WO2020059676A1

WO2020059676A1 - Shift range control device

Info

Publication number: WO2020059676A1
Application number: PCT/JP2019/036258
Authority: WO
Inventors: 坂口　浩二
Original assignee: 株式会社デンソー
Priority date: 2018-09-18
Filing date: 2019-09-16
Publication date: 2020-03-26
Also published as: JP2020045949A; JP7067382B2

Abstract

This shift range control device (40) is provided with drive circuits (41, 42) and a control unit (50). The drive circuits (41, 42) have switching elements (411-416, 421-426) for switching the electrical conduction of motor windings (11, 12). The control unit (50) has a motor angle computation unit (51), a drive control unit (53), and a duty limiting unit (55). The motor angle computation unit (51) computes a motor angle on the basis of a signal acquired from a rotational angle sensor (13) that detects the rotational position of a motor (10). The drive control unit (53) controls the driving of the motor (10) so that the motor angle reaches a desired rotation angle that corresponds to a desired shift range. The duty limiting unit (55) determines, in accordance with the motor angle, a duty limiting value for limiting the duty, which is the proportion of ON time of the switching elements (411-416, 421-426) in a prescribed period.

Description

Shift range control device

Cross-reference of related applications

This application is based on patent application No. 2018-173820 filed on Sep. 18, 2018, the contents of which are incorporated herein by reference.

The present disclosure relates to a shift range control device.

Conventionally, there is known a shift range control device that switches a shift range by controlling a motor in response to a shift range switching request from a driver. For example, in Patent Document 1, the motor is driven at the maximum duty until the motor speed becomes equal to or higher than the target motor speed.

Japanese Patent Application Laid-Open No. 2018-40464

For example, if the duty at the time of low-speed rotation is large, the current becomes large, and there is a possibility that the drive circuit or the like may break down. An object of the present disclosure is to provide a shift range control device capable of suppressing overcurrent.

The shift range control device of the present disclosure controls switching of the shift range by controlling driving of a motor having a motor winding, and includes a drive circuit and a control unit. The drive circuit has a switching element that switches energization of the motor winding.

The control unit has a motor angle calculation unit, a drive control unit, and a duty limit unit. The motor angle calculator calculates a motor angle based on a signal obtained from a rotation angle sensor that detects a rotation position of the motor. The drive control unit controls driving of the motor such that the motor angle becomes a target rotation angle corresponding to the target shift range. The duty limiter determines a duty limit value that limits a duty, which is a ratio of the ON time of the switching element during a predetermined period, according to the motor angle. Thereby, overcurrent can be suppressed.

The above and other objects, features and advantages of the present disclosure will become more apparent from 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 the first embodiment, FIG. 2 is a schematic configuration diagram illustrating a shift-by-wire system according to the first embodiment, FIG. 3 is a circuit diagram showing a motor and a motor driver according to the first embodiment, FIG. 4 is an explanatory diagram showing the relationship between the torque, the rotation speed, and the motor current according to the first embodiment. FIG. 5 is a flowchart illustrating a duty limit value calculation process according to the first embodiment. FIG. 6 is a time chart for explaining the drive control processing according to the first embodiment. FIG. 7 is a time chart for explaining the drive control processing according to the reference example. FIG. 8 is a flowchart illustrating a duty limit value calculation process according to the second embodiment. FIG. 9 is a time chart illustrating a drive control process according to the second embodiment. FIG. 10 is a time chart for explaining the drive control processing according to the reference example.

Hereinafter, a shift range control device according to the present disclosure will be described with reference to the drawings. Hereinafter, in a plurality of embodiments, substantially the same configuration is denoted by the same reference numeral, and description thereof is omitted.

(1st Embodiment)
A first embodiment is shown in FIGS. As shown in FIGS. 1 and 2, the shift-by-wire system 1 as a shift range switching system includes a motor 10, a shift range switching mechanism 20, a parking lock mechanism 30, a shift range control device 40, and the like. The motor 10 rotates when supplied with electric power from a battery 45 mounted on a vehicle (not shown), and functions as a drive source of the shift range switching mechanism 20. The motor 10 of the present embodiment is a permanent magnet type DC brushless motor.

