CN1282298C - Parallel driving method for DC brushless motors - Google Patents

Abstract

The invention provides a parallel driving method of DC brushless motors, which can obtain very large starting torque without complicating or enlarging the whole device. The DC brushless motors (M ₁ , M ₂ ) connected in parallel are driven at the same speed by a controller (200) with an inverter (202). Relays (R _y1 , R _y2 ) are respectively connected between the inverter (202) and the motor (M ₁ , M ₂ ). When starting, one relay (R _y1 ) is turned on. After the motor (M1) is accelerated, the The said relay (R _y1 ) in the on state is closed, and the motor (M ₁ ) is rotated by inertia, after which, the relay (R y2 ) corresponding to the other motor (M ₂ ) is turned on, and the motor ( _{M 2 )} is accelerated, and at the same time, when When the phase angle difference of the rotor position of the motor (M ₁ , M ₂ ) is within the set value, it is judged that the two motors (M ₁ , M ₂ ) are synchronous, and the relay (R _y1 ) of the corresponding motor (M ₁ ) ) is switched on, and the two motors (M ₁ , M ₂ ) are running in parallel.

Description

Parallel driving method of DC brushless motor

technical field

The present invention relates to a parallel driving method for driving a plurality of DC brushless motors connected in parallel to each other in order to operate a plurality of fans or pumps at the same speed.

Background technique

As prior art for driving a plurality of DC brushless motors connected in parallel with each other by one drive circuit, a parallel drive circuit as shown in FIG. 8 is known.

In Fig. 8, 100 is an AC power supply; 200' is the controller of the driving circuit; M ₁ and M ₂ are DC brushless motors such as three-phase (U, V, W phase) running in parallel; 301 and 302 are According to each phase of U, V, and W phases, position detection elements such as Hall elements are used to detect the rotor positions of the motors M ₁ and M ₂ ; 201 rectifies and smoothes the AC voltage of the AC power supply 100 to obtain a specified DC voltage Rectification/smoothing circuit; 202 is a three-phase voltage-shaped inverter for passing through the stator coils of each phase of the motors M ₁ and M ₂ ; 203 is to detect the rotor position and rotational speed by the output signals of the position detection elements 301 and 302 Position detection circuit; 204 is a speed control circuit that outputs operation and stop commands and speed graphs (speed commands) of the motors _M1 and _M2 ; 205 is a control operation circuit that generates an inverter 202 based on the speed graph and rotation speed detection value 206 is based on the output signal (PWM signal) of the control operation circuit 205 to generate a driving signal (arcing signal) for each switching element of the inverter 202. logic circuit.

Fig. 9 is a timing chart at the start of the parallel drive circuit.

When an operation command is given at time _T1 , the inverter ₂₀₂ applies a DC voltage to the stator coils of the motors _M1 and _M2 until time T2 is reached.

In this way, the same direct current flows through the coils of the motors _M1 and _M2 , and the magnetic poles of the stators are excited to the same magnetic field, and the rotors of the respective motors _M1 and _M2 formed of permanent magnets are pulled to positions with the same phase angle. .

At this time, the phase angles of the rotors of the respective motors M ₁ and M ₂ are the same. Therefore, if the applied voltage is gradually increased from the time T ₃ shown in FIG. 9 and accelerated sequentially, the two motors M ₁ and M ₂ accelerate simultaneously , the applied voltage is shifted to the specified operation after about time _T4 .

Furthermore, for example, Patent Document 1 describes a parallel drive circuit in which the output voltage of one drive circuit formed by an inverter is equally applied to a plurality of DC brushless motors connected in parallel to drive Parallel drive circuits for DC brushless motors for these motors.

Patent Document 1: JP-A-2003-37987 (FIG. 1, FIG. 3).

In the prior art shown in FIG. 8 and FIG. 9 mentioned above, it is difficult to obtain a large starting torque because the output current of the inverter 202 is equally supplied to the motors M ₁ and M ₂ at the time of starting. For this reason, in the case of using an outdoor fan, etc., in winter, when snow or ice adheres to the fan, it cannot be started smoothly.

In addition, in order to obtain a desired starting torque, it is conceivable to install and drive a controller including an inverter for each motor, but there is a problem that the entire device becomes complicated and large, and the cost is also high.

Contents of the invention

The present invention provides a parallel driving method of DC brushless motors, which can obtain very large starting torque without complicating and increasing the size of the whole device.

