of the invention. In addition, it is contemplated that the functions of the microcomputer illus-trated in the drawings can be alternatively implemented in thepractice of the invention by any appropriate means, including but not limited to digital or analog circuits of a variety of types whether operatiny from a stored program, utilizing firm-ware, or being implemented in hardware, in custom or semi-custom integra~d circuit form or having discrete components.
A voltage digitizing circui~ 71 is coupled to thewinding stages and receives their terminal voltages Val Vb, and Vc through high-low speed switching circuit 41 and constitutes means for simultaneously converting the voltages across the winding stages to digital form thereby to digitize the voltages. Digitizing circuit 71 also constitutes means for generating a first logic level when the voltage across a respective winding stage exceeds a predetermined value and a second logic level when ~he voltage across it falls below the predetermined value, the digital form of the voltage across each respective winding stage comprising the logic levels so generated. Digitizing circuit 71 has outputs A, ~, and C
which are connected to corresponding inputs of microcomputer 61.

~V ~ 7 03~ 5938 Microcomputer 61 of FIG. 1 constitutes ~eans for producing s~ccessive pat~erns of digital signals in at least one preselected sequence, for selecting the digitized voltage across the at least one unpowered winding stage dependiny on the digital signal pattern produced, and for producing a fol-lowing pattern in sequence after a~ least one predetermined logic level o~ the selected digitized voltage has occurred.
In the preferred embodiment the following pattern in sequence is produced after complementary logic levels of the selected digitized voltage have occurred in a predetermined order depending on the pattern which is being produced. Microcom-puter 61 is a digital computer operating under stored program control and having inputs for the digitized voltages on lines A, B, and C. Microcomputer 61 has memory elements for storing data representing at least one preselected sequence of the patterns of the digital signals and for storing data, corre-sponding to each pattern of the digital signals, identifying the respective input for the digitized voltage fo~ the at least one unpowered winding stage. Microcomputer 61 succes-sively produces one of the pattérns of the digital signals,senses only the digitized voltage at the indentified input corresponding to the one pattern and prod~ces the following ` pattern in sequence after at least one predetermined logic level of the digitized voltage at the identified input has occurred. When the motor M is ~irst being started, there is no back emf to digitize until the rotor 15 begins to rotate.
For this reason, microcomputer 61 operates to produce the fol-lowing pattern in sequence after a predetermined time period if the at least one predetermined logic level of the selected digitized voltage has not occurred during the predetermined time period. Then as soon as the rotor 15 begins to turn, the following pattern is produced in sequence in response to the digitized voltage and the successive patterns are effectively synchronized with the rotor and accelerate the rotor to an operating speed.

lf~J'~ 7 03AM 5938 Current interrupt and speed controlling circuit 81 compares the current flowing in the other powered winding stages of the electronically commutated motor M with a prede-termined level by sensing a voltage VI proportional to the current on line 83, and upon the level being exceeded, inter-rupting microcomputer 61 on line 85 and sending a signal Q on line 87 for causing the control signal generator 51 to gener-ate a pattern of control signals 32 to reduce the current.
In FIG. 3 power supply 12 has diodes 101, 103, 105 and 107 connected as a full wave bridge rectifier for 117 volt single phase AC power received at plug 109. Full wave recti-fied DC is filtered by capaci~or 111 and applied as voltage V
across first and second conductors 113 and 115 for supplying DC power to commutating circuit 31 and motor M. A voltage drop VI is developed across shunt résistor RS proportional to the current from power supply 12 which is flowing in the motor M.
Commutating circuit 31 is composed of three identi-cal switching circuits 121, 123, and 125 which selectively switch the win~ing stages to supply conductors 113 and 115 leaving at leajt one of the winding stages unpowered at any one time while the other winding stages are powered. For con-ciseness only switching circuit 121 is described in further detail.
Switching circuit 121 has a set or pair of series-connected upper and lower electronic devices 127 and 129 con-nected across the supply conductors 113 and 115. The pair of devices 127 and 129 has a junction point 131 connected through high-low speed switching circuit 41 to winding stage Sl in the connection arrangement selected by high-low speed switching circuit 41. Switching ciecuits 123 and 125 are respectively connected to winding stages S2 and S3 similarly.
The switching circuits 121, 123, and 125 each con-stitute sets of electronic devices connected across supply 37 conductors 113 and 115, each set having at least one junction 7 03~M 5s3g point connected to a respective one of the winding stages.
Each of the electronic devices, e.g., L27 and 12g, is able to be switched by 2 corresponding one of the control signals in each pattern of control signals 32. For instance, when con-trol signal A+ is high, transistors 133 and 135 turn on tran-sistor 137 in electronic device 127. When control signal Ais high, ~ransistors 139, 1~1, and 143 turn on transistor 145 in electronic device 129. When transistor 137 is on in elec-tronic device 127, and a relay 147 in high-low speed switching circuit 41 is set as shown in FIG. 3, then winding stage Sl terminal Tl is effectively switched to supply conductor 113.
When transistor 137 is off in electronic device 127 and tran-sistor 145 is on in electronic device 129, winding stage Sl terminal Tl is switched to supply conductor 115.
It is evident that when a control signal A+, B~, or C+ is High, a corresponding winding stage Sl, S2, or S3 is switched to supply conductor 113, and when a control signal A-, B-, or C- is High, a corresponding winding stage Sl, S2, or S3 is switched to supply conductor 115.
Relay 147 in High-low speed switching circuit 41 has three-pole-double-throw (3PDT) contacts for electrically sub-stituting sections SlA, S2A, and S3A of the winding stages Sl, S2, and S3 in place of the winding stages as a whole. The winding stages are connected together at neutral N. Relay 147 is driven by transistor 149. Transistor 149 is protected by base resistor 151 and freewheeling diode 153. When a High appears on line H, transistor 149 conducts, closing relay 147 and moving relay armature 155 upward from the Low Speed posi-tion shown to a High Speed position, which accomplishes the substitution of the high speed winding sections SlA, S2A, S3A
in place of the winding stages Sl, S2, S3 and thereby selec-tively electrically energizes at least one of the winding sec-tions SlA, S2A, S3A of each winding stage Sl, S2, S3 to effect -commutation. ~hen relaying from low to high speed is t3 occur, microco~puter 61 outputs a Low on line D86, which is inverted by NAND-gate 157 and ~ed as the High on line H.
Lines marked for voltages Va, Vb, and Vc are connected to relay armature 155 to allow sensing of voltages on terminals Tl, T2, T3 or Il, I2, I3 for each winding stage as selected by relay 147. The Va, Vb~ Vc lines are con-nected to the voltage digitizing circuit 71 as shown in FIG. 1.
In FIG. 4, control signal generator 51 generates successive patterns of highs and lows for control signals 52 on the lines respectively marked for each control signal A+,A-,B+,B-,C+, and C- which are fed to the correspondingly marked inpNts of commutating circuit 31 of FIG. 3. The suc-cessive patterns ~f the control signals are produced in response to successive patterns of digital signals produced by microcomputer 61 on lines 62.
Control signal generator 51 acts in the preferred embodiment as a protective device and switching means for pulse width modulation. If a pair of the control signals hav-ing the same le~ter designation, such as A~ and A-, were both high simultaneo~sly, electronic devices 127 and 129 of FIG. 3 could short the supply conductors 113 and 115. Microcomputer 61 is capable of producing patterns of digital signals at extremely high rates, and an undesired pattern of control sig-nals such as A+,A- high should not be permitted to occur over an extended period of operation. Control signal generator 51 is hardwired logic circuitry which constitutes means for pre-venting control signal patterns such as A~,A- high from being generated regardless of the patterns of digital signals pro-duced by microcomputer 61.
Control signal generator 51 has three identical protective circuits 161, 163, and 165. For conciseness, only protective circuit 161 is described in detail. Protective circuit 161 has first and second AND-gates 167 and 169 feeding control signals A+ and A- to the sets of electronic devices ~ 7 03AM 5938 127 and 129. ~ND-gates 167 and 169 have inpUtS 171 and 173 driven ~y a respective pair of digital signals through invert-ing buffers 175 and 176 from port P2 lines 0 and 3 from micro-co~puter 61. Correspondiny AND-gates in protective circuits 163 and 165 respectively feed control signals B~, Band C+, C-to switching circuits 123 and 125 in FIG. 3. These corre-sponding AND-gates in protective circuits 163 and 165 have their own inputs driven by digital signal pairs through in-verting buffers 177,178 (port P2 lines 2 and 5) and inverting buffers 179,180 IPort P2, lines 4 and 1) respectively.
Exclusive-OR gate 183 has inputs connected to the inputs of AND-gates 167 and 169 driven by a pair of the digi-tal signals. Exclusive-OR gate 183 has its output feeding both AND-gates 167 and 169 for disabling them when the pair of digital signals on lines 0 and 3 of port P2 have identical logic levels in the pair. Exclusive-OR gates corresponding to gate 183 in protective circuits 163 and 165 are identically wired so that no pair of the control signals 52 having the same letter designation can become high simultaneously. In this way the contingency of control signals occurring which could short the power supply is prevented, and reliability is enhanced.
Control signal generator 51 thus constitutes ~eans ~or preventing at least one pattern of control signals 52 from being generated regardless of the patterns of digital signals on lines 62 produced by microcomputer 61.
Microcomputer 61 prod~ces an additional pair of digital signals, which are differen~ in logic level from each other, on lines 7 and 6 of por~ P2 which respec~ively feed NAND gates 185 and 187. A disabling input Q on line 87 is provided to both NAND gates 185 and 187 when power is to be removed from the winding stages. In this way NAND-gates 185 and 187 constitute means for disabling in response to disabl-ing signal Q a single one of the NAND-gates 167 and 169 in J~; I 7 03AM 5938 each of the protective circuits 161, 163, and 165. The NAND-gate 167 or 169 to b~ disabled in each protective circuit is effectively identified by the additional pair of digital signals on lines 7 and 6.
The control signal patterns during commutation are normally the logical complements of the digital signal pat-terns on lines 0-5 from port P2. FIG. 4A illustrates currents 190 being caused to flow in motor M in the low speed connec tion arrangement in a preselected sequence 190.0, 190.1, 190.2, 190.3, 190.4, 190.5 in response to successive patterns of the control signals 52. Terminals Tl, T2, and T3 of motor M are selectively switched to "+" supply conductor 113 of FIG.
3 and to "-" supply conductor 115 depending on the direction of desired current flow indicated by the current arrows in FIG. 4A. For instance, the first current 190.0 in the se-quence is to flow inside motor M from terminal Tl to terminal T3. Terminal Tl is switched to "+" conductor 113 by A+ high, and terminal T3 is switched to "-" conductor 115 by C- high.
Next, current 190.1 is produced by keeping C- high, returning A+ low to disconnect terminal Tl, and bringing B+ high to con-nect terminal T to "+" conductor 113. Next, c~rrent 190.2 is produced by keeping B+ high, returning C- low, to disconnect terminal T3, and bringing A- high to connect terminal Tl to "-" conductor 115. The sequence is continued to produce cur-rents 190.3, 190.4, and 190.5 and then repeated beginning with current 190.0 again. It is seen that during commutation at least one of the winding stages is unpowered at anv one time while the other winding stages are powered by application of the current in sequence through selective switching.
Table I has columns corresponding to each point or current step in the preselec~ed sequence just described above.
Currents 190.0-190.5 in FIG. 4A correspond to the columns of control signals shown in Table I in order from left to right and indexed from 0 through 5 therein. The control signals 1~3~ 03AM 5938 result in clockwise rotation of the rotatable assembly of motor ~t when applied in the preselected sequence of Table I.
Counterclock~ise rotation is obtained by applying the control signals in a second preselected sequence shown in Table II
which is the reverse o~ the sequence of Table I. The column entries for the control signals of Table II are seen to be the same when read from right to left as the column entries o~
Table I read from left to right.
In FIG. 4 the control signals 52 are normally the complement of the digital signals on lines 0-5 of port P2 of the microcomputer 61. Tables I and II summarize the relation-ship of the digital signals to the control signals in each column. The first eight rows of each Table show the outputs for each digital signal pattern in sequence from each P2 port line from 7 down to zero. It is seen that in lines 5 through zero there are exactly two lines in any one column which are logic zero, or low. For example, in the left-most column in the sequence in Table I, these two lines are lines 1 and 0.
By inspection of FIG. 4, lows on lines 1 and 0 are inverted by inverting buffers 175 and 180 and bring control signals A+ and C- high throug~ protective circuits 161-and 165. Table I, left-most column, also shows control signals A~ and C-tabulated at this point in the sequence. Comparison of the rest of the columns of Tables I and II with FIG. 4A demon-strates the preselected sequences of digital signal patternscorrelated with control signal patterns for clockwise and counterclockwise rotation.
The digital signal patterns and control signal pat~
terns are here recognized as signifying directives produced by microcomputer 61 and control signal generator 51 for motor M.
The directives are not only used for commutation in clockwise and counterclockwise directions but for other operations of motor M.

