JPH0421390A - Brushless motor drive system - Google Patents

Abstract

PURPOSE:To regulate the phase of driving current electrically to a predetermined amount by obtaining a sine wave and a cosine wave from two position detecting elements and then adding/subtracting one of them to/from the other with same ratio through an amplifier. CONSTITUTION:A variable gain amplifier 52c multiplies a 90 deg. leading position detection signal C by K to produce a signal KC which is then added to a position signal S in an adder/subtractor 52a thus producing a position detection signal +Ss having phase lead alpha ahead S. A variable gain amplifier 52d multiplies a 90 deg. phase leading position detection signal -S by K to produce a signal -KS which is then added to the position detection signal C in an adder/subtractor 52b thus producing a position detection signal +Cs having phase lead alpha ahead S. The adder/subtractor then adds the signals +Ss, +Cs and their inverted signals -Ss, -Cs, while weighing according to a resistance ratio, thus combining the timing signal.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Industrial field of application B. Outline of the invention C1. Prior art 1. Problem to be solved by the invention E. Means for solving the problem F1. Effect G. Example G1. Brushless motor configuration and position detection element arrangement (
Figure 1) Configuration of Gx and brushless motor drive circuit (Figures 2 and 3)
Figure) G3. Operation and effects of the embodiment (Figures 4 and 5) G4
．． Application Examples (Figures 6 and 7) H1 Effects of the Invention A Industrial Field of Application The present invention relates to a brushless motor drive system that is particularly suitable for multi-phase drive of an iron-core brushless motor that rotates in both directions. .

B2 Summary of the Invention The present invention is a method of driving a brushless motor having a multi-phase magnetic circuit configuration, in which the outputs of two position detection elements are made into sine waves and cosine waves, and these waves are sent to each other at the same ratio through an amplification means. By adding and subtracting, the switching timing in multiphase drive can be electrically advanced as desired.

C1 Conventional technology Conventionally, a magnet is arranged on the rotor, and a drive coil and a position detection element such as a Hall element, which constitute a multiphase magnetic circuit, are arranged on the stator, and the position of the magnet is detected by this position detection element. Brushless motors are known in which a rotor is rotated by controlling the current flowing through a drive coil to constantly generate rotational force in a magnet. A conventional example of such a drive device for a brushless motor is disclosed in Japanese Patent Application Laid-Open No. 60
There is one disclosed in No.-134792. moreover,
BACKGROUND ART Known brushless motors have a structure in which a drive coil is wound around a slot in an iron core, as a type of brushless motor based on the structure on the stator side.

D3 Problems to be Solved by the Invention However, in the iron-core brushless motor according to the above-mentioned conventional technology, when a large current flows through the drive coil, the position detection element such as a Hall element is affected by the magnetic field created by the current. The problem was that the output waveform of the motor was distorted, or the switching timing of the drive current was delayed, making it impossible to obtain sufficient motor characteristics. Furthermore, during high-speed rotation, the drive current lags behind the timing of the switching due to the inductance of the drive coil, resulting in the problem that the rotation speed cannot be increased sufficiently. In this case, for spindle motors that rotate in one direction and at a constant speed, there are known methods, such as shifting the mounting position of the position detection element in the advancing direction to advance the phase of the drive current. In the case of variable speed or variable speed, the amount of advance changes, so it could only be applied in limited cases.

The present invention was devised to solve the above problems, and an object of the present invention is to provide a brushless motor drive method that can electrically adjust the phase of a drive current to a predetermined amount.

E9 Means for Solving Problem The structure of the drive system of the brushless motor of the present invention to achieve the above-mentioned object is as follows: means for controlling the current flowing through the drive coil to rotate a rotor made of magnets; Two position detection elements are placed at a 90 degree electrical angle so that their respective outputs are sine waves and cosine waves at positions that are not affected by the magnetic field created by the current of the drive coil, and the gain is adjusted by an external electrical signal. The present invention is characterized in that the sine wave and cosine wave are added to and subtracted from each other through variable amplification means, and the timing necessary for controlling the current is created from the result of the addition and subtraction.

F1 action The present invention obtains a sine wave and a cosine wave from two position detection elements, and adds and subtracts them to each other at the same ratio through an amplification means, thereby changing the phase of the sine wave and cosine wave, and generating a sine wave. By controlling the gain of the amplifying means to control the timing phase of the drive coil current created from the cosine wave, the phase of the drive coil current can be electrically controlled to a predetermined amount.

