DE2339260C2 - Brushless DC motor - Google Patents

Description

- In the active rotor position transmitter designed as a control winding (13; 96,97; 123) a voltage is induced which is phase-shifted by approximately 90 ° compared to the voltage induced in the drive stator winding,

- This voltage is fed to an integrating element (44; 85, 86; 144; 170) which in turn interacts with the semiconductor element (40, 41; 143; 189) and

- During the switch-on process, a stator winding is controlled with current via the integrating element (44; 85, 86; 144; 170).

2. Motor according to claim 1, characterized in that the voltage induced in the control winding (13; 96, 97; 123) is phase shifted by 70 to 110 ° with respect to the voltage induced in the drive stator winding.

3. Motor according to claim 1 or 2, characterized in that the means for generating a defined starting position of the rotor have at least one permanent magnet (30; 126, 127) arranged on the stator (10) and cooperating with the rotor (31; 101) .

4. Motor according to claim 3, characterized in that in addition to at least one permanent magnet (126, 127) and at least one soft iron part (133, 133 ') is provided on the stator.

5. Motor according to claim 3 or 4, characterized in that the at least one permanent magnet (30; 126, 127) is offset by η χ 180 ° el. Relative to a drive stator winding, where η = 0.1, 2 .. . is.

6. Motor according to claim 5, characterized in that the drive stator winding supported by the action of the permanent magnet (30; 126, 127) has a reduced number of turns.

7. Motor according to one of claims 3 to 6, characterized in that the at least one permanent magnet (126, 127) provided on the stator (110) is provided instead of a stator winding (Fig. 1 I).

8. Motor according to one of the preceding claims, characterized in that for generating a start pulse in a motor with an active integrator (! 44) switching means (147, 151) are provided which feed this integrator a pulse when the motor is switched on (Fi g. 11).

9. Motor according to claim 8, characterized in that in the case of an active integrator (144) designed as a Miller integrator, a resistor (151) is provided, via which a charging current can be fed to the capacitor (146) of the Miller integrator when the motor is switched on (Fig. 11).

10. Motor according to claim 9, characterized in that the capacitor (146) of the Miller integrator (144) arranged between the collector and base of a transistor (145) , a resistor (147) is connected in parallel (Fig. 11).

11. Motor according to one of claims 8 to 10, characterized in that the active integrator (144) is assigned a capacitor (166) as an energy store, which via a diode (164) from the direct current network (42, 43) this motor can be charged and which, after the motor has been switched off, maintains a voltage necessary for the operation of the integrator (144) during its idle time.

12. Motor according to one of claims 1 to 7, characterized in that a capacitor (58; 178) is provided for generating the start pulse in a motor with a passive integrator (44; 170) which can be connected to a charging circuit when the motor is switched on and the charging current of which causes a switch-on pulse for a current supply to at least one drive stator winding (12; 142) .

13. Motor according to claim 112, characterized in that the output voltage of the passive integrator (44; 170 ) can be fed to an amplifying element (54, 57; 173).

14. Motor according to claim 13, characterized in that the gain element is designed as an operational amplifier (173) (F i g. 12).

15. Motor according to claim 13, characterized in that the gain element is designed as a differential amplifier (54, 57) , the two inputs of which the output voltage of the passive integrator (44) can be fed in phase opposition and at the two outputs of which, if necessary via amplifier, one drive each -Stator winding (11, 12; 115, 116) is connected.

16. Motor according to claim 15, characterized in that the two drive stator windings (11, 12; 115, 116) are electrically offset from one another by (180 ° + π χ 360 °), where η = 0.1.2 .. . is.

17. Motor according to one of the preceding claims, characterized in that a restarting circuit (80, 82, 83) which is effective when the motor is switched on and not running is provided (FIG. 5) which has a capacitor (82) with a charging circuit (80 , 70, 72) , which the latter is connected to a voltage dependent on the speed of the motor, the charging voltage of this capacitor (82) controlling the repetition of starting (FIG. 5).

18. Motor according to claim 17, characterized in that that on the capacitor (82) a voltage-dependent, preferably a current positive feedback having discharge circuit connected

I - A ... . «Lnl · A ~ L“; _m f _Λ ; ( _ΛΗ ^ ,,, _Λ , ^ _ηη rtlM «" · «L · MHIAM ill

131, WV, IV, 1IV * 1 LS \ ~ 11II UVIlVllUn V, I UVII Vinvii nui! .Bit, ui.i start command causes an effective current pulse in a drive stator winding (12).

The invention relates to a brushless equal

Electricity motor in the preamble of claim 1 specified type

Kollclctorlosc DC motors need to commutate the current flowing in the windings Sensing elements that report the position of the rotor to the commutation device, so that the current in each case flows in the correct winding and a torque is generated in the desired direction. Contactless sensors are particularly suitable as sensing elements Devices such as Hall generators, magnetic diodes, etc., which are not actually subject to wear and tear and thereby enable a very long service life of such motors with good efficiency.

The simplest and often cheapest sensing element is a winding in the stator, in which the poles of the An alternating voltage is induced in the rotor, which is used to control the commutation of the armature current can. Since it is in principle a so-called active position transmitter that uses its energy withdrawn directly from the test object, this principle fails when the motor, i.e. such a motor, is at a standstill can only be commutated by a voltage induced in this winding when the rotor is already moving turns.