~ 7 03A~ 593~

FIG 4B illustrates interpretations of some of the digital and control signal patterns by showing corresponding equivalent circuits in the electronic devices 127 and 129 of switching circuits 12~, 123, and 125 of FIG. 3.
S When microcomputer 61 produces all ones on lines 0 through 7, (11111111 binary which is FF hexadecima ), a con-trol signal pattern consisting of all Lows is generated by control signal generator 51. Commutating circuit 31 has tran-sistors 137 and 145 off in each switching circuit 121, 123, and 125 and motor M is turned off. Only freewheeling diodes, such as diode 197 in electronic device 127 and its counterpart in electronic device 129 of FIG. 3, appear as shown in FIG. 48 in the equivalent circuit.
The motor M is effectively braked when the rotor is spinning, by connecting all of the winding stages together.
In FIG. 4B this is accomplished by bringing A+, B+, and C+
high, corresponding to control signals 101010 and digital sig-nals 10010101. The electronic device 127 in FIG. 3 in each of switching circuits 121, 123, and 125 becomes conductive and the winding stages of motor M are all tied to the positive supply conducto: or rail 113. Mechanical energy in motor M is rapidly dissipated, braking the ro~atable assembly 15 of FIG.

2. It is to be noted that a complementary braking pattern (not shown~ brings A-, B-, and C- high when A+, B~, and C+ are low.
As already discussed in connection with Tables I and II, two of the windings in a wye-connected motor are powered at any one ~ime, leaving the third unpowered, by bringing two control signals high in two of the switching circuits 121, 123, and 125 of FIG. 3. In FIG. 4B, for illustration, control signals B+ and A- are brought high, causing current I to flow from voltage V through an upper transistor turned on by control signal B* through two winding stages of motor M and to ground through a lower transistor turned on by control signal A-. Different "Commutate" patterns are applied in at least .
.
.

.

~ ~¢^~ ~'7 03AM 5938 one preselected sequence to rotate the rotatable assembly in a predetermined direction~
When the Commutate patterns are applied, at least one of the winding stages is unpowered in sequence (see FIG.
4B) while the other winding stages are powered in sequence.
FIG. 5 illustrates the voltage behavior across an unpowered winding stage from a terminal thereof to neutral N during a commutation period when the other winding stages are powered.
Initially a voltage 191 having a high magnitude occurs because of the collapsing field of the unpowered winding resulting from i~s having been previously powered in the sequence. Field collapse voltage portion 191 dissipates, revealing a ramp-shaped back emf 195 induced in the winding by virtue of the rotation of rotatable assembly 15. Back emf 195 is useful for position sensing of the rotatable assembly 1~, while field collapse voltage 191 is not believed to be so useful for position sensing.
The position of the rotor 15 is able to be monitored as it is coasting, by allowing "half n of an electronic switch-ing device to be connected to "half" a winding stage, by turn-ing off one of the two electronic switching devices which would otherwise be both on. Then the proper pair of elec-tronic switching devices is turned on, as dictated by the present rotor position (and not by the position when the power was turned off), and the ECM M continues normal operation.
In FIG. 4B a pattern herein called a "Monitor" pat-tern is temporarily applied to eliminate the field collapse voltage 191 and reveal the back emf 195 sooner. A single one of the control signals, e.g., B+, is kept high while a pre-viously high control signal, e.g., A- from the Commutate pattern, is brought low. The current I reewheels through the B+ transis~or and diode 197 and the voltage at neutral N rises from about half the supply voltage V to essentially the full supply voltage V. The unpowered winding stage in FIG. 4B has ~ 'J' '~ 03AM 5938 a current flowing therein when the field collapse voltage 191 of FIG, 5 is occurring. When the other winding stages are being powered by the commutating circuit 31 in response to a Commutate pattern of control signals B+ and A- as shown, the unpowered winding stage temporarily has current 19~ circulat-ing through the system as shown and transferring energy from its magnetic field to the rest of the system at a ~oderate rate because the voltage at neutral N is about half of the supply voltage V. When a monitor pattern for a fast rate of energy extraction is applied as shown, for example by turning off control signal A- and thereby removing its transistor from the circuit, the current in the unpowered winding stage, now designated 199, must release its energy into the full voltage of the power supply 12 through diode 197, thereby transferring energy away from the unpowered winding stage at a much faster rate. In this way, temporary application of a monitor pattern as shown in FIG. 4B eliminates the field collapse voltage l91 of FIG. 5 and reveals the back emf 195 sooner.
It is also recognized that a monitor pattern for slow rate of energy extraction exists when control signal Ais kept on and consrol signal B+ is turned off, thereby removing the B+ transistor and keeping the A- transistor. Then current I freewheels through ground ~conductor 115) and the voltage of neutral N is brought near ground potential (not shown in FIG.
4B), resulting in a relatively slow rate of energy extraction for current 198. Since in some of the contemplated applica-tions of the invention, the control signals such as A- or B+, are pulse width modulated as a result of the disabling signal Q of FIG. 4 or by means of microcomputer 61 directly, the rate of energy extraction is of interest and can be chosen, for instance, between fast and slow by the proper selection of the monitor patterns for achieving at least some of the objects of the invention.

~ 7 03AM 5g38 It is contemplated that the various digital signal patterns and control signal patterns be appLied as directives to an electronically commutated motor M in any sequence or order, so as to accomplish at least some of the objects of the invention.
The voltage behavior (see FIG. 5) across the unpowered winding stage during a commutation period is inverted in polarity compared to the voltage across the wind-ing stage which was unpowered in the next previous commutation period. Accordingly, FIG. 5 shows but one example of voltage behavior across an unpowered winding stage, and it is to be noted that the back emf 195 approaches the zero level from Opposite directions in successive commutation periods. In other words, in one commutation period the back emf 195 ramps up as shown, and in the next commutation period the back emf 195 ramps down with inverted polarity compared to FIG. 5.
In FIG. 3, terminal voltages Val Vb~ and V
for the winding stage terminals selected by relay 147 are all available. Microcomputer 61 automatically and correctly selects the vo tage for the unpowered winding stage by looking up an identifi_ation corresponding to the unpowered winding stage in a table relating the poin~ in the sequence of commu-tation to the identi~ication of the unpowered winding stage.
The relationship, or function, is different for clockwise and counterclockwise rotation.
In a further feature the voltages across the winding stages are simultaneously converted by circuit 71 to digital form thereby to digitize the voltages. As shown in FIG. 6, the digitizing is accomplished with the use of voltage compar-ators 201, 203, and 205. Comparators 201, 203, and 205 eachhave noninverting t~) and inverting (-) input terminals for accepting signals to be compared, and when one signal falls below the other at a given comparator, the output of the respective comparator changes s~ate. The noninverting input ~ ."" ,~ 03AM 5938 terminals of the comparators 201, 203, and 205 are respective-ly co~pled by three voltage dividers having resistors 207,209;
211,213; and 215,217 to the the respective winding stages via the lines 206 bearing terminal voltages Vc, Vb, and Va.
The voltage dividers are equal in their voltage division ratio. The inverting input terminals of the comparators are coupled by direct connection to a network of resistors 219, 221, 223, 225 for synthesizing a neutral ~1' from the voltages available from the voltage dividers having resistors 207,209;
211,213; and 215,217. The resistor network constitutes means for providing a voltage corresponding to the neutral N of the winding stages in FIG. 3. The output terminals C, B, and A of comparators 201, 203, and 205 are respectively coupled to port Pl input lines 2, 0, and 1 of microcomputer 61 and provided with pullup resistors collectively designated 227. It is noted that the neu~ral N can be directly brought to the cir-cuit of FIG. 5 without use of the resistor network for synthe-sizing a neutral and that a variety of circuits for digitizing the voltages can be utilized for achieving at least some of the objects of the invention.
Beca~se of the voltage dividers 207,209; 211,213;
and 215,217 each comparator 201, 203, and 205 respectively sees at its noninverting input terminal a voltage proportional to a terminal voltage Vat Vbl and Vc of a respective winding stage Sl, S2, and S3. Each comparator at its invert-ing input terminal sees the voltage VNI which is proportion-al with the same constant of proportionality to the voltage VN of the neutral N. The constant of proportionality is then effectively disregarded in the comparing process. Each of the comparators generates a first logic level ~one) when the voltage Va - VN- Vb - VN~ or Vc N
respective winding stage exceeds a predetermined value of zero (i.e. when the voltage across a respective winding stage is positive) and generates a second logic level when the voltage .

