JP2004173361A - Parallel drive circuit and parallel drive method for dc brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely perform synchronous pull-in of a plurality of DC motors, to stably accelerate and decelerate until reaching a set speed, and further to achieve cost reduction or the like by automatizing the setting of the time for synchronous pull-in and simplifying the circuit constitution. <P>SOLUTION: This parallel drive circuit of the DC brushless motor generates switching signals of switching elements T1 to T6 by using rotor-position detection signals of the motors MA, MB for driving at a constant speed the plurality of DC brushless motors MA, MB connected to each other in parallel by using a drive circuit comprising a plurality of semiconductor switching elements T1 to T6. A theoretical sum is detected by an OR circuit 41 at each phase from the rotor-position detection signals of the motors MA, MB, a control rotor-position detection signal is generated at each phase, and the switching signals are generated based on the control rotor-position signals. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a parallel drive circuit and a parallel drive method for driving a plurality of DC brushless motors connected in parallel to operate a plurality of fans and pumps at the same speed.
[0002]
[Prior art]
As a conventional technique for driving a plurality of brushless motors connected in parallel by one drive circuit, a brushless motor drive circuit described in Patent Document 1 described below is known.
This drive circuit uses a predetermined frequency-divided signal divided according to the number of brushless motors as a reference signal, sequentially switches the position detection signal based on the reference signal, and outputs the position detection signal to the drive driver. A plurality of brushless motors are driven by drive signals corresponding to the signals.
[0003]
However, in the above drive circuit, the timing of switching the position detection signal is not completely synchronized with the position detection signal. Easy to become unstable.
In addition, in this prior art, since switching is generally performed by a reference signal having a cycle longer than the cycle of the position detection signal, a motor in which the position detection signal is not used is operated regardless of the position detection signal during that time. There has been a problem that the operation tends to be unstable.
[0004]
For this reason, the present applicant has proposed a parallel drive circuit of a DC brushless motor mainly for stabilizing the drive as Japanese Patent Application No. 2001-222412 (the application was not published at the time of this application, and is hereinafter referred to as the prior application). Filed. Hereinafter, the prior invention will be described.
[0005]
FIG. 17 shows the entire configuration of a 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. 17, a DC power supply E is connected to a three-phase bridge circuit including semiconductor switching elements T1 to T6. DC brushless 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, and the Hall elements HU, HV, HW provided respectively are connected to the rotor position. It is connected to the detection circuits 21 and 22.
[0006]
The rotor position detection signals of the motors MA and MB output from the rotor position detection circuits 21 and 22 are input to a signal selection circuit 40, which can select which motor MA or MB to use. Has become. The signal selection circuit 40 outputs a control signal to the switching signal generation circuit 30 to turn on / off the switching elements T1 to T6 according to the rotor position detection signal of the selected motor.
In FIG. 17, reference numeral 11 denotes a stator, 12 denotes a rotor, and CU, CV, and CW denote coils of each phase of the stator 11.
[0007]
As shown in FIG. 18, the signal selection circuit 40 includes XOR (exclusive OR) gates IC1 and IC2 to which the rotor position detection signal of the motor MA is input, and NAND gates IC3 to IC3 connected to the output side of the XOR gate IC2. IC7, NAND gates IC8 to IC10 to which a rotor position detection signal of the motor MB is input, resistors R1 to R10 such as pull-up resistors, a capacitor C1, and diodes D1 to D7 on the output side of the NAND gates IC5 to IC10. , And output-side transistors TR1 to TR3.
When the rotor position detection signal of each phase of the motors MA and MB as shown in FIG. 19 is input, the signal selection circuit 40 supplies the switching signal generation circuit 30 with one or two phases of the motors MA and MB. To output a control signal for driving the switching element from the transistors TR1 to TR3.
[0008]
Hereinafter, the operation of the prior application of FIG. 17 will be described in detail with reference to FIGS.
Now, 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 as shown in FIG. In FIG. 19, a signal related to the motor MA is denoted by A, and a signal related to the motor MB is denoted by B.
Here, the rotor position detection signals of the motors MA and MB shown in FIG. 19 are substantially equal to the output signals of the hall elements HU, HV and HW in FIG.
