JP7363648B2 - motor control device - Google Patents

Description

The present invention relates to a motor control device.

Conventionally, automatic transmissions in which the range switching mechanism is driven by a motor are known. For example, in Patent Document 1, a reference position is learned by executing a hitting control in which the range switching mechanism is rotated until it hits the limit position of the movable range.

Japanese Patent Application Publication No. 2014-100041

In Patent Document 1, the current at the collecting portion of the motor is controlled to be constant based on the output of the current sensor. Furthermore, the motor torque is kept constant by controlling the control current value when energizing one phase to be 1/2 of the control current value when energizing two phases. Here, during low speed rotation, there is a possibility that the motor torque may vary depending on the positional relationship between the rotor and the stator. The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a motor control device that can suppress fluctuations in motor torque.

The motor control device of the present invention controls the drive of a motor (10) having windings (111 to 113), and includes a drive circuit section (41), a current detection section (45), and a rotation detection section. (13) and a control section (50). The drive circuit section has switching elements (411 to 413) provided corresponding to each phase of the winding. The current detection section detects the current in the winding. The rotation detection section detects a motor rotation position, which is a rotation position of the motor.

The control section includes a rotation speed calculation section (52), a target current calculation section (53), an energization command section (54), and a switch control section (55). The rotational speed calculation section calculates a motor rotational speed that is the rotational speed of the motor. The target current calculation section calculates a current control target value. The energization command section commands the energization phase according to the detected value of the rotation detection section. The switch control section controls the on/off operation of the switching element so that the current applied to the winding reaches a current control target value. When the motor rotational speed is in a low rotational speed region, the current control target value is made variable according to the motor rotational position. This makes it possible to suppress torque fluctuations caused by motor rotational position.

FIG. 1 is a perspective view of a shift-by-wire system according to one embodiment. FIG. 1 is a schematic configuration diagram showing a shift-by-wire system according to one embodiment. FIG. 1 is a block diagram illustrating a shift range control device according to an embodiment. FIG. 3 is an explanatory diagram illustrating the correspondence between energized phase numbers and energized phases according to one embodiment. 5 is a time chart illustrating current control according to an embodiment. 5 is a flowchart illustrating current control processing according to an embodiment. 5 is a time chart illustrating current control processing according to an embodiment. 7 is a time chart illustrating current control processing according to a reference example.

(One embodiment)
Hereinafter, a motor control device according to the present invention will be explained based on the drawings. One embodiment is shown in FIGS. 1-7. As shown in FIGS. 1 and 2, a shift-by-wire system 1 that 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 when electric power is supplied 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 motor windings 11 wound around salient poles of a stator (not shown). Motor winding 11 has U-phase winding 111, V-phase winding 112, and W-phase winding 113. By controlling the energization to 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 rotational position of the rotor of the motor 10. The encoder 13 is, for example, a magnetic rotary encoder, and includes a magnet that rotates together with a rotor, a Hall IC for magnetic detection, and the like. The encoder 13 outputs encoder signals, which are A-phase and B-phase pulse signals, at predetermined angle intervals 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 reduces the rotation speed of the motor 10 and outputs the speed to the output shaft 15 . Thereby, 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 includes a detent plate 21, a detent spring 25, etc., and transfers the rotational driving force output from the 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 protrudes parallel to the output shaft 15. Pin 24 is connected to manual valve 28 . As 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 linear motion and transmits the linear motion to the manual valve 28 . Manual valve 28 is provided in valve body 29. By reciprocating the manual valve 28 in the axial direction, a hydraulic pressure supply path to a hydraulic clutch (not shown) is switched, and the engagement state of the hydraulic clutch is switched, thereby changing the shift range.

