Motor control device and motor control method

Abstract

To provide a motor control device, etc. in which an electric charge in a capacitor for absorbing ripples can be discharged without feedback control of a q-axis current and a d-axis current.SOLUTION: A motor control device includes a drive circuit that drives a motor, a ripple absorbing capacitor connected to a power supply line of the drive circuit, a feedback control unit that gives a first drive signal according to an electric angle to the drive circuit in accordance with feedback control of a d-axis current and a q-axis current, a phase voltage control unit that gives a second drive signal corresponding to a prescribed phase voltage according to the electric angle to the drive circuit without using feedback control, and a selection unit that alternatively selects the first drive signal or the second drive signal and gives the selected signal to the drive circuit. During discharge of an electric charge in the ripple absorbing capacitor, the selection unit selects the second drive signal, and the phase voltage control unit outputs the second drive signal corresponding to the prescribed phase voltage to supply a prescribed d-axis current to the motor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor control device and a motor control method. [Background technology]

[0002] Patent Document 1 discloses a motor control device that discharges the charge of a ripple absorption capacitor using a d-axis current via a drive circuit. In this motor control device, when discharging the charge of the ripple absorption capacitor, feedback control of the q-axis current and the d-axis current is performed to maintain the value of the q-axis current at zero while allowing the d-axis current to flow. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-134550 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the above technique, for example, during a period when feedback control of the q-axis current and the d-axis current is not possible, the charge in the ripple absorption capacitor cannot be discharged.

[0005] An object of the present invention is to provide a motor control device and the like that can discharge the charge of a ripple absorption capacitor without performing feedback control on the q-axis current and the d-axis current. [Means for solving the problem]

[0006] In order to solve the above problem, one aspect of the present invention is to a drive circuit for driving the motor; a ripple absorption capacitor connected to a power supply line of the drive circuit; a feedback control unit that provides the drive circuit with a first drive signal that corresponds to an electrical angle based on feedback control of a d-axis current and a q-axis current; a phase voltage control unit that applies a second drive signal corresponding to a predetermined phase voltage according to an electrical angle to the drive circuit without using the feedback control; a selection unit that alternatively selects the first drive signal or the second drive signal and provides the selected signal to the drive circuit; Equipped with A motor control device is provided in which, when the charge of the ripple absorption capacitor is discharged, the selection unit selects the second drive signal, and the phase voltage control unit outputs the second drive signal corresponding to the predetermined phase voltage that supplies a predetermined d-axis current to the motor. [Effects of the Invention]

[0007] According to the present invention, the charge in the ripple absorbing capacitor can be discharged without performing feedback control on the q-axis current and the d-axis current. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of a motor control device according to a first embodiment. [Figure 1A] FIG. 2 is a diagram illustrating an example of a circuit configuration of an output section of a drive circuit. [Figure 2] FIG. 2 is a block diagram showing the functions of a three-phase voltage control unit in the first embodiment. [Figure 3] FIG. 10 is a diagram showing a sin map. [Figure 3A] FIG. 4 is a diagram showing waveforms of three-phase voltage values. [Figure 3B] FIG. 3 is a diagram illustrating waveforms of three-phase current values. [Figure 4] FIG. 10 is a diagram illustrating the configuration of a motor control device according to a second embodiment. [Figure 5] FIG. 10 is a block diagram showing the functions of a three-phase voltage control unit in the second embodiment. [Figure 6] 10A and 10B are diagrams illustrating waveforms of three-phase voltage values ​​affected by dead time. [Figure 6A] 10A and 10B are diagrams illustrating waveforms of three-phase current values ​​affected by dead time. [Figure 7] FIG. 10 is a diagram illustrating an example of a waveform of a q-axis current value affected by a dead time. [Figure 7A] FIG. 10 is a diagram illustrating an example of a waveform of a d-axis current value affected by dead time. [Figure 8] FIG. 10 is a diagram illustrating an example of a waveform of a q-axis current value in the second embodiment. [Figure 8A] FIG. 10 is a diagram illustrating an example of a waveform of a d-axis current value in the second embodiment. [Figure 9] 10 is a diagram illustrating waveforms of three-phase voltage values ​​indicated by a second drive signal S2 in a second embodiment. FIG. [Figure 9A] FIG. 10 is a diagram illustrating waveforms of three-phase voltage values ​​in the second embodiment. [Figure 9B] FIG. 10 is a diagram illustrating waveforms of three-phase current values ​​in the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating the configuration of a motor control device according to a third embodiment. [Figure 11] FIG. 10 is a block diagram showing the functions of a phase voltage control unit in the third embodiment. [Figure 12] FIG. 10 shows a signal generation map. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (First Example) 1 is a diagram showing the configuration of a motor control device according to a first embodiment. The motor control device according to each embodiment can be used, for example, as a device for controlling a brushless motor for an in-vehicle electric power steering (EPS), but its use is arbitrary. For example, the motor control device according to each embodiment can be widely applied to the control of brushless motors used as power sources for two-wheeled electric vehicles and other brushless motors.

