WO2021205997A1

WO2021205997A1 - Motor control device

Info

Publication number: WO2021205997A1
Application number: PCT/JP2021/014257
Authority: WO
Inventors: 宏平西田; 牧野　孝則
Original assignee: 株式会社デンソー
Priority date: 2020-04-06
Filing date: 2021-04-02
Publication date: 2021-10-14
Also published as: JP2021166426A; JP7363648B2

Abstract

A control unit (50) has a rotation speed computation unit (52), a target current computation unit (53), an energization command unit (54), and a switch control unit (55). The rotation speed computation unit (52) computes a motor rotation speed, which is a rotation speed of a motor (10). The target current computation unit (53) computes a current control target value. The energization command unit (54) issues a command for an energization phase in accordance with a detection value from a rotation detection unit (13). The switch control unit (55) controls an on-off operation of switching elements (411-413) such that the current applied to winding (111-113) achieves the current control target value. When the motor rotation speed is in a low-speed rotation region, the current control target value is varied in accordance with the motor rotation position.

Description

Motor control device

Cross-reference of related applications

This application is based on Patent Application No. 2020-068381 filed on April 6, 2020, and the contents of the description are incorporated herein by reference.

This disclosure relates to a motor control device.

Conventionally, it is known that the range switching mechanism of an automatic transmission is driven by a motor. For example, in Patent Document 1, the reference position is learned by executing the abutting control of rotating the range switching mechanism until it hits the limit position of the movable range.

Japanese Unexamined Patent Publication No. 2014-100041

In Patent Document 1, the collective current of the motor is controlled to be constant based on the output of the current sensor. Further, the motor torque is kept constant by controlling the control current value when the first phase is energized to be half of the control current value when the two phases are energized. Here, at low speed rotation, the motor torque may fluctuate depending on the positional relationship between the rotor and the stator. An object of the present disclosure is to provide a motor control device capable of suppressing fluctuations in motor torque.

The motor control device of the present disclosure controls the drive of a motor having windings, and includes a drive circuit unit, a current detection unit, a rotation detection unit, and a control unit. The drive circuit unit has a switching element provided corresponding to each phase of the winding. The current detector detects the winding current. The rotation detection unit detects the motor rotation position, which is the rotation position of the motor.

The control unit has a rotation speed calculation unit, a target current calculation unit, an energization command unit, and a switch control unit. The rotation speed calculation unit calculates the motor rotation speed, which is the rotation speed of the motor. The target current calculation unit calculates the current control target value. The energization command unit commands the energization phase according to the detection value of the rotation detection unit. The switch control unit controls the on / off operation of the switching element so that the current applied to the winding becomes the current control target value. When the motor rotation speed is in the low speed rotation range, the current control target value is made variable according to the motor rotation position. As a result, torque fluctuations caused by the motor rotation position can be suppressed.

The above objectives and other objectives, features and advantages of the present disclosure will be clarified by the following detailed description with reference to the accompanying drawings. The drawing is
FIG. 1 is a perspective view showing a shift-by-wire system according to an embodiment. FIG. 2 is a schematic configuration diagram showing a shift-by-wire system according to one embodiment. FIG. 3 is a block diagram showing a shift range control device according to an embodiment. FIG. 4 is an explanatory diagram for explaining the correspondence between the energized phase number and the energized phase according to the embodiment. FIG. 5 is a time chart illustrating current control according to one embodiment. FIG. 6 is a flowchart illustrating the current control process according to the embodiment. FIG. 7 is a time chart illustrating the current control process according to the embodiment. FIG. 8 is a time chart for explaining the current control process according to the reference example.