As shown in FIG. 3, the motor 10 has two sets of motor windings 11 and 12 wound around a stator (not shown). The first motor winding 11 has a U1 coil 111, a V1 coil 112, and a W1 coil 113. The second motor winding 12 has a U2 coil 121, a V2 coil 122, and a W2 coil 123.

エンコーダ As shown in FIG. 2, the encoder 13 as a motor rotation angle sensor detects the rotation position of the rotor 105. The encoder 13 is, for example, a magnetic rotary encoder, and includes a magnet that rotates integrally with the rotor, a Hall IC for detecting magnetism, and the like. The encoder 13 is a three-phase encoder that outputs an A-phase, a B-phase, and a C-phase pulse signal, which are pulse signals 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 reduces the rotation of the motor 10 and outputs the rotation to the output shaft 15. Thus, 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 for detecting the angle of the output shaft 15. The output shaft sensor 16 of the present embodiment 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 a rotational driving force output from the reduction gear 14 to a manual valve 28 and a parking lock mechanism 30. Communicate to

The detent plate 21 is fixed to the output shaft 15 and is driven by the motor 10. In the present embodiment, the direction in which the detent plate 21 moves away from the base of the detent spring 25 is defined as a forward rotation direction, and the direction in which the detent plate 21 approaches the base is defined as a reverse rotation direction.

The detent plate 21 is provided with a pin 24 projecting in parallel with 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 movement of the motor 10 into a linear movement and transmits the linear movement to the manual valve 28. The manual valve 28 is provided on a 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

concave portions

22 and 23 are provided on the detent spring 25 side of the detent plate 21. In this embodiment, the side closer to the base of the detent spring 25 is referred to as the concave portion 22 and the side farther from the base is referred to as the concave portion 23. In the present embodiment, the concave portion 22 corresponds to a NotP range other than the P range, and the concave portion 23 corresponds to the P range.

The detent spring 25 is a plate-like member that can be elastically deformed, and has a detent roller 26 at the tip. The detent spring 25 urges the detent roller 26 toward the center of rotation of the detent plate 21. When a rotational force greater than a predetermined value is applied to the detent plate 21, the detent spring 25 is elastically deformed, and the detent roller 26 moves between the

concave portions

22 and 23. When the detent roller 26 fits into one of the

recesses

22 and 23, 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 is changed. The shift range of the machine 5 is fixed. The detent roller 26 fits into the concave portion 22 when the shift range is the NotP range, and fits into the concave portion 23 when the shift range is the P range.

The parking lock mechanism 30 includes a parking rod 31, a cone 32, a parking lock pawl 33, a shaft 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. On the other end 312 side of the parking rod 31, a cone 32 is provided. The conical body 32 is formed so as to decrease in diameter toward the other end 312 side. When the detent plate 21 swings in the reverse rotation direction, the cone 32 moves in the P direction.

The parking lock pawl 33 is in contact with the conical surface of the cone 32, and is provided so as to be swingable about a shaft portion 34. On the parking gear 35 side of the parking lock pawl 33, a convex portion capable of meshing with the parking gear 35 is provided. 331 are provided. When the detent plate 21 rotates in the reverse rotation direction and the cone 32 moves in the P direction, the parking lock pole 33 is pushed up, and the projection 331 and the parking gear 35 mesh. On the other hand, when the detent plate 21 rotates in the normal rotation direction and the cone 32 moves in the NotP direction, the engagement between the projection 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 projection 331 of the parking lock pole 33. When the parking gear 35 and the projection 331 mesh with each other, the rotation of the axle is restricted. When the shift range is the NotP range, the parking gear 35 is not locked by the parking lock pawl 33, and the rotation of the axle is not hindered by the parking lock mechanism 30. 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

motor drivers

41 and 42 as drive circuits, an ECU 50, and the like. As shown in FIG. 3, the first motor driver 41 is a three-phase inverter that switches energization of the first motor winding 11, and the switching elements 411 to 416 are bridge-connected. One end of the U1 coil 111 is connected to a connection point of the pair of

U-phase switching elements

411 and 414. One end of the V1 coil 112 is connected to a connection point of the V-

phase switching elements

412 and 415 that form a pair. One end of the W1 coil 113 is connected to a connection point of the W-

phase switching elements

413 and 416 that form a pair. The other ends of the coils 111 to 113 are connected by a connection section 115.