[0011] As shown in FIG. 1, the motor control device of the first embodiment includes a drive circuit 10, a ripple absorption capacitor C, a feedback control unit 20, a three-phase-two-axis conversion unit 21 (an example of a detection unit), a three-phase voltage control unit 30 (an example of a phase voltage control unit), and a selection unit 40.

[0012] The drive circuit 10 drives a three-phase brushless motor M having U, V, and W phases. A power supply device 11 (for example, an on-board battery) is connected to the drive circuit 10 via a power supply line L and a switch SW.

[0013] The ripple absorbing capacitor C is connected between the power supply line L of the drive circuit 10 and the ground, and has functions such as lowering the power supply impedance for the drive circuit 10.

[0014] The feedback control unit 20 provides the drive circuit 10 with a first drive signal S1 that corresponds to the electrical angle based on feedback control of the d-axis current and the q-axis current.

[0015] The three-phase voltage control unit 30 provides the drive circuit 10 with a second drive signal S2 corresponding to a predetermined phase voltage according to the electrical angle, without using feedback control by the feedback control unit 20. The second drive signal S2 is a signal indicating phase voltages that are mutually phase-shifted by 120° among the three phases U, V, and W.

[0016] The selection section 40 alternatively selects either the first drive signal S1 or the second drive signal S2 and provides the selected signal to the drive circuit 10.

[0017] As shown in FIG. 1, the feedback control unit 20 includes a PI (proportional-integral) calculation unit 22 that receives the q-axis current value and the d-axis current value output from a three-phase to two-axis conversion unit 21, and a two-axis to three-phase conversion unit 23.

[0018] The three-phase-two-axis conversion unit 21 converts the U-phase current value Iu, the V-phase current value Iv, and the W-phase current value Iw obtained by the current detection unit 51 into a q-axis current value and a d-axis current value based on the electrical angle θ of the brushless motor M obtained by the angle detection unit 52.

[0019] 1, a target q-axis current value and a target d-axis current value are input to the PI calculation unit 22. The PI calculation unit 22 outputs, by PI calculation, a q-axis voltage value and a d-axis voltage value that cause the q-axis current value and the d-axis current value input from the three-phase-two-axis conversion unit 21 to approach the target q-axis current value and the target d-axis current value.

[0020] The two-axis to three-phase conversion unit 23 converts the q-axis voltage value and d-axis voltage value input from the PI calculation unit 22 into three-phase voltage values ​​of U, V, and W based on the electrical angle θ of the brushless motor M acquired by the angle detection unit 52.

[0021] FIG. 1A is a diagram showing an example of a circuit configuration of an output section of a drive circuit.

[0022] 1A, a pair of semiconductor switches SU1 and SU2, a pair of semiconductor switches SV1 and SV2, and a pair of semiconductor switches SW1 and SW2 corresponding to the U, V, and W phases are connected in series between ground and a power supply line L. Furthermore, the U, V, and W phase terminals of the brushless motor M are connected to the midpoints of each pair of semiconductor switches SU1 and SU2, semiconductor switches SV1 and SV2, and semiconductor switches SW1 and SW2, respectively.

