JP4432292B2 - 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, DC brushless motors have the advantages of permanent magnet type DC motors and do not generate mechanical noise or electrical noise, and have a long service life. It is used for purposes.
Here, FIG. 4 shows a conventional driving circuit for driving this type of DC brushless motor.
[0003]
In FIG. 4, 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. 5, 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 generation 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. 4 is basically for driving one motor M. For example, two drive circuits are required to drive two motors, which complicates the circuit configuration. 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]
The drive circuit described in the above Japanese Patent Laid-Open No. 2000-262082 uses a predetermined divided signal divided according to the number of brushless motors as a reference signal, and sequentially switches position detection signals based on this reference signal to drive drivers. The drive driver operates a plurality of brushless motors with a drive signal corresponding to the position detection signal.
[0007]
[Problems to be solved by the invention]
However, in the drive circuit disclosed in Japanese Patent Laid-Open No. 2000-262082, the timing for switching the position detection signal is not completely synchronized with the position detection signal, so that the voltage applied to the motor at the moment when the position detection signal is switched. The phase changes suddenly and the operation tends to become unstable.
Further, in this prior art, since switching is generally performed using a reference signal having a period longer than the period of the position detection signal, a motor that does not use the position detection signal is operated regardless of the position detection signal during that period. There is a problem that the operation tends to be unstable.
[0008]
Accordingly, the present invention is intended to provide a parallel drive circuit for a DC brushless motor that enables stable driving and is inexpensive.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 is a parallel drive circuit for driving a plurality of DC brushless motors connected in parallel to each other by a drive circuit having a plurality of semiconductor switching elements. In the parallel drive circuit of the DC brushless motor, the generating means creates the switching signal of the switching element using the rotor position detection signal of each motor.
While the rotor position detection signal of each motor does not change, the rotor position detection signal used for generating the switching signal is switched between the motors, and the switching signal is generated using the rotor position detection signal of the motor after switching. Further, signal selection means for outputting a control signal to the switching signal generation means is provided.
[0010]
The invention described in claim 2 is the parallel drive circuit of the DC brushless motor described in claim 1,
The switching signal generating means outputs a PWM pulse by a sine wave PWM control system as a switching signal.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 shows an overall configuration of a drive circuit according to this embodiment, and is a case where two DC brushless motors MA and MB are driven by a single drive circuit. The same components as those in FIG. 4 are denoted by the same reference numerals.
[0012]
In FIG. 1, DC brassless motors MA and MB having the same configuration are connected in parallel to the phase output terminals U, V, and W of the three-phase bridge circuit, and Hall elements HU, HV, and HW provided in the respective terminals. Are connected to the rotor position detection circuits 21 and 22.
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, and the motor MA and MB position detection signals to be used can be switched and selected. It has become. 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 according to the selected position detection signal of the motor.
[0013]
As shown in FIG. 2, the signal selection circuit 40 includes XOR (exclusive OR) gates IC1 and IC2 to which a position detection signal of the motor MA is input, and NAND gates IC3 to 3 connected to the output side of the XOR gate IC2. IC7, NAND gates IC8 to IC10 to which a position detection signal of the motor MB is input, resistors R1 to R10 such as a pull-up resistor, a capacitor C1, and diodes D1 to D7 on the output side of the NAND gates IC5 to IC10, It comprises output side transistors TR1 to TR3.
This signal selection circuit 40 receives the one-phase or two-phase of the motors MA and MB with respect to the switching signal generation circuit 30 when the position detection signals of the phases of the motors MA and MB as shown in FIG. It operates to output control signals for driving the switching elements from the transistors TR1 to TR3.
[0014]
The operation of the embodiment of FIG. 1 will be described below with reference to FIGS.
Now, assuming that the motors MA and MB are operated at the same speed synchronously, the respective position detection signals are output synchronously as shown in FIG. In FIG. 3, a signal related to the motor MA is indicated by A, and a signal related to the motor MB is indicated by B.
Here, the position detection signals of the motors MA and MB shown in FIG. 3 are substantially the same as the output signals of the Hall elements HU, HV and HW shown in FIG. 5 of the prior art.
[0015]
In order to operate both the motors MA and MB in synchronization with the position detection signal, the rotor rotation angles (space angles) in FIG. 3 are timings of 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °. As the position detection signal changes, the switching signal output from the switching signal generation circuit 30 needs to be changed.
[0016]
On the other hand, the rotation angle in FIG. 3 is between 0 ° and 60 °, between 60 ° and 120 °, between 120 ° and 180 °, between 180 ° and 240 °, between 240 ° and 300 °, and 300 °. Between 0 ° and 0 °, the position detection signals of the motors MA and MB remain unchanged and remain constant (for example, between 0 ° and 60 °, the U phase is used as the position detection signal of the motors MA and MB). In addition, a state in which a W-phase signal is detected continues, and a state in which only a U-phase signal is detected as a position detection signal for the motors MA and MB continues between 60 ° and 120 °.
[0017]
Therefore, there is no adverse effect even if the position detection signal of the motor MA and the position detection signal of the motor MB are switched while the position detection signal remains unchanged and remains constant as described above.