(One Embodiment)
Hereinafter, the motor control device according to the present disclosure will be described with reference to the drawings. One embodiment is shown in FIGS. 1 to 7. As shown in FIGS. 1 and 2, the shift-by-wire system 1 which is a motor drive system includes a motor 10, a shift range switching mechanism 20, a parking lock mechanism 30, a shift range control device 40 as a motor control device, and the like. .. The motor 10 rotates by being supplied with electric power from a battery 90 mounted on a vehicle (not shown), and functions as a drive source for the shift range switching mechanism 20. The motor 10 is, for example, a switched reluctance motor. As shown in FIG. 3, the motor 10 has a motor winding 11 wound around a salient pole of a stator (not shown). The motor winding 11 has a U-phase winding 111, a V-phase winding 112, and a W-phase winding 113. By controlling the energization of the motor winding 11, a rotor (not shown) is rotated. For example, the number of salient poles of the stator is 12, and the number of salient poles of the rotor is 8.

As shown in FIG. 2, the encoder 13 which is a rotation angle sensor detects the rotation position of the rotor of the motor 10. The encoder 13 is, for example, a magnetic rotary encoder, which is composed of a magnet that rotates integrally with the rotor, a Hall IC for magnetic detection, and the like. The encoder 13 outputs an encoder signal, which is an A-phase and B-phase pulse signal, at predetermined angles in synchronization with the rotation of the rotor.

The speed reducer 14 is provided between the motor shaft of the motor 10 and the output shaft 15, and decelerates the rotation of the motor 10 to output to the output shaft 15. As a result, the rotation of the motor 10 is transmitted to the shift range switching mechanism 20. The output shaft 15 is provided with an output shaft sensor 16 that detects the angle of the output shaft 15. The output shaft sensor 16 is, for example, a potentiometer.

As shown in FIG. 1, the shift range switching mechanism 20 has a detent plate 21, a detent spring 25, and the like, and applies the rotational driving force output from the speed reducer 14 to the manual valve 28 and the parking lock mechanism 30. Communicate to.

The detent plate 21 is fixed to the output shaft 15 and driven by the motor 10. The detent plate 21 is provided with a pin 24 that projects parallel to the output shaft 15. The pin 24 is connected to the manual valve 28. When the detent plate 21 is driven by the motor 10, the manual valve 28 reciprocates in the axial direction. That is, the shift range switching mechanism 20 converts the rotational motion of the motor 10 into a linear motion and transmits it to the manual valve 28. The manual valve 28 is provided on the valve body 29. When the manual valve 28 reciprocates in the axial direction, the hydraulic supply path to the hydraulic clutch (not shown) is switched, and the shift range is changed by switching the engagement state of the hydraulic clutch.

Two valleys are provided on the detent spring 25 side of the detent plate 21. The detent spring 25 is a plate-shaped member that can be elastically deformed, and a detent roller 26 is provided at the tip thereof. The detent spring 25 urges the detent roller 26 toward the center of rotation of the detent plate 21. When a predetermined or greater rotational force is applied to the detent plate 21, the detent spring 25 is elastically deformed, and the detent roller 26 moves between the valleys. By fitting the detent roller 26 into any of the valleys, the swing of the detent plate 21 is regulated, the axial position of the manual valve 28 and the state of the parking lock mechanism 30 are determined, and the automatic transmission 5 The shift range of is fixed.

The parking lock mechanism 30 has a parking rod 31, a cone 32, a parking lock pole 33, a shaft portion 34, and a parking gear 35. The parking rod 31 is formed in a substantially L shape, and one end 311 side is fixed to the detent plate 21. A cone 32 is provided on the other end 312 side of the parking rod 31. The conical body 32 is formed so that the diameter is reduced toward the other end 312 side. When the detent plate 21 rotates in the direction in which the detent roller 26 fits into the valley corresponding to the P range, the cone 32 moves in the direction of the arrow P.

The parking lock pole 33 comes into contact with the conical surface of the conical body 32 and is provided so as to be swingable around the shaft portion 34. On the parking gear 35 side of the parking lock pole 33, a convex portion 331 that can mesh with the parking gear 35 is provided. When the cone 32 moves in the direction of the arrow P due to the rotation of the detent plate 21, the parking lock pole 33 is pushed up and the convex portion 331 and the parking gear 35 mesh with each other. On the other hand, when the cone 32 moves in the direction of the arrow NotP, the meshing between the convex portion 331 and the parking gear 35 is released.