G. EXAMPLES Hereinafter, examples of the present invention will be described in detail based on the drawings.

G. Configuration of brushless motor and arrangement of position detection elements (Figure 1) Figures 1 (a) and (b) show the configuration of an iron core type planless motor and the arrangement of position detection elements in an embodiment of the present invention. It is an explanatory view showing arrangement. (a) shows the iron core l that makes up the stator.
This is a plan view of the figure, and H5 and Hc are Hall elements of position detection elements. These two Hall elements Hs and Hc are arranged at an electrical angle of 90° in the commutating pole portion la of the iron core l. (b
) shows a cross-sectional view of the brushless motor having the above-mentioned iron core l, 2 is a rotor yoke that rotates around the shaft 2a, and 3 is an annular shape fixed to the inside of the rotor yoke 2 so as to face the magnetic pole of the iron core l. The magnet 4 is an annular FG magnet for detecting rotation.

The planless motor in this embodiment has a five-phase magnetic circuit configuration, and the magnet 3 on the rotor side has a 20-pole configuration. Here, the iron core L has slots formed to have 20 equally spaced poles for winding the drive coils A, B, C, D, and E of each phase, and a complementary pole part for the I pole where no drive coil is wound. 1a. The commutative pole portion 1a is provided corresponding to the two poles of the magnet 3, and the remaining 20 poles for winding the drive coil are provided corresponding to the 18 poles of the magnet 3, with a mechanical angle of 1.
6. Provided at 2° intervals. +A, - shown in FIG. 1(a)
In A, . . ., A, etc. are drive coils such as A phase, +
indicates forward winding, - indicates reverse winding, and the l-phase drive coil has four poles: positive, reverse, and positive.

It consists of four windings wound in opposite directions and connected in series. Hereinafter, the drive coils for the B phase, C phase, D phase and 1E phase are similarly configured.

In such a brushless motor, the two Hall elements Hs and Hc are located near the magnet 3 and near the commutative pole portion 1a at an interval of 90° electrical angle (9° mechanical angle). Deploy. Thereby, each Hall element Hs, Hc can detect the position of the magnetic pole of the rotating magnet 3 as a sine wave or a cosine wave without being affected by the magnetic field created by the current flowing through the drive coils AE. These sine waves and cosine waves are input to the subsequent drive circuit,
The switching timing of the drive coil current is created, and five-phase drive is performed.

Configuration of drive circuit for Gx and brushless motor (FIGS. 2 and 3) Next, an embodiment of the drive circuit will be described.

FIG. 2 is a block diagram showing the configuration of a brushless motor drive circuit in one embodiment of the present invention.

The drive circuit 5 of this embodiment includes the two Hall elements H5 described above.
, the Hall voltage output of HC is amplified and the position detection signal ±S (=
±sinθ), +C(-+cosθ), and a phase lead position detection signal ±Ss, ±05 which is electrically advanced by a predetermined phase in response to these position detection signals ±S, +C. The phase advance circuit 52 to be created and the five-phase switching timing signal TA are obtained by multiplying these signals ±Ss and ±05 by a coefficient based on the resistance ratio and performing addition and subtraction.
, TB, TCTD, Tl: Addition/subtraction circuit 5
3, an energization waveform synthesis circuit 54 that creates an energization signal waveform for each phase by combining the five-phase timing signals T A - T e, and a voltage amplitude control circuit 55 that controls the voltage amplitude of the energization signal by current feedback. , a voltage-current conversion circuit 56 converts the energization signal voltage into a current, and the motor power supply Vcc+ is switched with the current to bidirectionally energize the coils A, B, CD, and E of the five-phase star-connected brushless motor. It is composed of a driver circuit 57 that performs phase drive.

First, the configuration regarding the phase lead circuit 52 will be described.

FIG. 3 is a circuit diagram showing its configuration.

Each Hall element Hs, Hc is connected to a 5V voltage source Vcc.
2, a bias current is caused to flow through the resistors R, , R2. If the output of one Hall element Hs is a sine wave (sinθ), the output of the other Hall element Hc is a cosine wave (cos
θ). The Hall element amplifier 51 includes three differential amplifiers 51a and 51b each consisting of an operational amplifier and a resistor.
, 51c, the output of the Hall element H5 is input to the amplifier 51a, the output of the Hall element HC is input to the amplifier 51b, and the output of the Hall element Hs is input with opposite polarity to the amplifier 51c. These human powers are used for each differential amplifier 51
The inverting input (-
) side through a resistor, and its non-inverting input (+) side is given a reference level of v cat/2. As a result of the above, the position detection signal S is output from the amplifier 51a.
The amplifier 51b outputs a position detection signal C, and the amplifier 5
The output of 1c is a position detection signal -8 which is in an inverse relationship with +S.
is obtained.

