JP4143958B2 - DC brushless motor parallel drive circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a parallel drive circuit for driving a plurality of DC brushless motors connected in parallel to each other in order to operate a plurality of fans, pumps and the like at the same speed.
[0002]
[Prior art]
As is well known, a DC brushless motor has the advantages of a permanent magnet type DC motor, and does not generate mechanical noise and electrical noise, and has a long life. It is used for purposes.
Here, FIG. 12 shows a conventional drive circuit for driving this type of DC brushless motor.
[0003]
In FIG. 6, E is a DC power source, T1 to T6 are semiconductor switching elements such as transistors connected in a three-phase bridge, U, V, and W are output terminals of a three-phase bridge circuit, M is a DC brushless motor, 11 is a stator, 12 is a rotor made of a permanent magnet, CU, CV, and CW are coils of U, V, and W phases arranged on the stator 11, and HU, HV, and HW are rotor positions that detect the magnetic pole position (rotor position) of the rotor 12. A hall element as a sensor, 20 is a rotor position detection circuit connected to the hall elements HU, HV, and HW, and 30 is a rotor position detection signal (hereinafter simply referred to as a position detection signal as needed). This is a switching signal generation circuit that generates and outputs switching signals for the switching elements T1 to T6.
[0004]
In this drive circuit, as shown in FIG. 7, in accordance with the position detection signals detected by the Hall elements HU, HV, HW, the optimum switching elements are turned on by 120 ° by the switching signal generating circuit 30, thereby The rotor 12 is rotated by a magnetic attraction force or a repulsive force between the stator 11 and the rotor 12 by applying positive or negative voltages V _U , V _V , V _W to the CU, CV, CW.
This driving method is called a 120 ° energizing square wave driving method.
[0005]
However, the configuration shown in FIG. 6 is basically for driving one motor M. For example, two drive circuits are required to drive two motors, and the circuit configuration is complicated. And price increases cannot be avoided.
In view of these points, a brushless motor drive circuit described in Japanese Patent Application Laid-Open No. 2000-262082 is known as a conventional technique for driving a plurality of motors by one drive circuit.
[0006]
As shown in FIG. 8, the drive circuit described in the above Japanese Patent Laid-Open No. 2000-262082 includes rotor position detection sensors 50 and 60 for detecting the rotor positions of two brushless motors M1 and M2 connected in parallel. The sensor signal switching circuit 70 to which these output signals and the oscillation signal P from the oscillator 80 are applied, and the drive driver 90 to which the output signals are added together with the motor drive command are provided. U1, V1, W1, U2, V2, and W2 are coils for each phase of the motors M1 and M2, and 50u, 50v, 50w, 60u, 60v, and 60w are rotor position detection elements.
[0007]
The operation of this drive circuit will be briefly described with reference to FIG. 9. First, an oscillation signal P divided according to the number of brushless motors (for example, when driving two motors M1 and M2) A half-cycle signal obtained by dividing one cycle of the signal into two) is used as a reference signal, and this oscillation signal P has a cycle T and a duty ratio of 50% (T1 = T2).
The sensor signal switching circuit 70 uses the oscillation signal P to switch the rotor phase detection signals (for example, 50u and 60u) of the same phase of the two motors M1 and M2 every half cycle of the oscillation signal P. The drive driver 90 supplies a drive signal corresponding to the rotor position detection signal to the U-phase coils U1 and U2 of the motors M1 and M2 to operate the motors M1 and M2.
[0008]
However, in the drive circuit described in Japanese Patent Laid-Open No. 2000-262082, as shown in FIG. 9, the timing for switching the rotor position detection signal by the oscillation signal P is not completely synchronized with the rotor position detection signal. The phase of the voltage applied to the coil changes suddenly immediately after switching the drive signal based on this rotor position detection signal, and the operation tends to become unstable.
Further, in this prior art, since the rotor position detection signal is generally switched using the oscillation signal P having a period longer than the period of the rotor position detection signal as a reference signal, the motor for which the rotor position detection signal is not selected, Since the operation is performed regardless of its own rotor position detection signal, there is a problem that the operation tends to become unstable.