The parking gear 35 is provided on an axle (not shown) so as to be able to mesh with the convex portion 331 of the parking lock pole 33. When the parking gear 35 and the convex portion 331 mesh with each other, the rotation of the axle is restricted. When the shift range is the NotP range, which is a range other than P, the parking gear 35 is not locked by the parking lock pole 33, and the rotation of the axle is not hindered by the parking lock mechanism 30. Further, when the shift range is the P range, the parking gear 35 is locked by the parking lock pole 33, and the rotation of the axle is restricted.

As shown in FIGS. 2 and 3, the shift range control device 40 includes a drive circuit unit 41, a current detection unit 45, an ECU 50, and the like. As shown in FIG. 3, the drive circuit unit 41 has three switching

elements

411, 412, and 413. In the present embodiment, the drive circuit unit 41 is provided between the windings 111 to 113 of each phase and the ground. The switching elements 411 to 413 are provided corresponding to the windings 111 to 113 of each phase, and switch the energization of the corresponding phase. The switching elements 411 to 413 of this embodiment are MOSFETs, but may be IGBTs or the like.

The windings 111 to 113 of the motor winding 11 are connected by the connection portion 115. Power is supplied to the connection portion 115 from the battery 90 via the power supply line 901. The power supply line 901 is provided with a relay unit 91, and when the relay unit 91 is turned on, power is supplied to the connection unit 115.

The current detection unit 45 has current detection elements 451 to 453, and detects the currents of the windings 111 to 113 for each phase. The current detection elements 451 to 453 of the present embodiment are shunt resistors, but a Hall element or the like other than the shunt resistor may be used. The current detection element 451 is provided between the switching element 411 and the U-phase winding 111, and detects the U-phase current Iu. The current detection element 452 is provided between the switching element 412 and the V-phase winding 112, and detects the V-phase current Iv. The current detection element 453 is provided between the switching element 413 and the W-phase winding 113, and detects the W-phase current Iw. The detected values of the current detecting elements 451 to 453 are output to the current limiting circuit 55. Hereinafter, the detection value of the current detection element 451 is referred to as a U-phase current detection value Iu_det, the detection value of the current detection element 452 is a V-phase current detection value Iv_det, and the detection value of the current detection element 453 is a W-phase current detection value Iw_det.

The ECU 50 has a microcomputer 51 and a current limiting circuit 55. The ECU 50 includes a CPU, ROM, RAM, I / O, and a bus line connecting these configurations, which are not shown inside. Each process in the ECU 50 may be a software process by executing a program stored in advance in a physical memory device such as a ROM (that is, a readable non-temporary tangible recording medium) on the CPU, or a dedicated process. It may be hardware processing by an electronic circuit.

As shown in FIG. 2, the ECU 50 controls the switching of the shift range by controlling the drive of the motor 10 based on the shift signal according to the driver required shift range, the signal from the brake switch, the vehicle speed, and the like. Further, the ECU 50 controls the drive of the shift hydraulic control solenoid 6 based on the vehicle speed, the accelerator opening degree, the driver required shift range, and the like. The shift stage is controlled by controlling the shift hydraulic control solenoid 6. The number of shift hydraulic control solenoids 6 is provided according to the number of shift stages and the like. In the present embodiment, one ECU 50 controls the drive of the motor 10 and the solenoid 6, but the motor ECU for controlling the motor 10 and the AT-ECU for solenoid control may be separated. Hereinafter, the drive control of the motor 10 will be mainly described.

The microcomputer 51 has a rotation speed calculation unit 52, a target current calculation unit 53, and an energization command unit 54 as functional blocks. The rotation speed calculation unit 52 calculates the motor rotation speed based on the encoder signal from the encoder 13. The target current calculation unit 53 calculates the current control target value X. The energization command unit 54 commands the energization phase based on the encoder signal from the encoder 13. In the present embodiment, the energizing phase is commanded by an interrupt calculation according to the pulse edge detection of the encoder signal.