~ ~It~ 6~ 03~ 5938 across it falls below the predetermined value of zero ~i.e.
~hen the voltage across a respective winding stage is negative).
Where it is desired to provide a voltage offset such as by adjustment of the value of resistor 219 or Sy other means, it is to be understood that the predetermined voltage value departs from zero.
The voltage digitizing circult of EIGS. 1 and 5 thus constitutes means for providing a voltage corresponding to a neutral for the winding stages and further includes a plural-ity of comparators each having an output and first and second input terminals, the first input terminals being respectively coupled to the respective winding stages, the second input terminals being coupled to the neutral voltage means, the out-put terminals being respe~tively coupled to the inputs of thedigital computer (microcomputer 61~.
The digital form of the voltage across each respec-tive winding stage comprises the logic levels so generated at outputs C, B, and A. FIG. 6A illustrates a digitized voltage at output B corresponding the analog voltage Vb - VN of FIG. 5. The d gitized voltage in FIG. 6A begins high during the field collapse voltage l91, goes low when the field col-lapse voltage l91 ends, and then goes back high as soon as zero crossing 229 occurs. It is to be understood that in the following commutation period, the voltage behavior shown in FIG. 5 is inverted in polarity, so that the digitized voltage corresponding to FIG. 6A for the unpowered winding in the fol-lowing commutation period is the logical complement of the pulses shown in FIG. 6A. In either event a transition 230 occurs in the digitized voltage of FIG. 6A substantially simultaneous with zero crossing 229 and corresponding to a specific physical position of the rotatable assembly 15 in relation to the poles of motor M. In the preferred embodi-ment, the zero crossing 229 is used to trigger the beginning ~ J~ 03AM 5938 of the next commutation period by causing microcomp~Jter 61 to advance in the sequence of commutation and produce a following pattern of control signals.
Referring again to FIG. 5, microprocessor 61 is pro~
vided with a set of swi~ches 231.1-231.9 for providing the Commands indicated in FIG. 1. Switches 231.1-231.9 are pro-vided with pullup resistors collectively designated 233 and are respectively connected to lines 3,4,5,6,7 (in Port Pl) and lines DB0, DBl, DB2, and DB3. One or more of switches 231.1-231.9 are incorporated in user-operable mechanisms of any familiar type on laundry apparatus 11 which accomplish laundering of different types of fabrics by washing, LinSing, and spinning the fabrics with different temperatures of water and by executing the various operations of the laundry appa-lS ratus for different lengths of time. Switches for operations which are relevant to controlling an electronically commutated motor M in laundry apparatus 11 are discussed below.
ON/OFF switch 231.5 is used to signal microprocessor 61 to tell it whether the laundry apparatus is to be on or off. This switch 231.5 is suitably polled every six commuta-tions, or each revolution of the motor. ~eception of a logic 0 at line 7 of port Pl indicates the Off condition. Line 7 is polled continuously when line 7 is low. When line 7 goes~
high, the microcomputer 61 commences operations to run the motor M.
WASH/SPIN switch 231.4 provides a logic level on line 6 of port Pl by which microcomputer 61 determines whether a washing or spinning mode is called for.
CW/CCW rotational direction switch 231.3 provides a logic level on line 5 of port Pl for setting the direction of rotation of motor M in the SPIN mode. Microprocessor 61 uti-lizes this direction information in determining whether a pre-selected sequence of digital signal patterns should be pro-duced for clockwise rotation or another preselected sequence 03AM 593~3 should be prod~ced for counterclockwise rotation. In some embodiments the setting of the CW/CCW switch 231.3 is ignored by microcomputer 61 when the WASH/SPI~ switch 231.4 is set to WASH.
5/250 REV switch 231.2 provides a logic level on line 4 of port Pl. This switch 231.2 is used when microcom-puter 61 counts revolutions of the rotatable means 15 by counting successive patterns o~ digital signals produced. A
revolution counter in microcomputer 61 is set to 5 when the switch 231.2 is set to the "S" position, as for setting the number of revolutions of motor M in a washing mode of a center-post~agitator-type laundry apparatus. ~hen an 8:1 speed reducer is used with motor M, a stroke of agitation of less than one revolution results in the laundry apparatus.
The revolution counter is illustratively set to 250 by switch 231.2 for setting the number of revolutions to be similarly reduced in a washing mode of tumbler-type laundry apparatus.
HI/LOW SPEED switch 231.1 is connected to line 3 of port Pl, and is usable, for instance, to indicate when micro-computer 61 is to issue a signal on line DB6 for controllingHigh-low speed switching circuit 41 of FIG. l.
Switches 231.6, 231.7~ 231.8 and 231.9 are able to be utili~ed for other control functions as desired by the skilled worker. For instance, if the SPIN mode is selected on switch 231.4, these switches are suitably used to provide logic levels on lines DB0-DB3 which determine the maximum speed to which the ECM M accelerates. The motor is caused to accelerate or decelerate to the speed selected at a maximum rate preestablished in memory. A value is suitably selected from a table stored in the microcomputer 61 to determine the desired elapsed time between commutations and therefore the maximum speed. Power to the motor is pulse width modulated with adjustable duty cycle to accelerate as fast as possible without exceeding a maximum motor current level to the ~ J~ 7 03AM 5938 selected speed level. Microcomputer 61 can also be programmed to execute dynamic braking to zero motor speed ~hen the lines DB0-DB3 a~e all low.
In further control functions obtainable ~ith the switches 231~6-231.9, microco~puter 61 interpretS any one of 16 possible settings of the four switches as instructions for amplitudes and waveshapes of agitation speed profiles (effec-tive voltage to motor M) or torque profiles (current in motor ~1) when switch 231.4 is in the WASH position.
In FIG. 6, hexadecimal numbers are set off in quotes and marked inside the rectangle symbolizing microcomputer 61 to identify the lines 0-7 of port 1 when microcomputer 61 selects or "masks" the port to read the logic level on a given one of the lines. It is noted that each of the hexadecimal lS numbers 01,02,04,08,10,20,40,80 in binary notation is all zeros except for a "1" in a bit position corresponding to the number of its respective line. When the hexadecimal number is ANDed with the logic levels of the lines in an accumulator register (not shown) of microcomputer 61, only the logic level, if a one (1), of the line signified by the hexadecimal number remains in the accumulator. When it is desired to mask the port for a multiple number of lines such as lines 0,1, and 2 to determine whether any of the lines is active, the masking number ALLHI = 07 ~00000111) is ANDed with the logic levels of the lines in the accumulator.
Referring again to Tables I and II, each of the digital signal patterns and control signal patterns in the sequence is identified by values of an index in the row marked INDEX. Another index row is designated INDEXR to correlate with the flow diagrams discussed below in connection with FIGS. 9,11,14,16, and 19. The INDEXR row has entries which are distinct to each pattern in the sequence and different for Table I and Table II, so that a given pattern is uniquely identified for clockwise and counterclockwise rotation.

, ~3~'~ 03AM 5g38 In Tables I and II, the hexadecimal value for rnask-ing port Pl and thereby selec~ing the digitized voltage across the at least one unpoweeed winding stage is tabulated in the row "Digitized Voltage ~lask. n The mask number depends on, and is a function of, INDEX and therefore also depends on and is a function of the digital signal pattern produced by microcom-puter 61. The comparator 201, 203, 205 output designation A, B, or C which is selected is also entered for mnemonic pur-poses in Tables I and II beneath the hexadecimal mask number.
Microcomputer 61 outpu~s a pattern of digital sig-nals from a column in Table I when clockwise rotation is selected on switch 231.3 of FIG. 6. The next pattern of digi-tal signals is produced by incrementing INDEX after comple-mentary logic levels are sensed on ~he masked line from the lS unpowered winding stage. The complementary logic levels which microcomputer 61 seeks depend on the point its operations have reached in the sequence, so the logic levels are tabulated in the row "Test Bit Order~ in Table I as a function o INDEX.
For example, assume that INDEX is zero, and microcomputer 61 has just produced the digital signal pattern 01111100 causing control signals A~ and C- to go high. Then microcomputer 61 masks port Pl with "01" to obtain only ~he B output from the comparators corresponding to winding stage S2. As shown in FIG. ~A, microcomputer 61 senses the digitized voltage for that winding stage in repeated operations indicated by arrows 235.1-23S.8. (It is to be understood that the arrows do not necessarily correspond in number and spacing to the actual rate of instances of sensing by microcomputer 61 in any par-ticular embodiment.) During the duration of field collapse voltage 191 in FIG. 5, only logic ones are sensed correspond-ing to arrows 235.1 and 235.2. Since the test bit order in Table I calls for 0,1 the operations continue looking first for the initial zero. At arrow 235.3, the initial zero is found. Now microcomputer 61 looks for the logic level one in ~1 ~ 03AM 5g3~

the 0,1 test bit or~er. It continues looking but senses 0 at times indicated by arrows 235.4, 235.5, 235.6 and 235.7. Then at the time indicate~ by arrow 235.8, just when the back emf 195 has had its zero crossing 229 and transition 230 has occurred in the digitized voltage, microcomputer 61 senses a logic level 1 matching the second entry in the test bit orderO
The complementary logic levels 0,1 of the selected digitized voltage B have now occurred in the predetermined order.
Microcomputer 61 now advances in the sequence of commutation by incrementing INDEX by 1, produces the digi~al signal pat~
tern 10111001, masks with mask 02 (comparator output A), and advances in sequence after complementary logic levels in the order 1,0 for the digitized voltage A have occurred, indicat-ing another zero crossing.
In FIG. 7, a source of 5 volts DC is connected to positive voltage supply pin Vcc of microcomputer 61, and supply return pin VDD is connected to ground. A crystal 241 with associated capacitors 243 and 245 is connected to pins XRLl and XRL2~ The operations o~ microcomputer 61 are reset by a circuit connecting input RESET-bar to reset switch 247 and capacitor 249 to ground, and RESET-bar is also connected to Vcc through reverse-biased diode 251. Pin EA of the 874a chip is connected to ground. The connections described in this paragraph are conventional and are not described further.
The current interrupt and speed circuit 81 of FIG. 1 is now described in more detail using FIG. 7. Comparator 261 has its inverting input connected through resistor 263 to voltage VI from shunt resistor RS of FIG. 3. The nonin-verting input of comparator 261 is connected to a voltage divider 265 consisting of resistors 267 and 269 and variable resistor 271 ~or setting a current interrupt level. Adjusting variable resistor 271 sets a predetermined level. Comparator 261 with its pullup resistor 262 compares the current flowing in the powered winding stages of motor M with the predeter-mined level fed to the noninverting input of comparator 261.