[0009]
In order to operate both motors MA and MB in synchronization with the rotor position detection signal, the rotor rotation angles (space angles) in FIG. 19 are 0 °, 60 °, 120 °, 180 °, 240 °, and 300 °. 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 timing.
[0010]
On the other hand, the rotation angles in FIG. 19 are between 0 ° to 60 °, between 60 ° to 120 °, between 120 ° to 180 °, between 180 ° to 240 °, between 240 ° to 300 °, and 300 °. Between 0 ° and 0 °, the rotor position detection signal of each of the motors MA and MB does not change and remains constant (for example, between 0 ° and 60 ° as the rotor position detection signal of the motors MA and MB). The state in which the U-phase and W-phase signals are detected continues, and the state in which only the U-phase signal is detected as the rotor position detection signal of the motors MA and MB continues between 60 ° and 120 °).
[0011]
Therefore, there is no adverse effect even if the rotor position detection signal is switched between the motors MA and MB while the rotor position detection signal remains unchanged and unchanged.
For example, a switching signal for driving the motor MA using the rotor position detection signal of the motor MA (which may be a switching signal for driving the motor MB because the motors MA and MB are connected in parallel). In this case, it is possible to switch to the rotor position detection signal of the other motor MB and output a switching signal for driving the motor MB (also a switching signal for driving the motor MA). If the switching is performed during a period in which there is no change in the rotor position detection signal, there is no fear that the voltage applied to the motor changes suddenly at the moment of the switching. Further, if the drive is switched in a cycle shorter than the cycle of the rotor position detection signal, the operation is less likely to be unstable.
[0012]
Therefore, in the invention according to the prior application, the angle is between 0 ° to 60 °, between 60 ° to 120 °, between 120 ° to 180 °, between 180 ° to 240 °, and 240 ° to 300 °. Signal selection circuit 40 detects the rotor position detection signals of motors MA and MB at 30 °, 90 °, 150 °, 210 °, 270 °, and 330 ° between 300 ° and 0 ° (360 °). Are alternately switched between the motors and selected, and a switching signal for driving the motors MA and MB is output based on the selected rotor position detection signal.
[0013]
That is, as shown in FIG. 19, for example, during 330 ° to 30 °, the rotor position detection signal of the motor MA is selected, and based on this signal, the switching signal generation circuit 30 makes the U-phase coil CU and the W-phase coil CW The switching signal is output so as to energize (different periods). Further, the rotor position detection signal of the motor MB is selected between 30 ° and 90 °, and based on this signal, the switching signal generation circuit 30 energizes the U-phase coil CU and the W-phase coil CW (the period is respectively Create a switching signal as shown in FIG.
[0014]
Thereafter, similarly, the rotor position detection signal of the motor MA is selected between 90 ° and 150 °, and based on this signal, the switching signal generation circuit 30 switches the U-phase coil CU and the V-phase coil CV so that the switching signal is supplied. And the rotor position detection signal of the motor MB is selected between 150 ° and 210 °. Based on this signal, the switching signal generation circuit 30 switches the U-phase coil CU and the V-phase coil CV so that the switching signal is supplied. Create
[0015]
In FIG. 19, for convenience of explanation, the rotor position detection signals of the motors MA and MB are switched at angles of 30 °, 90 °, 150 °, 210 °, 270 °, and 330 °. Without limitation, 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 by switching between 300 ° and 0 ° (360 °) at an angle at which the rotor position detection signals of the motors MA and MB do not change.
[0016]
When the operation of the signal selection circuit 40 shown in FIG. 18 is confirmed, for example, the rotor position detection signals (U-phase, V-phase, and W-phase) of the motors MA and MB between 30 ° and 60 ° in FIG. Is also expressed by logic (1, 0, 1). If these are input as the rotor position detection signals of the motors MA and MB in FIG. 18, the output transistors TR1, TR2, TR3 (U The logic of the output signals of (phase, V phase, W phase) is (1, 0, 1), and the rotor position detection signals (U phase, V phase, Assuming that each of the W-phases is logic (1, 0, 0), the logic of the output signal of the output transistors TR1, TR2, TR3 (U-phase, V-phase, W-phase) is (1, 0, 0), The output (control signal) of the signal selection circuit in the period of 30 ° to 90 ° in FIG. It can be seen that the match and of.
