JP2019050643A - Driving device for motor - Google Patents

Abstract

To provide a driving device for a motor capable of stably fixing a rotor on a normal position at the activation of the motor.SOLUTION: In a driving device 1 for a sensorless brushless motor including a three-phases sensorless brushless motor 11 comprising a stator 21 and a rotor 22, and a control part 12 controlling driving of the sensorless brushless motor 11, the control part 12 executes three-phases excitation twice at the activation of the sensorless brushless motor 11 to position the rotor 22.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a drive of a motor, and more particularly to a drive of a sensorless brushless motor.

  As a prior art, there is a drive device for an electric motor as disclosed in Patent Document 1. In this device, when starting the synchronous motor, two IGBTs are turned on to excite the stationary phase to fix the rotor in the normal position (specific position).

JP 2008-67600 A

  In the apparatus disclosed in Patent Document 1, when starting the synchronous motor, two-phase excitation is performed to flow a current between two selected phases to fix the rotor in a normal position. However, when performing two-phase excitation in this way, only the magnetic field is generated in two of the three phases in the stator, so the attractive force generated between the stator and the rotor becomes insufficient, and the rotor May not be fixed in the correct position.

  Then, this indication is made in order to solve an above-mentioned problem, and it aims at providing the drive device of the electric motor which can fix a rotor in a normal position stably at the time of starting of an electric motor.

  One embodiment of the present disclosure made to solve the above problems is a drive device for a motor including a three-phase motor including a stator and a rotor, and a control unit that controls the drive of the motor. The control unit performs three-phase excitation a plurality of times at the time of startup of the motor to position the rotor.

  According to this aspect, since positioning of the rotor is performed by performing three-phase excitation at startup of the motor, the attractive force generated between the stator and the rotor is larger than when performing two-phase excitation as in the related art. be able to. Therefore, the rotor can be stably fixed at the normal position when the motor is started.

  Furthermore, although the possibility that the rotor can not be fixed at the correct position can not be completely eliminated by performing the three-phase excitation only once, the three-phase excitation is performed multiple times, so the rotor can be more stably positive. It can be fixed in position.

  In the above aspect, it is preferable that the control unit changes a duty ratio of a voltage applied to the motor when performing the three-phase excitation in accordance with an elapse of an excitation time.

  According to this aspect, it is possible to suppress the over-rotation of the motor and to improve the robustness of the positioning of the rotor.

  In the above aspect, it is preferable that the control unit convert a duty ratio of a voltage applied to the motor when performing the three-phase excitation into a value corresponding to a magnitude of the voltage.

  According to this aspect, the robustness of the positioning of the rotor can be improved with respect to the fluctuation of the output power of the power supply for driving the motor.

  In the above aspect, the control unit repeatedly performs positioning of the rotor until the activation of the motor succeeds, counts the number of activation failures which is the number of times the activation of the motor fails, and fails the activation When the number of times exceeds a predetermined number of times, it is preferable to change the setting conditions for performing the three-phase excitation.

  According to this aspect, even if startup of the motor is not successful, the rotor is fixed at the normal position at startup of the motor by changing the setting conditions when performing three-phase excitation, and startup of the motor Can be successful.

  According to the drive device for an electric motor of the present disclosure, the rotor can be stably fixed at the normal position when the electric motor is started.

It is a block diagram which shows the structure of the drive device of the sensorless brushless motor in this embodiment. It is a flowchart of control performed at the time of starting of a motor. It is a figure which shows an example of the timing chart of the control performed at the time of starting of a motor. It is a figure which shows a mode (normal time) until a rotor is fixed to a normal position by implementing 3 phase excitation twice. It is a figure which shows a mode (at the time of reverse phase) until a rotor is fixed to a normal position by implementing 3 phase excitation twice. It is a figure which shows the relationship between the magnitude | size of a voltage, and the value of duty ratio.

  Embodiments of a motor drive device of the present disclosure will be described in detail with reference to the drawings. Therefore, first, after describing the configuration of the drive device, a control method of the drive device in the present embodiment will be described.