The second motor driver 42 is a three-phase inverter for switching the energization of the second motor winding 12, and the switching elements 421 to 426 are bridge-connected. One end of the U2 coil 121 is connected to a connection point of the pair of

U-phase switching elements

421 and 424. One end of the V2 coil 122 is connected to a connection point of the V-

phase switching elements

422 and 425 that form a pair. One end of the W2 coil 123 is connected to a connection point of the paired W-

phase switching elements

423 and 426. The other ends of the coils 121 to 123 are connected at a connection portion 125. Although the switching elements 411 to 416 and 421 to 426 of the present embodiment are MOSFETs, other elements such as IGBTs may be used.

モータ As shown in FIGS. 2 and 3, a motor relay 46 is provided between the motor driver 41 and the battery 45. A motor relay 47 is provided between the motor driver 42 and the battery 45. The motor relays 46 and 47 are turned on when a start switch such as an ignition switch is turned on, and power is supplied to the motor 10 side. Further, when the motor relays 46 and 47 are on, power is supplied from the battery 45 to the motor 10, and when the motor relays 46 and 47 are off, power from the battery 45 to the motor 10 is cut off. On the high potential side of the battery 45, a voltage sensor 48 for detecting a battery voltage is provided.

As shown in FIG. 2, the ECU 50 is mainly configured by a microcomputer or the like, and includes a CPU, ROM, RAM, I / O, bus lines for connecting these components, and the like, which are not shown. . Each process in the ECU 50 may be a software process by executing a program stored in advance in a substantial memory device such as a ROM (ie, a readable non-temporary tangible recording medium) by the CPU, or a dedicated process. Hardware processing by an electronic circuit may be used.

The ECU 50 controls the on / off operations of the switching elements 411 to 416 and 421 to 426 so that the driver requested shift range input by operating a shift lever or the like (not shown) matches the shift range in the shift range switching mechanism 20. , And controls the driving of the motor 10. Further, the ECU 50 controls the driving of the shift hydraulic control solenoid 6 based on the vehicle speed, the accelerator opening, the driver's requested shift range, and the like. The shift speed is controlled by controlling the shift hydraulic control solenoid 6. The number of shift hydraulic control solenoids 6 is provided in accordance with the number of shift stages. In the present embodiment, one ECU 50 controls the driving of the motor 10 and the solenoid 6, but the motor ECU for controlling the motor 10 for controlling the motor 10 and the AT-ECU for controlling the solenoid may be separated. Hereinafter, the drive control of the motor 10 will be mainly described.

The ECU 50 includes an angle calculation unit 51, a drive control unit 53, a duty limit unit 55, and the like. The angle calculator 51 counts the pulse edges of each phase of the encoder signal output from the encoder 13 and calculates the encoder count value θen. The encoder count value θen is a value corresponding to the rotational position of the motor 10, and corresponds to “motor angle”.

The drive control unit 53 controls the drive of the motor 10 so that the encoder count value θen becomes the target count value θcmd set according to the target shift range. In the present embodiment, the motor 10 is rotated by switching the energized phase based on the encoder count value θen. For example, if the energized phase is the UV phase, the switching

elements

411 and 421 as the upper arm elements of the U phase are turned on, and the switching

elements

415 and 425 as the lower arm elements of the V phase are turned on and off at the set duty D. The duty D is a ratio of the ON time in one cycle, and in the present embodiment, the time during acceleration is defined as positive and the time during deceleration is defined as negative. The duty limiter 55 sets a duty limit value Dlim for limiting the duty D.