The phase advance circuit 52 includes two two-man-powered addition/subtraction circuits 52a.
, 52b, and two non-inverting variable gain amplifiers 52.
52d, two inverting amplifiers 52e and 52f, a current source 52g and a switch circuit 52h, and a gain control circuit including an external resistor R5. The variable gain amplifier 52cy52cl can vary the gain K according to the voltage generated in the external resistor R5 connected to the shift set terminal (SHIFT 5ET), and controls the switch circuit 52h by inputting to the shift terminal (SHIFT). When closed, the gain K can be set to 0. Non-inverting input (+) of variable gain amplifier 52c
A position detection signal C is input to the side, a position detection signal -8 is input to the non-inverting input (+) side of the variable gain amplifier 52d, and V is input to each inverting input (-) side. o, /2
A reference level is given. In the addition/subtraction circuit 52a, the position detection signal S and the position detection signal C multiplied through the variable gain amplifier 52c are added on the inverting input ( ) side, and the phase is advanced by an electrical angle α determined by the gain. A position detection signal -5s (=-sin(θ+α)) is created. Further, in the addition/subtraction circuit 52b, the position detection signal terminal C and the variable gain amplifier 52cl are connected to the inverting input (-) side.
The multiplied position detection signal -8 is added through
Similarly, a position detection signal =05 (=-cos(θ+α)) whose phase is advanced by an electrical angle α determined by the gain is created. A reference level of V((, /2) is applied to the non-inverting input (+) side of the adder/subtractor circuits 52a, 52b. The signal is input to the inverting input (-) side and inverted, and the inverted position detection signals +Ss and +Cs are obtained as respective outputs.

Next, returning to FIG. 2, the configuration of the addition/subtraction circuit 53 that creates a timing signal for switching the drive coil current will be described. The addition/subtraction circuit 53 includes four operational amplifiers 53a, 53
It consists of four adder circuits consisting of 53b, 53c, and 53cl. In the adder circuit of the operational amplifier 53a, the position detection signal Ss is connected to the inverting input terminal (-) of the operational amplifier 53a through a resistor R3, and the position detection signal -
Cs and its own output is connected through a resistor R5, and the reference level of V CC2/2 is applied to its non-inverting input terminal (+) through a resistor R6. Similarly, in the adder circuit of the operational amplifier 53b, the inverting input terminal (-) of the operational amplifier 5'3b is connected to
The position detection signal -8s is connected through the resistor R7, the position detection signal -Cs is connected through the resistor R8, and its own output is connected through the resistor R9, and the reference level Vcct/2 is applied through the resistor RIQ. Also, operational amplifier 5
In the adder circuit 3c, the position signal -Ss is connected to the inverting input terminal (-) of the operational amplifier 53c through the resistor R11, the position signal terminal 0s is connected through the resistor R1, and its own output is connected through the resistor R33. Reference level V through R14. . , gives /2. In addition, in the addition circuit of the operational amplifier 53d, a position detection signal terminal 85 is connected to the inverting input terminal (-) of the operational amplifier 53d through a resistor R15.
, position signal terminal 〇s through resistor R18, resistor R17
Connect their own outputs through +I
lc+! -T'3 7- "'g I == Neck HA
l, I+I, MV/Q k-k-樑With the above configuration, a timing signal TB is obtained at the output of the adder circuit of the operational amplifier 53a, and a timing signal T is obtained at the output of the adder circuit of the operational amplifier 53b.

is obtained, a timing signal TD is obtained at the output of the adder circuit of the operational amplifier 53c, and a timing signal TE is obtained at the output of the adder circuit of the operational amplifier 53d. Here, the timing signal TA is obtained as TA=+S5.

The driver circuit 57 includes npn type power transistors T whose respective collectors are connected to the motor power supply Vcc+.
r +, T r! + T rs, T r4+ T
rs and one end to the power ground G of the motor power supply VCC+
An npn type power transistor Tr whose respective emitters are connected to the other end of a common feedback resistor R7 connected to ND.
e, Trt, Tre, Tr+++ Trio,
The power transistors Tr + and Tr 6 are connected by emitter and collector to the coil A, and the power transistors Tr 2. Connect T r 7 at the emitter and collector, connect it to coil B, and connect the power transistor hA-〒
-9-1-2-h L -+ l, h)+-Rashi 1
The coil C is connected to the power transistor TraTr.
The emitter and collector are connected to the coil D, and the power transistor Tr5. Tr+. The emitter and collector are connected to the coil E. Emitter of each power transistor Tre~Tr+a and feedback resistor R
The connection point of r is connected to one of the inputs of a comparator circuit 58 for controlling the amplitude of the voltage amplitude control circuit 55. A control signal corresponding to the motor command signal is connected to the other input of the comparison circuit 58. This control signal is the comparator circuit 5
Output from 9. The comparison input of the comparison circuit 59 receives the motor command signal VCTL and a constant level reference voltage V.
REF is connected and V as the above control signal.