Various arrangements have become known to avoid these difficulties:

In one arrangement (US 30 25 443 or 27 53 501), a mechanical one is used during start-up Auxiliary commutator or a contact system which is put out of operation after a successful run-up. The disadvantages of such arrangements are additional Effort and the basic disadvantages of mechanical contacts.

In another known arrangement (US 30 67 370) a special electro-magnet is provided, by means of which the engine is started via a centrifugal clutch. Such an arrangement is also very complex and naturally also prone to failure.

In another known arrangement (US 28 10 843) the motor is started as a synchronous motor, by designing the commutation circuit as a self-oscillating oscillator. The one in many Cases serious disadvantage of this principle is that the motor only has very small additional Can set centrifugal masses in motion, because with larger masses it does not fall into step, i.e. does not reach the operating number and thus no regular run comes about.

In motors in which the starting position of the rotor is controlled by a permanent magnet arranged on the stator is defined (US 31 35 842, Fig. 4), it is also known by a current pulse caused when switching on in to give the motor a start pulse to the winding to be switched on first when it starts up. Of the The disadvantage here is that such a motor only loads with small moments of inertia, for example Clocks or the like, as a prerequisite for the effectiveness of such an arrangement is that the engine starts up very quickly. You can namely the number of turns used for commutation In such arrangements, do not choose a winding of 7.11, otherwise voltages that are too high would occur in this winding during operation, which are necessary for the control of the current in the motor were used to destroy semiconductor elements. At low speeds it is therefore the induced voltage in this winding is too small for the commutation, and such a motor can therefore only run up if it overcomes these low speed ranges, so to speak, in the first attempt. A prerequisite for this, however, is that the masses to be accelerated are very small.

The motors mentioned at the beginning with commutation by semiconductor elements do not have these disadvantages, that is, a torque is generated with them from standstill so that these motors start themselves and also in the correct direction. The known, for this purpose usable semiconductors work only at relatively low temperatures. For example, in the known Hall generators of gallium arsenide, the operating temperature is limited to 65 ° C which in many cases is not sufficient For example, occur in the interior of a motor vehicle in summer temperatures of over 9O ⁰ C, and desha'b have all the parts for intended to be used in motor vehicles to function safely at temperatures in this range. However, this requirement cannot be met with Hall generators. The same applies to fans, which are used, for example, to cool data processing systems. Here, too, it is required that these fans run safely at an ambient temperature of 85 ° C. Since the fans heat up beyond the ambient temperature during operation due to electrical losses, this means that they must still function reliably at temperatures in the range of 110-120 ° C. Motors with commutation by a voltage induced in a stator winding can easily meet these requirements for temperature stability, but have the disadvantages mentioned at the beginning.

A combination of both principles has therefore already been proposed, i.e. start-up with a Hall generator and operation by means of induced voltage, see DE-OS 20 63 351. If one ignores the fact that such motors are too expensive for most applications, one recognizes In any case, it is easy to see that such a motor, once it has reached temperatures above 65 ^° C. during operation, can no longer start itself after it has been switched off before it has cooled down sufficiently. Such an operating behavior of an engine is, however, not permissible in most cases.

Finally, FR 15 31 531 on which the preamble of claim 1 is based is a collectorless one DC motor known, which has a permanent magnet fixed to the housing for generating a starting position having. In addition, a special start-up winding is provided for when the motor circuit is switched on by briefly closing a switch assigned to it, a current pulse via a Capacitor and thereby causes the motor to start. The measure taken here to ensure However, the start-up is quite time-consuming. In addition, the permanent magnet provided here generates when it is running Motor a disturbing alternating torque.

The invention is based on the object of avoiding the disadvantages explained above and in a simple manner Assign a generic motor to increased start-up reliability without special additional equipment create whose commutation device also enables greater temperature independence and thus better utilization of the temperature resistance of modern insulation materials. Furthermore, such a Brushless DC motor also has a start-up with relatively large masses to be driven enable.

This object is achieved according to the invention by what is stated in the characterizing part of claim 1

Features solved.

The present invention is based on the following consideration:

As is known, to control the commutation, it is necessary to know the instantaneous position of the rotor poles relative to the stator, that is, to know the direction of the magnetic exciter induction. The difficulty described above when starting a motor of this type (with commutation by a voltage induced in a stator winding) arises from the fact that the voltage induced in an armature winding is not proportional to the excitation flux Φ, but its change over time, i.e. its derivation according to the Time corresponds

15 hours ■

According to the present invention, this principle-related differentiation can be achieved by a subsequent integration, which is expediently carried out electronically, because it applies

dt + C = k

, German + C.

25th

If an arbitrary integration constant C ^ O is given to such a motor at start-up, this electrically means that a current flows in at least one drive winding when it is switched on and sets the motor in motion. With a suitable design, even very low speeds are sufficient to generate a signal at the output of the integrator, which signal is proportional to the flux Φ , that is to say indicates the direction of the magnetic exciter induction. If the initial condition of the rotor position at the start was not appropriate, this can mean that the motor initially tries to start in the wrong direction. As a result, however, the integrating element becomes effective immediately, the output signal of which indicates the direction and magnitude of the excitation flow Φ independently of the direction of rotation, so that the integrating element then works practically exactly like a Hall generator, for example, i.e. the motor is immediately reversed and runs in the correct direction Direction of rotation high. Since the output signal of the integrator is proportional to the excitation flux Φ , its amplitude is practically independent of the speed, so that such an arrangement is equally suitable for high and low speeds. Since the inicgrierglied .Speichereigenschaften has, it can even vt a iingela'ifencn in the wrong direction motor in the right direction to change direction.