(4) Here, FIG. 4 shows the relationship among the motor rotation speed, the torque, and the motor current. In FIG. 4, the horizontal axis represents torque, and the vertical axis represents motor speed and motor current. As shown in FIG. 4, when a large torque is output in a state where the motor speed is low, the motor current increases. If the motor current Im exceeds the upper limit Ilim, the

motor drivers

41 and 42 may fail.

As a reference example, assuming that the duty in the acceleration range at the initial stage of motor driving is 100% in order to improve the responsiveness so that the range switching time is shortened, the motor current Im exceeds the upper limit Ilim at the time of motor low speed, and the motor driver 41, There is a possibility that a circuit failure of 42 will be caused. As a countermeasure for avoiding this, a current limiting circuit can be provided, but a component for realizing the function is required separately, which increases the number of components and the mounting area on the board. In addition, when the current limiting function is provided by software, high-spec operation performance such as AD conversion at a predetermined timing of the ON time of the switching element is required. In addition, when the current is limited by the current limiting circuit or software, the responsiveness is reduced because the maximum torque is reduced.

Thus, in the present embodiment, by changing the duty limit value Dlim according to the encoder count value θen, the overcurrent is prevented without changing the circuit, sacrificing the response, and preventing the

motor drivers

41, 42. To protect.

デューティ The duty limit value calculation processing of the present embodiment will be described based on the flowchart of FIG. This process is executed by the duty limiting unit 55 at a predetermined cycle during range switching. Hereinafter, the “step” of step S101 will be omitted, and will be simply referred to as a symbol “S”. The other steps are the same.

Prior to the description of the duty limit value calculation processing, the drive count θA and the remaining count θB will be described. When the target shift range is switched, the encoder count value θen_init at the start of driving, which is the encoder count value before the driving of the motor 10 is started, is held in a storage unit (not shown). The absolute value of the difference between the current encoder count value θen and the encoder count value at the start of driving θen_init is defined as the drive count θA (see equation (1)).

ΘA = | θen-θen_init | (1)

(4) When the target shift range is switched, the target count value θcmd according to the target shift range is set. The absolute value of the difference between the target count value θcmd and the current encoder count value θen is defined as the remaining count θB (see Equation (2)).

ΘB = | θcmd-θen | (2)

In S101 in FIG. 5, the duty limiter 55 determines whether the drive count θA is smaller than one. When it is determined that the drive count θA is smaller than 1 (S101: YES), the process proceeds to S102, and the duty limit value Dlim is set to 50%. When it is determined that the drive count θA is 1 or more (S101: NO), the process proceeds to S103.

In S103, the duty limiter 55 determines whether the drive count θA is smaller than two. When it is determined that the drive count θA is smaller than 2 (S103: YES), the process proceeds to S104, and the duty limit value Dlim is set to 60%. When it is determined that the drive count θA is 2 or more (S103: NO), the process proceeds to S105.

In S105, the duty limiter 55 determines whether the drive count θA is smaller than three. When it is determined that the drive count θA is smaller than 3 (S105: YES), the process proceeds to S106, and the duty limit value Dlim is set to 70%. When it is determined that the drive count θA is 3 or more (S105: NO), the process proceeds to S107.

In S107, the duty limiter 55 determines whether the drive count θA is smaller than four. If it is determined that the drive count θA is smaller than 4 (S107: YES), the flow shifts to S108 to set the duty limit value Dlim to 80%. When it is determined that the drive count θA is 4 or more (S107: NO), the process proceeds to S109.

In S109, the duty limiter 55 determines whether the drive count θA is smaller than 5. If it is determined that the drive count θA is smaller than 5 (S109: YES), the flow shifts to S110 to set the duty limit value Dlim to 90%. When it is determined that the drive count θA is 5 or more (S109: NO), the process proceeds to S111.