The above operation enables the two motors MA and MB to be stably driven in parallel by a single drive circuit in synchronization with the rotor position detection signal.
[0017]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-262082 (Claim 1, FIGS. 1-3)
[0018]
[Problems to be solved by the invention]
However, in the above-mentioned prior invention, the configuration of the drive circuit is generally complicated, which causes an increase in cost.
If the two motors are started from non-identical (asynchronous) rotors and the speed is rapidly increased, a large circulating current will flow irregularly until the motors are pulled in synchronously, resulting in instability. And sometimes did not synchronize.
In addition, at the time of synchronization pull-in, it is necessary to supply a direct current to the motor for a certain period of time regardless of the magnitude of the load connected to the motor and the number of rotations, and it is necessary to operate the motor at a low speed for a certain period of time. Since management of time (synchronization pull-in time) is complicated, automation thereof has been desired.
[0019]
Accordingly, the present invention ensures synchronous pull-in of a plurality of DC brushless motors, enables stable acceleration / deceleration up to a set speed, and further reduces the cost by automating the synchronous pull-in time and simplifying the circuit configuration. It is an object of the present invention to provide a parallel drive circuit and a parallel drive method for a DC brushless motor which enables the above.
[0020]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 provides a switching signal generating means for driving a plurality of DC brushless motors connected in parallel at the same speed by a drive circuit having a plurality of semiconductor switching elements. In the DC brushless motor parallel drive circuit that creates a switching signal of the switching element using a rotor position detection signal of each motor,
A logical sum or a logical product is detected for each phase from a rotor position detection signal of each motor to create a control rotor position detection signal for each phase, and the switching signal is generated based on these control rotor position detection signals. To create.
[0021]
According to a second aspect of the present invention, in the parallel drive circuit of the DC brushless motor according to the first aspect,
When the motor is started, DC current is applied to the coil of the motor until the load angle, which is the difference between the output voltage phase angle of the drive circuit and the rotor phase angle based on the control rotor position detection signal, is equal to or less than a predetermined set value. When the load angle is equal to or less than the set value, it is determined that the synchronous pull-in of the plurality of motors is completed, and the motors are accelerated.
[0022]
According to a third aspect of the present invention, in the method for driving a DC brushless motor according to the second aspect,
The command value of the DC current is variably controlled in proportion to the load angle.
[0023]
According to a fourth aspect of the present invention, there is provided a method for driving a DC brushless motor in parallel according to the second or third aspect,
After synchronizing a plurality of motors, the motors are accelerated while changing the limit value of the output voltage phase angle of the drive circuit according to the output frequency.
[0024]
According to a fifth aspect of the present invention, there is provided a method for driving a DC brushless motor in parallel according to the second or third aspect,
After synchronizing a plurality of motors, an output voltage command of the drive circuit is created by adding a compensation voltage proportional to the load angle to an output voltage obtained from an electromotive voltage of the motor.
[0025]
According to a sixth aspect of the present invention, there is provided a method for driving a DC brushless motor in parallel according to the second or third aspect,
After synchronous pull-in of a plurality of motors, a fine adjustment time proportional to the load angle is added to a load acceleration / deceleration time obtained from load characteristics to obtain an acceleration / deceleration time of the motor.
[0026]
According to a seventh aspect of the present invention, in the parallel driving method of the DC brushless motor according to the second or third aspect,
After synchronous pull-in of a plurality of motors, the motors are driven at a constant speed in a low-speed region for a fixed time, and then accelerated to a set speed.
[0027]
According to an eighth aspect of the present invention, there is provided a method for driving a DC brushless motor in parallel according to the fifth, sixth or seventh aspect.
An output voltage of the drive circuit is cut off for a certain period of time when an abnormality occurs in which the logic level of the control rotor position detection signal becomes a High level or a Low level in all phases, and thereafter, the synchronization pull-in processing according to claim 2 is executed again. This is provided with a retry function.