In order to solve the above problems, as described in the first aspect of the present invention, in the parallel driving method of DC brushless motors, a plurality of DC brushless motors connected in parallel to each other are connected in the same speed drive,

Switching devices are respectively connected between the output side of the above-mentioned driving circuit and each motor,

When starting, turn on the switch device corresponding to one motor, after accelerating the motor, turn off the above switch device that is in the on state, rotate the above one motor by inertia, and then turn on the switch device corresponding to other motors, Accelerate the other motors, and at the same time, when the difference between the phase angle of the rotor position of the above-mentioned one motor and the phase angle of the rotor positions of the above-mentioned other motors is within the set value, it is judged that these motors are synchronous, and the corresponding one will be The switching device of the motor is turned on, and multiple motors are operated in parallel.

As described in the second aspect of the present invention, as the condition for judging the synchronization of multiple motors, in addition to the condition that the phase angle difference of the rotor position of each motor is within the set value as described in the first aspect of the present invention, It is a condition that the difference in rotational speed of each motor is within a set value.

As described in the third aspect of the present invention, in the parallel driving method of DC brushless motors described in the first or second aspect of the present invention,

When a plurality of motors are operated in parallel by turning on the switch device corresponding to one motor while the switch device corresponding to the other motor is turned on, the rotational speed of each motor at the start of the parallel operation is maintained for a certain period of time.

As described in the fourth aspect of the present invention, in the parallel driving method of the DC brushless motor described in the first, second or third aspect of the present invention,

From the rotor position detection signals of each motor, a logical sum or a logical product is detected for each phase, and a control rotor position detection signal is generated for each phase. drive signal.

Furthermore, as the drive circuits described in the first to fourth aspects of the present invention, as described in the fifth aspect of the present invention, for example, a three-phase voltage-type inverter is used.

Description of drawings

FIG. 1 is a block diagram of a parallel drive circuit used in an embodiment of the present invention.

Fig. 2 is a time chart at the start of the embodiment of the present invention.

FIG. 3 is a flow chart showing the starting method corresponding to FIG. 2 .

Fig. 4 is a flowchart showing another activation method according to the embodiment of the present invention.

Fig. 5 is a flowchart showing another activation method according to the embodiment of the present invention.

FIG. 6 is a configuration diagram showing an example of the position detection circuit shown in FIG. 1 .

FIG. 7 is a time chart showing the operation of FIG. 6 .

Fig. 8 is a block diagram showing a prior art parallel drive circuit.

Fig. 9 is a time chart at the time of startup in the prior art.

Explanation of symbols: 100 AC power supply; 200 controller; 201 rectification/smoothing circuit; 202 three-phase voltage-shaped inverter; 2031, 2032 position detection circuit; 204 speed control circuit; , 302 position detection element; 41UA, 41VA, 41WA, 41UB, 41VB, 41WB: and circuit; 42U, 42V, 42W: or circuit; 43 running motor selection circuit; M ₁ , M ₂ DC brushless motor; R _y1 , R _y2 relay.

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 1 is a block diagram showing the configuration of a parallel drive circuit used in the embodiment of the present invention. The same constituent elements as in FIG. 8 are assigned the same symbols.

In Fig. 1, 200 is the controller of the drive circuit used in the embodiment of the present invention, and the output signals of the position detection elements 301 and 302 provided corresponding to the respective motors _M1 and _M2 are input into the respective position detection circuits 2031 and 2032, these The output signal is input to the control arithmetic circuit 205 together with the output signal of the speed control circuit 204 .

From the control operation circuit 205 to the arc _starting logic circuit 206, the drive signal for controlling the three-phase voltage-shaped inverter 202 is output _. Between the control signals of the relays R _y1 and R _y2 as switching devices.

Next, FIG. 2 is a time chart at the start of the embodiment of the present invention, and FIG. 3 is a flowchart corresponding to FIG. 2 .

The starting method according to the embodiment of the present invention will be described below with reference to these figures.

First, if _an operation instruction is provided to _the control computing circuit 205 _at time _T11 in FIG. S2).

After a certain period of time, (S3 in FIG. 3 ), at time T ₁₂ , the relay R _y1 is turned off (OFF), and at the same time, the relay R _y2 is turned on (ON), and the motor M ₂ is driven (Fig. 3 of S4, S5). Also, after the relay _Ry1 is turned off (OFF), the motor _M1 coasts to rotate.

In this state, based on the position detection signals output from the position detection circuits 2031, 2032, the control operation circuit 205 finds the difference between the phase angles α ₁ , α ₂ of the respective motors M ₁ , M ₂ , and if the difference is within the set value α Inside, the relay _Ry1 on the motor _M1 side is turned on (ON) (S6, S7 in FIG. 3). Also, in FIG. 2 , it is assumed that the difference of the phase angles α ₁ , α ₂ at time T ₁₃ is within the set value α.