Switching of the energizing phase will be described with reference to FIG. As shown in FIG. 4, the energized phase number and the energized phase are associated with each other, and each time the pulse edge of the encoder signal is detected, the energized phase number is shifted by 1 and the energized phase is switched to rotate the motor 10. Let me. In the example of FIG. 4, 0 to 11 are defined as one cycle of the energized phase number, and the phase energized at each energized phase number is indicated by a circle. In the present embodiment, when the motor 10 rotates in the forward direction, the energized phase number is incremented by 1 for each encoder pulse edge, and when the energized phase number reaches 11, the energized phase number returns to 0, and so on. Further, when the motor 10 rotates in the reverse direction, the energizing phase number is decremented by 1 for each encoder pulse edge, and when the energizing phase number becomes 0, the current state returns to 11 and so on. Hereinafter, when the energized phase number is 1, as in the case where the energized phase number is 2, 3, 6, 7, 10, 11, one phase is energized, and the energized phase number is 0, 1, 4, 5, 8, When the energizing phase is two phases as in the case of 9, two-phase energization is performed.

The current limiting circuit 55 is composed of hardware and controls the on / off operation of the switching elements 411 to 413 based on the current detection values Iu_det, Iv_dt, and Iw_det. The on / off operation of the switching element 411 based on the U-phase current detection value Iu_det will be described with reference to FIG.

When the U-phase current detection value Iu_det reaches the upper limit value X_hi, the switching element 411 is turned off, and when it decreases to the lower limit value X_lo, the switching element 411 is turned on. The upper limit value X_hi and the lower limit value X_lo are set so that the current control target value X is at the center. Assuming that the control width of the U-phase current Iu is α, the upper limit value X_hi = X + (1/2) × α and the lower limit value X_lo = X− (1/2) × α. As a result, the U-phase current Iu is controlled to the current control target value X on average. Since the V phase and the W phase are the same as the U phase, the description thereof will be omitted. Further, the current control method may be, for example, a duty change by feedback control or the like.

By the way, when learning the drive limit position of the motor 10 by driving the motor 10 until the detent roller 26 comes into contact with the wall portion of the detent plate 21, it is preferable to perform it at a low speed from the viewpoint of durability and the like. Here, as in the reference example shown in FIG. 8, when the motor 10 is driven in a low speed rotation region (for example, 300 [rpm] or less), even if the current is controlled so as to have a rectangular wave, the rotor and the stator Torque ripple may occur due to the change in inductance due to the positional relationship. Specifically, the torque during one-phase energization is relatively larger than that during two-phase energization.

Therefore, in the present embodiment, the torque ripple is reduced by making the current control target value X variable in the low speed rotation region. The current control process of this embodiment will be described with reference to the flowchart of FIG. This process is executed in the microcomputer 51 at a predetermined cycle during the current control. Hereinafter, the “step” in step S101 is omitted and simply referred to as the symbol “S”.

In S101, the microcomputer 51 calculates the motor rotation speed. In S102, the microcomputer 51 determines whether or not it is in the low-speed rotation region. Here, when the motor rotation speed is equal to or less than the low speed determination value (for example, 300 [rpm]), it is determined that the motor rotation speed is in the low speed rotation region. When it is determined that the rotation is not in the low-speed rotation region (S102: NO), the process shifts to S104, and the current control target value X is set as the initial value Xa. When it is determined that the rotation speed region is low (S102: YES), the process proceeds to S103.

In S103, the microcomputer 51 determines whether or not the energization pattern is one-phase energization. When it is determined that the energization pattern is not one-phase energization (S103: NO), that is, when the energization pattern is two-phase energization, the process shifts to S104, and the current control target value X is set as the initial value Xa. When it is determined that the energization pattern is one-phase energization (S103: YES), the process proceeds to S105.

In S105, the microcomputer 51 changes the current control target value X from the initial value Xa to Xa × k. The coefficient k is set to an arbitrary value of 0 <k <1 (for example, 0.75) by matching or the like so that the torque ripple in the low speed rotation region is suppressed. Further, in the low speed rotation region, the control width α may also be made variable by multiplying by the coefficient j. The coefficients k and j may have the same value or may have different values.