, ~pon the predetermined level heing exceeded by voltage VI, the output of comparator 261 goes low at the PRESET input o~ a 74LS74 flipflop, OL latch, 273, so that output Q of flipflop 273 goes high and output Q-bar (complement of Q) goes low.
Output Q-bar going low interrupts microcomputer 61 at low-active interrupt pin INT-bar. Output Q going high causes the control signal generator 51 of FIG. 4 to generate a pattern of control signals to reduce the current in the winding stages by changing the Commutate pattern to a Monitor pattern (see FIG.
4B).
Current interrupt and speed circuit 81, microcom-puter 61, and control signal generator 51 together constitute means for producing the successive patterns of the control signals in at least one preselected sequence to s~itch on only one electronic device in each of at least two of the sets of the electronic devices at once and cause a current to flow in the winding stages to rotate the rotatable means, and for sub-sequently producing a pattern of the control signals to switch off one of the electronic switching devices which was pre-vicusly switc~ed on so that the commutating circuit 31 leavesall of the winiing stages temporarily unpowered and also pro-vides a current path ~or the previously-powered winding stages. Current interrupt and speed circuit 81 together with microcomputer 61 constitute means for producing the successive patterns of the digital signals in at least one preselected sequence to switch on only one electronic device in each of at least two of the sets of the electronic devices at once and cause a current to flow in the winding stages to rotate the rotatable means, and for subsequently producing a pattern of the digital signals to switch off one of the electronic switching devices which was previously switched on, the identity of the one device swi~ched off depending on the last pattern produced in the sequence (e.g. as a result of the Rail Disable information in the first two rows of Tables I and II), ~ q~ 03A~ 5938 so that the commutating means leaves all o the winding stages temporarily unpowered and also provides a current ~ath for the previously-powered winding stages.
Control signal generator 51 constitutes means responsive to successive pat~erns of digital signals for gen-erating the successive patterns of the control signals for the commutating means, the generating means including first and second logic gate means (e.g, 167 and 169) feeding the sets of electronic devices in the commutating means and having inputs driven by respective pairs of digital signals (e.g. inverting buffers 175,176; 177,178; and 179,180) in the digital signal patterns, means for disabling the first and second logic gate means when any of the pairs of digital signals has identical logic levels in the pair (e.g. exclusive-OR gate 183), and means for disabling (e.g, NAND gates 185 and 187) in response to a disablin~ ,ignal (e.g. Q) a single one of the first and second logic gate means identified by an additional pair of digital signals in the digital signal patterns te.g. on port P2 lines 7 and 6~. Microcomputer 61 constitutes means for producing the successive patterns of the digital signals in at least one preselected sequence to switch on only one elec-tronic device in each of at least two of the sets of the elec-tronic devices at once and cause a current to flow in the winding stages to rotate the rotatable means, and for produc-ing the additional pair of digital signals to have logiclevels depending on each pattern in the sequence (e,g. top and bottom disable signals in first two rows of Tables I and II).
Current interrupt and speed circuit 81 constitutes means for providing the disabling signal (e.g. Q) in response to an occurrence of a predetermined condition (e.g. excessive current) thereby to switch off one of the electronic devices which was previously switched on.
FIG. 7 illustrates an embodiment adapted for supply-ing the disabling signal Q by a hardwired circuit comprised in r~ 0 3 AM 5 9 3 8 current interr~pt and speed circuit 81 which is outboard of microcomputer 61. It is to be understood that Monitor pat-terns as in FIG. ~B are in alternative embodiments produced by performing operations inside microcomputer 61. In order to accomplish such operations in microcomputer 61, monitor pat-terns which vary as a function of IND~X are stored in the memoey These monitor patterns are output on lines 62 when-ever desired, and they are tabulated for clockwise and counterclockwise rotation respectively in Tables V and VI.
In Fig. 7A, logically complementary waveforms for the Q and Q-bar outpu~s of flip~lop 273 show Q low until the PRESET input of flipflop or latch 273 receives the aforemen-tioned outpu~ from comparator 261 or becomes otherwise preset.
After a predetermined period of time Tl of nominally 100 microseconds, microcomputer 61 completes an interrupt routine and sends a pulse on line DB7 to input CLR to clear flipflop 273, causing the Q output to go low again, and Q-bar to go high If and when the motor current rises above the predeter-mined level again, comparator 261 again presets flipflop 273, protecting motor M from overcurrents. Flipflop 273 has its data (D) input and clock (CLK) inputs grounded. The output of comparator 261 is also connected to the T0 testable input of microcomputer 61 for advantageous flexibility of operations.
In addition to protecting motor M, circuit 81 also provides a means for producing pulses at an adjustable rate, as if the predetermined level were exceeded, when the current is actually less than the predetermined level, so that the speed of the motor in the laundry apparatus 11 is adjustable.
With output Q of flipflop 273 low, inverter 275 produces an output High, charging capacitor 277 through resistor 279. The time constant of capacitor 277 with resistor 279 is on the order of one millisecond, for example. The voltage across capacitor 277 is applied through a voltage divider consisting of resistors 281 and 283 to the inverting (-) input of a com-parator 285. Comparator 285 has a positive feedback resistor 4s 287 for hysteresis. The noninverting ~+) input of comparator285 is fed with the adjustable speed-related output of a voltage divider consisting of resistor 289 and potentiometer 291 through resistor 293. As capacitor 277 charges, it reaches a voltage greater than that set by potentiometer 291, causing the output o~ comparator 285 to go low. The low out-put of comparator 2B5 is fed to the preset input of flipflop 273, causing output Q to go high and Q-bar to go low, inter-rupting microcomputer 61. During time Tl, the High from out-put Q is inverted by inverter 275 so that the output ofinverter 275 goes low and at least partially discharges capac-itor 277, Microcomputer 61 clears flipflop 273 after time Tl, causing output Q to go low. Inverter 275 in turn goes high, progressively charging capacitor 277. Then comparator 285 in circuit portion 295 of current interrupt and speed circuit 81 causes flipflop 273 to produce a disabling signal Q high and interrupt microcomputer 61 again when a second time interval T2 has elapsed. Setting potentiometer 291 to a higher voltage position increases the time interval T2. Increasing time interval T2 increases the speed of the motor because the speed of the motor increases ~ith increasing duty cycle, and the duty cycle is the ratio T2/ (T2 + Tl) . It is noted that in the embodiment of FIG. 7, Tl is set inside the microcomputer 61, and T2 is set outside by circuit 295. In other embodiments Tl is set outside microcomputer 61 and T2 is set inside the microcomputer 61. In still other embodiments both T1 and T2 are set inside microcomputer 61. In yet other embodiments both Tl and T2 are set outside microcomputer 61.
-~L~ 7 03AM 5938 TABLE I

DATA FOR CLOCKWISE ROTATION

P2 ~ail Line Disable Seauence of Patterns D 7 Top 0 1 0 1 0 I

G 6 Btm 1 0 1 0 1 0 I

T ___________._______________ _________ L

S

G

A

S

____________________________________ INDEX: 0 1 2 3 4 5 INDEXR: 0 1 2 3 4 5 CONTROL A+ B+ B+ C+ C+ A+
SIGNALS: C- C- A- A- B- B-DIGITIZED

MASK: (~ ~A~ (C) ~Bl ~A) ~C) TEST BIT
ORDER: 0,1 1,0 0,1 1,0 0,1 1,0 ., ' .

:' ' " ~.
, ~ 4~ 03AM 5938 TABLE II .

DATA FOR COUNTERCLOCKWISE ROTATION

P2 Rail Line Disable Sequence o~ Patterns . . _ D 7 Top 0 1 0 1 0 G 6 Btm 1 0 1 0 1 0 __________ ____ ____________________ A

I

N

L

~ ~ S O 01 1 1 1 0 __________~________________________ INDEX: o 1 2 3 4 5 INDEXR: 12 13 14 15 16 17 CONTROL A+ C~ C+ B+ B~ A~
SIGNALS: B- B- A- A- C- C-DIGITIZED

MAS~: (C) (A) (B) (C) ~A) (B) TEST BIT
ORDER: 0,1 1,0 ~ 0,1 1,0 0,1 1,0 .
~ ' ' ' .

~L29~;Lq~7 03AM 5938 TABLE I I I

CLOCKWISE ROTOR POSITION SENSING

Pl Di~itized Back EMFs HEX: 6 2 3 1 5 4 R3: -4 1 -2 4 -1 2 OFFSET R3: - 8 5 - 6 8 - 5 6 INDEX: ` 1 0 5 4 3 2 INDEXR: 1 0 5 4 3 2 DIGITI ZED
VOLTAGE ALLHI=07. Mask for A, B, C at same time.
MAS~: ~
. - : ~

\
\ :
~ \ .
` ~ \ : .

:

,~ '' TABLE IV

COUNTERCLOCKWISE ROTOR POSITION SENSING

Pl Diqitized Back EMFs 0 B . 1 0 0 0 l A l l 1 0 2 C 0 0 l 1 l 0 ____________________________________ HEX: 3 2 6 4 5 R3: -l 4 -2 l -4 2 INDEX: 1 0 5 4 3 INDEXR: 13 12 17 16 15 14 DIGITIZED
VOLTAGE :ALLHI=07. Mask for A, B, C at same time.
MASK:

\
;

: ~ .

