WO2024080244A1

WO2024080244A1 - Motor control device

Info

Publication number: WO2024080244A1
Application number: PCT/JP2023/036572
Authority: WO
Inventors: 大祐山本; 純山田; 健一大石
Original assignee: 株式会社デンソー
Priority date: 2022-10-12
Filing date: 2023-10-06
Publication date: 2024-04-18

Abstract

A motor control device (40) includes a drive circuit (41) and a control unit (50). The control unit (50) includes: a drive control unit (55) that controls driving of a motor (10) by feedback control based on the detected values from a rotational position sensor (13) that detects a rotation position of the motor (10); and an abnormality determination unit (52) that determines a disconnection failure. At the time of a one-phase disconnection, if an engaging member (26) is caused to move with, as a target valley portion, a valley portion (221, 224) adjacent to a wall portion (228, 229) in normal phase driving for driving the motor (10) using a normal phase, the drive control unit (55): performs feedback control such that the engaging member (26) is between the wall portion and mountain portions located on both sides of the target valley portion; and thereafter performs current limit switching control for applying a current limit to drive the motor (10) such that the engaging member (26) moves in the direction to the wall portion.

Description

Motor Control Device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on Patent Application No. 2022-163875, filed on October 12, 2022, the contents of which are incorporated herein by reference.

This disclosure relates to a motor control device.

　There are known motor control devices that control the drive of a motor. For example, in Patent Document 1, a disconnection detection circuit is provided in each current carrying line of the winding for each phase to detect disconnection.

JP 2004-129450 A

Even if one phase is broken, the motor can be driven if inertia can pass through the broken phase where the break occurs. However, when one phase is broken, there is greater variation in positioning compared to normal times. The purpose of this disclosure is to provide a motor control device that can appropriately switch the detent mechanism even when one phase is broken.

The motor control device disclosed herein controls the driving of a motor in a motor driving system that includes a motor having motor windings of three or more phases and a detent mechanism driven by the motor, and includes a driving circuit and a control unit. The driving circuit has switching elements that switch the supply of current to each phase of the motor winding. The control unit has a driving control unit that controls the driving of the motor by feedback control based on the detection value of a rotational position sensor that detects the rotational position of the motor, and an abnormality determination unit that determines a wire breakage fault.

The detent mechanism has a detent member in which multiple valleys separated by peaks are formed, an engagement member that can move in the valleys when driven by a motor, and a biasing member that biases the engagement member in a direction that fits into the valleys, and walls that regulate the drive of the engagement member are formed on both sides of the arranged valleys.

When the control unit moves the engaging member with a valley adjacent to the wall as the target valley in normal phase drive, which drives the motor using a normal phase when one phase is broken, it performs feedback control so that the engaging member is between the peaks on either side of the target valley and the wall, and then performs current limit switching control to drive the motor by limiting the current so that the engaging member moves in the direction of the wall. This makes it possible to switch the detent mechanism appropriately even when one phase is broken.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
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 an embodiment; FIG. 3 is a schematic diagram illustrating setting of a switching target value based on a wall reference position according to an embodiment; FIG. 4 is a schematic diagram illustrating setting of a switching target value based on a valley reference position according to an embodiment; FIG. 5 is a flowchart illustrating a range switching process according to an embodiment. FIG. 6 is a time chart illustrating a range switching process according to an embodiment. FIG. 7 is a time chart illustrating a range switching process according to an embodiment. FIG. 8 is a time chart illustrating a range switching process according to an embodiment. FIG. 9 is a time chart illustrating the range switching process according to one embodiment.

(One embodiment)
A motor control device according to the present disclosure will be described below with reference to the drawings. One embodiment is shown in Figures 1 to 9. As shown in Figures 1 and 2, a shift-by-wire system 1 includes a motor 10, a detent mechanism 20, a parking lock mechanism 30, and an ECU 40 as a motor control device.

The motor 10 rotates by receiving power from a battery installed in the vehicle (not shown) and functions as a drive source for the detent mechanism 20. The motor 10 in this embodiment is a switched reluctance motor, a three-phase motor having U-phase, V-phase, and W-phase motor windings wound around a stator (not shown).