[0023] A pulse width modulated signal corresponding to the first drive signal S1 or the second drive signal S2 is input to each pair of semiconductor switches SU1, SU2, semiconductor switches SV1, SV2, and semiconductor switches SW1, SW2.

[0024] Next, the operation of the motor control device of the first embodiment will be described.

[0025] During normal operation of the brushless motor M, the switch SW is closed and power is supplied from the power supply device 11 to the drive circuit 10 via the power supply line L.

[0026] Furthermore, the selection unit 40 selects the first drive signal S1 indicating the three-phase voltage values ​​calculated by the two-axis-to-three-phase conversion unit 23, and the first drive signal S1 is input to the drive circuit 10. Therefore, the drive circuit 10 supplies the brushless motor M with the three-phase voltage values ​​corresponding to the first drive signal S1.

[0027] At this time, the feedback control unit 20 performs feedback control based on the q-axis current value and the d-axis current value obtained from the three-phase-two-axis conversion unit 21. That is, the feedback control unit 20 feedback-controls the three-phase voltage values ​​so that the q-axis current value and the d-axis current value approach the target q-axis current value and the target d-axis current value.

[0028] As a result, during normal operation of the brushless motor M, the rotation of the brushless motor M is controlled so that the q-axis current value and the d-axis current value approximately match the target q-axis current value and the target d-axis current value.

[0029] On the other hand, when the charge in the ripple absorbing capacitor C is to be discharged, the switch SW is opened and the power supply line L is disconnected from the power supply device 11.

[0030] Furthermore, the selector 40 selects the second drive signal S2 indicating the phase voltage values ​​output from the three-phase voltage controller 30, and the second drive signal S2 is input to the drive circuit 10. Therefore, the drive circuit 10 supplies the brushless motor M with the three-phase voltage values ​​corresponding to the second drive signal S2 without relying on feedback control by the feedback controller 20.

[0031] The timing of discharging the charge of the ripple absorbing capacitor C is arbitrary, but for example, discharging is performed when the normal operation of the brushless motor M starts, after the start of the normal operation, when the brushless motor M is inspected, etc.

[0032] FIG. 2 is a block diagram showing the functions of the three-phase voltage control unit.

[0033] As shown in FIG. 2, the three-phase voltage control unit 30 functionally includes a three-phase electrical angle generation unit 31, a phase control unit 32, a sine map 33, and an amplifier .

[0034] The three-phase electrical angle generating unit 31 generates three-phase electrical angles based on the electrical angle θ detected by the angle detecting unit 52.

[0035] FIG. 3 is a diagram showing a sine map.

[0036] In the example shown in Fig. 3, the sine map 33 shows the relationship between the torque constant and the electrical angle θ for each of the U, V, and W phases. Note that, although Fig. 3 shows the relationship between the torque constant and the electrical angle θ for all three phases, the sine map 33 may show this relationship for only one phase. In the latter case, the relationship between the torque constant and the electrical angle θ for all three phases can be obtained by shifting this relationship by 120°.

[0037] Next, the operation of the three-phase voltage control unit 30 will be described.

[0038] 2, the three-phase electrical angle generation unit 31 generates three-phase electrical angles based on the electrical angle θ detected by the angle detection unit 52. The three-phase electrical angles correspond to the phases of the U, V, and W phases indicated by the sine map 33.

[0039] 2, the three-phase electrical angles generated by the three-phase electrical angle generation unit 31 are input to the phase control unit 32. A delay phase of 90° is also provided to the phase control unit 32, and three-phase electrical angles that are 90° behind the three-phase electrical angles generated by the three-phase electrical angle generation unit 31 are output. The three-phase electrical angles that are 90° behind the phases of the three-phase electrical angles generated by the three-phase electrical angle generation unit 31 are provided to a sine map 33 by the phase control unit 32, and three-phase sine waves that are 90° behind the sine waves shown in the sine map 33 are input to the amplifier 34. The amplitudes of the three-phase sine waves (three-phase voltage values) that are 90° behind the phases of the three-phase sine waves are controlled by the amplifier 34, and the three-phase sine waves are output from the amplifier 34 as a second drive signal S2.

[0040] FIG. 3A is a diagram illustrating waveforms of three-phase voltage values, and FIG. 3B is a diagram illustrating waveforms of three-phase current values.