The current control of this embodiment will be described with reference to the time chart of FIG. In FIG. 7, the energization pattern, U-phase current, V-phase current, W-phase current, and motor torque are shown from the top. The same applies to FIG. In the present embodiment, the current control target value X is set so that the current during one-phase energization, which tends to generate torque relatively easily, is smaller than that during two-phase energization due to the positional relationship between the rotor and the stator, and the current waveform is set. By fluctuating, the change in inductance is absorbed. Thereby, the torque ripple can be reduced. Further, the process of changing the current control target value X according to the motor rotation position is performed in the low-speed rotation region, and is not performed in other than the low-speed rotation region. As a result, an increase in the load on the microcomputer can be suppressed.

As described above, the shift range control device 40 controls the drive of the motor 10 having the three-phase windings 111 to 113, and includes the drive circuit unit 41, the current detection unit 45, and the encoder 13. , ECU 50. The drive circuit unit 41 has switching elements 411 to 413 provided corresponding to each phase of the windings 111 to 113. The current detection unit 45 detects the currents of the windings 111 to 113. The encoder 13 detects the motor rotation position, which is the rotation position of the motor 10.

The ECU 50 has a rotation speed calculation unit 52, a target current calculation unit 53, an energization command unit 54, and a current limiting circuit 55. The rotation speed calculation unit 52 calculates the motor rotation speed, which is the rotation speed of the motor 10. The target current calculation unit 53 calculates the current control target value X. The energization command unit 54 commands the energization phase according to the encoder count value, which is the detection value of the encoder 13. The current limiting circuit 55 controls the on / off operation of the switching elements 411 to 413 so that the current applied to the windings 111 to 113 becomes the current control target value X.

When the motor rotation speed is in the low speed rotation range, the current control target value X is made variable according to the motor rotation position. In the present embodiment, by making the current control target value X variable according to the encoder count value, the torque ripple generated by the tooth positional relationship between the rotor and the stator can be reduced, and the drive torque of the motor 10 is stabilized. Can be done. Further, by limiting the variable current control target value X according to the encoder count value to the low-speed rotation region and not changing the current control target value X in the high-speed rotation region, the computing load of the microcomputer 51 during high-speed rotation Can be reduced.

The ECU 50 rotates the motor 10 by switching between one-phase energization that energizes one phase of windings 111 to 113 and two-phase energization that energizes two phases of windings 111 to 113 according to the motor rotation position. .. The target current calculation unit 53 sets the current control target value X so that the current during one-phase energization is smaller than that during two-phase energization in the low-speed rotation region. This makes it possible to suppress torque fluctuations of the motor 10 depending on the energized state and the rotor position.

When the motor rotation speed is equal to or less than the low speed determination value, the target current calculation unit 53 converts the current control target value at the time of one-phase energization into the current control target value at the time of two-phase energization with a conversion coefficient k (however, 0 <k <1). Is the value multiplied by. Thereby, the torque fluctuation between the one-phase energization and the two-phase energization can be appropriately suppressed.

The current limiting circuit 55 turns off the switching elements 411 to 413 when the current energized in the windings 111 to 113 reaches the upper limit value X_hi, which is a value larger than the current control target value X, and is smaller than the current control target value X. When the value drops to the lower limit value X_lo, the switching elements 411 to 413 are turned on. In the low-speed rotation region, the control width α, which is the width between the upper limit value X_hi and the lower limit value X_lo, is different between the one-phase energization and the two-phase energization. Thereby, the current flowing through the windings 111 to 113 can be appropriately controlled.

In the present embodiment, the shift range control device 40 corresponds to the "motor control device", the encoder 13 corresponds to the "rotation detection unit", the ECU 50 corresponds to the "control unit", and the current limiting circuit 55 corresponds to the "switch control unit".

(Other embodiments)
In the above embodiment, the case where the motor rotation speed is equal to or less than the low speed determination value is set as the low speed rotation region, and the current control target value at the time of one-phase energization is set by multiplying by a predetermined coefficient k. In another embodiment, in the low-speed rotation region, the current control target value may be gradually reduced according to the rotation speed, or may be gradually reduced. Further, in the above embodiment, the current control target value is made variable between the one-phase energization and the two-phase energization. In another embodiment, the current control target value may be changed according to the motor rotation position so that the change in inductance due to the relationship between the rotor and the stator can be absorbed regardless of the number of energized phases.