:

::

9 ~7 03AM 5938 TABLE V

MONITOR PATTERNS FOR CLOCKWISE ROTATION

P2 Rail Line Disable Sequence of Patterns D 7 Top O 1 0 1 0 G 6 Btm 1 0 . 1 0 1 0 I

T _____________ ______________~_______ A 5 ` 1 1 1 1 1 0 L
4 1 1 ' 1 1 0 S

G

A

S

` ~ ~ O 1 ' 1 ______________._____________________ INDEX: O 1 2 3 4 5 INDEXR: O 1 2 3 4 5 .

CONTROL
SIGNALS: ~ A~ C- B~ A- C+ B-., ~ ~ c.~ 0 3AM 5 9 3 8 TABLE VI
t~lONITOR PATTERNS FOR COUNTERCLOCKWISE ROTATION
P2 Rail Line Disable Sequence of Patterns D 7 Top 0 1 0 1 0 G 6 Btm 1 0 1 0 1 0 ______________________________ _____ A

I

N

A
L

___ _________________________ ______ INDEX: 0 1 2 3 4 5 INDEXR: 12 13 14 15 16 17 CONTROL
SIGNALS :A+ B- ~ C+ A B+ C-.

:

~= . ... ~

:. .

Y ~'7 The flow diagrams of FI5S. 8-17 and 19 describe pro-cesses, methods, and operations contemplated in some of the embodiments of the invention, regardless of any particular manner of implementation using hardware or software. A list-ing of an illustrative assembly language program for the Intel8748 microcomputer as microcomputer 61 is included in the present application as Appendix I. A table correlating the listing of ~ppendix I with the flow diagrams is included as Appendix II. It is to be understood that the assembly lan-guage program is used in microcomputer 61 to make it performmany of the same processes, methods and operations shown in the flow diagrams while differing in order of listing and in some details from the flow diagrams of FIGS. 8-17 and 19.
Thus Appendix I further illustrates and discloses some of the variety of implementations possible in the practice of the invention according to the principles thereof.
In FIG. 8, operations commence at START 301 and at step 305 equates are made to set up in memory some or all of the information contained in Tables I through VI of the pres-ent specification. More specifically, the information in-cludes the patterns of digital signals for clockwise and counterclockwise rotation, which are designated "Control Driver Pattern For Clockwise Direction" and "Control Pattern For Running Counter Clockwise Direction" in Appendix I. In 2S addition, the information includes identified inputs to the microcomputer 61 in the rows designated "Digitized Voltage Mask" in Tables I and II and the lines designated "Test Pattern For CW/CCW" in Appendix I. Control equates are also made in Appendix I for masking the input lines to port Pl from the switches for On/Off, Wash/Spin, CW/CCW, 5/250 REV, and Hi/Low Speed, for clearing flipflop 273 of ~IG. 7, setting certain time values, and for other purposes.
At step 307 and step 309 outputs are turned off and other housekeeping functions are accomplished. These include producing a digital signal pattern "OFF" consisting of all ~;.3~J.~ 03AM 5938 ones from output port P2 on lines 62 ~f FIG. 4 so that all zeros are generated by control signal generator 51 for turning ofE the motor M. Flip~lop 273 is cleared, High/Low Speed circuit 41 of FIG. 1 is set to Low, and initializing of the microcomputer 61 is performed.
A point 311 in the operations is designated STRTST.
STRTST is located at the beginning of operations which deter-mine whether the laundry apparatus is still on and whether the wash or spin mode is to be changed. At step 313 the state of On/Off switch 231.5 is read at port Pl, line 7, and at step 315 operations branch back to STRTST until switch 231.5 is turned from the Off position to the On position. When switch 231.5 is on, point 316 designated RUN is reached. Then at step 317 the CW/C~ switch 231.3 is read at port Pl, line 5, and the setting as clockwise or counterclockwise is stored.
At step 319 the Wash/Spin switch 231.4 is read at port Pl, line 6, and the mode commanded by it is stored. At step 321, the mode stored is tested, and if it is "Wash", operations proceed to point 323 and FIG. 9, otherwise to "Spin" point 325 and FIG. 14.
In FIG. 9, the wash mode is executed beyinning at point 323. A predetermined point in the preselected sequence for clockwise rotation ~left-most column of Table I) is selected by setting INDEX and INDEXR to zero at step 351.
Flipflop 273 is cleared and current and timer interrupts are enabled at step 353. Steps 355, 357, and 359 check INDEXR to assure that it does not have a value clearly indicating some error in the system. If INDEXR is negative or greater than 23, an OFF digital signal pattern ~all ones) is produced at step 359, and operations loop back to step 351.
Next at step 363 a ~igital signal pattern is obtained from memory and stored in the accumulator. For example, the first digital signal pattern so obtained is 01111100 from the leftmost column of Table I. Next at step 365, the digital signal pattern is produced from the ~ o~M ~g38 accumulator as an output on lines 62 for control signal gener-ator 51 (termed "driver logic" on the flow diagram). In step 367 a test pattern, ~hich is 0,1 or 1,0 is obtained from mem-ory for use in testing the digitized voltage as explained in connection with FIG. 6A. The test pattern to be used is tabu-lated in Tables I and II in the same column as the digital signal pattern which has just been produced. Equivalently, and as discussed in connection with FIGS. 10 and 15, the test bit order is directly implemented in the coding as a function of whether INDEX is even or odd, and step 367 is omitted. At step 369 a register for a flag FLGl is set to zero, indicating that the low speed connection arrangement for the winding stages is intended. At step 371 and as more fully discussed in connection with FIG. 10, the digitized voltage of FIG. 6A
is tested, and as soon as complementary bits, or logic levels, in the proper test bit order have been sensed, operations pro-ceed to advance in sequence to commutate the winding stages.
If complementary bits are not sensed in the predetermined proper test bit order in a predetermined time period, opera-tions proceed to advance in the sequence anyway andforce-commutate the motor.
At step 372 the rail disable signals on lines 7 and 6 of port P2 of microcomputer 61 are reversed. "Rail" as used herein means either one of supply conductors 113 and 115. In this way control signal generator 51 is prepared by microcom-puter 61 for any pulse width modulation (PWM) which may occur by output Q going high as soon as the back emf routine 371 is complete. As such~ microcomputer 61 constitutes means for also selecting the digitized voltage across the at least one unpowered winding stage when digital signal patterns are pro-duced in sequence and changing the logic levels of the addi-tional pair of digital signals (e.g. on lines 7 and 6 of port P2) as soon as at least one predetermined logic level (e.g. of the test bits) of the selected digitized voltage has occurred.

. .

.~ .

~ ,s~ 03AM 593g At steps 373 and 375, IMDE%R and INDEX are respec-tively incremented, moving one column to the right, in effect, in Table I or II. If I~DEX has not reached the number 6 at step 377, operations loop back to a point 379 designated ~IAINl and continue with the sequence of steps 355-377, commutating the motor until INDEX reaches 6. When INDEX reaches 6, a branch is made from step 377 to step 381. The value I~D~X is essentially treated modulo 6, so that operations cycle through Tables I and II, to commutate the motor as long as desired.
INDEX is reset to zero at step 381. At step 383r INDEXR is decreased by 6. The latter operation recognizes that when counterclockwise rotation is being executed in Table II, INDEXR reaches the number 18 when INDEX is 6, so that INDEXR
must be cycled back to a permitted number 12 in Table II by subt~action by 6.
At step 385 the On/Off switch 231.5 of FIG~ 6 is tested. If the switch has been turned off, a branch is made from step 387 to step 389 whence the pattern OFF (all ones on lines 62) is output to shut the motor off, and operations return to STRTST point 311 in FIG. 8 to poll the switch ~ntil it is turned on. Assuming On/Off switch is on when step 387 was first reached, operations proceed to step 391 to decrement a revolution counter which has been originally loaded in step 309 of FIG. 8 with a number 5 (center-post agitator laundry apparatus~ or a number 250 (tumbler-type laundry apparatus).
In this way microcomputer 61 counts revolutions of rotatable means 15 in step 391 by counting at steps 375, 377, and 381 the successive patterns of digital signals produced. When the revolution counter has been decremented at step 391, a test of its contents at step 393 for the number zero is made to deter mine whether all of the revolutions in a stroke of agitation have been completed by motor M. If not, operations loop to MAINl and continue with step 355 and the subsequent steps to continue commutating motor M in the same direction of rota-tion. If the revolution counter has reached zero, a branch is '7 03AM 5g38 made from step 393 to step 395 where the counter is reloadedwith the number 5 or 250, depending on the setting of switch 231.2 of FIG. 6. In step 397, operations are performed to prepare for commutation in the opposite direction, as dis-cussed more fully in connection with FIG. 11.
In FIG. 10, low speed back emf routine 371 commenceswith BEGIN 401. A ~wo-millisecond interrupt timer is started running at step 403. At step 405, the value of INDEX repre-senting the point in the sequence in the Table I or II is checked for being even or odd. If it is even (INDEX = 0,2,4) the test bit order is 0,1. The digitized voltage o~ FIG. 6A
is tested at step 407 and the testing is repeated by branching back from step 409 until the first test bit of 0 is found, whence the two-millisecond interrupt timer is cleared at step 411 and step 417 is reached. It is noted that the repeated execution of steps 407 and 409 until the zero (0) is found corresponds to arrows 235.1-235.3 in FIG. 6A. If INDEX is odd (1,3,5), the test bit order utilized is 1,0. The digitized voltage (which is inverted in polarity from that of FIG. 6A~
is tested at step 413 and the testing is repeated by branching back from step 415 until the first test bit of 1, this time, is found, whence the two-millisecond interrupt timer is cleared at step 411 and step 417 is reached. If the repeated testing at either step 407 or 413, as the case may be, con-tinues for 2 milliseconds without avail, a timer interruptoccurs and operations proceed to step 417.
An 18-millisecond interrupt timer is star~ed running at step 417. ~t step 419, the value of INDEX representing the point in the sequence in the Table I or II is checked for be-ing even or odd. If it is even (INDEX = 0,2,4)~ the test bitorder is 0,1 as already stated. The digitized voltage of FIG.
6A is tested at step 421 and the ~esting is repeated by branching back from step 423 until the second test bit of 1 (in 0,1) is found, whence the 18-millisecond interrupt timer ~23~ 7 03AM 593~3 is cleared at step 42S and RETURN 4~7 is reached. It is noted that the repeated execution of steps 421 and 423 until the one (1) is found corresponds to arrows 235.4-235.8 in FIG. 5A. I~
INDEX is odd (1,3,5), the test bit order utilized is 1,0 as 5 already stated. The digitized voltage (which is inverted in polarity from that of FIG. 6A) is tested at step 429 and the testing is repeated by branching back from step 431 until the second test bit of O (zero), this time, is found, whence the 18-millisecond interrupt timer is cleared at step 425 and 10 RETURN 427 is reached. If 'che repeated testing at either step ~21 or 429, as the case may be, continues for a full 18 milli-seconds without avail, a timer interrupt occurs and operations proceed to RETU~N 427.
FIG. 11 shows the reversing routine 397 of FIG. 9 in 15 greater detail. Operations commence therein at BEGIN 451.
INDEX is initialized to zero at step 453. The direction vari-able DIRECT is tested at step 455 If DIRECT is 0, for clock-wise (CW) rotation, s~cep 457 changes it to 1, for counter-clockwise (CCW) rotation, and INDEXR is increased by 12 at 20 step 459 in order to enter the range of INDEXR in Table II.
If DIRECT is 1 for CCW rotation in step 455, step l61 changes it to 0, for C~ rotation, and INDEXR is decreased by 12 at step 463 in order to enter the range of INDEXR in Table I
Steps 455-463 in ef~ect are operations by which microcomputer 25 61 changes INDEXR and the direction variable DIRECT which are subsequently used in producing successive patterns of digital signals for achieving the desired direction of rotation of motor ~1.
Before the motor M is commutated in the opposite ~0 direction from that in which it was turning previously, it is caused to stop ro~ating by operations which commence at MTROFF
point 465, and proceed to produce an OFF pattern ~all ones on lines 62) at step 467. The motor M, having its power removed, coasts to a stop. However, microcomputer 61 needs to know 35 when the motor has actually stopped. This information is