[0041] As is clear from a comparison with Fig. 3, the U-, V-, and W-phase sine waves shown in Fig. 3A are each delayed by 90° relative to the U-, V-, and W-phase sine waves shown in Fig. 3. The phase of the phase voltage values ​​shown in Fig. 3A corresponds to the phase of the d-axis current, and the phase current values ​​shown in Fig. 3B also show waveforms corresponding to this. As a result, the charge in the ripple absorption capacitor C can be discharged via the brushless motor M without generating torque from the brushless motor M.

[0042] 2, the amplifier 34 is supplied with an amplitude A that defines the amplitude of the phase voltage value output from the amplifier 34, and the amplifier 34 outputs a second drive signal S2 whose amplitude of the phase voltage value is amplitude A. Since the amplitude A is reflected in the d-axis current value, it can be determined according to the discharge time of the charge in the ripple absorption capacitor C. For example, if it is desired to increase the d-axis current value and shorten the discharge time, the amplitude A can be set to a larger value.

[0043] According to the first embodiment, it is possible to prevent the brushless motor M from inadvertently generating torque when the charge in the ripple absorption capacitor C is discharged. For example, when the brushless motor M is used as a power source for a two-wheeled electric vehicle, it is possible to prevent unintended movement of the vehicle when the charge in the ripple absorption capacitor C is discharged. Furthermore, the technology disclosed in JP 2019-134550 A requires a current detection sensor for feedback control of the q-axis current and the d-axis current during d-axis discharge. Therefore, if the current detection sensor fails, for example, when applied to an electric power steering motor, self-steering or vibration may occur during discharge. However, in this embodiment, even if a current detection sensor (e.g., current detection unit 51) fails, such behavior does not occur, and safe discharge is possible. Furthermore, in the technology disclosed in JP 2019-134550 A, even if the electric power steering motor transitions to discharge processing while in operation, a current detection sensor is required for feedback control of the q-axis current and the d-axis current during d-axis discharge. Therefore, a failure of the current detection sensor may cause similar behavior. However, in this embodiment, even if a current detection sensor fails, such behavior does not occur, and safe discharge is possible.

[0044] Furthermore, the charge in the ripple absorption capacitor C can be discharged without relying on feedback control by the feedback control unit 20. Therefore, even when feedback control of the q-axis current and the d-axis current by the feedback control unit 20 is not possible, the charge in the ripple absorption capacitor C can be discharged.

[0045] (Second Example) The motor control device of the second embodiment will be described below.

[0046] FIG. 4 is a diagram showing the configuration of a motor control device according to the second embodiment.

[0047] 4, the motor control device of the second embodiment includes a three-phase voltage control unit 30A instead of the three-phase voltage control unit 30 in the first embodiment. The other configuration is the same as that of the first embodiment, so a description thereof will be omitted.

[0048] FIG. 5 is a block diagram showing the functions of the three-phase voltage control unit in the second embodiment.

[0049] As shown in FIG. 5, the three-phase voltage control unit 30A functionally includes the configuration of the three-phase voltage control unit 30, as well as a current feedback control unit 35 and a phase control unit 32A.

[0050] 4 and 5, the current feedback control unit 35 receives the target q-axis current value and the q-axis current value output from the three-phase-two-axis conversion unit 21. The current feedback control unit 35 provides the phase control unit 32A with a feedback signal based on the target q-axis current value and the q-axis current value.

[0051] Next, the operation of the motor control device of the second embodiment will be described.

[0052] As in the first embodiment, during normal operation of the brushless motor M, the switch SW is closed and power is supplied from the power supply device 11 to the drive circuit 10 via the power supply line L.

[0053] Furthermore, the selection unit 40 selects the first drive signal S1 indicating the three-phase voltage values ​​calculated by the two-axis-to-three-phase conversion unit 23, and the first drive signal S1 is input to the drive circuit 10. Therefore, the drive circuit 10 supplies the brushless motor M with the three-phase voltage values ​​corresponding to the first drive signal S1.