  In the present embodiment, as an example of a drive device for a motor, for example, a drive device 1 for a sensorless brushless motor used in a fuel pump (hereinafter simply referred to as “motor drive device 1” as appropriate) will be described. The motor drive device 1 is a device for controlling the drive of the sensorless brushless motor 11 (hereinafter, also simply referred to as “motor 11” as appropriate), and as shown in FIG. 1, the control unit 12 and the drive circuit 13 And.

  The motor 11 is a three-phase motor (electric motor), and the drive circuit 13 employs a three-phase inverter circuit. The motor 11 includes a stator 21 provided with three-phase (U-phase, V-phase, W-phase) coils 21A, 21B, 21C, and a rotor 22 (magnet rotor). In order to detect the magnetic pole position (rotor position) of the rotor 22 with respect to the stator 21, the motor 11 uses an induced voltage generated by the coils 21A to 21C of each phase without using a Hall element. Then, when the rotor 22 rotates, the motor 11 detects the rotor position based on the induced voltage generated by the coils 21A to 21C of each phase, and each phase to be energized based on the detected rotor position. The “induced voltage drive” is performed to determine the coils 21A to 21C (energized phase) of the above.

  The drive circuit 13 supplies drive power to the motor 11. The drive circuit 13 is connected to a DC power supply BATT via a power supply circuit 14 and includes six transistors. Then, in the drive circuit 13, the rotational drive of the motor 11 is controlled by switching each transistor at a predetermined timing based on the signal from the control unit 12.

  The control unit 12 controls the drive of the motor 11 via the drive circuit 13. A direct current power supply BATT is connected to the control unit 12 via a power supply circuit 14. Further, the ECU 16 is connected to the control unit 12 via the I / F circuit 15. The control unit 12 is configured of, for example, a custom IC. In the present embodiment, the ECU 16 instructs the number of rotations (target rotation number) of the motor 11.

  Next, control performed when the motor 11 is started in the present embodiment will be described. In the present embodiment, the control unit 12 performs control based on the flowchart shown in FIG. 2 when the motor 11 is started.

  As shown in FIG. 2, first, current is supplied to all the three-phase coils 21A, 21B, 21C, and the first three-phase excitation is performed until a predetermined excitation time elapses (steps S1, S2) . At this time, for example, direct current is caused to flow between the U-phase coil 21A and the V-phase coil 21B and between the U-phase coil 21A and the W-phase coil 21C to perform three-phase excitation. Then, as shown in FIG. 4A, the U-phase magnetic pole (in detail, the magnetic pole on the rotor 22 side of the U-phase coil 21A) is made the S pole, and the V-phase and W-phase magnetic poles (in detail V-phase) The magnetic pole on the side of the rotor 22 in the coil 21B of FIG. Further, as shown in FIG. 2, a predetermined excitation time is set to an excitation time T1, and a duty ratio of a voltage applied to the motor 11 is set to a duty ratio D1. At this time, in the timing chart shown in FIG. 3, it corresponds to a time zone of “positioning (first time)”.

  In addition, “the duty ratio of the voltage applied to the motor 11” refers to (the time during which the switching of the transistor is turned on when the switching of the transistor in the drive circuit 13 is turned on / off and the voltage applied to the motor 11 is controlled). It is a value calculated by the equation: / {(time to turn on switching of transistor) + (time to turn off switching of transistor)}.

  Here, the duty ratio D1 may be constant until the excitation time T1 elapses, or may be changed according to the passage of time. Further, as shown in FIG. 6, the duty ratio D1 may be changed according to the magnitude of the voltage applied to the motor 11. In the example shown in FIG. 6, the duty ratio D1 is changed to be smaller as the voltage is larger.

  Note that, as an example of a specific numerical value, here, the duty ratio D1 is, for example, 27.5% as constant until the excitation time T1 elapses. Further, the excitation time T1 is set to, for example, 20 ms.