It is of course particularly advantageous when starting up Immediately to specify the correct integral consistency for the rotor position in which the rotor is located is currently located. In practice, this means that one or more of these rotor positions are adequate when switched on Windings receive power, which means that the motor always starts in the correct direction can be achieved expediently in that the motor in a known manner means for generating has a defined starting position of its rotor relative to the stator, for which purpose it is expedient in known per se Way, a permanent magnet cooperating with the rotor is provided on the stator.

A particularly advantageous procedure is that soft iron parts and at least one permanent magnet are provided on the stator, which together define the starting position of the rotor and that the at least one permanent magnet provided on the stator is electrically offset by π · 180 ° C relative to an associated drive stator winding where η = 0, 1,2, ... etc. The magnetic resistance of the iron circle is expediently made variable over the path of rotation in such a way that a driving torque of a predetermined magnitude is available at certain areas of the rotor rotation.

According to a further, very advantageous feature of the invention, this is also done in such a way that the through the effect of the permanent magnet assisted stator winding has a reduced number of ampere-turns and, during operation, preferably generates a torque which is constantly smaller than that of the motor moment to be given. In this way, both the desired starting position and a favorable one are obtained Course of the torque delivered by the engine. A particularly simple and inexpensive solution results further characterized in that the permanent magnet provided on the stator is provided instead of a stator winding is

Further details of the invention emerge from those described below and in the drawing illustrated embodiments. It shows

Fig. 1 shows a first embodiment of a brushless DC motor according to the invention, the in this embodiment is designed as a motor with a flat air gap, seen along the line I-l of the F i g. 2, together with the associated circuit,

2 shows a section through the engine according to FIG. 1, seen along the line H-II of Fig. 1,

3 shows a section, seen along the line 11 I-I 11 the fig. 1,

F i g. 4 diagrams to explain the mode of operation of the FIG. 1 - 3 engine shown,

5 shows a second embodiment of an inventive Circuit in which only the windings of the associated motor are shown,

6 shows a third embodiment of an inventive brushless DC motor,

F i g. 7 shows a section through a brushless direct current motor according to the invention according to a fourth Exemplary embodiment of the invention, seen along the line VII-VII of> ig. 8th,

8 shows a section, seen along the line VIIl-VIII of Fig. 7,

F i g. 9A shows a development of the engine according to FIGS. 7. and 8, in which the dimensions of the air gap for better vcranschatilichiing in greatly enlarged Scale are shown,

9B shows the course of the induction over the in F i g. 9A shown unwound Roiormagnetcn,

Ι · 'ί g. 10 illustration to explain how it works of the engine according to FIGS. 7-9,

11 shows a fifth exemplary embodiment of a device according to the invention brushless direct current motor with only one drive winding,

FIG. 12 shows an alternative to that shown in FIG Circuit, also for operation with a motor that has only a single drive winding,

13 Diagrams for explaining the mode of operation of the engine according to FIG. 11 or 12.

1 shows a plan view of a plate 10 made of insulating material, which has recesses, in which three ironless flat windings 11, 12 and 13 are attached, of which the two to Windings 11 and 12 used to drive the drive are diametrically

opposite, while the third winding 13, which is used to control the commutation, is offset mechanically by 45 ° and 90 ° electrically with respect to the winding 12. (The permanent magnetic disc rotor of this motor has four poles, as indicated by the letters N and 5.)

As shown, the plate 10, which can also carry the electronic switching elements of the motor, for example in the form of a printed circuit, four mounting holes 14 and a central recess

15, through which a shaft 16 protrudes, which at its lower end (based on FIG. 2), in (not shown) Storage is stored. Like F i g. 2 shows are on the shaft

16, held at a precisely predetermined distance from one another by a spacer sleeve 17, two soft iron disks 18 and 19, on each of which an axiai poiarized, ring-shaped permanent magnet 22 or 23 is attached, for example by gluing, that an air gap 26 is formed between these magnetic rings in which the stator plate 10 is arranged.

The position of the pole gaps 24 of the ring magnet 22, which exactly corresponds to the position of the pole gaps of the ring magnet 23 is a mirror image is shown in FIG. 1 indicated with dash-dotted lines. The ring magnets 22 and 23 are respectively magnetized trapezoidally, that is, the induction in them has approximately that in FIG. 9B shown curve, which is of course not exactly trapezoidal, but in electrical engineering referred to as trapezoidal magnetization. This is characterized by relative narrow pole gaps and a wide area with relatively constant induction.

The coil 13, together with the circuit assigned to it, replaces what is usually a commutation element used hall generator. The location of this Hall generator, which is otherwise required but does not exist here is in Fig. 1 is drawn in with dash-dotted lines and labeled 25. This hall generator 25 would therefore be mechanically offset by 45 ° to the center axis of the winding 12, as shown. How one also from FIGS. 1 and 2 recognizes, the windings 12 and 13 are partially on top of each other. With circuits with only one drive winding, as will be described in detail below, the winding can 13 are designed to be completely flat, since the winding 12 is not required there.