[0028]
According to a ninth aspect of the present invention, there is provided a method for parallel driving a DC brushless motor according to the eighth aspect,
The number of executions of the retry function can be arbitrarily set as the number of retries, and when the number of retries is exceeded, an abnormal signal is output to the outside.
[0029]
According to a tenth aspect of the present invention, there is provided a method for driving a DC brushless motor in parallel according to the fifth, sixth or seventh aspect.
In the event that the logic level of the control rotor position detection signal is high or low in all phases, the acceleration is stopped and the control is switched to constant speed control in the event of an abnormality. In addition to the output, when the abnormal time is resolved within a predetermined time, the acceleration operation is performed again.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 shows a signal selection circuit of the present embodiment corresponding to the signal selection circuit 40 of FIG.
In FIG. 1, UA, VA, WA, and CM are rotor position detection signals of the motor MA, UA, VA, and WA indicate detection signals of the U, V, and W phases, respectively, and CM indicates common. These rotor position detection signals UA, VA, WA, and CM are the rotor position detection signals (MA) input to the signal selection circuit 40 in FIG. 17, that is, the motor MA rotor position detection described in FIGS. Signal.
[0031]
Similarly, UB, VB, WB, and CM are rotor position detection signals of the motor MB, UB, VB, and WB are detection signals of the U, V, and W phases, respectively, and CM is common. These rotor position detection signals UB, VB, WB, and CM are the rotor position detection signals (MB) input to the signal selection circuit 40 in FIG. 17, that is, the motor MB rotor position detection described in FIGS. Signal.
[0032]
In FIG. 1, reference numeral 41 denotes the logical sum of the U-phase rotor position detection signals UA and UB, the logical sum of the V-phase rotor position detection signals VA and VB, and the logical sum of the W-phase rotor position detection signals WA and WB. This is an OR circuit to be obtained, and each phase output terminal of the OR circuit 41 is connected to a power supply (+24 V) via diodes 42U, 42V, 42W, resistors 43U, 43V, 43W and resistors 44U, 44V, 44W, respectively.
Light emitting elements in photocouplers 45U, 45V, 45W are connected to both ends of the resistors 44U, 44V, 44W, respectively, and capacitors 46U, 46V, 46W are connected to both ends of the light receiving elements in the photocouplers 45U, 45V, 45W. Is connected.
[0033]
One end of each of the capacitors 46U, 46V, 46W is connected to a power supply (+ 5V) via a pull-up resistor 47U, 47V, 47W, respectively, and an output terminal 48U, which outputs a control rotor position detection signal of each phase. 48V and 48W, respectively.
The other ends of the capacitors 46U, 46V, and 46W are collectively connected to a ground terminal (5G).
[0034]
Next, FIG. 2 shows a rotor position detection signal UA of each phase of U, V and W when the two motors MA and MB are synchronized (each rotor is stopped at the same position) at the time of starting. , UB, VA, VB, WA, and WB together with the output of the OR circuit 41. Here, the output of the OR circuit 41 is equal to the control rotor position detection signal of each phase output from the output terminals 48U, 48V, 48W in FIG.
In this case, since the control rotor position detection signal (OR circuit output) of each phase is shifted by 120 ° and continues by 180 °, the switching signal generating circuit 30 of FIG. It is determined that MA and MB are synchronized, and the vehicle accelerates quickly.
[0035]
3 and 4 show a state in which the two motors MA and MB are not synchronized, and the motor MB is delayed by 45 ° with respect to the motor MA (FIG. 3), and the motor MB is 75 ° with respect to the motor MA. The state of being late (FIG. 4) is shown.
Also in these cases, the control rotor position detection signals (OR circuit outputs) of the respective phases are shifted by 120 °, but since they continue for 180 ° or more, the switching signal generating circuit 30 uses two motors MA, It is determined that the MB is not synchronized.
[0036]
5 to 7 use an AND circuit (not shown) in place of the OR circuit 41 in FIG. 1 and use the logical product of the U-phase rotor position detection signals UA and UB of the two motors MA and MB. When the logical product of the V-phase rotor position detection signals VA and VB and the logical product of the W-phase rotor position detection signals WA and WB are obtained, the rotor position detection signals UA, UB and VA of the respective U, V and W phases are obtained. , VB, WA, and WB together with the output of the AND circuit.