  Next, current is supplied to all the three-phase coils 21A, 21B, and 21C, and the second three-phase excitation is performed until a predetermined excitation time passes (steps S3 and S4). At this time, for example, direct current is caused to flow between the V-phase coil 21B and the U-phase coil 21A, and between the V-phase coil 21B and the W-phase coil 21C to perform three-phase excitation. Then, as shown in FIGS. 4 (b) and 4 (c), the V-phase magnetic pole is S-pole, and the U-phase and W-phase magnetic poles are N-pole. Further, as shown in FIG. 2, a predetermined excitation time is set to an excitation time T2, and a duty ratio of a voltage to be applied to the motor 11 is set to a duty ratio D2. At this time, in the timing chart shown in FIG. 3, it corresponds to a time zone of “positioning (second time)”.

  Here, the duty ratio D2 may be constant until the excitation time T2 elapses, or may be changed according to the passage of time. Further, the duty ratio D2 may be changed according to the magnitude of the voltage applied to the motor 11, as shown in FIG. In the example shown in FIG. 6, the duty ratio D2 is changed to be smaller as the voltage is larger.

  As an example of a specific numerical value, the excitation time T2 is set to, for example, 80 ms. Then, here, the duty ratio D2 is changed in such a manner as to decrease according to the elapse of time until the excitation time T2 elapses. Thus, for example, the duty ratio D2 is set to 20.0% for 20 ms, and then 10.0% for 60 ms.

  In this manner, in the present embodiment, three-phase excitation is performed twice when the motor 11 is started, so that the magnetic pole position of the rotor 22 with respect to the stator 21 is moved to the normal position and fixed (stopped). The rotor 22 is positioned. The details of the positioning of the rotor 22 will be described later.

  Next, forced commutation is performed to slightly rotate the rotor 22 (step S5), and if this forced commutation succeeds (step S6: YES), it is determined that the motor 11 has started successfully, and the process shifts to sensorless control ( Step S7). Here, “forced commutation” means that the rotor 22 is slightly rotated by energizing any one of the phases of the stator 21 (for example, between the U phase and the V phase). Then, if the position of the rotor 22 is detected based on the induced voltage at this time, and transition can be made to normal energization (energization for performing sensorless control) based on this detected position, “forced commutation succeeded It can be said that. Moreover, "sensorless control" is control which performs said "induced voltage drive."

  On the other hand, when the forced commutation is not successful in step S6 (step S6: NO), the number X of startup failures is counted up (increased by one) (step S8). In the case where the forced commutation is not successful, for example, foreign matter is caught in the rotor 22 and the rotor 22 becomes difficult to rotate, so the rotor 22 can not be fixed at the normal position, and the forced commutation succeeds. If not, it is possible.

  Then, if the activation failure number X is less than the predetermined number N (step S9: NO), the process returns to the step S1 as it is.

  On the other hand, if the number of start failures X is equal to or more than the predetermined number N in step S9 (step S9: YES), it is determined that the rotor 22 is difficult to rotate and the motor 11 is locked. After performing (step S10), the process returns to step S1.

  Here, as the “change of start-up method” in step S10, for example, the duty ratio of the excitation time and the voltage set when three-phase excitation is performed in steps S1 to S4 is changed. That is, the excitation time T1 is set to the excitation time T1_L, and the duty ratio D1 is set to the duty ratio D1_L. Further, the excitation time T2 is set to the excitation time T2_L, and the duty ratio D2 is set to the duty ratio D2_L.

  Here, as an example of a specific numerical value, the excitation time T1_L is, for example, 40 ms, and the duty ratio D1_L is, for example, 27.5%. The excitation time T2_L is, for example, 160 ms, and the duty ratio D2_L is, for example, 20.0% for 40 ms, and 10.0% for 120 ms.

  As described above, in the present embodiment, the control unit 12 performs two-phase three-phase excitation in which current is supplied to all the three-phase coils 21A, 21B, and 21C when the motor 11 is started, thereby positioning the rotor 22. I do.

  Specifically, when performing the first three-phase excitation, the control unit 12 sets, for example, the U-phase magnetic pole as the S pole and the V-phase and W-phase magnetic poles as the N pole in the stator 21. Next, when the second three-phase excitation is performed, for example, in the stator 21, the V-phase magnetic pole is set to the S pole, and the U-phase and W-phase magnetic poles are set to the N pole.