In addition, a permanent magnet 30 is fastened in a recess in the stator plate 10, specifically in the area the outer circumference of the rotor designated by 31. The magnet 30 is also axially polarized and, as in FIG F i g. 3, its south pole at the top and its north pole at the bottom, so that it has the rotor 31 in its in FIG position shown pulls when the motor is de-energized To prevent the magnet 30 from rotating Ring magnets 22 and 23 are demagnetized when poles of the same name are opposite each other the ring magnets 22 and 23 and also the magnet 30 have a high coercive field strength, for example greater than that than 2000 Oe, and also part of the magnet 30 is outside of that between the ring magnets 22 and 23 formed air gap 26. As shown, the magnet 30 is somewhat closer to the winding 12 than to the Winding 11 to give the rotor 31 a somewhat asymmetrical starting position in which the (imaginary) Hall generator 25 would already be outside the area of a pole gap 24, as shown. Such The starting position is favorable for the start-up.

To control the current in the two drive windings 11 and 12, a transistor 40 or 41 is provided, the structure of which (so-called npn Darlington circuit) from FIG. 1 shows. The emitters of the transistors 40 and 41 are connected to the minus pole 42 of a DC voltage source of 12 V, for example connected, the plus pole of which is denoted by 43. One connection of the windings 11 and 12 is in each case with connected to the collector of the associated transistor 40 or 41, the other to the positive line 43. The The winding sense and the current direction for the windings 11 and 12 are shown in FIG. 1 drawn.

The winding 13, which is used to control the commutation of the current in the windings 11 and 12, is connected to a passive integrator 44, which has a resistor 45 (z. B. 20 kOhm) and a capacitor 46 (e.g. 50 microfarads). The terminal 47 of the winding 13 is as shown in series with the Resistor 45, the capacitor 46 and the other winding connection 48 connected so that the voltage induced in winding 13 is integrated by integrating element 44 and across capacitor 46 a corresponding alternating voltage is produced, the amplitude of which can be 50 mV, for example. the Winding 13 can be designed, for example, so that the induced in it directly after the start-up process Voltage has approximately the amplitude of 1 V. - The connection 48 is via a Zener diode 49 with the positive line 43, via a resistor 53 to the base of a pnp transistor 54 and via a resistor 55 with the negative line 42 connected.

The connection point, denoted by 56, between resistor 45 and capacitor 46 is with the base a pnp transistor 57 and - connected to the negative line 42 via a capacitor 58. The transistors 54 and 57 together form a differential amplifier, that is, when the current in a transistor increases, the current in the other transistor decreases and vice versa. The emitters of these transistors are used for this purpose each connected via a resistor 61 or 62 to a node 63, which in turn via a resistor 64 is connected to the positive line 43. The collector of transistor 54 is through a resistor 65, a node 66 connected to the base of transistor 40, and a resistor 67 to the Minus line 42 connected. Similarly, the collector of transistor 57 is through a resistor 7G, one with The node 71 connected to the base of the transistor 41 and a resistor 72 to the negative line 42 tied together.

The motor described works as follows:
Before it is switched on, the rotor 31 is in the position shown in FIG. 1 shown rest position. If a DC operating voltage is now applied between the lines 43 and 42, a charging current flows through the Zener diode 49 to the initially uncharged capacitors 46 and 58. (The Zener diode 49, together with the resistor 55, causes the common emitter current of the differential amplifier 54, 57 is practically constant through the common resistor 64.)

The potential of point 56 therefore initially corresponds to the potential of negative line 42 when switched on and then becomes more positive, that is, the transistor 57 is initially fully conductive when switched on and leaves a base current to flow to transistor 41, so that this also becomes fully conductive and a current to the winding 12 flows as a result of this, the rotor 31 rotates clockwise in the direction of arrow 73 (FIG. 1) offset.

When switching on, the capacitor 58 thus generates a current that corresponds to the starting position of the rotor 31 is adapted and causes its startup in the correct direction of rotation. Mathematically speaking, this means that the integrator 44 is given the correct initial condition for this rotor position at the start.

The properties of the differential amplifier cause that the transistors 54 and 40 are blocked as long as the transistors 57 and 41 conduct.

As soon as the rotor 31 rotates, a voltage is induced in the winding 13 which, due to the choice of the number of turns of this winding, is sufficiently high to generate the necessary voltage on the capacitor 46 for modulating the differential amplifier 54, 57. F i g. 4 shows at a) this induced voltage 74 for a low speed / J ₁ and at d) the induced voltage 74 'for a speed twice as high / 72 = 2x / j |. 74 can be, for example, the induced voltage immediately after start-up. (To simplify the illustration, these voltages 74 and 74 'are shown as sinusoidal voltages, although in practice they may differ from the sinusoidal shape; however, this is of no significance for the explanation of the mode of operation.)

The integrated voltage 75 or 75 'across capacitor 46 is shown in FIG. 4 shown in the second row. (Her The amplitude is much smaller than the amplitude of the voltages 74 and 74 ', that is, the curves 75, 75' have a different amplitude scale.) The voltages 75 and 75 'have despite the different sizes of the induced voltages 74 and 74 'as illustrated have practically the same amplitude, for example each 50 mV. This is a consequence of integration; As already stated at the beginning, the voltages 75 and 75 'are dem The flow in the air gap 26 is proportional, and this flow is a quantity which is not dependent on the speed.

As one can see from FIG. 4 recognizes, the integration results in a position of the phase shifted by 90 ° Tension 75 (or 75 ') relative to tension 74 (or 74'). But since the winding 13 by 90 ° electrical to Winding 12 is offset, the amplitude maxima of the voltage 75 (or 75 ') fall with the maxima of the voltages together that are induced by the rotor 31 in the winding 12 (or 11). This is very important for that correct commutation of the currents in the windings 11 and 12, since the current maxima match the maxima of the in These windings induced voltages should coincide in time.