For example, a switching signal for driving the motor MA using the position detection signal of the motor MA (the motors MA and MB are connected in parallel and may be a switching signal for driving the motor MB) is output. In this case, even if the switching signal for driving the motor MB by switching to the position detection signal of the other motor MB (which may also be a switching signal for driving the motor MA) is output. If it is performed during a period when there is no change in the position detection signal, there is no fear that the applied voltage of the motor changes suddenly at the moment of switching. In addition, when switching is performed at a cycle shorter than the cycle of the position detection signal as in the present embodiment, there is little possibility that the operation becomes unstable.
[0018]
For this reason, in this embodiment, the angle is between 0 ° to 60 °, 60 ° to 120 °, 120 ° to 180 °, 180 ° to 240 °, 240 ° to 300 °, At the time of 30 °, 90 °, 150 °, 210 °, 270 °, and 330 ° between 300 ° and 0 ° (360 °), the signal selection circuit 40 sends the position detection signals of the motors MA and MB between the motors. The switching signals for driving the motors MA and MB are output based on the selected position detection signals.
[0019]
That is, as shown in FIG. 3, for example, the position detection signal of the motor MA is selected between 330 ° and 30 °, and based on this signal, the switching signal generation circuit 30 applies the U-phase coil CU and the W-phase coil CW. A switching signal is output so as to be energized (periods differ). In addition, the position detection signal of the motor MB is selected between 30 ° and 90 °, and the switching signal generation circuit 30 energizes the U-phase coil CU and the W-phase coil CW based on this signal (periods are different from each other). ) Create the switching signal as follows.
Thereafter, similarly, a position detection signal of the motor MA is selected between 90 ° and 150 °, and based on this signal, the switching signal generating circuit 30 sends a switching signal so as to energize the U-phase coil CU and V-phase coil CV. The position detection signal of the motor MB is selected between 150 ° and 210 °. Based on this signal, the switching signal generation circuit 30 generates a switching signal so that the U-phase coil CU and the V-phase coil CV are energized. To do.
[0020]
In FIG. 3, for convenience of explanation, the position detection signals of the motors MA and MB are switched at angles of 30 °, 90 °, 150 °, 210 °, 270 °, and 330 °. However, the switching angle is limited to these values. Not between 0 ° and 60 °, between 60 ° and 120 °, between 120 ° and 180 °, between 180 ° and 240 °, between 240 ° and 300 °, as described above. A similar effect can be obtained if the position detection signals of the motors MA and MB are switched at an angle between 0 ° and 0 ° (360 °) with no change.
[0021]
When the operation of the signal selection circuit 40 shown in FIG. 2 is confirmed, for example, the rotor position detection signals (U phase, V phase, W phase) of the motors MA, MB between 30 ° to 60 ° in FIG. 2 is also expressed by logic (1, 0, 1), and these are input as position detection signals of the motors MA and MB in FIG. 2, the output side transistors TR1, TR2, TR3 (U-phase) are output by the logic circuit in FIG. , V phase, W phase) output signal logic is (1, 0, 1), and position detection signals (U phase, V phase, W phase) of motor MA, MB between 60 ° and 90 ° ) Is logic (1, 0, 0), the logic of the output signals of the output side transistors TR1, TR2, TR3 (U phase, V phase, W phase) is (1, 0, 0). Coincides with the change of the output (control signal) of the signal selection circuit in the period of 30 ° to 90 ° Understood.
[0022]
With the operation as described above, the two motors MA and MB can be stably driven in parallel by a single drive circuit in synchronization with the rotor position detection signal.
[0023]
A sine wave PWM control method is well known in which the switching element is PWM (pulse width modulation) controlled so that the applied voltages to the motors MA and MB are equivalently sine waves. By applying this method to the switching signal generation circuit 30 and driving the switching element with a PWM pulse, the motor can be operated more stably.
[0024]
Moreover, although the said embodiment demonstrated the case where two DC brushless motors were operated in parallel, this invention is applicable also when three or more motors are operated in parallel.
[0025]
【The invention's effect】
As described above, according to the present invention, a plurality of DC brushless motors can be stably driven by a single drive circuit, as compared with the drive circuit disclosed in Japanese Patent Application Laid-Open No. 2000-262082, which is a conventional technique. Yes, it can be provided at a lower cost than when a drive circuit is provided for each motor.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of the present invention.
2 is a circuit diagram showing a configuration of a signal selection circuit in FIG. 1; FIG.
FIG. 3 is a timing chart showing the operation of FIG. 1;
FIG. 4 is an explanatory diagram of a conventional drive circuit that drives one DC brushless motor.
FIG. 5 is a timing chart showing the operation of FIG. 4;
[Explanation of symbols]
E DC power sources T1 to T6 Switching elements U, V, W Output terminals MA, MB DC brushless motors CU, CV, CW Coils HU, HV, HW Hall element 11 Stator 12 Rotor 21, 22 Rotor position detection circuit 30 Switching signal generation circuit 40 Signal selection 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, wherein the switching signal generating means uses a rotor position detection signal of each motor. In the parallel drive circuit of the DC brushless motor for creating the switching signal of the switching element,
While the rotor position detection signal of each motor does not change, the rotor position detection signal used for generating the switching signal is switched between the motors, and the switching signal is generated using the rotor position detection signal of the motor after switching. In addition, the DC brushless motor parallel drive circuit further comprises signal selection means for outputting a control signal to the switching signal generation means. 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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