[0054] As in the first embodiment, the feedback control unit 20 feedback-controls the three-phase voltage values ​​so that the q-axis current value and the d-axis current value approach the target q-axis current value and the target d-axis current value. As a result, during normal operation of the brushless motor M, the rotation of the brushless motor M is controlled so that the q-axis current value and the d-axis current value approximately match the target q-axis current value and the target d-axis current value.

[0055] Furthermore, when discharging the charge in the ripple absorption capacitor C, the switch SW is opened to disconnect the power supply line L from the power supply device 11, as in the first embodiment. The selector 40 selects the second drive signal S2 indicating the phase voltage values ​​output from the three-phase voltage controller 30A, and the second drive signal S2 is input to the drive circuit 10. Therefore, the drive circuit 10 supplies the brushless motor M with three-phase voltage values ​​corresponding to the second drive signal S2 without relying on feedback control by the feedback controller 20.

[0056] In the second embodiment, a three-phase voltage control unit 30A controls the phases of the three-phase voltage values ​​so that the q-axis current value approaches a target q-axis current value. Specifically, a current feedback control unit 35 provides a feedback signal based on the target q-axis current value and the q-axis current value to a phase control unit 32A. The phase control unit 32A performs feedback control of the q-axis current value by further adjusting the phases of the three-phase voltage values ​​delayed by 90° by the phase control unit 32. Setting the target q-axis current value to zero allows the torque of the brushless motor M to be stably suppressed to a small value.

[0057] In contrast to this, in the first embodiment, the operation timing of the drive circuit 10 includes dead time, and the dead time may have a significant effect on the three-phase current.

[0058] 1A, a time period called dead time may be provided in which both semiconductor switches SU1 and SU2 are open to prevent a temporary short circuit between the ground and the power supply line L. The same applies to the semiconductor switches SV1 and SV2 and the semiconductor switches SW1 and SW2.

[0059] FIG. 6 is a diagram illustrating waveforms of three-phase voltage values ​​affected by dead time, FIG. 6A is a diagram illustrating waveforms of three-phase current values ​​affected by dead time, FIG. 7 is a diagram illustrating waveforms of q-axis current values ​​affected by dead time, and FIG. 7A is a diagram illustrating waveforms of d-axis current values ​​affected by dead time.

[0060] When the dead time has a large effect, the three-phase voltage values ​​are reduced and exhibit distorted waveforms, as shown in Fig. 6. In Fig. 6, curve 61U indicates the U-phase voltage value actually applied to brushless motor M, and curve 62U indicates the U-phase voltage value indicated by second drive signal S2, or the target U-phase voltage value. The V-phase and W-phase indicate the phase voltage values ​​actually applied to brushless motor M.

[0061] Furthermore, as shown in Fig. 6A, distortion occurs in the three-phase current values. In the example of Fig. 6A, the section of electrical angle θ where the phase current values ​​are substantially zero due to the dead time is expanded compared to Fig. 3B.

[0062] 7, a q-axis current value is generated, and a torque corresponding to the q-axis current according to the electrical angle θ is generated in the brushless motor M. Furthermore, as shown in FIG. 7A, a fluctuation according to the electrical angle θ also occurs in the d-axis current value.

[0063] In contrast to this, in the second embodiment, feedback control of the q-axis current causes substantially no q-axis current to be generated, and therefore no torque is generated in the brushless motor M.

[0064] FIG. 8 is a diagram illustrating an example of a waveform of a q-axis current value in the second embodiment, and FIG. 8A is a diagram illustrating an example of a waveform of a d-axis current value in the second embodiment.

[0065] As shown in Fig. 8, in the second embodiment, feedback control of the q-axis current results in substantially no q-axis current being generated. Therefore, no torque is generated in the brushless motor M. Furthermore, as shown in Fig. 8A, the d-axis current value does not fluctuate according to the electrical angle θ, and the d-axis current value remains substantially constant.

[0066] FIG. 9 is a diagram illustrating waveforms of three-phase voltage values ​​indicated by the second drive signal S2 in the second embodiment, FIG. 9A is a diagram illustrating waveforms of three-phase voltage values ​​in the second embodiment, and FIG. 9B is a diagram illustrating waveforms of three-phase current values ​​in the second embodiment.