Output TL VREF. Note that the energization waveform synthesis circuit 54 can switch the energization signal waveform and switch the energization angle as necessary to obtain static characteristics that match the motor state.

G3. Operations and effects of the embodiment (FIGS. 4 and 5) The operations and effects of the embodiment configured as described above will be described.

FIG. 4 is an explanatory diagram of the dam, in which two Hall elements H
Position detection signal S with a 90° phase difference obtained from s and Hc,
A vector diagram is shown in the case where a signal 55Cs that is advanced by a predetermined phase α from C is obtained. The position detection signal S is multiplied by the position detection signal C advanced by 90 degrees by the variable gain amplifier 52c, and becomes the signal KC, which is sent to the addition/subtraction circuit 52a.
Therefore, a position detection signal 188 whose phase is ahead of S by α is obtained. In addition, position detection signal C
, the position detection signal advanced by 9° is multiplied by -8 by the variable gain amplifier 52d, and the signal -KS is added in the addition/subtraction circuit 52b. A detection signal of 10 seconds is obtained.

The signals +Ss, +Cs obtained here and the signals -Ss, Cs obtained by inverting each of them are weighted and added in the adding/subtracting circuit 53 as follows according to the resistance ratio. Timing signal TA that is the basis of the phase energization signal.

It is possible to synthesize TB, TC, To, and TE.

T A-+S, s= sin (θ+α) T B=
0.309x 5in (θ1α) 0.951Xco
s(θ+α) sin(θ+α−72°) T c−−0,809X 5in(θ+a ) −0,
588x cos(θ+α) sin(θ0a −144
°) To=-0,809X 5in(θ+α)+0.5
88xcos(θ+α)-sin(θ+α-216°) T t--0,309X 5in(θ+α)+〇,9
51X cos(θ+α)=sin(θ+α−288@
) An example of the resistance value to realize the weighted addition and subtraction as described above is R3 = R1s = 6, 47 kΩ.
R4”Rre=2, I Ok Q, Ra=R
11”” R+s=R17=10Ω, R,=R,,
= 1.4 kΩ, R7=Ω to RII2.47, R*=
RIx=3.40 and Ω, R1°=R14-1,3 and Ω.

As is clear from the above equations, even in the five-phase timing signals, the phase can be advanced by α, and this electrical angle α changes the gain K of the variable gain amplifiers 52c and 52d by setting the external resistor R8. By changing, the phase of the five-phase energization signal can be freely adjusted electrically because it can be changed arbitrarily. When the operating state of the motor is at the rated load and at low speed, it is better not to advance the phase, so control the shift terminal (SHIFT) to turn on the switch circuit 52h and set the gain = O. . During high-speed rotation, the switch circuit is turned off and the phase is advanced by the amount set in the gain corresponding to the voltage generated across the external resistor R5. In this case, as shown in the application example below, the shift set terminal (SHIFT 5ET
) can also be linearly controlled according to the motor speed signal.

FIG. 5 is a motor characteristic diagram showing the effects of this embodiment. (1) and (2) show the characteristics of rotation speed N and current I with respect to torque T when the phase of the energization signal is adjusted at high speed and low speed according to the above example, and (3) and (4) shows the characteristics of the same brushless motor when the phase lead is adjusted to be constant by adjusting the position of the pole element as in the conventional case.

As is clear from this extraneous factor, the above embodiment can improve motor characteristics such as widening the dynamic range.

G4. Application example (Fig. 6, Fig. 7) Next, an application example of the above embodiment will be described.

FIG. 6 is an explanatory diagram showing the first application example.

In this application example, the phase advance angle α is automatically adjusted according to the speed of the motor. Timing signals TA and Ta for creating the energization signal shown in (a).

By comparing TC, TD, and TE respectively and taking their exclusive OR, the speed signal shown in (b) can be obtained. Alternatively, the speed signal can also be obtained from the detection output of the FG magnet 4 shown in FIG. In this application example, these speed signals f are converted into (frequency) - ■ (voltage) to obtain the second
This is the voltage signal of the shift set terminal (SHIFT 5ET) in the figure.