  In this manner, three-phase excitation is performed in the motor 11 to intentionally break the current balance between the H phase and the L phase, thereby positioning the rotor 22. As a result, the rotor 22 can be stably fixed (stopped) at a normal position where predetermined rotation can be started without depending on the initial position of the rotor 22.

  That is, at normal times, the rotor 22 can be fixed at the normal position when the motor 11 is started as follows. First, as shown in FIG. 4A, after the first three-phase excitation, the rotor 22 moves to a position where the U phase (S pole) of the stator 21 faces the N pole of the rotor 22 by attraction. Stop. After the second three-phase excitation (FIG. 4 (b)), as shown in FIG. 4 (c), the rotor 22 is such that the V phase (S pole) of the stator 21 attracts N force of the rotor 22. It moves to the position opposite to the pole, that is, the normal position, and stops. At this time, the positions of the U phase and the W phase of the stator 21 are positions facing the boundary between the S pole and the N pole of the rotor 22.

  Further, even if the time different from the above-mentioned normal time (in the reverse phase time), the rotor 22 can be fixed at the normal position as follows. First, as shown in FIG. 5A, after the first three-phase excitation, the rotor 22 receives the U-phase (S pole) of the stator 21 by the action of the repulsive force generated between the stator 21 and the rotor 22. Is stopped at an unstable position where it faces the S pole of the rotor 22 (reverse phase lock state). And, even in such a reverse phase lock state, according to the present embodiment, after the second three-phase excitation (FIG. 5 (b)), it is shown in FIG. 5 (c) Thus, the rotor 22 moves to a position where the V phase (S pole) of the stator 21 is opposite to the N pole of the rotor 22 by attraction, that is, the normal position, and then stops.

  As described above, in the present embodiment, three-phase excitation is performed when the motor 11 is started to position the rotor 22. Therefore, since it is possible to generate a greater attractive force than one of the other two phases in one of the three phases in stator 21, it is more stable when motor 11 is started than when two-phase excitation is performed as in the prior art. Thus, the rotor 22 can be fixed at the normal position.

  Furthermore, although the possibility of being in the reverse phase lock state where the rotor 22 can not be fixed at the normal position can not be completely eliminated by performing the three phase excitation only once, in the present embodiment, the three phase excitation is Since the operation is performed once, the rotor 22 can be fixed in the correct position more stably. And since it is possible to fix the rotor 22 in the normal position in this way, when trying to rotate the motor 11 after that, it is clearly determined from which phase the rotation of the rotor 22 should be started by energizing. Become. Therefore, without estimating the magnetic pole position of the rotor 22, it is possible to accurately set the energization phase to each of the coils 21A, 21B, 21C. Therefore, sensorless control can be performed by starting the motor 11 stably and immediately after forced commutation.

  The three-phase magnetic poles of the stator 21 when performing three-phase excitation may be different between when performing the first three-phase excitation and when performing the second three-phase excitation. The combination of the three-phase magnetic poles of 21 can be changed as appropriate. For example, when the first three-phase excitation is performed, the control unit 12 sets the magnetic pole of the first phase of the stator 21 as one of the S pole and the N pole, and the second phase and the third phase of the stator 21. The other magnetic pole of the S pole and the N pole is used as the Then, when performing the second three-phase excitation, the control unit 12 sets the second phase magnetic pole of the stator 21 as the one magnetic pole and the first and third phase magnetic poles as the other magnetic pole. Good. Here, the first, second, and third magnetic poles of the stator 21 are, in detail, the magnetic poles of the first, second, and third phase coils of the stator 21 on the rotor 22 side.

  Further, the control unit 12 may change the duty ratios D1 and D2 of the voltage applied to the motor 11 when performing the three-phase excitation according to the elapse of the excitation time. Thus, it is possible to suppress the voltage applied to the motor 11 from becoming excessive and to suppress the rotational torque of the rotor 22 from becoming excessive. Therefore, excessive rotation of the motor 11 can be suppressed, and the robustness of the positioning of the rotor 22 can be improved.