FIG. 5 shows a case where the motors MA and MB are synchronized, FIG. 6 shows a state where the motors MA and MB are not synchronized and the motor MB is delayed by 45 ° with respect to the motor MA, and FIG. Respectively show the state where the motor MB is delayed by 75 °.
As described above, even when the AND circuit is used instead of the OR circuit 41, it is possible to determine the synchronization or the asynchronous from the control rotor position detection signals (the output of the AND circuit) of each phase.
[0037]
Next, the synchronization pull-in condition when the two motors MA and MB are not synchronized as shown in FIGS. 3, 4, 6 and 7 will be described with reference to FIG. In FIG. 8, a solid arrow indicates a logical sum or a logical product output (control rotor position detection signal) of a rotor position detection signal of a certain phase (for example, U phase) of the two motors MA and MB in FIG. Arrows indicate the U-phase rotor position of the motor MA, and broken-line arrows indicate the U-phase rotor position of the motor MB.
[0038]
First, as shown in FIG. 8 (a), when the motors MA and MB are not synchronized and their respective rotor positions are different, the switching signal from the switching signal generation circuit causes the three-phase bridge circuit of FIG. Is turned on, a DC current is supplied to the stator coil, and the phase angle of the U-phase output voltage is controlled to an arbitrary value as shown in FIG. 8B. Here, a fixed angle range (shaded area) around the output voltage phase angle is defined as a load angle setting range.
[0039]
By passing the DC current through the coil in this manner, the motors MA and MB move so that the rotor positions match the output voltage phase angle, and as shown in FIG. 8C, the rotor positions fall within the load angle setting range. For example, it is determined that the two motors MA and MB are synchronized, and the mode shifts to the acceleration mode.
As shown in FIG. 8D, if one of the rotor positions is outside the load angle setting range and the phase angle of the control rotor position detection signal does not fall within the load angle setting range, the two motors MA , MB are not synchronized, and direct current is continuously supplied to the coil.
[0040]
Here, the magnitude of the DC current when the DC current flows through the coil because the two motors MA and MB are not synchronized will be described with reference to FIG.
The difference (load angle) between the output voltage phase angle and the logical sum or logical product output phase angle (referred to as rotor phase angle) of the rotor positions of the motors MA and MB is substantially proportional to the generated torque of the motor. By variably controlling the DC current command value in proportion to the angle, the torque required at the time of pull-in can be optimally controlled, and the time required for pull-in can be minimized.
[0041]
That is, FIG. 9A shows a case where the load angle is large. In this case, the DC current command value is increased. FIG. 9B shows the case where the load angle is small. In this case, the DC current command value is reduced.
Control of these DC current command values is executed by a switching signal generation circuit.
[0042]
FIG. 10 is a flowchart showing the above-described synchronization pull-in procedure.
First, when it is determined that the two motors MA and MB are not synchronized, an arbitrary output voltage phase angle is output (S1). Next, a load angle is obtained from the phase angle of the control rotor position detection signal detected in FIG. 1, that is, the rotor phase angle, and the output voltage phase angle (S2). It is determined whether or not it is within the load angle setting range defined by the set value (S3). If the load angle is outside the load angle setting range, the DC current command value is controlled by the method of FIG. The output current is controlled (S4).
If the rotor phase angle is within the load angle setting range, it is determined that synchronization pull-in has been completed (S5), and the mode shifts to the acceleration mode.
[0043]
If the load angle is too large, it is difficult to maintain the synchronous state of the two motors. In particular, in a low-speed region where the output frequency is low, such as during acceleration, a large starting torque is required and the load angle tends to increase. Therefore, when the output frequency is low, the output voltage phase angle does not advance too much. It is effective to limit the output voltage phase angle by a limiter so that the load angle does not become too large.
FIGS. 11 and 12 are diagrams for explaining the operation of the output voltage phase angle limiter. When the output frequency is small (for example, fa in FIG. 11), the output voltage phase angle is limited to near the lower limit, and the output frequency is reduced. When it is large (for example, fb in FIG. 11), the output voltage phase angle is limited by the upper limit.