In S111, the duty limiter 55 determines whether the remaining count θB is smaller than two. If it is determined that the remaining count θB is smaller than 2 (S111: YES), the flow shifts to S112 to set the duty limit value Dlim to 50%. When it is determined that the remaining count θB is 2 or more (S111: NO), the process proceeds to S113.

In S113, the duty limiter 55 determines whether the remaining count θB is smaller than three. When it is determined that the remaining count θB is smaller than 3 (S113: YES), the process proceeds to S114, and the duty limit value Dlim is set to 60%. When it is determined that the remaining count θB is 3 or more (S113: NO), the process proceeds to S115.

In S115, the duty limiter 55 determines whether the remaining count θB is smaller than four. If it is determined that the remaining count θB is smaller than 4 (S115: YES), the flow shifts to S116 to set the duty limit value Dlim to 70%. When it is determined that the remaining count θB is 4 or more (S115: NO), the process proceeds to S117.

In S117, the duty limiter 55 determines whether the remaining count θB is smaller than 5. If it is determined that the remaining count θB is smaller than 5 (S117: YES), the flow shifts to S118, where the duty limit value Dlim is set to 80%. If it is determined that the remaining count θB is 4 or more (S117: NO), that is, if the drive count θA is 5 or more and the remaining count θB is 5 or more, the duty control is not performed, and this processing is performed. finish.

In FIG. 5, the duty limit value Dlim at the beginning of driving is set to 50%, and the duty limit value Dlim is increased by 10% each time the encoder count value θen changes by one count. The restriction has been removed. Further, the duty limit value Dlim when the remaining 4 counts are reached up to the target count value θcmd is set to 80%, and the duty limit value Dlim is reduced by 10% every time the encoder count value θen changes by one count, until the target count value θcmd. The duty limit value Dlim for the remaining one count is set to 50%. The duty limit value Dlim and the count width for switching the duty limit value Dlim shown in FIG. 5 are merely examples, and can be arbitrarily set.

駆動 The drive control processing of the present embodiment is shown in the time chart of FIG. In FIG. 6, the horizontal axis is a common time axis, and the shift range switching request, angle, duty, rotation speed, and motor current are shown from the top. As for the angle, the encoder count value θen is indicated by a solid line, and the target count value θcmd is indicated by a chain line. The encoder count value corresponding to the P range is described as (P), and the angle corresponding to the notP range is described as (notP). In the present embodiment, the actual duty D is indicated by a solid line, the duty limit value Dlim is indicated by a two-dot chain line, and acceleration is defined as positive and deceleration is defined as negative. In other words, even if the sign is different, if the absolute value is the same, the ratio of the ON time in the predetermined period is the same, and the duty limit value Dlim is set to a value on both the positive and negative sides having the same absolute value. Here, a case where the range is switched from the P range to the notP range will be described as an example. 7, 9, and 10 are the same.

As shown in FIG. 6, when the required shift range is switched from the P range to the notP range at time t10, the switching request is turned on. Further, the control mode is switched from the standby mode to the feedback mode, and the target count value θcmd is set. In the present embodiment, an acceleration range is from time t10 to time t12, a constant speed range is from time t12 to time t13, and a deceleration range is from time t13 to time t15. At time t15, when the encoder count value θen falls within a predetermined range including the target count value θcmd (for example, ± 2 counts), the mode is switched from the feedback mode to the stop mode. In the stop control, the motor 10 is reliably stopped by performing fixed-phase energization at a predetermined duty. The stop control is not limited to the stationary phase energization, and may be any control. After performing the stop control for a predetermined time, the mode is switched to the standby mode at time t16.

Here, as in the reference example shown in FIG. 7, when the motor 10 is driven at a duty of 100% without performing the duty limitation at the time of the low-speed rotation immediately after the start of the driving, for example, from the time tx1 to the time tx2, the upper limit value is set. A motor current Im exceeding Ilim flows. In addition, even during deceleration, if the motor 10 is driven with, for example, a duty of −100% without performing duty limitation, a current exceeding the upper limit Ilim flows during a period from time ty1 to time ty2.

