JP2003116294A - Synchronous operation unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and inexpensive synchronous operation unit for operating a plurality of DC brushless motors synchronously and stably. SOLUTION: The synchronous operation unit comprises a signal select circuit 40 delivering a control signal to a switching signal generating circuit 30 such that a rotor position detection signal used for generating a switching signal is switched between respective motors within a period where the rotor position detection signals of DC brushless motors MA and MB having the same arrangements and characteristics do not vary and a switching signal is generated using a switched rotor position detection signal of the motor, a speed control circuit 50 delivering a control signal to the switching signal generating circuit 30 depending on a speed set value and turning switching elements T1-T6 on/off at a specified timing, and a soft start circuit 100 for providing the speed control means with the speed set value while varying gently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous driving device for driving a plurality of DC brushless motors driving a load such as a conveyor in synchronization at the same speed.

[0002]

Prior Art and Problems to be Solved by the Invention FIG.
FIG. 4 is a block diagram showing a conventional synchronous operation device that operates two motors MA ′ and MB ′ in synchronization. In FIG. 6, encoders EA, E are provided for the motors MA ', MB'.
B are attached respectively. Each encoder EA,
The error of the number of output pulses of the EB is detected by the error detection device 130, and the speed of the motor MB ′ is controlled by the speed control device 120 so that the error approaches zero.
Synchronous operation of A'and MB 'is performed. Incidentally, 140 is an adder, and 110 is a speed control device for the motor MA ′.

According to this prior art, each motor M
Since the speed control devices 110 and 120 are required for A ′ and MB ′, and the encoders EA and EB for speed detection need to be attached to the respective motors MA ′ and MB ′, the price is high and the device is high. There was a problem that the whole became large.

Further, although not shown, a method of synchronously operating two synchronous motors with induction windings by one inverter is also known. However, in this case, the magnet must be attached to the rotor of the motor and the induction winding must be attached, which has a drawback that the cost of the motor becomes very high.

Therefore, the present invention is intended to provide a synchronous operation device which can be downsized at a lower cost than conventional ones and can stably operate a plurality of motors in a synchronous manner.

[0006]

In order to solve the above-mentioned problems, the invention described in claim 1 provides a plurality of DC brushless motors having the same structure and the same characteristics, which are connected in parallel to each other, and a plurality of semiconductor switching elements. In order to drive the motors at the same speed by a single control device, the switching signal generating means uses the rotor position detection signals of the respective motors to generate the switching signals of the switching elements. While the detection signal does not change, the rotor position detection signal used to create the switching signal is switched between the motors,
Signal selecting means for outputting a control signal to the switching signal generating means so as to create a switching signal using the rotor position detection signal of the switched motor,
A speed control means for outputting a control signal to the switching signal generation means according to a speed set value to turn on / off the switching element at a predetermined timing, and the speed control means for gently changing the speed set value. And a soft start means to give to.

According to a second aspect of the present invention, in the synchronous operation device according to the first aspect, the switching signal generating means outputs a PWM pulse by a sine wave PWM control method as a switching signal.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, MA and MB are DCs having the same characteristics.
Brushless motors, which are connected in parallel with each other. As is well known, the rotor of a DC brushless motor is composed of permanent magnets. Therefore, the two DC brushless motors MA and MB connected in parallel are operated by one control device 200.
If the same voltage is applied to the stator coils of the respective phases of the motors MA and MB, the motors MA and MB will operate synchronously.

However, if an attempt is made to change the speed too quickly during acceleration or deceleration of the motors MA and MB, the inertia of the machine may prevent each of the motors MA and MB from following the speed change well, resulting in loss of synchronization. . Therefore, the soft start circuit 100 is provided before the control device 200,
A speed set value is input to the soft start circuit 100, and the speed set value for each motor MA, MB is slowly changed during acceleration and deceleration.

FIG. 2 is a circuit diagram specifically showing the main part of FIG. In FIG. 2, the DC brassless motors MA, MB having the same configuration and the same characteristics are provided at the phase output terminals U, V, W of the three-phase bridge circuit including the switching elements T1 to T6 in the DC brassless motor control device 200. Are connected in parallel, and the Hall elements HU, HV, HW provided in the respective motors MA, MB are connected to the rotor position detection circuits 21, 22. In FIG. 2, E is a DC power source, and 1 in each motor MA, MB.
1 is a stator, 12 is a rotor, and CU, CV, and CW are coils of each phase.