The voltage 75 (or 751 ') on the capacitor 46 thus causes the transistors 54 and 57 to be switched on alternately after startup, so that, as in FIG. 4 at c) and f), the currents iw (in transistor 40 and winding 11) and / ^ ₁ (in transistor 41 and winding 12) are each commutated at the correct point in time. In operation, such an arrangement behaves like the (imaginary) equivalent Hall generator 25 with the essential difference that the temperature resistance (up to approx. 125 ^° C.) in an engine according to the invention is far better than in an engine with a Hall generator, which has a maximum operating temperature of around 65 ° C. In addition, a motor according to the invention results in a better degree of efficiency, since the not inconsiderable direct current required for the operation of the Hall generator is eliminated. The invention thus makes it possible to better utilize a direct current motor.

The engine shown in FIGS. 1 to 4 generated drive torque corresponds roughly to the shape of curves c) or f) according to FIG. 4, that is, this moment has gaps. This is a result of the engine design. If the motor is switched off according to FIGS. 1 to 4, it requires, depending on the flywheel coupled to it, a certain time to run out. If it is switched on again during this period, the result is The described switch-on process occurs again by charging the capacitor 58. In this case, however, is no defined start-up position specified, since the switch-on command is then given at any angular position of the motor is possible, that is, the initial condition which is given to the integrating element 44 in this case may be wrong, so that the rotor 31, for example, by the current in the winding 12 is not driven, but would be braked to a standstill and then stop. For most use cases however, a safe start-up of the motor is required.

The circuit according to FIG. 5, this disadvantage is avoided in a simple manner, namely by that in such a case the switch-on pulse is automatically repeated until the motor starts is. So if the motor is braked at the first switch-on pulse, it can indeed briefly in its through the Permanent magnets 30 predetermined start position stop, but runs at the next switch-on pulse to Example after a second or two, again on.

The circuit according to FIG. 5 is largely identical to the circuit according to FIG. 1 identical. Also that of this circuit The associated motor can be constructed in the same way as the motor according to FIG. 1 - 3.

The following additional switching elements are provided for repeating the switch-on command:

A resistor leads from the collector of transistor 41

80 through a node 81 and a capacitor 82 to the collector of the transistor 57. A diode 83 is with its cathode connected to the base of transistor 54 and with its anode connected to node 81.

The circuit according to FIG. 5 works as follows:

When switched on, the capacitor 46, as already described, receives an initial charge via the capacitor 58. If the motor does not start, this charge is discharged through the resistor within a relatively short time 45 and the winding 13, and the differential Ver stronger 54,57 is then in his electrical Equilibrium in which so little current flows in both transistors 54 and 57 that neither transistor 40 the transistor 41 still conduct. The capacitor 82 is then connected via the winding 12 and the resistors 80, 70, 72 gradually charged until the potential of the node 81 becomes more positive than the potential at the base of the transistor 54. A current then flows through the diode 83 to the base of the transistor 54, which is its collector current reduced and thus - due to the constant emitter current impressed by the resistor 64 - The collector current of the transistor 57 is increased

The voltage drop across the resistor 70 now creates an additional positive feedback effect, since the The voltage at the collector of the transistor 57 now becomes more positive, as a result of which the potential at the node point

81 becomes more positive and transistor 54 is blocked even more. This continues until the transistor 41 is fully conductive, that is, it will be exactly the same Effect achieved, which was achieved by the capacitor 58 at the first start. If the engine starts now, this results in the same mode of operation of the integrating element 44 as was previously described in connection with FIG. 4th

has been described in detail.

If the motor cannot start even now, for example because its rotor 31 is blocked, it will switch Current in transistor 41 by itself after a short time, for example 1/10 second, decreases again because the capacitor B2 is quickly discharged through the base-emitter path of transistor 54. Repeat the process described then according to a time interval predetermined by the size of the components, for example after a few seconds.

Since the motor only receives short current pulses even when the rotor 31 is blocked, it cannot be overheated. This represents a significant additional advantage of the circuit of FIG. 5 (also the engine after F i g. 1 remains de-energized when the rotor 31 is blocked.)

! In normal operation, the potential of point 81 is always more negative than the base of transistor 54, that is, diode 83 is then permanently blocked; the described The device is only effective when the engine has not started; with the engine running it switches itself off.

As already explained, the arrangement according to the invention can practically be imagined as a replacement for a Hall generator, since they are very similar in operation Has properties like one, including two control outputs in antiphase, as well as its size the induction, but not the speed dependent amplitudes of the output signal.

In motors of the usual design, which are usually provided with four windings arranged in a star shape, in order to generate a largely uniform electromagnetic drive torque over the angle of rotation, it is known that two Hall generators are required. These Hall generators can according to the arrangement according to FIG. 6 can also be replaced by arrangements according to the invention in order, for example, to enable higher operating temperatures. There are then two circuits according to FIG. 5 is required, which is shown in FIG. 6 are denoted by 85 and 86, to which initial conditions C1 and C 2 are assigned in each case according to a starting position of the rotor denoted by 88 of this motor 89 predetermined by a permanent magnet 87, for example by appropriate selection of the capacitor 58 according to FIG. 5, in order to ensure a start-up in the desired direction of rotation.