3~

obtained by fi~st loading a co~nter at step 469 with a prede-termined number indicative of a predetermined time peeiod duL-ing which there should be no back emf observed ~hen and if the motor has actually stopped. ~ext at step 471 one or more of the port Pl inputs 0, l, and 2 is sensed for its digitized voltage As long as the rotor is coasting, the digitized voltage from each of the winding stages is a succession of highs and lows. If a zero, or low, is sensed, the rotor may still be coasting or it may have stopped, but if a one, or high, is sensed, the rotor must still be coasting. According-ly, a branch is made from step 473 if a high bit, or logic level of one, is sensed and the counter is reloaded with the predetermined number at step 469 since the rotor must still be coasting. On the other hand, operations proceed from step 473 to step 474 if a low bit, or logic level of zero, is sensed, and the counter is decremented. Since the rotor may still be coasting, however, a branch is made from step 477 back to testing step 471 unless the coun~er has been decremented to zero. In this way if the rotor is still coasting, a one (l) bit indicating existence of back emf is sensed sooner or later at step 471 and the counter can be reloaded at step 469 as a result of the branch from step 473. Eventually the rotor stops and a sufficient time period elapses without back emf to assure microcomputer 61 that the rotor has stopped. The counter is decremented to zero and operations proceed from step 477 to RETURN 479.
In having the capability to perform the reversing routine of FIG. 11, microcomputer 61 and control signal gener-ator 51 together constitute means for causing the rotatable means to reverse in its direction of rotation by producing a pattern of the control signals for causing the commutating means to remove power from 311 of the winding stages, for sensing the digitized voltages while the power is so removed, and for producing successive patterns of the control signals in a second preselected sequence to rotate the rotatable means '7 03AM 5g38 in the reverse diLection only after a predeteLmined time peri-od has elapsed subsequent to the last occurrence of a prede-termined logic level in any of the digitized voltages.
FIG. llA shows a series of operations of microcom-5 puter 61 for braking motor M to stop the rotation more quickly than occurs when motor r~ is permitted to coast to a stop as in FIG. 11. The operations of FIG. 11~ are performed in substi-tution for the steps 467,469,471,473,475,477 and 479 of FIG.
11 in a reversing routine and performed at any point in the 10 operations of microcomputer 61 where braking is deemed desir-able by the skilled worker. Braking operations commence with BEGIN 481 and proceed to produce an OFF pattern 483 (all ones on lines 62) for leaving all of the winding stages of motor M
unpowered. Microcomputer 61 waits for a delay period of lS illustratively 3 milliseconds at step 485 before proceeding to step 487. At step 487 a braking pattern o~ the digital sig-nals is produced as shown at FIG. 4B in connection with the entry "BRAKE." The braking pattern causes commutating circuit 31 to connect together all of the terminals of the winding 20 stages selected by High-low speed circult 41. The mechanical energy stored in the rotor is rapidly dissipated electrically because the winding stages are in efect shorted together. At step 489 another delay period, this time for 12.5 milli-seconds, is executed by microcomputer 61. Another OFF pattern 25 is produced at step 491, followed by another 3 milllsecond delay by the microcomputer 61 at step 493, and braking opera~ions are completed at RETURN 495.
In having the capability to perform the steps described in connection with FIG. llA, microcomputer 61 and 30 control signal generator ~1, as pattern producing and digi-tized voltage sensing means, constitute means for also produc-ing a pattern of the control signals which causes the commu-tating circuit 31 to switch all of the winding stages to one of the supply conductors 113 or 115, thereby braking the motor 35 M.

~ 7 03AM 5938 An interrupt low at the INT~bar pin of microcomputer 61 can occur at any time during the washing mode or spin mode operations of laundry apparatus 11. FIG. 12 illustrates a sequence of operations which occurs upon interrupt. Interrupt opera~ions commence at B~GIN 501. OptionaL step 507 is described later in connection with FIG. 13. The high-low speed flag FLG1 is checked at step 513. If the flag is a zero (low speed winding selection~, an internal timer (not shown~
in microcomputer 61 is loaded with a number corresponding to the predetermined time period Tl (FIG. 7A) of 100 microseconds in step 515, and if the flag is a one (high speed winding selection~ the timer is loaded for a predetermined time period Tl of 50 microseconds at step 517 to take account of the higher motor speeds. Next at steps 519 and 521 the timer is decremented until it reaches æero thereby to execute a delay for the time period Tl and indicating that time period Tl has elapsed. An optional step 523 is discussed below in connectiOn with FIG. 13. At step 525 microcomputer 61 trans-mits a pulse on the line DB7 of FIG. 7 to clear the latch or flipflop 273 whence interrupt operations are completed at RETURN 527.
In FIG. 7A the duty cycle of pulse width modulation (PWM) for motor M is controlled by causing the Q and Q-bar OUtputs of latch 273 to change state between time periods Tl and T2 as shown. FIG. 7 reflects a hard~are approach for set-ting T2 by means of circuit por~ion 295, and the microcomputer 61 sets Tl in the interrupt routine of FIG. 12.
In FIG. 13 a software approach is suggested for con-trolling the time period T2 when the motor M is powered. The circuit portion 295 of FIG. 7 is deleted in a now-described alternative embodiment. An otherwise unused output line such as DB5 (not shown~ is connected to the PRESET input of latch 273. Variable duty cycle instructions corresponding to the operations called for in FIG. 13 are inserted between steps 315 and 317 of FIG. 8 at the point designated RUN. At step ~ 03AM 5938 531 input information corresponding to the desired duty cycle is read in to microcomputer 16 as from switches 231.6, 231.7, 231.8, and 231.9 at pins DB0-DB3 of ~IG. 6. This duty cycle information is a 4 bit binary code when pins DB0-D~3 are used for input, so that 16 values of duty cycle Dl are selectable.
Given a predetermined time period Tl value, there corresponds a particular value of T2 which solves the du~y cycle equation Dl = T2/ (T2 + Tl) ~11 The duty cycle equation (l) is solved for time period T2 for time-on with result:

T2 = Tl(Dl/(l-Dl)) (2) Values of T2 are stored in a table in memory corresponding to the values of desired duty cycle Dl which can be read in in step 531. When one of the values Dl is read in, the corre-sponding value of T2, or time-on, is fetched from the table in step 533. At step 535 the interrupt process is enabled so that microcomputer 61 can be in~errupted by excessive current sensed by comparator 261 of FIG. 7. Then at step 537 a timer is loaded with a number corresponding to ~he time-on T2 and set running. The timer (not shown) is an internal timer in microcomputer 61 which is for present purposes called a duty interrupt timer. Microcomputer 61 executes the operations of FIG 8 and of the washing and spin modes selected, but is interrupted when the duty interrupt timer times out at t~e end of time period T2, beginning the interrupt routine of FIG. 12.
The FIG. 12 interrupt routine now is described with the optional steps 507 and 523 included. At step 507 inter-rupt pin INT-bar is masked to avoid interaction with latch 273, and latch 273 of FIG. 7 is set by transmitting a zero or Low from microcomputer 61 to its PRESET input. The Q output ~ '7 03AM 5938 of latch 273 goes high, leaving motor M unpowered through con-trol signal generator 51 and commutating circuit 31. The interrupt operations proceed in steps 513-521 so that prede-termined time period T1 elapses. At step 523, the duty inter-~upt ~imer in microcomputer 61 is reloaded with a value corre-sponding to time period T2 and set running again. Latch 273 is cleared at step 525, bringing its Q output low and powering the motor M again. Also at step 525 interrupt pin INT-bar is enabled so that any overcurrent interrupt caused by comparator 261 can be sensed.
The spin mode of laundrr ap,aratus 11 has operations shown in FIG. 14 which commence at point 325. Microcomputer 61 clears latch 273 and ~nables interrupts in step 551, The value of INDEX is set to zero (O) for purposes of Tables I and II in step 553. The direction in which the motor M is to turn during the spin mode is determined from the setting of switch 231,3 (CW/CCW in FIG. 6) in step 555. If switch 231.3 is set to CW, operations proceed from step 557 to step 559 and the preselected sequence defined in Table I is selected by setting INDEXR to zero in step 559. If switch 231.3 is set to CCW, operations proceed from step 557 to step 561 and the preselec-ted sequence defined in Table II is selected b~ setting INDEXR
to 12 in step 561~ Operations of microcomputer 61 reach point 563 designated MAIN2 when either step 561 or step 559 has been completed.
Steps 565, 567, and 569 check INDEXR to assure tha,t it does not have a value clearly indicating some error in th,e system. If INDEXR is negative or greater than 23, an OFF ~
digital signal pattern (all ones) i5 produced a~ step 569, a~nd operations loop back to step 553.
When operations reach step 571, the high-low speed winding flag FLG1 is tested to determine which selection is being made by high-low speed circuit 41. Assume that the ~ 7 03AM 593~