The rotor position detection signals of the motors MA and MB output from the rotor position detection circuits 21 and 22 are input to the signal selection circuit 40, and the position detection signal of which motor MA or MB is used is switched. It is selectable. Then, from the signal selection circuit 40, the switching elements T1 to T1 are selected according to the position detection signal of the selected motor.
A control signal to the switching signal generation circuit 30 is output to turn on / off T6. Reference numeral 50 denotes a speed control circuit for each of the motors MA and MB, to which a slowly changing speed set value is input from the soft start circuit 100 shown in FIG.

As shown in FIG. 3, 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 an XOR gate IC.
NAND gates IC3 to IC7 connected to the output side of 2
, NAND gates IC8 to IC10 to which the position detection signal of the motor MB is input, and a resistor R1 such as a pull-up resistor
~ R10, capacitor C1, and NAND gate IC5
~ IC10 includes output side diodes D1 to D7 and output side transistors TR1 to TR3.

The signal selection circuit 40 is provided to the switching signal generation circuit 30 when the position detection signals of the respective phases of the motors MA and MB shown in FIG.
The transistors TR1 to TR3 operate to output control signals for driving the one-phase or two-phase switching elements A and MB.

The operation of this embodiment will be described below with reference to FIGS. The switching elements T1 to T6 of the DC brassless motor control device 200 shown in FIG. 2 are turned on / off at the timings shown in FIG.
Voltages V _U , V _V , V _{W on} MB coils CU, CV, CW
Is applied. The driving method shown in FIG. 5 is known as a 120 ° conduction square wave driving method. As a result, the motors MA and MB are synchronously operated at the same speed, and the rotor position detection signals of the motors MA and MB at that time are as shown in FIG. Note that, in FIG. 4, a signal regarding the motor MA is indicated by A and a signal regarding the motor MB is indicated by B.

In order to operate both motors MA and MB in synchronization with the position detection signal, the rotor rotation angles (spatial angles) of FIG. 4 are 0 °, 60 °, 120 °, 180 °, 240.
It is necessary to change the switching signal output from the switching signal generation circuit 30 in accordance with the change of the position detection signal at the timings of 0 ° and 300 °. on the other hand,
When the rotation angle in FIG. 4 is 0 ° to 60 °, 60 ° to 12
Between 0 °, 120 ° to 180 °, 180 ° to 240
During 240 °, between 240 ° and 300 °, and between 300 ° and 0 °, there is no change in the position detection signal of each of the motors MA and MB, and a constant state is maintained. Therefore, as described above, 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 constant.

For example, a switching signal for driving the motor MA using the position detection signal of the motor MA (since the motors MA and MB are connected in parallel, the motor MB
When it is outputting a switching signal for driving the motor MB, the switching signal for switching the position detection signal of the other motor MB to drive the motor MB (also the switching signal for driving the motor MA). (Possible) is output, if the switching is performed during a period when the position detection signal does not change, there is no concern that the voltage applied to the motor suddenly changes at the moment of switching. Further, if the switching is performed in a cycle shorter than the cycle of the position detection signal as in this example, there is little possibility that the operation becomes unstable.

Therefore, in this embodiment, the angle is 0 ° to 60 °.
Between 60 ° and 120 °, between 120 ° and 180 °, between 180 ° and 240 °, between 240 ° and 300 °, between 300 ° and 0 ° (360 °) 30 °, 9
At the time of 0 °, 150 °, 210 °, 270 °, and 330 °, the signal selection circuit 40 alternately selects the position detection signals of the motors MA and MB between the motors to select the selected position detection signal. Based on the motor MA,
A switching signal for driving the MB is output.

That is, as shown in FIG. 4, for example, 330 °
The position detection signal of the motor MA is selected between ˜30 °, and the switching signal generation circuit 30 is selected based on this signal.
Outputs a switching signal so that the U-phase coil CU and the W-phase coil CW are energized (the periods are different from each other).
Further, 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 (the period is different from each other). ) To create a switching signal.

Similarly, thereafter, the position detection signal of the motor MA is selected between 90 ° and 150 °, and the switching signal generating circuit 30 energizes the U-phase coil CU and the V-phase coil CV based on this signal. Create a switching signal,
A position detection signal of the motor MB is selected between 150 ° and 210 °, and the switching signal generation circuit 30 creates a switching signal based on this signal so as to energize the U-phase coil CU and the V-phase coil CV.