[0009]
That is, in FIG. 9, during the period in which the drive signal is determined based on the rotor position detection signal 50u of the motor M1, the rotor position detection signal 60u of the motor M2 is not taken into consideration. The U-phase coil is not energized, which may make the rotation of the motor M2 unstable.
[0010]
In order to solve the above problems, the present applicant has previously filed a parallel drive circuit of a DC brushless motor (hereinafter referred to as the prior invention) as Japanese Patent Application No. 2001-387671. The invention described in claim 2 of the present application is a parallel drive circuit for driving two DC brushless motors connected in parallel to each other at the same speed by a drive circuit having a plurality of semiconductor switching elements, and generating a switching signal In the parallel drive circuit of the DC brushless motor, wherein the means generates the switching signal of the switching element using the control signal generated from the rotor position detection signal of each motor, the rotor position detection signal of two motors for each phase The signal selection means for outputting the control signal created using the above to the switching signal generating means is constituted by AND means.
[0011]
FIG. 10 shows the entire configuration of the drive circuit according to the invention of the prior application, in which two DC brushless motors MA and MB are driven by one drive circuit.
In FIG. 10, DC brassless motors MA, MB having the same configuration are connected in parallel to the respective phase output terminals U, V, W of the three-phase bridge circuit having the semiconductor switching elements T1 to T6. The hall elements HU, HV, HW thus connected are connected to the rotor position detection circuits 21, 22.
[0012]
The rotor position detection signals of the motors MA and MB output from the detection circuits 21 and 22 are input to the signal selection circuit 40 for each phase, and the motor MA and MB position detection signals to be used are switched. Can be selected. The signal selection circuit 40 outputs a control signal for the switching signal generation circuit 30 to turn on / off the switching elements T1 to T6 in accordance with the selected rotor position detection signal of the motor.
[0013]
Assuming that the motors MA and MB are operating at the same speed in synchronization, the respective rotor position detection signals are output in synchronization with each other as shown in FIG. In FIG. 11, a signal related to the motor MA is indicated by A, and a signal related to the motor MB is indicated by B.
[0014]
In order to operate both motors MA and MB in synchronization with the rotor position detection signal, the rotor rotation angle (spatial angle) is 0 °, 60 °, 120 °, 180 °, 240 °, 300 in all three phases. It is necessary to change the switching signal from the switching signal generation circuit 30 in accordance with the change of the rotor position detection signal at the timing of °.
Here, focusing only on the U phase of the three phases, it is necessary to change the switching signal in accordance with the change of the rotor position detection signal at the timing of 0 ° and 180 ° every 180 ° in the rotor rotation angle. It is desirable to obtain the signal selection circuit output (control signal) shown in FIG.
[0015]
In order to stably operate two motors MA and MB in parallel by one drive circuit, the rotor position detection signals of the motors MA and MB are switched as finely as possible, and a switching signal is generated based on the switched signals. There is a need.
Therefore, in this prior art, for each phase, a control signal is created from the logical product of the rotor position detection signals of the two motors MA and MB, and a switching signal is created based on this control signal.
[0016]
That is, the signal selection circuit 40 is composed of, for example, an AND circuit AND shown in FIG. Here, FIG. 12 shows a rotor position detection signal processing circuit for one phase (for example, U phase) of the motors MA and MB, and the actual signal selection circuit is the AND circuit AND of FIG. Is also provided.
U-phase rotor position detection signals of the motors MA and MB are input to the U-phase AND circuit AND. Here, the AND circuit AND constitutes the signal selection circuit 40 in the sense that the logical product is selected and output from the two rotor position detection signals.
[0017]
FIG. 13 is a timing chart when the motors MA and MB are operated synchronously, that is, when the rotor position detection signals of the motors MA and MB are synchronized.