Two valleys are provided on the detent spring 25 side of the detent plate 21. The detent spring 25 is an elastically deformable plate member, and a detent roller 26 is provided at the tip. The detent spring 25 urges the detent roller 26 toward the center of rotation of the detent plate 21. When a predetermined rotational force or more is applied to the detent plate 21, the detent spring 25 is elastically deformed, and the detent roller 26 moves between the valleys. When the detent roller 26 fits into one of the valleys, the swinging of the detent plate 21 is restricted, 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 is fixed.

The parking lock mechanism 30 includes 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 body 32 is provided on the other end 312 side of the parking rod 31 . The conical body 32 is formed so that its diameter decreases 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 arrow P.

The parking lock pawl 33 is provided in contact with the conical surface of the conical body 32 and is swingable about the shaft portion 34 . A convex portion 331 that can mesh with the parking gear 35 is provided on the parking gear 35 side of the parking lock pole 33. When the cone 32 moves in the direction of 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 are engaged with each other. On the other hand, when the cone 32 moves in the direction of the arrow NotP, the engagement between the convex portion 331 and the parking gear 35 is released.

The parking gear 35 is provided on an axle (not shown), and is provided 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, rotation of the axle is restricted. When the shift range is a 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 prevented by the parking lock mechanism 30. Further, when the shift range is in the P range, the parking gear 35 is locked by the parking lock pole 33, and rotation of the axle is regulated.

As shown in FIGS. 2 and 3, the shift range control device 40 includes a drive circuit section 41, a current detection section 45, an ECU 50, and the like. As shown in FIG. 3, the drive circuit section 41 includes three switching elements 411, 412, and 413. In this embodiment, the drive circuit section 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 in this embodiment are MOSFETs, but may also be IGBTs or the like.

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

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

ECU 50 includes a microcomputer 51 and a current limiting circuit 55. The ECU 50 internally includes a CPU, ROM, RAM, I/O, and a bus line connecting these components, all of which are not shown. Each process in the ECU 50 may be a software process in which the CPU executes a program stored in a physical memory device such as a ROM (i.e., a readable non-temporary tangible recording medium), or a dedicated It may also be hardware processing using an electronic circuit.

As shown in FIG. 2, the ECU 50 controls switching of shift ranges by controlling driving of the motor 10 based on a shift signal according to a driver-requested shift range, a signal from a brake switch, 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, the shift range requested by the driver, and the like. The gear position is controlled by controlling the gear shift hydraulic control solenoid 6. The number of shift hydraulic control solenoids 6 is provided in accordance with the number of gears and the like. In this embodiment, one ECU 50 controls the driving of the motor 10 and the solenoid 6, but a motor ECU for motor control that controls the motor 10 and an AT-ECU for solenoid control may be separated. The drive control of the motor 10 will be mainly described below.

The microcomputer 51 includes a rotation speed calculation section 52, a target current calculation section 53, and an energization command section 54 as functional blocks. The rotational speed calculating section 52 calculates the motor rotational speed based on the encoder signal from the encoder 13. The target current calculation section 53 calculates the current control target value X. The energization command section 54 commands the energization phase based on the encoder signal from the encoder 13. In this embodiment, the energization phase is commanded by interrupt calculation in response to pulse edge detection of the encoder signal.

Switching of the energized phase will be explained based on FIG. 4. As shown in FIG. 4, the energized phase number and the energized phase are associated with each other, and each time a 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 In the example of FIG. 4, the energized phase numbers 0 to 11 are defined as one cycle, and the phases that are energized at each energized phase number are indicated by circles. In this embodiment, when the motor 10 rotates forward, the energized phase number is incremented by 1 at every encoder pulse edge, and when the energized phase number reaches 11, it returns to 0. Further, when the motor 10 rotates in reverse, the energized phase number is decremented by 1 at every encoder pulse edge, and when the energized phase number reaches 0, it returns to 11. Hereinafter, when the energized phase number is 2, 3, 6, 7, 10, 11, when the energized phase is 1 phase, 1 phase is energized, and when the energized phase number is 0, 1, 4, 5, 8, 9, the case where there are two energized phases is defined as two-phase energization.