[0067] 9, in the second embodiment, as a result of feedback control of the q-axis current, the three-phase voltage values ​​indicated by the second drive signal S2 are corrected so as to cancel the effect of the dead time. Therefore, as shown in FIG. 9A, distortion in the three-phase voltage values ​​applied to the brushless motor M is eliminated, and distortion in the three-phase current values ​​is also eliminated.

[0068] According to the second embodiment, when the charge of the ripple absorption capacitor C is discharged, it is possible to prevent the brushless motor M from inadvertently generating torque. For example, when the brushless motor M is used as a power source for a two-wheeled electric vehicle, it is possible to prevent unintended vehicle movement when the charge of the ripple absorption capacitor C is discharged. In particular, the second embodiment can effectively suppress the influence of dead time included in the operation timing of the drive circuit 20. Therefore, it is possible to appropriately manage the torque of the brushless motor M when the charge of the ripple absorption capacitor C is discharged. Furthermore, the technology disclosed in JP 2019-134550 A requires a current detection sensor for feedback control of the q-axis current and the d-axis current during d-axis discharge. Therefore, if the current detection sensor fails, for example, when applied to an electric power steering motor, self-steering or vibration may occur during discharge. However, in this embodiment, even if a current detection sensor (e.g., current detection unit 51) fails, such behavior does not occur, and safe discharge is possible. Furthermore, in the technology disclosed in JP 2019-134550 A, even if the electric power steering motor transitions to discharge processing while in operation, a current detection sensor is required for feedback control of the q-axis current and the d-axis current during d-axis discharge. Therefore, a failure of the current detection sensor may cause similar behavior. However, in this embodiment, even if a current detection sensor fails, such behavior does not occur, and safe discharge is possible.

[0069] Furthermore, the charge in the ripple absorption capacitor C can be discharged without relying on feedback control by the feedback control unit 20. Therefore, even when feedback control of the q-axis current and the d-axis current by the feedback control unit 20 is not possible, the charge in the ripple absorption capacitor C can be discharged.

[0070] (Third Example) The motor control device of the third embodiment will be described below.

[0071] FIG. 10 is a diagram showing the configuration of a motor control device according to the third embodiment.

[0072] 10, the motor control device of the third embodiment includes a three-phase voltage control unit 30B instead of the three-phase voltage control unit 30A in the second embodiment. The other configurations are the same as those in the first and second embodiments, and therefore a description thereof will be omitted.

[0073] FIG. 11 is a block diagram showing the functions of the phase voltage control unit in the third embodiment.

[0074] 11, the three-phase voltage control unit 30B is configured by replacing part of the configuration of the three-phase voltage control unit 30A with a signal generation map 36. That is, the signal generation map 36 essentially has the functions replaced by the phase control unit 32, the current feedback control unit 35, the phase control unit 32A, and the sine map 33 in the second embodiment.

[0075] FIG. 12 is a diagram showing a signal generation map.

[0076] As shown in FIG. 12, the signal generation map 36 is a map showing the relationship between three-phase voltage values ​​and the electrical angle θ.

[0077] In the second embodiment, the three-phase electrical angles output from the three-phase electrical angle generator 31 are provided to a signal generation map 36, and a second drive signal indicating three-phase voltage values ​​( FIG. 12 ) corresponding to the electrical angle θ is output from the signal generation map 36. Note that the function corresponding to the three-phase electrical angle generator 31 may be omitted from the three-phase voltage control unit 30B, and the electrical angle θ may be input directly to the signal generation map 36.

[0078] As can be seen by comparing the signal generation map 36 shown in FIG. 12 with FIG. 9, the signal generation map 36 can generate a second drive signal S2 that indicates three-phase voltage values ​​similar to those in the second embodiment. In the third embodiment, feedback control of the d-axis current value is not performed. Therefore, when the rotation speed of the brushless motor M ranges widely, it is difficult to accurately adjust the d-axis current value to zero using only a single signal generation map 36. However, when conditions are met, such as when the brushless motor M does not rotate at high speed when discharging the charge of the ripple absorption capacitor C, the signal generation map 36 can effectively suppress the d-axis current value, i.e., the torque of the brushless motor M. Note that multiple signal generation maps 36 may be used depending on conditions such as the rotation speed of the brushless motor M.