Here, if α is set to a smaller value than the degree to which the two motors M ₁ and M ₂ are regarded as synchronous, the two motors M 1 and M 2 can be synchronized when the difference between the phase angles α ₁ and α ₂ is within the set value α. The two motors M ₁ and M ₂ are judged to be synchronous. At this time, if the relay Ry1 in the off state is turned on (ON), the two motors M ₁ and M ₂ can be operated in parallel in a synchronous state.

Then, after time _T13 , the vehicle may be accelerated up to the set speed by the speed control circuit 204 (S8 in FIG. 3 ).

Also, although the case in which the phase angles α 1 , α ₂ of the motors M ₁ , M ₂ of FIG. 2 are changed linearly has been described, actually the phase angles α ₁ , _{α 2 change} in a sinusoidal wave.

FIG. 4 is a flowchart showing another activation method.

In the starting method of Fig. 3, if the synchronization is detected when the speed of the motors _M1 and _M2 is very low, there is no problem, but only if the difference of the phase angle is within the set value as the synchronization detection condition, there will be the following In the above case, when the difference in the rotational speeds of the motors M ₁ , M ₂ is large, smooth transition to synchronous operation cannot be achieved.

Then, as shown in FIG. 4, the difference in rotational speed is set to a small value N, the difference in the speeds N ₁ and N ₂ of the motors M ₁ and M ₂ is within the set value N, and at the phase angle α ₁ When the difference between , α ₂ is within the set value α, it is judged that the two motors M ₁ , M ₂ are synchronized (S16, S17 in FIG. 4 ). Furthermore, S11 to S15, S18, and S19 in FIG. 4 are substantially the same procedures as S1 to S5, S7, and S8 in FIG. 3 .

Here, the speeds N ₁ and N ₂ of the motors M ₁ and M ₂ can be easily detected from the frequency of the detection signal by the position detection circuits 2031 and 2032 in FIG. 1 .

Next, FIG. 5 is a flow chart showing another starting method.

According to the starting method in Fig. 3, when two motors M ₁ and M 2 are operated in parallel by judging that the difference in phase angle is within the set value and the two motors M 1 and M ₂ are running in parallel, there is still some speed difference and phase In the case of corner difference, if you accelerate immediately in this state, you cannot accelerate quickly.

Then, as shown in FIG. 5, the difference of the phase angle is within the set value, and the parallel connection of the two motors M ₁ and M ₂ is started by turning the relay R _y1 in the OFF state to ON. After running, run the two motors _M1 , _M2 at the current speed only for a certain time _Tx (S28 of FIG. 5), and then accelerate up to the set speed (S29 of FIG. 5). S21 to S27 and S29 in FIG. 5 are substantially the same procedures as S1 to S7 and S8 in FIG. 3 .

In Fig. 2, the parallel operation starts from time _T13 , but according to the starting method shown in Fig. 5, the speeds _N1 and _N2 of the motors _M1 and _M2 are not accelerated immediately after time _T13 , as shown by the dotted line indicates that the speed at time _T13 is maintained for a predetermined time.

Here, the processing method of the position detection signal in the following case will be described below. That is, as shown in _{FIG .} 2 _{and FIG} . M ₂ , the case of immediate acceleration.

FIG. 6 shows a specific example of the position detection circuits 2031 and 2032 in FIG. 1 .

In FIG. 6 , UA, VA, and WA are rotor position detection signals of the motor M1, and UB, VB, and WB are rotor position detection signals of the motor _M2 . The control rotor position detection signal used in actual control uses 6 sum circuits (AND circuits) 41UA, 41VA, 41WA, 41UB, 41VB, 41WB and 3 OR circuits (OR circuits) 42U, 42V, 42W, and uses the operating motor The output signal of the selection circuit 43 is selected to use the rotor position detection signal of _the motor _M1 or the rotor position detection signal of the motor _M2 , or the logical sum of the rotor position detection signals of the motors M1 and _M2 .

That is, at the time of initial startup (after the relay R _y1 is turned on (ON) by step S2 in FIG. 3 and a certain time has elapsed by step S3), the output A (corresponding to the motor M ₁ ) of the operating motor selection circuit 43 is: High level, output B (corresponding to motor M2) is low level. In this way, the rotor position detection signals UA, VA, and WA of the motor _M1 input to the AND circuits (AND circuits) 41UA, 41VA, and 41WA are input to the OR circuits (OR circuits) 42U, 42V, and 42W as they are. The output signals of 41UB, 41VB, and 41WB are always at low level, and only the rotor position detection signals UA, VA, and WA of the motor _M1 are effectively used as the rotor position detection signals for control.

Likewise, in the following steps (after turning relay R _y1 off (OFF) in step S4 of FIG. 3 and turning on (ON) relay R _y2 in step S5 ), the motor selection circuit 43 is operated. Output B goes high and output A goes low. In this way, only the rotor position detection signals UB, VB, and WB of the motor _M2 are effectively used as the rotor position detection signals for control.