The motor 89 has four drive windings 92,93,94 and 95, each with a connection to plus. The other connections of windings 93 and 95 are connected to the outputs of circuit 85 and the other connections to windings 92 and 94 to the outputs of the circuit 86. A control magnet 95 is coupled to the rotor 88, the 2 measuring windings 96 and 97 are assigned. The voltage induced in the winding 96 during operation is used in the circuit 85 integrated and the voltage induced in the winding 97 is integrated in the circuit 86 for switching on a switch 98 is used, which connects to the negative pole of the DC voltage source

Before switching on, the rotor 88 is in the starting position shown as a result of the magnet 87. When the switch 98 is switched on, the two initial conditions CX and C2 become effective and cause a corresponding current pulse, for example in the stator windings 92 (to attract the rotor magnet 88) and 95 (to repel the rotor magnet 88). The motor then starts clockwise and the two integration circuits, which, as explained, correspond in structure to the circuit according to FIG. 5, then control the commutation.

If the motor does not start, the start repetition (parts 80, 82, 83 according to FIG. 5) becomes effective. Appropriate becomes the repetition interval in the integrating circuits 85 and 86 chosen differently. As a result of the start-up repetition, it can be seen that that the motor initially starts in the wrong direction. As soon as the engine is running, however, both integrating circuits 85, 86 fully effective and control now

ίο turn the motor so that it goes in the right direction runs, that is, such a motor then comes to a short standstill again - with in the capacitor 46 (FIG. 5) a voltage value corresponding to the position of the rotor remains stored - and accordingly With this voltage value, the rotor then starts running in the correct direction. This also shows very clearly the Analogous to the Hall generator, which automatically reverses the direction of rotation when the engine is running, for example is started manually in the wrong direction.

In a variant of this, not shown in the drawing, the rotor magnet 88 acts directly on the measuring windings 96,97 by wrapping them directly in the stator in a suitable manner, for example. Of the Control magnet 95 is then unnecessary.

Another embodiment of a motor according to the invention is shown in FIGS. 7-9. The one shown there Motor 100, the mechanical structure of which is only indicated schematically, is an external rotor motor, its Rotor 101 a radially magnetized. 2-pole, massive Has magnetic ring. For a better illustration, a - purely hypothetical, i.e. in Equivalent Hall generator 102, which does not exist in reality, is shown. Also is for better illustration the north pole area of the rotor 101 is hatched and the south pole area is shown dotted. Like F i g. 9B shows, here too the induction profile over the rotor is trapezoidal in the sense of the above Executions. The pole gaps are labeled 103 and 104. The magnetic ring 101 is by means of an encompassing it Pot 105 connected to a shaft 106 which is mounted in a bearing 107 shown schematically is.

The stator 110 is attached to a stationary part 111 and has a double-T shape with the ends of the salient poles 112, 113 almost butting against each other and just enough space to introduce two connected in series via a center tap 114 Drive windings 115, 116 remain, the connections of which are labeled 117 and 118. The windings 115, 116 suitably have different wire sizes and / or different numbers of turns in this construction, in order to achieve a different number of ampere turns in these windings during operation. Naturally the same effect can also be achieved by using the same number of turns but different sizes Currents Used The winding 116 may, for example, have a smaller number of turns. The grooves for the windings 115, 116 are designated 119 and 120

Offset by 90 ° electrically (and mechanically) to the windings 115 and 116 is in two grooves 121, 122 of the Stator 110 housed a winding 123, which Provides output signal for the integrating element, for example for the integrating element 44 according to FIG. 5. Your outputs are denoted by 124. The direction of rotation specified by the shape of the air gap in this motor is through an arrow 125 indicated.

In the middle of the poles 112, 113 , a radially polarized permanent magnet 126 or 127 is attached. Both magnets 126 and 127 have their south pole at the top and their north pole at the bottom (with reference to FIG. 7). As shown, the magnets can each electrically extend over an angle of approximately 90 °. They are expediently glued into corresponding depressions in the stator after the winding 123 has been introduced

Is to make the magnetic resistance of the air gap indicated at 130 rotation angle epending and thereby generate a reluctance torque of very specific shape, as the below with reference to Fig. 10 explained, the outer periphery of the poles 112, 113, a very specific shape that best from the settlement according to FIG. 9A. Accordingly, the actual air gap 130 , that is measurable by means of a measuring instrument, increases from the grooves 119 or 120 viewed in the direction of rotation over a relatively short angular path of, for example, 30 ° electrically up to a maximum 131 or 131 'and from there monotonously down to the next groove.

Since the grooves 119, 120 practically represent an enlargement of the actual air gap, the equivalent, that is to say magnetically effective air gap can be approximated by the dashed lines 132 and 132 '. This equivalent air gap thus has its minima 133 or 133 ', viewed in the direction of rotation, in front of the assigned groove, for example 30 ° electrically in front of it.

Runs in the form of induction according to FIG. 9B shows a pole gap (e.g. 103) of the rotor 101 in the direction of rotation 125 over an area of decreasing air gap, the rotor 101 must be driven for this purpose, that is to say, an in FIG. 10c with 134 designated braking reluctance torque. Is reversed such a pole gap (eg., 103) over an area expanding equivalent air gap of time, as this causes a driving reluctance torque, which is designated in FIG. 10c with 135 The shape of the moments 134 and 135 can be seen from the shape of the equivalent air gap and can therefore be selected according to requirements.

The permanent magnets 126 and 127 also produce a moment during operation, the shape of which is shown in FIG. 10b. If the rotor 101 is moved, for example, from its position according to FIG. 7 further rotated in the direction of rotation, it must be driven for this purpose. This braking moment is denoted by 136 in FIG. 10b. A driving torque labeled 137 then begins approximately 180 ° further electrically.