As shown in FIG. 2, the encoder 13, which is a rotational position sensor, detects the rotational position of the rotor (not shown) of the motor 10. The encoder 13 is, for example, a magnetic rotary encoder, and is composed of a magnet that rotates together with the rotor, and a Hall IC for magnetic detection. The encoder 13 outputs an encoder signal, which is a pulse signal, for each specified angle in synchronization with the rotation of the rotor.

The 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 before outputting it to the output shaft 15. This allows the rotation of the motor 10 to be transmitted to the detent mechanism 20. An output shaft sensor 16 that detects the angle of the output shaft 15 is provided on the output shaft 15. The output shaft sensor 16 is, for example, a potentiometer.

As shown in FIG. 1, the detent mechanism 20 includes a detent plate 21, a detent spring 25, and a detent roller 26, and transmits the rotational driving force output from the reduction gear 14 to a manual valve 28 and a parking lock mechanism 30.

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. The pin 24 is connected to a manual valve 28. When the detent plate 21 is driven by the motor 10, the manual valve 28 moves back and forth in the axial direction. In other words, the detent mechanism 20 converts the rotational motion of the motor 10 into linear motion and transmits it to the manual valve 28. The manual valve 28 is provided in a valve body 29. When the manual valve 28 moves back and forth in the axial direction, the hydraulic supply path to the hydraulic clutch (not shown) is switched, and the engagement state of the hydraulic clutch is switched to change the shift range.

As shown in FIG. 3, four valleys 221-224 are formed on the detent spring 25 side of the detent plate 21, corresponding to the P (parking), R (reverse), N (neutral), and D (drive) ranges. A peak 225 is provided between the valley 221 corresponding to the P range and the valley 222 corresponding to the R range. A peak 226 is provided between the valley 222 corresponding to the R range and the valley 223 corresponding to the N range. A peak 227 is provided between the valley 223 corresponding to the N range and the valley 224 corresponding to the D range. A first wall 228 that limits the movement of the detent roller 26 is formed on the opposite side of the peak 225 of the valley 221 corresponding to the P range. A second wall 229 that limits the movement of the detent roller 26 is formed on the opposite side of the peak 227 of the valley 224 corresponding to the D range.

As shown in FIG. 1, the detent spring 25 is an elastically deformable plate-like member, and has a detent roller 26 at its tip. The detent spring 25 biases the detent roller 26 toward the center of rotation of the detent plate 21. When a rotational force of a predetermined magnitude or more is applied to the detent plate 21, the detent spring 25 elastically deforms, and the detent roller 26 moves between the valleys 221-224. When the detent roller 26 fits into one of the valleys 221-224, the oscillation 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 shift range of the automatic transmission 5 is fixed. The detent roller 26 fits into one of the valleys 221-224 that corresponds to the shift range.

In this embodiment, the location where the detent roller 26 fits into the bottom of the valleys 221 to 224 due to the spring force of the detent spring 25 according to the shift range is defined as the bottommost part of the valleys 221 to 224. The range in which the detent roller 26 can be dropped into the bottommost part of the valleys 221 to 224 by the spring force is defined as the suction range θs. The entire range on the

wall portions

228 and 229 side of the bottommost parts of the

valleys

221 and 224 is set to be included in the suction range θs.

The parking lock mechanism 30 has a parking rod 31, a cone 32, a parking lock pole 33, a shaft 34, and a parking gear 35. The parking rod 31 is formed in a roughly L-shape, and one end 311 is fixed to the detent plate 21. The other end 312 of the parking rod 31 is provided with a cone 32. The cone 32 is formed so that its diameter decreases as it approaches the other end 312.

The parking lock pole 33 abuts against the conical surface of the cone 32 and is arranged to be swingable around the shaft 34. A protrusion 331 capable of meshing with the parking gear 35 is provided on the parking lock pole 33's parking gear 35 side. When the cone 32 moves in the P direction due to the rotation of the detent plate 21, the parking lock pole 33 is pushed up and the protrusion 331 meshes with the parking gear 35. On the other hand, when the cone 32 moves in the NotP direction, the meshing between the protrusion 331 and the parking gear 35 is released.