In this case, all of the rotor position detection signals change from the low level to the high level when the rotation angle is 0 °, and change from the high level to the low level when the rotation angle is 180 °. Therefore, the control signal output from the AND circuit AND (that is, the signal selection circuit 40) is the same as the rotor position detection signal of the motors MA and MB.
[0018]
FIG. 14 shows a case where a slight time shift, that is, a shift in angle occurs between the rotor position detection signals of the motors MA and MB.
Similarly to FIG. 13, the rotor position detection signal of the motor MA changes from Low level to High level when the rotation angle is 0 °, and changes from High level to Low level when the rotation angle is 180 °. On the other hand, the rotor position detection signal of the motor MB changes from Low level to High level when the rotation angle is F ° (F> 0 °), and from High level to Low level when the rotation angle is G ° (G> 180 °). It has changed.
[0019]
For this reason, the control signal output from the AND circuit AND (that is, the signal selection circuit 40) is at the high level during the rotation angle of F ° to 180 °, and is at the low level during the other periods. The output of the AND circuit AND is slightly different from the rotor position detection signals of the motors MA and MB, but it has been confirmed that the two motors MA and MB can be operated in parallel without any problem in practice.
[0020]
[Problems to be solved by the invention]
FIG. 15 is a specific wiring diagram of the prior application invention shown in FIG. In FIG. 15, reference numeral 100 denotes a control circuit, which corresponds to an integrated circuit of the main circuit (DC power supply E, switching elements T1 to T6) and the switching signal generation circuit 30 in FIG.
[0021]
As shown in FIG. 15, in order to connect the rotor position detection circuits 21 and 22 and the signal selection circuit 40 of the motors MA and MB, power supply terminals C1A and C1B on the position detection circuits 21 and 22 side, detection of each phase Terminals X1A, X2A, X3A, X1B, X2B, X3B and common terminals CMA, CMB and a total of ten corresponding terminals C1A, X1A, X2A, X3A, CMA, C1B, X1B, X2B, X3B, on the signal selection circuit 40 side Since it is necessary to connect the CMB individually, the wiring work is large and the wiring work is complicated, and the number of terminals of the signal selection circuit 40 is large, resulting in an increase in size of the entire circuit and a complicated structure.
Even if the power supply terminals C1A and C1B and the common terminals CMA and CMB on the signal selection circuit 40 side are made common, a total of eight terminals are required, and a significant reduction in the number of terminals and simplification of wiring cannot be expected. .
[0022]
Therefore, the present invention aims to provide a DC brushless motor parallel drive circuit that simplifies wiring and reduces the number of connection terminals, reduces the labor of wiring work, and simplifies the structure of the entire apparatus and enables miniaturization. It is what.
[0023]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is a parallel drive circuit that drives a plurality of DC brushless motors connected in parallel to each other at the same speed by a drive circuit having a plurality of semiconductor switching elements, Rotor position detection for outputting the rotor position detection signal in a parallel drive circuit of a DC brushless motor in which the switching signal generating means generates a switching signal of the switching element using a control signal generated from the rotor position detection signal of each motor. The output side of the circuit is constituted by an open collector, and an AND signal obtained by collectively connecting the rotor position detection signals of a plurality of motors for each phase is input to the switching signal generating means.
[0024]
According to a second aspect of the present invention, in the DC brushless motor parallel drive circuit according to the first aspect, the switching signal generating means outputs a PWM pulse by a sine wave PWM control system as a switching signal.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a connection state between the output side of the rotor position detection circuits 21U and 22U for one phase (for example, U phase) of the motors MA and MB and the control circuit 200 in this embodiment. .
[0026]
The rotor position detection circuits 21U and 22U include U-phase Hall elements HU (not shown) of the motors MA and MB, respectively, and output terminals of the detection circuits 21U and 22U are output transistors (npn transistors) TA and TB. Connected to each base.
The collectors of the transistors TA and TB are connected to the rotor position detection signal output terminals HUA and HUB, respectively, and are connected to the power supply terminals C1A and C1B via the pull-up resistors RA and RB, respectively. The emitters of the transistors TA and TB are connected to the common terminals CMA and CMB, respectively.