The current limiting circuit 55 is configured by hardware, and controls the on/off operation of the switching elements 411 to 413 based on the detected current 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 explained based on FIG. 5.

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 centered. When 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. Thereby, the U-phase current Iu is controlled to the current control target value X as an average. Since the V phase and W phase are the same as the U phase, their explanation will be omitted. Further, the current control method may be, for example, changing the duty by feedback control.

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 of the detent plate 21, it is preferable to do it at a low speed from the viewpoint of durability and the like. Here, as in the reference example shown in FIG. 8, when driving the motor 10 in a low-speed rotation region (for example, 300 [rpm] or less), even if the current is controlled to have a rectangular wave, the rotor and stator There is a possibility that torque ripples may occur due to changes in inductance due to positional relationships. Specifically, the torque during one-phase energization becomes relatively large compared to when two-phase energization occurs.

Therefore, in this embodiment, 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 explained based on the flowchart of FIG. This process is executed by the microcomputer 51 at predetermined intervals during current control. Hereinafter, the "step" in step S101 will be 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 the rotation speed is in the low speed rotation region. Here, if the motor rotation speed is less than or equal to a low speed determination value (for example, 300 [rpm]), it is determined that the motor is in the low speed rotation region. If it is determined that the rotation speed is not in the low speed rotation region (S102: NO), the process moves to S104, and the current control target value X is set to the initial value Xa. If it is determined that the rotation speed is in the low speed rotation region (S102: YES), the process moves to S103.

In S103, the microcomputer 51 determines whether the energization pattern is one-phase energization. If it is determined that the energization pattern is not one-phase energization (S103: NO), that is, if the energization pattern is two-phase energization, the process moves to S104, and the current control target value X is set to the initial value Xa. If it is determined that the energization pattern is one-phase energization (S103: YES), the process moves 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 adaptation or the like so that torque ripple in a 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 a coefficient j. The coefficients k and j may be the same value or may be different values.

The current control of this embodiment will be explained based on the time chart of FIG. In FIG. 7, from the top, the current pattern, U-phase current, V-phase current, W-phase current, and motor torque are shown. The same applies to FIG. In this embodiment, due to the positional relationship between the rotor and stator, the current control target value By varying it, the inductance change is absorbed. Thereby, torque ripple can be reduced. Further, the process of changing the current control target value X based on the motor rotational position is performed in the low-speed rotation region, and is not performed in other than the low-speed rotation region. This makes it possible to suppress an increase in the microcomputer load.

As explained 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 section 41, the current detection section 45, and the encoder 13. , and an ECU 50. The drive circuit section 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 in the windings 111 to 113. Encoder 13 detects a motor rotational position, which is the rotational position of motor 10 .

The ECU 50 includes a rotation speed calculation section 52, a target current calculation section 53, an energization command section 54, and a current limiting circuit 55. The rotational speed calculation unit 52 calculates the motor rotational speed, which is the rotational speed of the motor 10. The target current calculation section 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 detected 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 flowing through the windings 111 to 113 reaches the current control target value X.

When the motor rotational speed is in a low rotational speed region, the current control target value X is made variable according to the motor rotational position. In this embodiment, by making the current control target value X variable according to the encoder count value, it is possible to reduce the torque ripple caused by the tooth positional relationship between the rotor and the stator, and to stabilize the driving torque of the motor 10. Can be done. In addition, by limiting the variable current control target value X according to the encoder count value to the low-speed rotation region and not varying the current control target value X in the high-speed rotation region, the calculation load on the microcomputer 51 during high-speed rotation is reduced. can be reduced.

The ECU 50 rotates the motor 10 by switching between 1-phase energization, in which one phase of the windings 111 to 113 is energized, and 2-phase energization, in which two phases of the windings 111 to 113 are energized, depending on the motor rotational 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 fluctuations in the torque of the motor 10 due to the energization state and rotor position.