selection is initially low and the spin mode is just begin-ning. FLGl is zero, indicating low speed winding, and opera-tions pass through point D to step 573 where HI/LOW Speed switch 231.1 is tested. In the present embodiment, switch 231.1 can be initially set in the LOW speed position and the motor M is brought up to a steady speed. Then switch 231.1 is changed to the HI speed position for commanding microcomputer 61 to cause relaying by High-low speed switching circuit 41 and causing motor M is accelerate to a higher speed. The operations of microcomputer 61 in responding to switch 231.1 are described in greater detail next.
When switch 231.1 is set to LOW, indicating that the motor M is to be in the low speed connection arrangement for the time being, a branch is made at step 575 to step 577. At step 577 a digital signal pattern is obtained from memory and stored in the accumulato~. For example, the first digital signal pattern so obtained is 01111100 from the leftmost col umn of Table I when CW/CCW switch 231.3 is in the CW position~
Next at step 579, the digital signal pattern is p~oduced from the accumulator as an output on lines 62 (termed "output run patrn" on the flow diagram) for control signal generator 51.
In step 581 a test pattern, which is 0,1 or 1,0 is obtained from memory for use in testing the digitized voltage as explained in connection with FIG. 6A. The test pattern to be used i5 tabulated in Tables I and II in the same column as the digital signal pattern which has just been produced. Equiva-lently, and as discussed in connection with FIGSo 10 and 15,~;
the test bit order is directly implemented in the coding as a function of whether I~DEX is even or odd, and step 581 is omitted. At step 583, depending on whether FLGl is set for ~
Low (0) or High (1) speed, a bran~h is made through point F to low speed back emf routine 371 or through point E to high speed back em~ routine 585. In each of back emf routine5 371 and 585 and as more fully discussed in connection with FIGS~

r~ 03AM 5938 10 and 15, the digitized voltage o FIG. 6A is tested for com-plementary bits, or logic levels, in the proper test bit order whence point G is reached.
When motor M is r~nning at low speed, flag FLGl has been set to zero. Assume that it is desired to accelerate motor M to a higher speed so that switch 231.1 is physically changed to HI. (It is also contemplated that the change from low to high can be alternatively accomplished in software.) FLGl is still set to zero and in FIG. 14 operations pass through point D to step 573. Now when switch 231.1 is tested at step 573, a branch is made from step 575 to step 587 where flag FLGl is set to one for High Winding Tap. Then a relaying routine at step 58B is executed for actually relaying from the low speed to the high speed winding connections to motor ~l and for determining the proper point in the sequence for resuming commutation when the relaying is completed. Relaying routine 588 is described in greater detail in connection with FIG.
17. When operations at steps 573, 575, 587, and 588 have been completed, motor M is commutated and accelerated, and steps 573, 575, 587, and 588 are bypassed by a NO branch from step 571 to step 577 subsequently during high speed rotation.
Steps 577, 579, and 581 are per~ormed. At step 583 flag FLGl ` is now set for High speed and operations pass through point E
to high speed back emf routine 585.
In FIG. 15 high speed back emf routine 585 is simi-lar to low speed back emf routine 371 of FIG. 10 except in being adapted for the shorter time intervals encountered at higher rotor speeds. Operations commence at BEGIN 589 and a one-millisecond interrupt timer is ~tarted at step 590. Step 591 unifies the operations performed in steps 405 and 419 of FIG. 10. At step 591, the value of INDEX representing the point in the sequence in the Table I or II is checked for being even or odd. If it is even ~INDEX = 0,2,4) the test bit order is 0,1. The digitized voltage of FIG. 6A is tested at step 593 and the testing is repeated by branching back from ~ .

~ 7 03AM 5938 step 595 until the first test bit of 0 is found. The digi-tized voltage of FIG. 6A is again tested at step 597 and the testing is repeated by branching back from step 599 until the second test bit of 1 is found. Then the one-millisecond interr~pt timer is cleared at step 601 and RETURN 603 is reached. It is noted that the repeated execùtion of steps 593 and 595 until the zero (0) is found corresponds to arrows 235.1-235.3 in FIG. 6A, and repeated execution of steps 597 and 599 until the one (1) is found corresponds to arrows 235.4-235.8. If INDEX is odd (1,3,5), the test bit order uti-lized is 1,0. The digitized voltage (which is inverted in polarity from that of FIG. 6A) is tested at step 605 and the testing is repeated by branching back from step 607 until the first test bit of 1, this time, is found. Then the digitized voltage is tested at step 609 and the testing is repeated by branching back from step 611 until the second test bit of 0, this time, is found, whence the one-millisecond interrupt timer is cleared at step 601 and RETURN 603 is reached. If the repeated testing at steps 593-599 or 605-611, as the case may be, continues for a full one millisecond without avail, a timer interrupt occurs and operations proceed to RETURN 603.
FIG. 16 shows more operations of microcomputer 61 in the spin mode continuing from point G from FIG. 14. The oper-ations advance in sequence of commutation beginning at step 621. At steps 621 and 623, INDEXR and INDEX are Lespectively incremented, moving one column to the right, in effect, in Table I or II. If INDEX has not reached the number 6, opera-tions branch from step 625 to the point 563 designated MAIN2 in FIG. 14 and continue with the sequence of steps from MAIN2 to point G, commutating the motor until INDEX reaches 6. When INDEX reaches 6, a branch is made from step 625 to step 627.
The value INDEX is essentially treated modulo 6, so that oper-ations cycle through Table I or II, depending on rotation direction, to commutate motor M as long as desired in the spin ~ 03AM 5938 mode. INDEX is reset to zero at step 627. At step 6Z9, INDEXR is decreased by 6. The latter operation recognizes that when rotation is being executed in either Table I or II, INDEXR reaches the num~er 6 or 18 when INDEX is 6, so that 5 INDEXR must be cycled back to a permitted number 0 or 12 in Table I o~ II by subtraction by 6.
At step 631 the On/Off switch 231.5 of FIG. 6 is tested. If the switch is still set to "On," operations pass from step 633 back to FIG. 14 point MAIN2 so that commutation continues If the switch has been turned off, a branch is made from step 633 to step 635 whence the pattern OFF (all ones on lines 62) is output to shut the motor off. At step 637 a loop or counting operation is provided so ~hat microcom-puter 61 waits 100 milliseconds or for any other desired time interval. In step 639 microcomputer 61 issues a High on line DB6 ~FIG. 3) producing a Low on line H from NAND gate 157, and causing relay 147 in high-low speed circuit 41 to switch back to a low speed connection arrangement. The high-low speed flag FLGl is reset to zero (low speed~ at step 641, and opera-tions pass to STRTST point 311 of FIG. 8, there to poll On/Offswitch 231.5 until it is turned on.
In FIG. 17 the relaying routine of step 588 of FIG.
14 is shown in greater detail. Operations commence with BEGIN
651 and proceed to produce the OFF pattern (all ones on lines 62) at step 653 to tu~n off the motor M. At step 65~ micro-computer 61 issues a Low on line DB6 (F~G. 3) producing a High on line H from NAND gate 157, and causing relay 147 in high-low speed circuit 41 to switch from the low speed connection arrangement to a high speed connection arrangPment~ Microcom-puter 61 waits for ten milliseconds as by any suitableroutine, such as counting from a preset number down to zero, in step 657 in order to permit the relay 147 armature 155 to come to rest in the high speed position. However, during this waiting period, the rotor 15 of motor M has, or may have, rotated a through a significallt angle for cornmutation pur~
poses. Accordingly, at step 659 a routine is executed for determining the value of INDEX from the sensed digitized volt-ages on comparator outputs A, B, and C of FIG. 6 when the winding stages are temporarily unpowered, and resuming produc-ing patterns of digital signals on lines 62 beginning with the pattern of digital signals (and thus a corresponding set of control signals from control signal generator 51) identified by the value of I~DEX so determined. After step 659 RETURN
661 is reached.
Step 659 of FIG. 17 recognizes that when motor M is unpowered and the rotor is coasting, all of the winding stages are producing back emfs. ~s shown in FIG. 6, the back emfs are digitized by comparators 201, 203, and 205. The digitized back emfs for three wye-connected winding stages Sl, S2, and 53 are illustrated in F~G. 18 and tabulated in Tables III and IV for clockwise and counterclockwise rotation respectively.
In FIG. 18 and in the first three rows of Tables III
and IV, the logic levels of the digitized voltages on input lines 0, 1, and 2 of microcomputer 61 are shown when rotor 15 is coasting. Each of the six columns shows the logic levels o~ the digitized back emfs present at any given time. As the rotor turns, the logic levels of a given column are replaced by the logic levels in the column next to the right. When the right-most column is reached, the logic levels begin again in the left-most column, cycling through the columns as before.
FIG. 18 shows superimposed on the logic zeros and ones a wave-shape of the digitized back emfs on the input lines 0, 1, and 2. The digitiz`ed back emfs at any one time and their changes to other values at other times bear sufficient in~ormation to permit sensing the position of the turning rotor 15 and to identify the proper point in sequence for beginning commuta-tion of such turning rotor and for resuming commutation when-ever commutation is interrupted or discontinued. Accordingly, the index-determining operations of step 659 as described in ~urther detail in FIG 19 are used in relaying routine 588 in the preferred embodiment, and are used in other embodiments of the invention whenever it is desired to begin commutation in sequence.
In FIG. 19 operations commence with BEGIN 671, and microcomputer 61 inputs all the lines 0,1, and 2 of port Pl at once by masking with ALLHI=07 (binary 00000111). As a result there resides in microcomputer 61 a three bit binary number having binary digits corresponding to each of the digitized voltages on the three lines. This binary number is designated DATAl and stored in step 673. Then at step 675, microcomputer 61 inputs all the lines 0,1, and 2 of port Pl again in search of digitized voltages corresponding to an adjacent column of digitized voltages in FIG. 18. In order to avoid error, if the latest set of digitized voltages is all zeros (decimal zero ~0)) or all ones (decimal seven (7)), then the index determining routine is aborted by passing to RETURN 679. The reason for this is that as shown in FIG. 18, the digitized voltages are never all high at the same time when the rotor is coasting. Also, the digitized voltages are all zero only when the rotor has stopped.
If the digitized voltages are not 0 or 7 as just discussed, then operations proceed from step 677 to step 681 where the digitized voltages just obtained in step 675 are stored and designated DATA2. In step 683, DATAl is compared with DATA2. If they are the same number, (i.e. DATAl-DATA2=0) the rotor has not turned sufficiently to move ~o the adjacent rightward column in FIG. 18 and in the Table III or IV corre-sponding to the direction of rotation. When DATAl=DATA2 abranch is made back to s~ep 675 to inpùt another set, or instance, of digitized voltages until an instance of digitized voltages is found at step 675 which is different from DATAl.
At step 685, the difference DATA2-DATAl is computed. Step 687 ' , , ~ 03~M 593~, checks the value of the difference, which ~rom inspection of differences between the hexadecimal equivalents of the digi-tized voltages (tabulated in row HEX of Tables III and IV) should not be equal to 3 or -3 if the data is unaffected by noise. If the difference is equal to the unpermitted numbers 3 or -3, a branch is made from step 687 to step 675, until a value of DATA2 is found which passes the test of step 687.
When step 689 is reached, microcomputer 61 has stored values of DATAl and DATAZ which are in adjacent columns of one of the Tables III or IV. Each Table III or IV lists values of R3, which is the difference DATA2-DATAl~ in the column corresponding to the digitized back emfs in DATAl.
Beneath a value of difference R3 in each of column of Table III or IV are values of INDEX and INDEXR. The values of INDEX
and INDEXR are precisely the values for identifying the proper Table I or II and the proper column therein containing the digital signal pattern which microcomputer 61 can and does then produce to resume commutation of the winding stages at the proper point in sequence. ~Beneath the tabulated value of R3 in Table III is an entry designated "Offset R3" which is a number calculated in the program listing of Appendix I for microcomputer table lookup purposes.) At step 689 mic~ocomputer 61 determines which direction the rotor 15 has been made to turn in. When switch 231.4 is in the spin mode, the direction is given by the setting of switch 231. 3 as CW or CCW. When switch 231.4 is in the wash mode, the direction is given by the value of the variable DIRECT of FIG. 11. In either mode the direction can also be obtained from INDEXR. If INDEXR is in the range 0-5, the direction is clockwise, and if ~NDEXR is in the range 12-17 the direction is counterclockwise.
If the direction determined is counterclockwise, a branch is made from step 689 to step 691 for table lookup in a table in microcomputer 61 having the information found in ~$~ ~7 03AM sg3~