As a result, it is possible to prevent the load angle from becoming too large to exceed the step-out limit, and to obtain a stable acceleration torque.
[0044]
Next, a driving method when the two motors are operated in parallel after the synchronization pull-in will be described with reference to FIGS.
When two motors are operated in parallel while accelerating after synchronous pull-in, there is, for example, a method shown in FIG. 13 as a method for keeping the two motors out of step.
[0045]
First, a motor output voltage pattern (V / f pattern) for a predetermined frequency from the back electromotive force of the motor is determined in advance, and the motor output voltage corresponding to the motor output frequency at the time of acceleration after pull-in is synchronized with the V / f output. It is stored as a voltage (S11). Next, the load angle is determined from the output voltage phase angle and the rotor phase angle (S12), and the output voltage proportional to the load angle is calculated by focusing on the fact that the load angle is substantially proportional to the motor generated torque. (S13). Next, an output voltage is obtained by adding the compensation voltage to the V / f output voltage (S14). By giving this output voltage as a command to the switching signal generating circuit 30, automatic torque compensation can be performed during acceleration.
[0046]
Next, the driving method shown in FIG. 14 is a method of obtaining an optimal acceleration / deceleration time by adding a fine adjustment time obtained from a load angle to a load acceleration / deceleration time predetermined according to a load.
That is, the acceleration / deceleration time obtained from the load characteristics is set and stored in advance as the load acceleration / deceleration time (S21). Next, a load angle is determined (S22), and an acceleration / deceleration time proportional to the load angle is calculated and set as a fine adjustment time (S23). Next, this fine adjustment time is added to the load acceleration / deceleration time to obtain a final acceleration / deceleration time (S24). By accelerating or decelerating according to the acceleration / deceleration time, the acceleration / deceleration time can be automatically adjusted in proportion to the load angle.
[0047]
The driving method shown in FIG. 15 is a method in which the motor is driven at a constant speed for a certain period of time at a low speed after the synchronization is pulled in, and then accelerates to a set speed.
First, it is determined whether or not there is a stop command (S31). If there is a stop command, the constant speed operation timer value is set to zero, and the mode shifts to the deceleration mode (S342, S372).
[0048]
If there is no stop command, it is determined whether the vehicle is accelerating and the output frequency is at a predetermined low speed point (S32). When both are denied, the constant speed operation timer value is set to zero and the process proceeds to the acceleration mode (S343, S373).
If the output frequency is at the predetermined low speed point during acceleration, it is determined whether or not the constant speed operation timer value is zero (S33). If zero, the constant speed operation timer value is set to the predetermined value (constant speed). (Corresponding to the operation time) (S341), and thereafter, the timer value is sequentially decremented (S35). If the constant speed operation timer value is not zero in step S33, the process jumps directly to step S35.
[0049]
Each time the constant speed operation timer value is incremented in step S35, it is determined whether or not the constant speed operation timer value has become zero (S36). The constant speed mode is continued until the value becomes zero (S371). The mode shifts to the acceleration mode (S373).
By such processing, synchronous operation can be established by low-speed operation for a certain period of time set by the constant-speed operation timer value, and thereafter, the operation can be shifted to accelerated operation in a stable state.
[0050]
FIG. 16 shows that all the switching elements in the three-phase bridge circuit of FIG. 17 are turned off when the synchronization pull-in is not successful, or when the danger of step-out increases after the synchronous operation is started. This is a drive method having a retry function of interrupting the output voltage of the drive circuit (supply voltage to the coils CU, CV, CW) and then executing again from the synchronization pull-in process.
[0051]
First, DC braking is started by turning on the operation command (S41, S42). Here, the DC braking means turning on the switching element in the three-phase bridge circuit of FIG. 17 and flowing DC current from the drive circuit to the stator coil as described above.
Thereafter, it is determined whether or not the two motors are synchronized (S43). If the two motors are not synchronized, it is determined that a timeout has occurred when a set time of DC braking has passed, and the process returns to step S41 again (S45). If the timeout has not been reached, the process proceeds to step S47 described later.
[0052]
When the two motors are synchronized, automatic acceleration is started (S44), and the process proceeds to the driving method shown in FIGS.