Then, if the difference of the phase angles of each phase of each motor M ₁ , M ₂ detected by FIG. 6 is within α° (step S6 of FIG. 3 ), in the next step, by step S7 of FIG. 3 The relay _Ry1 is turned on (ON), and at the same time, the outputs A and 1 of the running motor selection circuit 43 are both turned into high levels.

In this way, the rotor position detection signals UA, VA, WA, UB, VB, and WB of the motors M ₁ and M ₂ are all input into the OR circuits 42U, 42V, and 42W, and the logic of the rotor position detection signals of the motors M ₁ and M ₂ and are output to each phase as a rotor position detection signal for control. Thereafter, the two motors M ₁ , M ₂ are accelerated to the set speed (step S8 of FIG. 3 ).

Furthermore, in FIG. 6 , when two motors M ₁ and M ₂ are operated in parallel, the rotor position detection signal for control is obtained by using the logical sum of the rotor position detection signals of each phase of each motor M ₁ and M ₂ . signal, but it is also possible to use the logical product of the rotor position detection signals for each phase to obtain the control rotor position detection signal.

In addition, all the functions in Fig. 6 can also be replaced by a microcomputer.

FIG. 7 shows a case where the motors M ₁ and M ₂ are completely synchronized, and the rotor position detection signals of the respective phases are synchronized. In this case, the rotor position detection signals of the motors M ₁ , M ₂ and the output signals of the OR circuits 42U, 42V, 42W, that is, the rotor position detection signals for control, all become the same signal. That is, it shows that the motors M ₁ and M ₂ can operate synchronously with each other.

In the above-mentioned embodiment, the case where two DC brushless motors are operated in parallel has been described, but the operation method of the present invention is also applicable to the case where three or more motors are operated in parallel.

In addition, it does not matter whether the relays R _y1 and R _y2 in FIG. 1 have contacts or not, and semiconductor switches other than relays may be used as switching devices.

According to the above-mentioned present invention, the electric current passes through each motor in series when starting, and then, since the multiple motors are synchronously transferred to parallel operation, substantially the same function as starting each motor through a separate controller can be realized. In this way, sufficient starting current is provided for each motor, and a large starting torque can be obtained.

In addition, since there is no need to provide controllers for the number of motors, the device configuration does not become complicated or enlarged, and it also contributes to cost reduction.

Claims (5)

1. the driving method in parallel of a DC brushless motor, the drive circuit by having a plurality of thyristors is characterized in that with many DC brushless motors that identical speed drive is connected in parallel mutually,

Between the outlet side of described drive circuit and each motor, connect switching device respectively,

When starting, the switching device of corresponding 1 motor is connected, and after quickening this motor, the described switching device that will be in on-state cuts out, described 1 motor inertia rotation, afterwards, connect the switching device of corresponding other motor, quicken this other motor, simultaneously, when the difference at the phase angle of the rotor-position of the phase angle of the rotor-position of described 1 motor and described other motor is within the set point time, the switching device of described 1 motor of correspondence is connected many motors of parallel running.

2. the driving method in parallel of a DC brushless motor, the drive circuit by having a plurality of thyristors is characterized in that with many DC brushless motors that identical speed drive is connected in parallel mutually,

Between the outlet side of described drive circuit and each motor, connect switching device respectively,

When starting, the switching device of corresponding 1 motor is connected, after quickening this motor, the described switching device that will be in on-state cuts out, described 1 motor inertia rotation, afterwards, connect the switching device of corresponding other motor, quicken this other motor, simultaneously, when the difference of the rotary speed of the rotary speed of described 1 motor and described other motor is within the set point time, and, when the difference at the phase angle of the rotor-position of the phase angle of the rotor-position of described 1 motor and described other motor is within the set point time, the switching device of described 1 motor of correspondence is connected many motors of parallel running.

3. the driving method in parallel of DC brushless motor as claimed in claim 1 or 2 is characterized in that,

When under the state that the switching device of described other motor of correspondence is connected, during many motors of parallel running, the rotary speed of each motor when parallel running is begun is kept certain hour by the switching device of described 1 motor of correspondence is connected.

4. the driving method in parallel of DC brushless motor as claimed in claim 1 or 2 is characterized in that,

From the logic of the described rotor position detection signal of each phase of each motor of rotor position detection input of each motor and or logic product, each of described each motor is made control rotor position detection signal mutually, use the rotor position detection signal based on these controls, make drive signal corresponding to the thyristor in the described drive circuit.

5. the driving method in parallel of DC brushless motor as claimed in claim 1 or 2 is characterized in that, constitutes described drive circuit by three-phase voltage-type inverter.

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