[0027]
On the other hand, the control circuit 200 integrates the switching signal generation circuit 30 and the main circuit (DC power supply E, switching elements T1 to T6) as will be described later, and the power supply terminal C1 has power supplies for the motors MA and MB. The terminals C1A and C1B are connected together, the U-phase input terminal (the U-phase input terminal of the switching signal generation circuit 30) CHU is connected with the output terminals HUA and HUB on the motor MA and MB side, and The common terminals CM are connected to the common terminals CMA and CMB on the motor MA and MB side in a lump.
Here, the output terminals HUA and HUB are connected together as an open collector as illustrated in the configuration on the output side of the rotor position detection circuits 21U and 22U, so that the motors MA and MB are connected to the U-phase input terminal CHU of the control circuit 200. AND output of the U-phase rotor position detection signal can be obtained, and the circuit is the same as in FIG.
[0028]
FIG. 1 shows the connection relationship for the U phase between the motors MA and MB and the control circuit 200. FIG. 2 shows the three phases U, V and W. Further, the overall configuration of the drive circuit is as shown in FIG.
2, the control circuit 200 converts the three-phase AC power source into the DC power source E shown in FIG. 3, converts the DC voltage into a three-phase AC voltage by the switching operation of the switching elements T1 to T6, and outputs the output terminals U, V, Output from W. As described above, C1 is a power supply terminal, CM is a common terminal, CHU is a U-phase input terminal, CHV is a V-phase input terminal, and CHW is a W-phase input terminal.
[0029]
On the other hand, in the motors MA and MB in FIG. 2, UA, VA, WA, UB, VB, and WB are phase input terminals connected to the stator coils CU, CV, and CW, C1A and C1B are power supply terminals, and CMA and CMB. Is a common terminal, HUA, HUB, HVA, HVB, HWA, HWB are rotor position detection signal output terminals for U, V, W phases, respectively, among these, power supply terminals C1A, C1B, common terminals CMA, CMB, UWB The phase output terminals HUA and HUB have already been described with reference to FIG.
[0030]
As shown in FIG. 2, in this embodiment, the power terminals C1A and C1B of the two motors MA and MB are collectively connected to the power terminal C1 of the control circuit 200, and the common terminals CMA and CMB are shared by the control circuit 200. The rotor CM is connected to the terminal CM at the same time, and the rotor position detection signal output terminals HUA and HUB, the HVA and HVB, and the HWA and HWB are respectively connected to the terminals CM. It is connected to the CHV and W phase input terminals CHW at once.
[0031]
Accordingly, in the prior art shown in FIG. 15, a total of ten signal selection circuits 40 (a total of eight when the power supply terminal and the common terminal are commonly connected) are connected to the rotor position detection circuits 21 and 22. In contrast to the need for terminals, in this embodiment, a total of five terminals may be provided in the control circuit 200 for connection to the rotor position detection circuits 21 and 22 as shown in FIG. For this reason, it is possible to reduce the size and simplification of the device by reducing the number of terminals, and to reduce the labor of wiring work by reducing the number of wires.
[0032]
At the same time, since the open collector configuration shown in FIG. 1 functions as an AND circuit in the conventional signal selection circuit 40, the conventional signal selection circuit 40 is substantially unnecessary, and the circuit configuration can be further simplified. In other words, the output terminals of the rotor position detection circuits 21 and 22 of the motors MA and MB may be directly connected to the switching signal generation circuit 30 in the control circuit 200 as shown in FIG.
[0033]
FIG. 4 is a timing chart when the motors MA and MB are operated in synchronism and there is no deviation in the U-phase rotor position detection signals HUA and HUB of the motors MA and MB. As described above, since the output side of the rotor position detection circuit (U phase) 21U is configured by an open collector, the signal CHU input to the control circuit 200 is an AND output of the signals HUA and HUB. Therefore, the same function as FIG. 12 and FIG. 13 can be achieved.