The parking gear 35 is mounted on an axle (not shown) and is arranged so that it can mesh with the protrusion 331 of the parking lock pole 33. When the parking gear 35 meshes with the protrusion 331, the rotation of the axle is restricted. When the shift range is in a Not P range, which is a range other than the P range, 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. Also, when the shift range is in 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 FIG. 2, the ECU 40 includes a drive circuit 41 and a control unit 50. The drive circuit 41 has switching elements (not shown) that correspond to each phase of the motor winding. By switching the switching elements on and off, the current supply to the corresponding phase is switched.

The control unit 50 is mainly composed of a microcomputer and includes a CPU, ROM, RAM, I/O, and bus lines connecting these components (none of which are shown in the figure). Each process in the control unit 50 may be software processing in which the CPU executes a program pre-stored in a physical memory device (i.e., a readable non-transitory tangible recording medium) such as a ROM, or it may be hardware processing using a dedicated electronic circuit.

The control unit 50 controls the switching of the shift range by controlling the drive of the motor 10 based on a shift signal corresponding to the driver's requested shift range, a signal from the brake switch, the accelerator opening, the vehicle speed, etc. The control unit 50 also controls the switching of the connection and disconnection of the clutch 60 provided between the vehicle's drive source, such as the engine or main motor, and the axle.

The control unit 50 has, as functional blocks, a signal acquisition unit 51, an abnormality determination unit 52, a drive control unit 55, and the like. The signal acquisition unit 51 acquires detection signals from the encoder 13, the output shaft sensor 16, a current detection unit and a voltage detection unit (not shown), and the like. The abnormality determination unit 52 determines an abnormality in the shift-by-wire system 1, such as a disconnection abnormality. The drive control unit 55 controls the operation of the drive circuit 41, thereby controlling the drive of the motor 10. In this embodiment, the motor 10 is driven by switching the current phase of the motor winding through feedback control based on the encoder count value. Although one control unit 50 is shown in FIG. 1, some functions may be provided in an ECU different from the ECU 40.

FIG. 3 is a schematic diagram of the detent mechanism 20, with the direction of rotation of the motor 10 and output shaft 15 being the left-right direction on the page. In reality, the rotation of the detent plate 21 causes the detent roller 26 to move through the valleys 221-224, but FIG. 3 simply illustrates the movement of the detent roller 26.

The reducer 14 is provided between the motor shaft 105 and the output shaft 15, and there is "play" between the motor shaft 105 and the output shaft 15, including gear backlash. Hereinafter, the total play between the motor shaft 105 and the output shaft 15 is referred to as the play width θg. FIG. 3 conceptually illustrates the play, and describes the output shaft 15 and the reducer 14 as being integrated, and the motor shaft 105 as being able to move within the range of the play of the reducer 14, but it is also acceptable to configure the motor shaft 105 and the reducer 14 as being integrated, and for "play" to exist between the reducer 14 and the output shaft 15. The same applies to FIG. 4.

As shown in Fig. 3, under normal circumstances, the encoder count value when the detent roller 26 is in contact with the wall 228 is learned as the wall position reference value θr. When the shift range is switched, a switching target value θ ^* is set based on the learned wall position reference value θr and the wall valley angle θrb, and the driving of the motor 10 is controlled by feedback control based on the encoder count value. This makes it possible to accurately drop the detent roller 26 into the valley corresponding to the required shift range. Although Fig. 3 shows an example in which the wall 228 on the P range side is learned as the reference position, the wall 229 on the D range side may also be learned as the reference position.

For example, if a wire breakage occurs in the U-phase, no torque is generated in the region where only the U-phase is energized under normal circumstances, but the motor 10 can continue to be driven by passing through this region using inertia. In this embodiment, when one phase is broken, the shift range is switched by normal two-phase drive, which drives the motor 10 by energizing the two normal phases.

In normal two-phase driving, the torque varies widely, so when reference position learning is performed by hitting against a wall, the learned value varies widely. Therefore, if the switching target value θ ^* is set based on the reference position learned in normal two-phase driving and range switching is performed, the detent roller 26 may not fall into the suction range θs and may not fall into the valleys 221 to 224 corresponding to the required shift range.