When the shift range is switched, the driving of the motor 10 is started in response to the switching request, and the motor 10 is stopped at the target count value θcmd corresponding to the target shift range. Therefore, when the drive count θA and the remaining count θB are small, the motor 10 is rotating at a low speed, and the motor current Im may be large. Therefore, the duty limit value Dlim is set small. Thereby, the

motor drivers

41 and 42 can be protected. On the other hand, when the drive count θA and the remaining count θB are large, the motor 10 is rotating at a high speed of a certain degree or more and the motor current Im is small, so that the duty is not limited. Thereby, responsiveness can be secured without suppressing torque.

Specifically, as shown in FIG. 6, at time t10, since the drive count θA = 0, the duty limit value Dlim is set to 50%. Further, since the rotation speed of the motor 10 increases each time the drive count θA increases by one count, the duty limit value Dlim is gradually increased to 60%, 70%, 80%, and 90%. At time t11, when the drive count θA becomes 5 or more, the duty limit value Dlim is set to 100%, and the duty limit is released. Until the remaining count θB becomes 5, the state where the duty limitation is not performed is continued.

(4) At time t14, when the remaining count θB becomes 4, the duty limit value Dlim is set to 80%. Further, the rotational speed of the motor 10 decreases every time the remaining count θB decreases by one count, so the duty limit value Dlim is reduced to 70%, 60%, and 50%. As a result, the motor current Im from the start to the completion of the shift range switching can be suppressed to less than the upper limit Ilim.

As described above, the shift range control device 40 of the present embodiment controls the switching of the shift range by controlling the drive of the motor 10 having the motor windings 11 and 12, and includes a

motor driver

41, 42 and an ECU 50. The

motor drivers

41 and 42 have switching elements 411 to 416 and 421 to 426 for switching energization of the motor windings 11 and 12.

The ECU 50 includes a motor angle calculator 51, a drive controller 53, and a duty limiter 55. The motor angle calculator 51 calculates an encoder count value θen based on an encoder signal obtained from the encoder 13 that detects the rotational position of the motor 10. The drive control unit 53 controls the drive of the motor 10 so that the encoder count value θen becomes the target count value θcmd corresponding to the target shift range. The duty limiter 55 determines a duty limit value Dlim that limits a duty D, which is a ratio of the ON time of the switching elements 411 to 416 and 421 to 426 during a predetermined period, according to the encoder count value θen.

In the present embodiment, by changing the duty limit value Dlim based on the encoder count value θen, which is information that can be easily monitored, the

motor drivers

41 and 42 can be configured to suppress overcurrent without changing the circuit or the like. Can be protected, and range switching responsiveness can be ensured.

The duty limiter 55 increases the duty limit value Dlim as the drive count θA, which is the difference between the encoder count value θen_init at the start of driving the motor 10 and the current encoder count value θen, increases during motor acceleration. Then, the duty limit value Dlim is determined. Thus, an overcurrent at the time of low-speed rotation at the time of starting the motor can be prevented.

The duty limiter 55 determines the duty limit value Dlim such that the smaller the remaining count θBg, which is the difference between the target count value θcmd and the current encoder count value θen, during motor deceleration, the smaller the duty limit value Dlim. I do. This can prevent an overcurrent at the time of low-speed rotation before the motor stops.

In the present embodiment, the

motor drivers

41 and 42 correspond to a “drive circuit”, the ECU 50 corresponds to a “control unit”, and the encoder 13 corresponds to a “rotation angle sensor”. The encoder count value θen corresponds to “motor angle”, and the target count value θcmd corresponds to “target rotation angle”.

(2nd Embodiment)
A second embodiment is shown in FIGS. In the present embodiment, overcurrent due to the lock current is prevented by limiting the duty according to the encoder count value θen. The duty limit value calculation processing of the present embodiment will be described with reference to the flowchart of FIG. This process is executed at a predetermined cycle during a period from when the target shift range is switched to when the stop control is started, and can be performed in parallel with the duty limit value calculation process described with reference to FIG. is there.