In FIG. 4, for convenience of explanation, the angle is 30 °,
The position detection signals of the motors MA and MB are switched at 90 °, 150 °, 210 °, 270 °, 330 °, but 0
Between 60 ° and 60 °, between 120 ° and 1 °
Between 80 °, 180 ° -240 °, 240 ° -30
Between 0 °, between 300 ° and 0 ° (360 °),
The same effect can be obtained by switching at an arbitrary angle that does not change the position detection signals of the motors MA and MB.

The operation of the signal selection circuit 40 shown in FIG. 3 will be described. For example, the rotor position detection signals (U phase, V phase, W) of the motors MA and MB between 30 ° and 60 ° in FIG.
Each of the phases is represented by logic (1, 0, 1), and if these are input as position detection signals of the motors MA and MB, the output side transistor TR is converted by the logic circuit of FIG.
The logic of the output signals of 1, TR2, TR3 (U phase, V phase, W phase) is (1, 0, 1), and the position detection signals of the motors MA, MB between the next 60 ° and 90 ° ( U phase, V phase, W
If all the phases are logic (1, 0, 0), output side transistors TR1, TR2, TR3 (U phase, V phase, W phase)
The output signal has a logic of (1, 0, 0), which is 30 in FIG.
It can be seen that the output coincides with the change in the output (control signal) of the signal selection circuit during the period of 90 ° to 90 °.

By the above operation, the two motors M
It is possible to stably operate A and MB synchronously with the rotor position detection signal by the single control device 200. Further, by giving a speed set value to the speed control circuit 50 via the soft start circuit 100, the speed is gently changed without contending with the inertia of the motors MA and MB at the time of acceleration or deceleration, so that the speed changes rapidly. It is possible to prevent the occurrence of a shock due to and maintain the synchronous operation of both motors MA and MB.

The switching elements are PWM-controlled so that the voltages applied to the motors MA and MB are equivalently sinusoidal.
A sine wave PWM control method for controlling (pulse width modulation) is well known. This method is applied to the switching signal generation circuit 3
By applying 0 to driving the switching element by the PWM pulse, the motors MA and MB can be operated more stably. Further, in each of the above embodiments, the case where two DC brushless motors are operated in parallel has been described, but the present invention is also applicable to the case where three or more motors are operated in parallel.

[0024]

As described above, according to the present invention, it is possible to stably operate a plurality of DC brushless motors in synchronization by one controller, and drive each motor by an individual controller. It is possible to provide an inexpensive and small synchronous operation device as compared with the case. In particular, according to the present invention, by adding the speed set value to the control device via the soft start circuit, it is possible to surely perform the synchronous operation without causing the out-of-synchronization during acceleration or deceleration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram specifically showing a main part of FIG.

FIG. 3 is a circuit diagram showing a configuration of a signal selection circuit of FIG.

FIG. 4 is a timing chart showing the operation of FIG.

5 is a timing chart showing the operation of FIG. 1. FIG.

FIG. 6 is a block diagram showing a conventional technique.

[Explanation of symbols]

E DC power supply T1-T6 switching elements U, V, W output terminals MA, MB DC brushless motor CU, CV, CW coil HU, HV, HW Hall element 11 Stator 12 rotor 21,22 Rotor position detection circuit 30 Switching signal generation circuit 40 signal selection circuit 50 speed control circuit 100 soft start circuit 200 DC brushless motor controller

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3F027 AA01 DA01 FA02                 5H560 AA10 BB04 BB12 CC04 DA02                       DA19 DB02 EB01 HA01 RR10                       UA02 XA05 XA12

Claims (2)

[Claims] 1. A switching signal generating means for driving a plurality of DC brushless motors having the same configuration and the same characteristics, which are connected in parallel with each other, at the same speed by a single control device having a plurality of semiconductor switching elements. In the synchronous operation device that creates the switching signal of the switching element using the rotor position detection signal of each motor, within a period in which the rotor position detection signal of each motor does not change,
The rotor position detection signal used to create the switching signal is switched between the motors, and a control signal is output to the switching signal generating means so as to create the switching signal using the rotor position detection signal of the switched motor. Signal selection means, a speed control means for outputting a control signal to the switching signal generation means according to the speed setting value to turn on / off the switching element at a predetermined timing, and the speed setting value being gently changed. And a soft start means for giving the speed control means to the speed control means. 2. The synchronous operation device according to claim 1, wherein the switching signal generating means outputs a PWM pulse of a sine wave PWM control method as a switching signal.