[0079] According to the third embodiment, when the charge of the ripple absorption capacitor C is discharged, it is possible to prevent the brushless motor M from inadvertently generating torque. For example, when the brushless motor M is used as a power source for a two-wheeled electric vehicle, it is possible to prevent unintended vehicle movement when the charge of the ripple absorption capacitor C is discharged. In particular, the second embodiment can effectively suppress the influence of dead time included in the operation timing of the drive circuit 20. Therefore, it is possible to appropriately manage the torque of the brushless motor M when the charge of the ripple absorption capacitor C is discharged. Furthermore, the technology disclosed in JP 2019-134550 A requires a current detection sensor for feedback control of the q-axis current and the d-axis current during d-axis discharge. Therefore, if the current detection sensor fails, for example, when applied to an electric power steering motor, self-steering or vibration may occur during discharge. However, in this embodiment, even if a current detection sensor (e.g., current detection unit 51) fails, such behavior does not occur, and safe discharge is possible. Furthermore, in the technology disclosed in JP 2019-134550 A, even if the electric power steering motor transitions to discharge processing while in operation, a current detection sensor is required for feedback control of the q-axis current and the d-axis current during d-axis discharge. Therefore, a failure of the current detection sensor may cause similar behavior. However, in this embodiment, even if a current detection sensor fails, such behavior does not occur, and safe discharge is possible.

[0080] Furthermore, the charge in the ripple absorption capacitor C can be discharged without relying on feedback control by the feedback control unit 20. Therefore, even when feedback control of the q-axis current and the d-axis current by the feedback control unit 20 is not possible, the charge in the ripple absorption capacitor C can be discharged.

[0081] As described above, according to the first to third embodiments, the charge in the ripple absorption capacitor C can be discharged without relying on feedback control by the feedback control unit 20. Therefore, even when feedback control of the q-axis current and the d-axis current by the feedback control unit 20 is not possible, the charge in the ripple absorption capacitor C can be discharged. Furthermore, when the charge in the ripple absorption capacitor C is discharged, the torque in the brushless motor M can be appropriately managed.

[0082] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0083] The following additional notes are provided regarding the above-described embodiments of the present invention.

[0084] [Appendix 1] a drive circuit (10) for driving a motor (M); a ripple absorption capacitor (C) connected to the power supply line (L) of the drive circuit; a feedback control unit (20) that provides the drive circuit with a first drive signal (S1) that corresponds to an electrical angle based on feedback control of a d-axis current and a q-axis current; a phase voltage control unit (30, 30A, 30B) that applies a second drive signal (S2) corresponding to a predetermined phase voltage according to an electrical angle to the drive circuit without using the feedback control; a selection unit (40) that alternatively selects the first drive signal or the second drive signal and provides the selected signal to the drive circuit; Equipped with When the charge of the ripple absorption capacitor is discharged, the selection unit selects the second drive signal, and the phase voltage control unit outputs the second drive signal corresponding to the predetermined phase voltage that supplies a predetermined d-axis current to the motor.

[0085] According to the configuration described in Supplementary Note 1, when the charge in the ripple absorption capacitor is discharged, the phase voltage control unit outputs a second drive signal corresponding to a predetermined phase voltage that supplies a predetermined d-axis current to the motor, so that the charge in the ripple absorption capacitor can be discharged without performing feedback control on the q-axis current and the d-axis current.

[0086] [Appendix 2] a detection unit (21) that detects a current value of a q-axis current when the second drive signal is selected by the selection unit, 2. The motor control device according to claim 1, wherein the phase voltage control unit feedback controls the phase of the second drive signal based on the current value of the q-axis current detected by the detection unit.

[0087] According to the configuration described in Supplementary Note 2, the phase of the second drive signal is feedback controlled based on the current value of the q-axis current, so that the torque in the motor can be managed appropriately.