At this time, the logical level of the output signal (control rotor position detection signal) of the OR circuit 41 is "High" for all phases as shown in FIG. 4, or the output signal of the AND circuit (not shown) (control rotor position signal). Assuming that the logic level of the position detection signal) is "Low" in all phases as shown in FIG. 7, this means that the absolute value of the load angle is in the state of 60 ° ≦ | load angle | <120 °. This signifies an abnormal situation where there is a risk of loss of synchronism if accelerated further.
[0053]
Therefore, in the driving method of FIG. 16, in step S46, when the above-described abnormal situation occurs, the process shifts to the retry control side.
That is, the number of retries is set in advance, and if the number of retries is less than the set number, the output voltage of the drive circuit in FIG. If the time is over after elapse (S50), the process returns to step S41 to retry from the synchronization pull-in process.
If the number of retries reaches the set number (or if the above-mentioned abnormal situation is not resolved even after a certain period of time after the first retry), the output voltage is cut off and an abnormal situation such as disconnection occurs. And an abnormal signal (alarm) is output (S48).
[0054]
If the determination in step S46 is negative, it is determined whether the motor is stopped (S51). If the motor is stopped, a synchronization pull-in process is performed (S41 and subsequent steps). Is repeated.
Here, when the abnormal situation is resolved in step S46 as a result of the retry control, a normal control rotor position detection signal is output, and the motor may be accelerated again based on the signal.
If the output signals of the OR circuit 41 (AND circuit) are at the "High" (Low) level in all the phases in step S46, the acceleration is temporarily stopped, and based on the previous normal control rotor position detection signal for the previous time. The control may be switched to the constant speed control.
[0055]
In the above embodiment, 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.
[0056]
【The invention's effect】
As described above, according to the present invention, each motor is driven in parallel with a relatively simple circuit configuration based on the logical sum or logical product of the rotor position detection signals for each phase detected from a plurality of DC brushless motors. can do.
In addition, accurate determination of synchronization pull-in and automation of synchronization pull-in time are possible, and constant speed operation at a low speed and acceleration / deceleration operation to a predetermined speed can be reliably performed without synchronizing a plurality of motors. .
In general, according to the present invention, a parallel drive device such as a plurality of fans and pumps that require stable operation with low noise can be provided at low cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a signal selection circuit according to an embodiment of the present invention.
FIG. 2 is a timing chart showing a rotor position detection signal of each phase together with an output of an OR circuit when two motors are synchronized in the embodiment of the present invention.
FIG. 3 is a timing chart showing a rotor position detection signal of each phase together with an output of an OR circuit when two motors are not synchronized in the embodiment of the present invention.
FIG. 4 is a timing chart showing a rotor position detection signal of each phase together with an output of an OR circuit when two motors are not synchronized in the embodiment of the present invention.
FIG. 5 is a timing chart showing a rotor position detection signal of each phase together with an output of an AND circuit when two motors are synchronized in the embodiment of the present invention.
FIG. 6 is a timing chart showing a rotor position detection signal of each phase together with an output of an AND circuit when two motors are not synchronized in the embodiment of the present invention.
FIG. 7 is a timing chart showing a rotor position detection signal of each phase together with an output of an AND circuit when two motors are not synchronized in the embodiment of the present invention.
FIG. 8 is an explanatory diagram of a synchronization pull-in condition in the embodiment of the present invention.
FIG. 9 is an explanatory diagram of a method for determining a DC current command value in the embodiment of the present invention.
FIG. 10 is a flowchart illustrating a synchronization pull-in procedure according to the embodiment of the present invention.
FIG. 11 is a diagram illustrating an operation of an output voltage phase angle limiter according to the embodiment of the present invention.
FIG. 12 is a diagram illustrating an operation of an output voltage phase angle limiter according to the embodiment of the present invention.
FIG. 13 is a flowchart showing a procedure when two motors are operated in parallel after pulling in synchronization in the embodiment of the present invention.
FIG. 14 is a flowchart illustrating a procedure when two motors are operated in parallel after synchronization is pulled in the embodiment of the present invention.