Since this voltage signal changes according to the speed signal, the gains of the variable gain amplifiers 5-2c and 52d change according to the rotational speed of the motor, and therefore the phase advance angle α of the timing signal also changes according to the rotational speed of the motor. Can be switched.

FIGS. 7(a), (b), and (c) show an example of a circuit that simply obtains the voltage signal from the speed signal and its voltage signal waveform. Resistor R1 between 5v voltage source Vcct and ground
A switching circuit consisting of an NPN transistor Tr, . The collector output of this transistor Tr is directly connected to the base of the next stage npn) transistor Trtt,
Its collector is connected to a voltage source VCCt, and its emitter is connected to a current source 6, which has one end connected to signal ground, and a capacitor C1, which has one end connected to a voltage source VC,. The transistor T r , , is turned off/on by turning on/off the transistor Tr , , and is charged from +5V to Ov by the current source 6 when turned off, and discharged from OV to +5■ when turned on. At this time, the charging time constant is constant, so at high speeds shown in (b), the charging interval is short, so the average voltage V Avy is high, and at low speeds, shown in (c), the discharge intervals are long, so the average voltage VA
VE becomes low, and it is possible to obtain a voltage signal (2) to be applied to the shift set terminal according to the speed signal.

As a second application example of the present invention, the voltage signal (vr, etc.) obtained in the above first application example is
Created and added the voltage Vr proportional to the current from 7
, +VI to the 7-ftset terminal (SHIFT 5
ET) voltage signal.

This also makes it possible to improve the motor characteristics to a greater degree than the above.

As a third application example of the present invention, the gain control circuit shown in FIG. 2 is separately prepared for two variable gain amplifiers 52c and 52cl for setting the amount of phase lead. In this application example, the mounting accuracy of the Hall elements Hs and Hc can be electrically calibrated by selectively mounting a resistor (corresponding to R5) of each gain control circuit. However, in this case,
Since lead/lag compensation is required, a circuit configuration is required in which the gain takes on positive and negative values.

In addition, in Figure (b), the outer F of the FG magnet
If the Hall element is placed at a position away from the iron core 1, such as in the section, it will be less susceptible to the influence of the magnetic field created by the current of the drive coil, and it can be applied to ordinary iron core type brushless motors that do not have the commutating pole section 1a. is also possible. Further, other sensors such as a magnetically sensitive element can be used in place of the Hall element. Furthermore, the present invention is applicable to brushless motors configured with a number of coils and magnet poles other than those in the above embodiments, and is also applicable to brushless motors with a polyphase configuration including three phases other than five phases. be able to. As described above, the present invention can be applied in various ways and can take various embodiments in accordance with its gist.

H1 Effects of the Invention As is clear from the above explanation, according to the brushless motor drive method of the present invention, the phase of the drive coil current can be electrically controlled by controlling the gain of the amplification means. In the case of an iron core type brushless motor, a planless motor that rotates in both directions, or a case where the rotation speed changes from low to high speed, the motor characteristics can be improved by controlling the motor.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are explanatory diagrams showing the configuration of an iron-core brushless motor and the arrangement of position detection elements in an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the configuration of a brushless motor in an embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of the drive circuit, FIG. 3 is a circuit diagram showing the configuration of the phase advance circuit in the above embodiment, FIG. 4 is an explanatory diagram of the operation and effect of the above embodiment, and FIG. FIG. 6 is a motor characteristic diagram showing the effect. FIGS. 7(a), (b), and (c) are explanatory diagrams showing a first application example of the present invention. l... Iron core, 2... Rotor yoke, 3... Magnet, 5... Drive circuit, 52... Phase lead circuit, 5
2a, 52b...addition/subtraction circuit, 52c, 52d...
Variable gain amplifier, Hs, Hc-Hall element, A,
B, C, D. E-... Drive coil, TA, TB, TC, To TE
- Switching timing signals. (b) 1 prize, 3 prizes, 3 votes to 1 ML 8, 1 figure, 5

Claims (1)

[Claims] (1) A means for rotating a rotor made of magnets by controlling the current flowing through the drive coil, and a position detection element of the magnet at an electrical angle of 90 degrees so that the respective outputs become sine waves and cosine waves. The above sine wave and cosine wave are added to and subtracted from each other through an amplifying means whose gain is changed by an external electrical signal, and the above current is calculated from the result of the addition and subtraction. A brushless motor drive system that is characterized by creating the timing necessary for control.