[0088] [Appendix 3] the phase voltage control unit generates the second drive signal based on a signal generation map; 2. The motor control device according to claim 1, wherein the signal generation map defines the relationship between the electrical angle and the value of the second drive signal so as to suppress the current value of a q-axis current.

[0089] According to the configuration described in Supplementary Note 3, the current value of the q-axis current is suppressed by the signal generation map, so that the torque in the motor can be appropriately suppressed.

[0090] [Appendix 4] 4. The motor control device according to claim 2, wherein the operation timing of the drive circuit includes a dead time.

[0091] According to the configuration described in Supplementary Note 4, the q-axis current generated due to the dead time can be managed, and therefore the torque in the motor can be managed appropriately.

[0092] [Appendix 5] a feedback control step of providing a first drive signal corresponding to an electrical angle to a drive circuit that drives the motor based on feedback control of the d-axis current and the q-axis current; a phase voltage control step of applying a second drive signal corresponding to a predetermined phase voltage according to an electrical angle to the drive circuit without using the feedback control; a selection step section that alternatively selects the first drive signal or the second drive signal and provides the selected signal to the drive circuit; Equipped with a phase voltage control step of outputting the second drive signal corresponding to the predetermined phase voltage that supplies a predetermined d-axis current to the motor when a ripple absorption capacitor connected to a power supply line of the drive circuit is discharging;

[0093] According to the configuration described in Supplementary Note 5, when the charge of the ripple absorption capacitor is discharged, the phase voltage control unit outputs a second drive signal corresponding to a predetermined phase voltage that supplies a predetermined d-axis current to the motor, so that the charge of the ripple absorption capacitor can be discharged without performing feedback control on the q-axis current and the d-axis current. [Explanation of symbols]

[0094] 10. Drive circuit 20 Feedback control section 21 3-phase to 2-axis converter 30, 30A, 30B 3-phase voltage control unit 40 Selection section C Ripple absorption capacitor L Power supply line S1 First drive signal S2 Second drive signal

Claims

1. a drive circuit for driving the motor; a ripple absorption capacitor connected to a power supply line of the drive circuit; a feedback control unit that applies a first drive signal corresponding to an electrical angle to the drive circuit based on feedback control of a d-axis current and a q-axis current; a phase voltage control unit that supplies a second drive signal corresponding to a predetermined phase voltage and different from the first drive signal to the drive circuit; a selection unit that alternatively selects the first drive signal or the second drive signal and provides the selected signal to the drive circuit; Equipped with when the charge of the ripple absorption capacitor is discharged, the selection unit selects the second drive signal, and the phase voltage control unit outputs the second drive signal corresponding to the predetermined phase voltage that supplies a d-axis current to the motor according to an electrical angle detected during the discharge of the charge; A motor control device wherein the phase of the predetermined phase voltage value corresponds to the phase of the d-axis current.

2. a detection unit that detects a current value of a q-axis current when the second drive signal is selected by the selection unit, The motor control device according to claim 1 , wherein the phase voltage control unit feedback-controls the phase of the second drive signal based on the current value of the q-axis current detected by the detection unit.

3. the phase voltage control unit generates the second drive signal based on a signal generation map; The motor control device according to claim 1 , wherein the signal generation map defines a relationship between the electrical angle and the value of the second drive signal so as to suppress a current value of a q-axis current.

4. 4. The motor control device according to claim 2, wherein the operation timing of the drive circuit includes a dead time.

5. a feedback control step of providing a first drive signal corresponding to an electrical angle to a drive circuit that drives the motor based on feedback control of the d-axis current and the q-axis current; a phase voltage control step of applying a second drive signal corresponding to a predetermined phase voltage according to an electrical angle to the drive circuit; a selection step of alternatively selecting the first drive signal or the second drive signal different from the first drive signal and providing the selected signal to the drive circuit; Equipped with When a ripple absorption capacitor connected to a power supply line of the drive circuit is discharging, the selecting step selects the second drive signal, and the phase voltage control step outputs the second drive signal corresponding to the predetermined phase voltage that supplies a d-axis current to the motor according to an electrical angle detected during the discharging of the charge; A motor control method, wherein the phase of the predetermined phase voltage value corresponds to the phase of the d-axis current.

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