  For example, even if the motor 11 is fixed at the normal position after the first three-phase excitation, the duty ratio D2 is made constant at a large value (for example, 100%) when the second three-phase excitation is performed. If this is done, the rotational torque of the rotor 22 may become excessive, causing the motor 11 to over rotate and to be in the reverse phase lock state. However, by changing the duty ratio D2 so as to decrease according to the passage of the excitation time at the time of the second three-phase excitation, it is possible to suppress the rotational torque of the rotor 22 from becoming excessive and overrotate the motor 11. As a result, the motor 11 can be maintained in the normal position.

  Note that both of the duty ratios D1 and D2 may be changed according to the passage of the excitation time, or only one of the duty ratios D1 and D2 may be changed according to the passage of the excitation time. Further, the duty ratios D1 and D2 may be changed so as to gradually decrease according to the passage of the excitation time, or may be changed so as to gradually increase according to the passage of the excitation time.

  The control unit 12 may change the duty ratio of the voltage applied to the motor 11 in accordance with the passage of the excitation time for the purpose of suppressing the over-rotation of the motor 11 when the forced commutation is performed. Alternatively, the value may be converted into a value corresponding to the magnitude of the voltage applied to the motor 11.

  In addition, the control unit 12 monitors (monitors) the voltage applied to the motor 11 and sets the duty ratios D1 and D2 of the voltage applied to the motor 11 when performing the three-phase excitation to the magnitude of the voltage. It may be converted to a value according to that. Thus, even if the output power of the DC power supply BATT fluctuates, the motor 11 can be fixed at the normal position when the motor 11 is started. Therefore, the robustness of the positioning of the rotor 22 can be improved with respect to the fluctuation of the output power of the DC power supply BATT.

  Further, the control unit 12 repeatedly executes the positioning of the rotor 22 until the start of the motor 11 is successful. Then, the control unit 12 counts the number of startup failures X, which is the number of startup failures of the motor 11, and when the number of startup failures X exceeds a predetermined number N, the excitation time when three-phase excitation is performed Change the setting conditions such as duty ratio.

  As a result, even if the motor 11 does not start successfully, the rotor 22 is brought to the normal position when the motor 11 is started by changing the setting conditions such as the excitation time and duty ratio when performing three-phase excitation. By fixing it, the motor 11 can be started successfully.

  The embodiment described above is merely an example, and does not limit the present disclosure in any way, and it goes without saying that various improvements and modifications can be made without departing from the scope of the invention. For example, the control unit 12 may position the rotor 22 by performing three-phase excitation three or more times when the motor 11 is started.

1 Sensorless Brushless Motor Drive Device 11 Sensorless Brushless Motor 12 Control Unit 13 Drive Circuit 14 Power Supply Circuit 15 I / F Circuit 16 ECU
21 Stators 21A, 21B, 21C Coil 22 Rotor BATT DC power supply T1 Excitation time D1 Duty ratio T2 Excitation time D2 Duty ratio X Number of start failures N predetermined number of times T1_L Excitation time D1_L Duty ratio T2_L Excitation time D2_L Duty ratio

Claims (4)

A three-phase motor comprising a stator and a rotor;
A control unit that controls driving of the motor;
In a motor drive having
The control unit performs three-phase excitation a plurality of times at the time of startup of the motor to position the rotor.
A drive device for an electric motor characterized by In the motor drive device according to claim 1,
The control unit changing a duty ratio of a voltage applied to the motor when performing the three-phase excitation according to an elapse of an excitation time;
A drive device for an electric motor characterized by In the motor drive device according to claim 1 or 2,
The control unit may convert a duty ratio of a voltage applied to the motor when performing the three-phase excitation into a value corresponding to a magnitude of the voltage.
A drive device for an electric motor characterized by The drive device for an electric motor according to any one of claims 1 to 3.
The control unit
Repeatedly positioning the rotor until the motor is successfully started;
The number of startup failures, which is the number of startup failures of the motor, is counted, and when the number of startup failures exceeds a predetermined number, setting conditions for performing the three-phase excitation are changed.
A drive device for an electric motor characterized by

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