In the above embodiment, the rotation speed calculation unit, the target current calculation unit, and the energization command unit are composed of a microcomputer, and the switch control unit is composed of a hard circuit. In other embodiments, it does not matter whether each process in the control unit is configured by software or hardware.

In the above embodiment, the rotational position of the motor is detected by the encoder. In other embodiments, not only the encoder but also any resolver or the like may be used. In the above embodiment, a potentiometer is exemplified as an output shaft sensor. In other embodiments, the output shaft sensor may be any. Further, the output shaft sensor may be omitted.

In the above embodiment, the detent plate is provided with two recesses. In other embodiments, the number of recesses is not limited to two, and recesses may be provided for each range, for example. Further, the shift range switching mechanism, the parking lock mechanism, and the like may be different from those in the above embodiment.

In the above embodiment, a speed reducer is provided between the motor shaft and the output shaft. Although the details of the speed reducer are not mentioned in the above embodiment, for example, cycloid gears, planetary gears, spur gears that transmit torque from a speed reduction mechanism substantially coaxial with the motor shaft to the drive shaft, and these. Any configuration may be used, such as a combination of the above. Further, in another embodiment, the speed reducer between the motor shaft and the output shaft may be omitted, or a mechanism other than the speed reducer may be provided.

In the above embodiment, the motor control device is applied to the shift range switching system. In other embodiments, the motor control device may be applied to devices other than the shift range switching system. In particular, it is suitably applied to a device that requires a constant torque output from a motor in a low speed rotation region.

The controls and methods thereof described in the present disclosure are realized by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. May be done. Alternatively, the controls and methods thereof described in the present disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and method thereof described in the present disclosure may be a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. It may be realized by one or more dedicated computers configured. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as an instruction executed by the computer. As described above, the present disclosure is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the present embodiment.

This disclosure has been described in accordance with the embodiments. However, the present disclosure is not limited to such embodiments and structures. The present disclosure also includes various variations and variations within an equal range. Also, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are within the scope and ideology of the present disclosure.

Claims

A motor control device that controls the drive of a motor (10) having windings (111 to 113).
A drive circuit unit (41) having a switching element (411 to 413) provided corresponding to each phase of the winding, and a drive circuit unit (41).
A current detection unit (45) that detects the current of the winding, and
A rotation detection unit (13) that detects the motor rotation position, which is the rotation position of the motor, and
A rotation speed calculation unit (52) that calculates the motor rotation speed, which is the rotation speed of the motor, a target current calculation unit (53) that calculates the current control target value, and an energizing phase corresponding to the detection value of the rotation detection unit. A control unit (54) having an energization command unit (54) for commanding the above and a switch control unit (55) for controlling the on / off operation of the switching element so that the current energized in the winding becomes the current control target value. 50) and
With
A motor control device that changes the current control target value according to the motor rotation position when the motor rotation speed is in the low speed rotation region.
The control unit rotates the motor by switching between one-phase energization that energizes one phase of the winding and two-phase energization that energizes the two phases of the winding according to the motor rotation position.
The motor control device according to claim 1, wherein the target current calculation unit sets the current control target value so that the current during the one-phase energization is smaller than that during the two-phase energization in the low-speed rotation region.
When the motor rotation speed is equal to or lower than the low speed determination value, the target current calculation unit converts the current control target value during the one-phase energization into the current control target value during the two-phase energization by a conversion coefficient k (however, 0). The motor control device according to claim 2, wherein the value is multiplied by <k <1).
When the current energized in the winding reaches the upper limit value which is larger than the current control target value, the switch control unit turns off the switching element and reaches the lower limit value which is smaller than the current control target value. When it decreases, the switching element is turned on.
The motor control device according to claim 2 or 3, wherein the control width, which is the width between the upper limit value and the lower limit value, is different between the one-phase energization and the two-phase energization in the low-speed rotation region.