As shown in FIG. 4, when one phase is disconnected, where accurate control based on the wall position reference value θr is difficult, wall position learning is omitted and control is performed based on the valley position reference. In detail, when one phase is disconnected, the vehicle start switch, such as an ignition switch, is turned on, and the encoder count value at the completion of the initial drive, which is a current application process for matching the relative positions of the rotor and encoder 13, is learned as the valley position reference value θb. If the shift range when the start switch is on is the P range, the valley position reference value θb is the value when the detent roller 26 is at the bottom of the valley portion 221.

The valley position reference value θb is an encoder count value when the motor shaft 105 is at any position within the backlash, and therefore the value varies by the backlash width θg. Therefore, when switching to the P range, the motor 10 is driven by feedback control with the valley position reference value θb as the switching target value θ ^* , and then current limiting switching control is performed to drive the motor 10 while limiting the current in the direction in which the detent roller 26 moves toward the wall portion 228 so that the detent roller 26 is reliably within the suction range θs. When switching to the D range, feedback control is performed by setting the switching target value θ ^* based on the valley position reference value θb and the angle between the

valley portions

221 and 224, and then current limiting switching control is performed to drive the motor 10 while limiting the current in the direction in which the detent roller 26 moves toward the wall portion 229.

The range switching process of this embodiment will be described with reference to the flowchart in FIG. 5. This process is executed at a predetermined cycle by the control unit 50. Hereinafter, the "step" such as step S101 will be omitted, and the steps will simply be referred to as "S".

In S101, the control unit 50 determines whether or not there is a request to switch the shift range. If it is determined that there is no request to switch the range (S101: NO), the process from S102 onwards is skipped and the standby mode continues. If it is determined that there is a request to switch the shift range (S101: YES), the process proceeds to S102.

In S102, the control unit 50 determines whether the three-phase current paths are normal. Abnormality determination is performed separately from this process. If it is determined that at least some of the current paths are abnormal (S102: NO), the process proceeds to S107. If it is determined that the three-phase current paths are normal (S102: YES), the process proceeds to S103.

In S103, the drive control unit 55 sets a switching target value θ ^* based on the wall position reference. For example, in the case of switching to the P range, the switching target value θ* is set to a value obtained by adding the wall-valley angle ^θrb to the learned wall position reference value θr, and based on the angle between the wall 228 and the valley corresponding to the required shift range.

In S104, the drive control unit 55 drives the motor 10 by feedback control based on the encoder count value. In this case, since the three phases are normal, the motor 10 is driven using the three phases.

In S105, the drive control unit 55 judges whether the rotational position of the motor 10 has reached the set switching target value θ ^* . Here, if the encoder count value is within a predetermined range including the set switching target value θ ^* , the drive control unit 55 judges YES. If it is judged that the rotational position of the motor 10 has not reached the switching target value θ ^* (S105: NO), the process returns to S104 and continues the feedback control. If it is judged that the rotational position of the motor 10 has reached the switching target value θ ^* (S105: YES), the process proceeds to S106, where a stop control is performed to stop the motor 10 by applying fixed phase current to two phases according to the encoder count value. Then, the process proceeds to S119.

If it is determined that at least some of the current paths are not normal (S102: NO), the control unit 50 proceeds to S107, where it determines whether the abnormality is a single-phase break. If it is determined that the abnormality is not a single-phase break (S107: NO), that is, if there are two or more broken phases or there is a short circuit abnormality other than a break, the range cannot be switched in normal two-phase drive, so the processing from S108 onwards is skipped. If it is determined that the abnormality is a single-phase break (S107: YES), it proceeds to S108.

In S108, the drive control unit 55 sets a switching target value θ ^* based on the valley position. For example, when switching to the P range, the learned valley position reference value θb is set as the switching target value θ ^* . When switching to a range other than the P range, the switching target value θ ^* is set based on the valley position reference value θb and the angle between the valley portion 221 and the valley portion corresponding to the requested shift range.