FIG. 15 is a flowchart illustrating a procedure when two motors are operated in parallel after synchronization is pulled in the embodiment of the present invention.
FIG. 16 is a flowchart illustrating a procedure when two motors are operated in parallel after synchronization is pulled in the embodiment of the present invention.
FIG. 17 is a circuit diagram of a drive circuit according to the prior application.
18 is a circuit diagram showing a configuration of a signal selection circuit in FIG.
FIG. 19 is a timing chart showing the operation of FIG.
[Explanation of symbols]
E: DC power supply
T1 to T6: switching element
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
41: OR circuit
42U, 42V, 42W: Diode
43U, 43V, 43W, 44U, 44V, 44W: Resistance
45U, 45V, 45W: Photocoupler
46U, 46V, 46W: Capacitor
47U, 47V, 47W: Pull-up resistor
48U, 48V, 48W: output terminal

Claims (10)

In order to drive a plurality of DC brushless motors connected in parallel with each other at the same speed by a drive circuit having a plurality of semiconductor switching elements, a switching signal generating unit uses the rotor position detection signal of each motor to generate a signal for the switching elements. In a DC brushless motor parallel drive circuit for generating a switching signal,
A logical sum or a logical product is detected for each phase from a rotor position detection signal of each motor to create a control rotor position detection signal for each phase, and the switching signal is generated based on these control rotor position detection signals. A parallel drive circuit for a DC brushless motor, characterized by being created. The parallel drive circuit for a DC brushless motor according to claim 1,
When the motor is started, DC current is applied to the coil of the motor until the load angle, which is the difference between the output voltage phase angle of the drive circuit and the rotor phase angle based on the control rotor position detection signal, is equal to or less than a predetermined set value. A method of driving a DC brushless motor in parallel, comprising determining that synchronous pull-in of a plurality of motors has been completed when the load angle falls below the set value, and accelerating the motors. A method for driving a DC brushless motor in parallel according to claim 2,
A parallel driving method for a DC brushless motor, wherein a command value of the DC current is variably controlled in proportion to the load angle. The parallel driving method of a DC brushless motor according to claim 2 or 3,
A method of driving a DC brushless motor in parallel, wherein after accelerating a plurality of motors, the motor is accelerated while changing a limit value of an output voltage phase angle of the drive circuit according to an output frequency. The parallel driving method of a DC brushless motor according to claim 2 or 3,
A DC brushless DC brushless motor, wherein after compensating a plurality of motors, a compensation voltage proportional to the load angle is added to an output voltage obtained from an electromotive voltage of the motor to generate an output voltage command of the drive circuit. Parallel driving method of motor. The parallel driving method of a DC brushless motor according to claim 2 or 3,
After synchronous pull-in of a plurality of motors, a fine adjustment time proportional to the load angle is added to a load acceleration / deceleration time obtained from a load characteristic to obtain an acceleration / deceleration time of the motor. Parallel driving method. The parallel driving method of a DC brushless motor according to claim 2 or 3,
A method for driving a DC brushless motor in parallel, comprising: after synchronous pull-in of a plurality of motors, operating the motors at a constant speed in a low-speed region for a fixed time, and then accelerating to a set speed. The parallel driving method of a DC brushless motor according to claim 5, 6, or 7,
An output voltage of the drive circuit is cut off for a certain period of time when an abnormality occurs in which the logic level of the control rotor position detection signal becomes a High level or a Low level in all phases, and thereafter, the synchronization pull-in processing according to claim 2 is executed again. A parallel driving method for a DC brushless motor, comprising: A method for driving a DC brushless motor in parallel according to claim 8,
A method of parallel driving a DC brushless motor, wherein the number of times of execution of the retry function can be arbitrarily set as the number of retries, and an abnormal signal is output to the outside when the number of retries is exceeded. The parallel driving method of a DC brushless motor according to claim 5, 6, or 7,
In the event that the logic level of the control rotor position detection signal is high or low in all phases, the acceleration is stopped and the control is switched to constant speed control in the event of an abnormality. A method of driving a DC brushless motor in parallel, wherein the DC brushless motor outputs an output and, when the abnormality is resolved within a predetermined time, accelerates again.

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