In S201, the duty limiter 55 determines whether or not the encoder count value θen has changed. If it is determined that the encoder count value θen has changed (S201: YES), the process proceeds to S202, where the continuation count value Ct is cleared, and this routine ends. When it is determined that the encoder count value θen has not changed (S201: NO), the process proceeds to S203. In S203, the duty limiter 55 increments the continuous count value Ct that measures the time during which the encoder count value θen has not been switched.

In S204, the duty limiter 55 calculates the estimated rotation speed Ne. The estimated rotation speed Ne is a value when the motor 10 is rotating normally, and is calculated by a map calculation or the like based on the drive count θA.

In S205, the continuation determination time T_th is set based on the estimated rotation speed Ne. The continuation determination time T_th is set to a value equal to or longer than the same energized phase continuation time Te, which is the time during which the same energized phase is continued when the motor 10 is rotating at the estimated rotational speed Ne. Further, a count value corresponding to the continuation determination time T_th is defined as a determination count value Ct_th.

In S206, it is determined whether the continuation count value Ct is equal to or greater than the determination count value Ct_th. When it is determined that the continuation count value Ct is less than the determination count value Ct_th (S206: NO), the process of S207 is not performed, and the routine ends. When it is determined that the continuation count value Ct is equal to or greater than the determination count value Ct_th (S206: YES), the process proceeds to S207, and the duty limit value Dlim is set to 50%. The duty limit value Dlim set here is an arbitrary value at which the motor current Im does not exceed the upper limit value Ilim when the lock is energized and the energized phase can be switched in a normal state.

FIG. 10 shows a drive control process according to the reference example. The processing from time t10 to time t11 is the same as in the first embodiment. At time t11, the duty limit is released, and thereafter, the duty limit value Dlim becomes 100%. In a normal state, if the energized phases are sequentially switched, the current becomes small (see FIG. 6). On the other hand, at time tz1, which is a timing before time t12, which is a constant speed range in a normal state, when an abnormality occurs in which the motor 10 stops, if the lock current is supplied to the same energizing phase, the motor current larger than the upper limit Ilim Im may flow. If the motor current Im whose duty is not limited continues to flow, there is a possibility that the circuit of the

motor drivers

41 and 42 may fail until the abnormality is determined.

Therefore, in the present embodiment, as shown in FIG. 9, the estimated rotational speed Ne is calculated based on the drive count θA. Then, the same energized phase continuation time Te when the motor 10 is rotating at the estimated rotation speed Ne is determined (S204 in FIG. 8), and the continuation determination time T_th is set (S205). For example, when the estimated rotational speed Ne is 4000 [rpm] and the calculation is such that the energized phase is switched at 0.625 [ms], the continuation determination time T_th is set to 1 [ms]. Then, the duty limit value Dlim is set to 50% at a time tz2 when the continuation determination time T_th has elapsed from the time tz1 at which the abnormality in which the motor 10 stops occurs (S207). Further, at time tz3 when a predetermined time has elapsed from the occurrence of the abnormality, the abnormality is determined and the mode shifts to the fail mode.

As a result, even if an abnormality in which the motor 10 stops occurs, the motor current Im exceeding the upper limit Ilim does not flow before the abnormality is determined, so that the circuit failure of the

motor drivers

41 and 42 can be prevented. .

In the present embodiment, when the state where the encoder count value θen does not change continues for the continuation determination time T_th during the drive control of the motor 10, the duty limit unit 55 sets the duty limit value Dlim to be smaller than normal. . This suppresses an overcurrent in the event of a failure in which the motor 10 stops, so that the

motor drivers

41 and 42 can be protected.

The continuation determination time T_th is set according to the estimated rotation speed Ne estimated based on the drive count θA, which is the difference between the encoder count value θen_init at the start of motor driving and the current encoder count value θen. Accordingly, when a failure that stops the motor 10 occurs, the duty can be appropriately limited. Further, the same effects as those of the above embodiment can be obtained.