In S109, the drive control unit 55 performs pre-switching preparation processing. In normal two-phase driving, it is necessary to pass through the area corresponding to the broken phase with inertia. Therefore, the pre-switching preparation processing aligns the opposing positions of the stator and rotor so that range switching can be started from the opposing state where torque is generated.

In this embodiment, as pre-switching preparation processing, the energized phases are switched in the order of 1-phase energization → 2-phase energization → 1-phase energization. The first 1-phase energization is the phase that is energized before the broken phase, as viewed from the switching order of energized phases according to the direction of rotation. For example, in the case of a 1-2 phase excitation method in which the energization order when rotating the motor 10 forward under normal conditions is U phase → UV phase → V phase → VW phase → W phase → WU phase, during forward rotation with U phase disconnection, as pre-switching preparation processing, energization is performed in W phase → VW phase → V phase, and range switching begins from the so-called "1 phase 1 tooth" state in which the salient pole of the V phase faces the salient pole of the rotor.

In S110, the drive control unit 55 drives the motor 10 using a feedback control unit based on the encoder count value. In this case, because one phase is broken, the motor 10 is driven using the two normal phases.

The process of S111 is similar to the process of S105. If it is determined that the motor rotational position has not reached the switching target value θ ^* (S111: NO), the process returns to S110 and feedback control is continued. If it is determined that the switching target value θ ^* has been reached (S111: YES), the process proceeds to S112 and stop control is performed to stop the motor 10 by supplying fixed phase current to the two normal phases.

In S113, the control unit 50 determines whether or not the range is to be switched to the R range. If it is determined that the range is to be switched to the R range (S113: YES), the process proceeds to S119. If it is determined that the range is to be switched to a range other than the R range (S113: NO), the process proceeds to S114.

In S114, the control unit 50 determines whether or not there is a switch to the N range. If it is determined that there is a switch to the N range (S114: YES), the process proceeds to S115, where the clutch 60 is released, and the process proceeds to S119. The process of S115 may be omitted. If it is determined that there is no switch to the N range (S114: NO), that is, if there is a switch to the P range or D range, the process proceeds to S116. Note that a switch to the P range or D range is a switch to a range adjacent to the

walls

228, 229, and a switch to the R range or N range can be considered as a switch to an intermediate range that is not adjacent to the

walls

228, 229. In addition, the allocation of control based on the range determination may be performed before the start of driving the motor 10, for example, following S107.

The control unit 50 performs current limiting control in S116 and wall return control in S117. Details of the current limiting control and wall return control will be described later with reference to the time chart in FIG. 6. The process of S118 is the same as the process of S112. In S119, the range switching is completed and the system transitions to standby mode.

The range switching process of this embodiment will be explained based on the time charts in Figures 6 to 9. In Figure 6, the horizontal axis represents a common time axis, and from the top, motor control, one-phase open circuit state, shift request, and motor rotation angle are shown. The motor rotation angle is a value that can be converted from the encoder count value, and when the detent roller 26 is at the bottom of the valley portion 224, it is called a "D valley", when it is at the bottom of the valley portion 221, it is called a "P valley", and when it is in contact with the wall portion 228 without any bending, it is called a "P wall". The same is true for Figures 7 and 8.

6 shows an example of switching from the D range to the P range when the three phases are normal. When the three phases are confirmed to be normal at time x10 and a request to shift to the P range is acquired at time x11, the switching target value θ ^* is set based on the learned wall position reference value θr and wall valley angle θrb. The drive control unit 55 drives the motor 10 by feedback control so that the encoder count value becomes the switching target value θ ^* .

When the encoder count value reaches the switching target value θ ^* at time x12, stop control is performed, and at time x13 when the stop control time has elapsed, power supply to the motor 10 is turned off and the mode transitions to the standby mode.

Since the positioning accuracy θa is smaller than the suction range θs when the three phases are normal, the switching target value θ ^* may be set so that the positioning accuracy θa falls within the suction range θs, and for example, the median value of the suction range θs may be set as the switching target value θ ^* . This allows the detent roller 26 to reliably fall into the valley corresponding to the required range.