Adding the torque curves according to Fig. 10b and 10c, the curve according to FIG. 10d is obtained, that is to say, this is the torque curve which is measured, for example, with the spring balance when determining the torques acting on the rotor 101 with the motor in the various rotational positions de-energized. The torque curve according to FIG. 1Od has the value zero in two places 138 and 139. Point 138 corresponds to that in FIGS. 7 and 9A shown stable rest position. The corresponding angle alpha is entered in FIG. 7 and in FIG. 10d. The point 139 corresponds to an unstable rotor position from which the rotor 101 rotates with the slightest vibration. The distance between the point 139 and the subsequent stable point 138 ' is, as shown, greater than 180 ° electrical, which is important for the present invention insofar as one reaches the points 138 and 139 both in the first two Quadrants (0 to 180 ° electrical) so that the motor will still start in the correct direction even if it happened to come to a standstill in the unstable position 139 (the same applies to curve 159 according to FIG. 13d and its points 160 and 161).

Corresponding to the asymmetrical shape of the torque shown in FIG. 10d, so to speak built into the motor, the electromagnetic drive torque generated by the two drive windings 115, 116 must also be of different magnitude.

ίο This can be explained physically in such a way that the effect of the winding 116 is supported by the permanent magnets 126 and 127 , while these permanent magnets counteract the electromagnetic drive torque generated by the winding 115 , or in other words: the motor stores part of the current in the winding 115 in the motor pumped energy and releases this energy in the gaps of the electromagnetic drive torque, which are designated in Fig. 10a with 141 and 142 , and during the duration of the weaker electromagnetic drive torque. The drive torque generated by the coil 15 is designated 1 in Fig. 10a with Mus, the torque generated by the winding 116 Λίπβ
If we add the curves according to FIG. 10a and FIG. 1 Od, one obtains the in FIG. 10e shown, gap-free torque curve with which such a motor drives its load. The total _torque M gcs shown in Fig. 10e has a largely constant curve.
In the case of the engine according to FIG. 7, the coil 115 to the transistor 41 according to Figure 5, the coil 116 to the transistor 40 and the winding is thus 123 connected to the integrator 44 in the operation. When switching on, the winding 115 first receives current (through the capacitor 58 which determines the initial charge), so that the motor moves in the direction of arrow 125 from its position in FIG. 7 starts up, after which the integrating element 44 becomes effective as soon as a sufficiently high voltage is induced in the winding 123. The integrator then has practically the same effect as that in FIGS. Equivalent Hall generator 102 shown in FIGS. 7 and 9A.

Compared to the in F i g. The engine structure shown in FIG. 1 has the structure according to FIG. 7 - regardless of the way in which the commutation takes place - the essential advantage that the magnets 126 and 127 bring about the correct starting position, but generate a braking moment during operation, but not a moment which disturbs the overall course. In the embodiment according to FIG. 1, on the other hand, the magnet 30 causes a moment that is superimposed on the moment generated by the windings 11 and 12 as a disturbing alternating moment, and this practically forces this magnet 30 to be made as weak as possible. In the embodiment according to FIG. 7, on the other hand, the magnets 126 and 127 are always chosen to be strong enough so that they pull the rotor 101 into the desired starting position.

The motor according to FIGS. 7-10 can go further be simplified, and one then comes to the construction according to FIG. 11, which only has a single drive winding needed. (A construction of a flat motor analogous to the construction according to FIG. 11 is shown in in DE-OS 22 60 069, to which express reference is made to avoid excessive lengths will.)

The mechanical structure of the engine according to FIG. 11th corresponds to that of the engine according to FIGS. 7 to 10. The only drive winding of the motor after

F i g. 11 is denoted by 142. One connection is connected to the plus line 43 , the other connection to the collector of an npn transistor 143, the emitter of which is connected to the minus line 42. The integral element to which the winding 123 is connected here an active integral element in the form of a so-called Miller integrator 144 with an npn transistor 145, between whose collector and base an integrating capacitor 146 of, for example, 3 microfarads and a resistor 147 parallel to it are connected. The base of the transistor 145 is connected via a resistor 148 to one terminal of the winding 123 , the other terminal of which is connected to the negative line 42

A resistor 151 leads from the collector of the transistor 145 to the plus line 43 and a resistor 152 to the base of a pnp transistor 153, the emitter of which is connected to the plus line 43 and its collector via a resistor 154, one connected to the base of the transistor 143 Junction 155 and a resistor 156 are connected to the minus line 42

In the case of the engine according to FIG. 11, the permanent magnets 126 and 127 provided on the stator 110 are selected to be stronger than in the motor according to FIG. 7, so that the torque 157 generated by them during operation (FIG. 13b) has a greater amplitude. The reluctance torque 158 shown in FIG. 13c, on the other hand, has approximately the same form as that in FIG. 1 Oc moment shown. (The magnetization of the rotor 101 in FIG. 1 also has the course shown in FIG. 9B.) Correspondingly, a different form of the sum moment 159 shown in FIG. 13d results from the moments 157 and 158. The moment 159 has a stable point 160 corresponding to the rotor position according to FIG. 11 and an unstable point 161, both of which lie electrically within the first two quadrants, that is to say within the angular range of 0-180 °. The advantage already explained in FIG. 10 results in that the motor starts up in the correct direction of rotation even if it happens to have stopped in its unstable position 161.