(Other embodiments)
In the first embodiment, the duty is limited according to the drive count θA and the remaining count θB. In another embodiment, for example, when the motor current does not exceed the upper limit value without performing the duty limitation in the deceleration range, the duty limitation during the motor deceleration according to the remaining count θB may be omitted. In the above-described embodiment, (i) the duty limit during acceleration, (ii) the duty limit during deceleration, and (iii) the duty limit when a failure that stops the motor occurs. In other embodiments, some of the above (i) to (iii) may be omitted. In the second embodiment, the continuation determination time is made variable according to the drive count. In another embodiment, the continuation determination time may be fixed without depending on the drive count.

In the above embodiment, two sets of motor windings and motor drivers are provided. In other embodiments, there may be one set of motor windings and motor drivers, or three or more sets.

In the above embodiment, the motor rotation angle sensor that detects the rotation angle of the motor is a three-phase encoder. In another embodiment, the motor rotation angle sensor may be a two-phase encoder, and is not limited to an encoder, but may be any type such as a resolver. In the above embodiment, a potentiometer has been exemplified as the output shaft sensor. In other embodiments, the output shaft sensor may be any. Further, the output shaft sensor may be omitted.

では In the above embodiment, the detent plate is provided with two concave portions. In another embodiment, 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, the parking lock mechanism, and the like may be different from those in the above embodiment.

では In the above embodiment, the speed reducer is provided between the motor shaft and the output shaft. Although the details of the reduction gear are not mentioned in the above embodiment, for example, a cycloid gear, a planetary gear, a gear using a spur gear that transmits torque from a reduction mechanism substantially coaxial with the motor shaft to the drive shaft, 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. As described above, the present disclosure is not limited to the above embodiments, and can be implemented in various forms without departing from the gist of the present disclosure.

The control unit and the technique according to the present disclosure are implemented by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. May be done. Alternatively, the control unit and the technique described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method according to the present disclosure may be implemented by a combination of a processor and a memory programmed to perform one or more functions and a processor configured by 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 instructions to be executed by a computer.

The present disclosure has been described based on the embodiments. However, the present disclosure is not limited to the embodiment and the structure. The present disclosure also encompasses various modifications and variations within equivalent scope. In addition, various combinations and forms, and other combinations and forms including only one element, more or less, are also included in the scope and spirit of the present disclosure.

Claims

A shift range control device that controls switching of a shift range by controlling driving of a motor (10) having motor windings (11, 12),
Drive circuits (41, 42) having switching elements (411 to 416, 421 to 426) for switching energization of the motor windings;
A motor angle calculator (51) for calculating a motor angle based on a signal obtained from a rotation angle sensor (13) for detecting a rotation position of the motor, wherein the motor angle becomes a target rotation angle corresponding to a target shift range; A drive control unit (53) for controlling the driving of the motor, and a duty for determining a duty limit value for limiting a duty, which is a ratio of the ON time of the switching element in a predetermined period, according to the motor angle. A control unit (50) having a restriction unit (55);
A shift range control device comprising:
The duty limiter determines the duty limit value such that the larger the difference between the motor angle at the start of driving the motor and the current motor angle is, the larger the duty limit value becomes during motor acceleration. The shift range control device according to claim 1.
3. The motor according to claim 1, wherein the duty limiter determines the duty limit value such that the smaller the difference between the target rotation angle and the current motor angle is, the smaller the duty limit value becomes when the motor is decelerated. The shift range control device as described in the above.
2. The shift according to claim 1, wherein the duty limit unit sets the duty limit value to be smaller than a normal state when a state in which the motor angle does not change continues for a continuation determination time during drive control of the motor. Range control device.
5. The shift range control device according to claim 4, wherein the continuation determination time is set according to an estimated rotation speed estimated based on a difference between the motor angle at the start of driving of the motor and the current motor angle. 6. .