[0034]
FIG. 5 is a timing chart when the motors MA and MB are not completely synchronized and there is a slight deviation in the U-phase rotor position detection signals HUA and HUB of the motors MA and MB. Also in this case, the signal CHU input to the control circuit 200 becomes an AND output of the signals HUA and HUB, and can perform the same function as in FIGS.
That is, even if the AND circuit AND shown in FIG. 12 is not used as the signal selection circuit 40, the same operation as in the prior art can be obtained.
[0035]
As a driving method for the DC brushless motor, the 120 ° energizing square wave driving method shown in FIG. 7 is often used. However, this method is not very stable, and vibration and noise are likely to increase.
On the other hand, a sine wave PWM control system that performs PWM (pulse width modulation) control of the switching element so that the applied voltages to the motors MA and MB are equivalently sine waves is also widely known.
Therefore, as described in claim 2, the sine wave PWM control method is applied to the switching signal generation circuit 30 in the present embodiment, and the switching element is driven by the PWM pulse, so that the motor is operated more stably. It is possible.
[0036]
The present invention can also be applied to a case where three or more DC brushless motors are driven in parallel.
[0037]
【The invention's effect】
As described above, according to the present invention, a signal selection circuit that has been conventionally required is unnecessary, and the number of terminals of the control circuit connected to the rotor position detection circuit can be reduced as compared with the conventional circuit. The number of connection terminals can be reduced, and the labor of wiring work can be reduced, and the structure of the entire apparatus can be simplified and downsized.
[Brief description of the drawings]
FIG. 1 is a connection diagram of main parts of an embodiment of the present invention.
FIG. 2 is a connection diagram illustrating an embodiment of the present invention.
FIG. 3 is an overall circuit configuration diagram showing an embodiment of the present invention.
FIG. 4 is a timing chart showing the operation of the embodiment of the present invention.
FIG. 5 is a timing chart showing the operation of the embodiment of the present invention.
FIG. 6 is a prior art circuit diagram for driving one DC brushless motor.
7 is a timing chart showing the operation of FIG.
FIG. 8 is a circuit diagram of a conventional technique for driving two brushless motors.
9 is a timing chart showing the operation of FIG.
FIG. 10 is a circuit diagram of the prior art according to the invention of the prior application.
11 is a timing chart showing the operation of FIG.
12 is a configuration diagram of a signal selection circuit in FIG. 10;
13 is a timing chart showing the operation of FIG.
14 is a timing chart showing the operation of FIG.
15 is a specific wiring diagram of the circuit of FIG.
[Explanation of symbols]
E DC power supply T1 to T6 Switching element MA, MB DC brushless motor CU, CV, CW Coil HU, HV, HW Hall element TA, TB Output transistor RA, RB Pull-up resistor HUA, HVA, HWA, HUB, HVB, HWB Rotor Position detection signal output terminals C1, C1A, C1B Power terminals CM, CMA, CMB Common terminals CHU, CHV, CHW Input terminals U, V, W Output terminals UA, VA, WA, UB, VB, WB Input terminals 11 Stator 12 Rotor 21, 22, 21U, 22U rotor position detection circuit 30 switching signal generation circuit 200 control circuit

Claims (2)

A parallel drive circuit for driving a plurality of DC brushless motors connected in parallel to each other at the same speed by a drive circuit having a plurality of semiconductor switching elements, and a switching signal generating means is created from a rotor position detection signal of each motor In the parallel drive circuit of the DC brushless motor that creates the switching signal of the switching element using the control signal,
An output side of the rotor position detection circuit that outputs the rotor position detection signal is configured by an open collector, and an AND signal obtained by collectively connecting the rotor position detection signals of a plurality of motors for each phase is the switching signal generating means. A parallel drive circuit for a DC brushless motor, wherein In the parallel drive circuit of the DC brushless motor according to claim 1,
A parallel drive circuit for a DC brushless motor, wherein the switching signal generating means outputs a PWM pulse by a sine wave PWM control system as a switching signal.

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