The electromagnetic drive torque generated by the winding 142 during operation is shown in FIG. 13a and designated 162. Since it is electrically effective for less than 180 °, its gaps designated 265 must be bridged by the torque 159 (FIG. 13d), and by adding the moments 162 and 159 _{one obtains the gap-} free total moment M gcs shown in FIG. 13e , which has a largely uniform course.

The engine according to FIG. 11 works as follows:
When the engine is switched off, the rotor 101 is in the stable position 160 according to FIG. 13d, which is also shown in FIG. 11 is shown. If a voltage is now applied to the lines 42 and 43 , the capacitor 146 of the integrating element 144 is initially uncharged, so that the transistor 145 immediately becomes conductive and, in turn, controls the transistors 153 and 143 to be conductive, so that a current flows through the winding 142 and the rotor 101 is driven in the direction of arrow 125 .

As soon as the rotor 101 rotates, it induces in the μ · ^"0 Qn electrically offset Wickiup ** i? 3 * pin" which is integrated in the integrator 144, and then controls the current in the winding 142 so epnung S ^n, that the moment form 162 according to FIG. 13a results. If the integrator 144 were an ideal integrator, the motor according to FIG. 11 could continuously operate at any desired low speeds and thus accelerate any desired centrifugal masses. Practice has shown that the in F i g. The very simple integrating circuit shown in FIG. 11 is sufficient to reliably accelerate fairly large centrifugal masses, for example centrifugal masses which can be up to 30 times the moment of inertia of the rotor 101 .

Of course, you can operate the engine according to FIG. 11 also shows the integration circuits according to FIG. 1 or F i g. 5, in which case only one of the two outputs of the differential amplifier 54, 57 is used.

If in the circuit according to FIG. 11 wants to achieve that the integrating circuit 144 is still supplied with current after the motor has been switched off until the motor has come to a standstill, it is expedient to see a diode 164 in series with a resistor 165 in the supply line to the integrating circuit 144 , with over this diode 164 a relatively large capacitor 166 is fed. This capacitor 166 charges up during operation and, after being switched off, feeds the integrating circuit 144 until the motor comes to a standstill. If the motor is switched on again while it is coasting down, the integrating circuit 144 is still in operation and can immediately take over the control of the current in the winding 142 again. In this circuit variant, the diode 164 prevents current from flowing from the capacitor 166 to the transistors 153 and 143

F i g. 12 shows a further variant of the circuit according to FIG. 11. The integrator 170 is here as in FIGS. 1 and 5 are designed as passive integrators and consist of a capacitor 171 (e.g. 50 microfarads) which is fed from the winding 123 via a resistor 172 (e.g. 20 kOhm). An operational amplifier 173, which is known to have a high input resistance of, for example, 1 MOhm and is therefore particularly well suited for this task, is used to amplify the integrated voltage on the capacitor 171, which is naturally only very small. The one electrode of the capacitor 171 is connected through a resistor 179 to the output 180 and via a resistor 175 to the positive input 176 of the amplifier 173, its other electrode connected to the negative input 177. Further, this other electrode via a capacitor 178 , which defines the initial condition for the integration, connected to the plus line 43 . The input 176 is also connected to a voltage divider 183, 184 which defines the operating point of the amplifier. (The ratio of resistors 175 and 179 determines the gain factor.) - At output 180 is the

so the base of a pnp transistor 185 is connected, the emitter of which is connected to a voltage divider 186, 187 and the collector of which is connected via a resistor 188 to the line 42 and directly to the base of an npn power transistor 189 , the emitter of which is connected to the line 42 and the collector of which is connected to the line 43 via the winding 142 .

The circuit according to FIG. 12 works as follows:
Before it is switched on, the motor has its position shown in FIG. 11 shown stable rest position. When switched on, the capacitor 171 receives a current pulse via the starting capacitor 178 , which charges the former to a defined output voltage. This voltage controls the amplifier 173 in such a way that the transistors 185 and 189 become conductive and thus the start-up of the motor begins. As soon as the rotor 101 (FIG. 11) rotates, a voltage is induced in the winding 123 , which is integrated in the integrating element 170 and the further control of the amplifier 173 and thus the current in the single

17th

gene drive winding 142 takes over

The integration circuit 170 of FIG. 12 continues to work after switching off the supply voltage, so that this integration circuit 170 immediately takes over the control of the amplifier 173 again can if the engine is restarted while coasting. The resulting renewed switch-on pulse of the capacitor 178 is largely suppressed in this case. It is particularly expedient in FIG in this case, when the time constant A - C of the integration circuit 170 is approximately the same as the time after the switching off of the operating voltage passes until the rotor 101 comes to a standstill

The invention thus enables a substantial increase in the operating temperature at is with simple means brushless DC motors. By eliminating the need for the Hall generator or generators Control current, the efficiency is also significantly improved, especially with smaller motors, so that even with these efficiencies in the order of magnitude of 70% with the invention without special Efforts are achievable.

In addition 7 sheets of drawings

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Claims (1)

Patent claims: 1. Commutatorless direct current motor with a permanent magnetic rotor and at least one with this cooperating drive stator winding, which is a semiconductor element of a Commutation circuit 7 is assigned to control the current flowing in it, with an active, draws its energy directly from the rotor during operation, through its output signal with the semiconductor element cooperating rotor position transmitter, means for generating a defined starting position of the rotor relative to the stator, as well as a device that is independent of the output signal of the rotor position transmitter causes a drive torque on the rotor during the switch-on process marked that