Figure 7 shows an example of switching from D range to P range when one phase is broken. In Figure 7 and other figures, the area around the P valley is enlarged to explain current limit switching, and the ratio of the PD angle to the P valley wall angle, for example, differs from the actual ratio.

When a one-phase break occurs at time x20, the one-phase break is confirmed at time x21, and a range switch request is obtained at time x22, pre-switch preparation processing for normal two-phase drive is performed. In the example of FIG. 7, the range is switched from D range to P range, and the motor 10 is driven in the reverse direction. If there is a U-phase break, current is applied from V phase to VW phase to W phase as pre-switch preparation processing, resulting in a one-phase, one-tooth state with the W phase facing each other.

At time x23, when the pre-switching preparation process is completed, the valley position reference value θb is set as the switching target value θ ^* , and the motor 10 is driven by feedback control using the normal two phases. At time x24, when the encoder count value reaches the switching target value θ ^* , stop control is performed.

In normal two-phase drive when one phase is broken, the positioning accuracy θa is smaller than the range θrt between the wall portion 228 and the peak 225 of the mountain portion, but is larger than the suction range θs. In other words, θs<θa<θrt. If the stopping position at the end of feedback control is outside the suction range θs, the detent roller 26 cannot drop into the valley portion according to the required range.

In this embodiment, when the requested range is the P range or D range, which is the range adjacent to the

walls

228, 229, after feedback control ends, current limit switching control is performed to place the detent roller 26 in the suction range θs.

In the current limit switching control when switching to the P range, the switching target value θ ^* is set to an arbitrary value that is sufficiently behind the wall portion 228 even when taking into account the maximum amount of deflection θd of the wall portion 228, and the motor 10 is driven so that the detent roller 26 moves toward the wall portion 228. In the current limit switching control, the motor 10 is driven at an arbitrary current limit value that takes into consideration responsiveness and the like so that the current limit value is larger than the driven torque of the motor 10. The current limit value in the current limit switching control is set so that the torque is smaller than the wall contact limit value during wall position reference value learning that is set depending on, for example, the durability of the detent mechanism.

In normal two-phase drive, the range of positioning accuracy θa is relatively wide. Therefore, if current limiting switching control is performed in a state where the detent roller 26 has moved from the bottom of the valley portion 221 to the wall portion 228 side by feedback control, there is a possibility that the detent roller 26 may have pushed the wall portion 228 further back than its original position due to the deflection of the detent mechanism 20.

At time x26 when the current limit switching time has elapsed, the wall portion 228 is pushed toward the rear by the detent roller 26. If the power supply to the motor 10 is turned off in this state, the detent mechanism 20 will return to its original bending, and there is a risk that the detent roller 26 will exceed the suction range θs and be pushed back to the peak portion 225 side.

Therefore, after the current limit switching control, wall return control is performed to return the maximum amount of deflection θd of the detent mechanism 20. If the deflection has been returned to eliminate the deflection of the detent mechanism 20, the detent roller 26 will be dropped to the bottom of the valley portion 221 by the spring force of the detent spring 25 and will not exceed the suction range θs, so there is no need to return the detent roller 26 to the bottom of the valley portion 221 by wall return control.

At time x27 when the wall return control is completed, stop control is performed to energize normal two-phase current. At time x28, the current to the motor 10 is turned off and the system transitions to standby mode. When the current to the motor 10 is turned off, the detent roller 26 is dropped into the valley portion 221 by the spring force of the detent spring 25.

In FIG. 7, the detent roller 26 is driven by the current limit switching control to a position where it bends the wall portion 228, but the purpose of the current limit switching control is not to bring the detent roller 26 into contact with the wall portion 228, but to bring it into the suction range θs. Therefore, as shown in FIG. 8, depending on the current limit switching control time and the output torque of the current limit switching control, it is not a problem if the detent roller 26 does not reach the wall portion 228.