When the motor rotational speed is less than or equal to the low speed determination value, the target current calculation unit 53 converts the current control target value for one-phase energization into the current control target value for two-phase energization by a conversion coefficient k (0<k<1). The value multiplied by This makes it possible to appropriately suppress torque fluctuations between one-phase energization and two-phase energization.

The current limiting circuit 55 turns off the switching elements 411 to 413 when the current flowing through the windings 111 to 113 reaches an upper limit value X_hi which is a value larger than the current control target value When the voltage decreases to a 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 when one phase is energized and when two phases are energized. Thereby, the current flowing through the windings 111 to 113 can be appropriately controlled.

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

(Other embodiments)
In the embodiment described above, the case where the motor rotation speed is less than or equal to the low speed determination value is defined as the low speed rotation region, and the current control target value during one-phase energization is set by multiplying by a predetermined coefficient k. In other embodiments, the current control target value may be decreased gradually or in steps in accordance with the rotation speed in the low speed rotation region. Furthermore, in the embodiment described above, the current control target value is made variable between when one phase is energized and when two phases are energized. In another embodiment, the current control target value may be made variable in accordance with the motor rotational position so that inductance changes due to the relationship between the rotor and the stator can be absorbed regardless of the number of energized phases.

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

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

In the embodiment described above, the detent plate is provided with two recesses. In other embodiments, the number of recesses is not limited to two, and for example, a recess may be provided for each range. Further, the shift range switching mechanism, parking lock mechanism, etc. 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 reducer are not mentioned in the above embodiments, for example, there may be a cycloid gear, a planetary gear, a spur gear that transmits torque from a reduction mechanism approximately coaxial with the motor shaft to the drive shaft, or Any configuration may be used, such as a combination of the following. In other embodiments, the reduction gear between the motor shaft and the output shaft may be omitted, or a mechanism other than the reduction gear may be provided.

In the above embodiment, the motor control device is applied to a 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 devices that require a constant torque output from the motor in a low-speed rotation region.

The control unit and the method described in the present disclosure are implemented 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 controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium. As described above, the present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the spirit of the invention.

10...Motor 11...Motor winding 111-113...Each phase winding 13...Encoder (rotation detection section)
40...Shift range control device (motor control device)
41... Drive circuit section 411-413... Switching element 45... Current detection section 50... ECU (control section)
51...Microcomputer 52...Rotation speed calculation section 53...Target current calculation section 54...Electrification command section 55...Current limiting circuit (switch control section)

Claims (4)

A motor control device that controls driving of a motor (10) having windings (111 to 113),
a drive circuit section (41) having switching elements (411 to 413) provided corresponding to each phase of the winding;
a current detection unit (45) that detects the current in the winding;
a rotation detection unit (13) that detects a motor rotation position that is a rotation position of the motor;
A rotation speed calculation section (52) that calculates a motor rotation speed that is the rotation speed of the motor, a target current calculation section (53) that calculates a current control target value, and an energization phase according to a detected value of the rotation detection section. and a switch control unit (55) that controls the on/off operation of the switching element so that the current applied to the winding reaches the current control target value. 50) and
Equipped with
A motor control device that makes the current control target value variable according to the motor rotational position when the motor rotational speed is in a low rotational speed region. The control unit rotates the motor by switching between one-phase energization in which one phase of the winding is energized and two-phase energization in which two phases of the winding are energized, 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 such that the current during the one-phase energization is smaller than the current during the two-phase energization in a low-speed rotation region. The target current calculation unit converts the current control target value during the one-phase energization to 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). The switch control section turns off the switching element when the current flowing through the winding reaches an upper limit value that is larger than the current control target value, and the current flows to the lower limit value that is smaller than the current control target value. When the voltage decreases, the switching element is turned on,
4. The motor control device according to claim 2, wherein a control width, which is a 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.

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