Table IV in rows R3 and INDEX. When INDEX is found, INDE'~R is reset by adding 12 to INDEX. I~ the direction determined is clockwise, a branch is made from step 689 to step 693 for table lookup in a table in microcomputer 61 having the infor-mation found in Table III in rows R3 and INDEX~ INDEXR isreset as equal to INDEX when the direction is clockwise.
After step 691 or step 693 is executed, R~TURN 67g is reached.
The operations of FIG~ 19 can be described more gen-erally as follows. Microcomputer 61 identifies successive patterns of the control signals and of the digital signals of Tables I and II by values of an index designated INDEX. A
value of the index is determined from the sensed digitized voltages when the winding stages are temporarily unpowered.
~licrocomputer 61 resumes producing successive patterns of the digital signals which causes control signal generator 51 to generate successive patterns of ~he control signals in se-quence beginning with a pa~teLn of the digital signals and control signals determined from the sensed digitized voltages.
The lookup table information stored in microcomputer 61 is a function, i.e. a predetermined correspondence between members of two sets of numbers. The sets of numbers involved here are values of INDEX on the one hand and values of the differences ` R3. Equivalently, Tables III and IV can be regarded as tabu-lating INDEX as a function of digitized back emf itself. It ~5 is also to be understood that there are a multitude of equiva-lent ways màde known by the disclosure made herein, of setting up a function relating the digitized back emf information to some variable such as INDEX which can be used to determine the proper point ~or beginning in sequence when commutation begins again. When the successive patterns of digital signals and control signals are identified by values of an index, the index is advantageously determined as a function of a number represented by the sensed digitized voltages when the winding stages are temporarily unpowered, and microcomputer 61 resumes ~ 03AM 5938 prod~cing patterns beginning with the pattern o~ the control signals identified by the value of the index so determined.
The index is determined as a first function of a number repre-sented by the sensed digitized voltages when the winding stages are temporarily unpowered and the preselected sequence is for clockwise rotation of the rotatable means 15 and deter-mined as a second function of the number so represented ~Jhen the preselected sequence is for counterclockwise rotation, and microcomputer 61 resumes producing patterns beginning with the pattern of the control signals identified by the value of the index so determined. The value of the index is also deter-mined as a function of the difference of first and second num-bers represented by different instances of the sensed digi-tized voltages, and microcomputer 61 begins with the pattern of the control signals identified by the value of the index so determined. The value of the index is determined as a func-tion of the difference of ~irst and second numbers represented by different instances of the sensed digitized voltages unless one of the numbers is in a set of predetermined numbers, such as 0 and 7, and microcomputer 61 begins with the pattern o~
the control signals identified by the value of the index so determined. A difference of first and second numbers repre-sented by different instances of the sensed digitized voltages is calculated and a value of the inaex is determined as a function of the difference unless the difference is in a set of predetermined numbers, such as 0, +3, and -3, and microcom-puter 61 begins with the pattern of the control signals iden-tified by the value of the index so determined. Microcomputer 61 in this way prevents sensed digitized voltages representing a number in a predetermined set, such as 0 and 7, ~rom being used to determine the beginning pattern of control signals.
Microcomputer 61 in FIG. 19 repetitively senses the digitized voltages while the winding stages are temporarily unpowered and determines the beginning pattern of the control signals as ~ 3l 7 soon as a change occurs in any one of the sensed diyitized voltages.
In some applications of the invention involving cur-rent interrupt as in FIG. 7, the time period Tl when the motor M is unpowered can be long enough to make index-determination as in FIG. 19 advisa~le. In 5uch circumstances, the index-determining operati.ons of FIG. 19 are inserted in the inter-rupt routine o~ FIG. 12 immediately followiny step 521 so as to update INDEX and INDEXR. Then the control system of FIG. 1 constitutes means for comparing the current flowing the other powered winding stages of the electronically commutated motor M with a predetermined level, and upon the level being ex-ceeded, interrupting the digital computer and also causing the control signal generator 51 to generate a pattern of control signals to discon~inue the supply of power to the winding stages, ~he digital computer comprising means for also moni-toring the position of the rotatable means 15 when the winding stages are thus unpowered and resuming producing patterns of the digital signals af~er a predetermined time interval begin-ning with a pattern then corresponding to the posi ion of the rotatable means.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained~
As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An electronically commutated motor system comprising:
an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with said stationary assembly in selective magnetic coupling relative with said winding stages;
first and second conductors for supplying power;
means for commutating said winding stages by selectively switching said winding stages to the supply conductors in response to a pattern of control signals leaving at least one of said winding stages unpowered at any one time while the other said winding stages are powered;
means coupled to said winding stages for digitizing the voltages across said winding stages;
means responsive to successive patterns of digital signals for generating successive patterns of the control signals for said commutating means; and a digital computer operating under stored program control, said computer having inputs for the digitized voltages, said computer having memory elements for storing data representing at lease one preselected sequence of the patterns of the digital signals and for storing data, corresponding to each pattern of the digital signals, identifying the respective input for the digitized voltage for said at least one unpowered winding stage, said computer successively producing one of the patterns of the digital signals, sensing only the digitized voltage at the identified input corresponding to the one pattern and producing the following pattern in sequence after at least one predetermined logical level of the diqitized voltage at the identified input has occurred.

2. The electronically commutated motor system as set forth in claim 1 wherein said control signal generating means also comprises means for preventing at least one pattern of control signals from being generated regardless of the patterns of digital signals produced by said computer.

3. The electronically commutated motor system as set forth in claim 1 wherein said digital computer comprises means for producing the following pattern in sequence after complementary logic levels of the digitized voltage at the identified input have occurred in a predetermined order.

4. The electronically commutated motor system as set forth in claim 1 wherein said digital computer also comprises means for producing the following pattern in sequence after a predetermined time period if the at least one predetermined logic level of the selected digitized voltage has not occurred during the predetermined time period.

5. The electronically commutated motor system as set forth in claim 1 further comprising means for comparing the current flowing in said other powered winding stages of said electronically commutated motor with a predetermined level, and upon the level being exceeded, interrupting said digital computer and also causing said control signal generating means to generate a pattern of control signals to reduce the current.

6. The electronically commutated motor system as set forth in claim 5 wherein said digital computer also comprises means for enabling motor operation to resume after a predetermined time intenral upon the interruption of said digital computer.

7. The electronically commutated motor system as set forth in claim 1 wherein said commutating means comprises sets of electronic devices connected across said supply conductors, each set having at least one junction point connected to a respectivec one of said winding stages, each of said electric devices respectively being able to be switched by a corresponding one of the control signals in each pattern of control signals.

8. The electronically commutated motor system as set forth in claim 7 wherein each set of electronic devices includes a pair of said electronic devices connected in series.

9. The electronically commutated motor system as set forth in claim 7 wherein said control signal generating means comprises first logic circuit means having respective inputs to which the digital signals in each pattern are coupled and having outputs coupled to said electronic devices respectively, and second logic circuit means for disabling the first logic circuit means whenever the digital signals could otherwise cause said electronic devices to short said supply conductors.

l0. The electronically commutated motor system as set forth in claim 7 further comprising means for comparing the current flowing in said winding stages of said electronically commutated motor with a predetermined level, and upon the level being exceeded, interrupting said digital computer, said digital computer also having memory locations for storing data identifying one of said first and second conductors corresponding to each pattern of the digital signals, said digital computer also comprising means for disabling switching by said electronic devices to said one identified conductor corresponding to the pattern of the digital signals which is being produced when the interrupting occurs.

11. The electronically commutated motor system as set forth in claim 1 wherein said control signal generating means comprising first and second logic gate means for feeding said commutating means and having inputs driven by respective pairs of digital signals in the digital signal patterns, means for disabling said firs and second logic gate means when any of the pairs of digital signals has identical logic levels in the pair, and means for disabling at least one of said first and second logic gate means in response to a signal to cause the current in said other powered winding stages to be reduced.

12. The electronically commutated motor system as set forth in claim 1 wherein said digital computer also comprises means for counting revolutions of said rotatable means by counting the successive patterns of digital signals produced.