The control from time x30 to time x38 in FIG. 8 corresponds to the control from time x20 to time x28 in FIG. 7. If the detent roller 26 has not reached the wall 228, the return amount in the wall return control may be the maximum deflection amount θd, as in FIG. 7, or the backlash width θg. Also, in the example in FIG. 8, the detent roller 26 moves to the bottom of the valley 221 in the wall return control, but the behavior when the power supply to the motor 10 is turned off at time x38 is a matter of chance depending on the stopping position of the detent roller 26. In other words, if the position of the detent roller 26 at the end of the wall return control is deviated from the bottom of the valley 221, the detent roller 26 moves to the valley 221 due to the spring force of the detent spring 25 when the power supply to the motor 10 is turned off.

FIG. 9 shows an example of switching from D range to N range when one phase is broken. In FIG. 9, the horizontal axis represents a common time axis, and from the top, motor control, one phase broken state, shift request, clutch 60 state, and motor rotation angle are shown. The motor rotation angle when the detent roller 26 is at the bottom of the valley portion 223 is defined as "N valley." The processing from time x40 to time x43 is the same as the processing from time x20 to time x23 in FIG. 2, except that the requested range is N range.

At time x43, when the pre-switching preparation process is completed, a switching target value θ ^* is set based on the valley position reference value θb, and the motor 10 is driven by feedback control using the two normal phases. The switching target value θ ^* is set, in detail, based on the valley position reference value θb and the angle between the

valleys

221 and 223.

At time x44, when the encoder count value reaches the switching target value θ ^* , stop control is performed. Here, the suction range θs_N of the N range is relatively small, and the positioning accuracy θa_N is larger than the suction range θs_N. In addition, since the N range is an intermediate range that is not adjacent to the

walls

228, 229, it is not possible to perform current limiting switching control that moves the detent roller 26 toward the wall side as in the case of switching to the P range or D range. Therefore, if the position of the detent roller 26 at the end of the feedback control is outside the suction range θs_N of the N range, there is a risk that the automatic transmission 5 cannot be correctly put into the neutral state.

In this embodiment, when the shift range is switched to N range by normal two-phase drive in the event of one-phase disconnection, torque is cut on the automatic transmission 5 side at time x44 when feedback control ends. Specifically, the clutch 60 is released so that power is not transmitted to the axle side. At time x45, power to the motor 10 is turned off and the system transitions to standby mode.

As described above, in a shift-by-wire system 1 that includes a motor 10 having motor windings with three or more phases and a detent mechanism 20 driven by the motor 10, the ECU 40 controls the driving of the motor 10. The ECU 40 includes a drive circuit 41 and a control unit 50.

The drive circuit 41 has a switching element that switches the current supply to each phase of the motor winding. The control unit 50 has a drive control unit 55 that controls the drive of the motor 10 by feedback control based on the detection value of the encoder 13 that detects the rotational position of the motor 10, and an abnormality determination unit 52 that determines whether there is a wire breakage. Here, an "open circuit fault" is a fault that prevents current from being supplied to each phase coil of the motor winding, and includes not only a wire breakage in the motor winding itself, but also a wire breakage in the harness and a switching element stuck off.

The detent mechanism 20 has a detent plate 21 on which multiple valleys 221-224 are formed and separated by peaks 225-227, a detent roller 26 that can move between the valleys 221-224 when driven by the motor 10, and a detent spring 25 that urges the detent roller 26 in the direction of fitting into the valleys 221-224.

Walls

228, 229 that regulate the drive of the detent roller 26 are formed on both sides of the arranged valleys 221-224.

When the drive control unit 55 is in normal phase drive, which drives the motor 10 using a normal phase during one-phase disconnection, and moves the detent roller 26 with the

valleys

221, 224 adjacent to the

walls

228, 229 as the target valleys, it performs feedback control so that the detent roller 26 is between the peaks on either side of the target valley and the wall, and then performs current limiting switching control to drive the motor 10 with current limiting so that the detent roller 26 moves toward the wall. When the target valley is the valley 221, it performs feedback control so that the detent roller 26 is between the peaks 225 on either side of the valley 221 and the wall 228, and then performs current limiting switching control so that the detent roller 26 moves toward the wall 228.

In the case of normal phase drive with one broken phase, the positioning variation is larger than when all phases are normal, so even if the encoder count value is controlled to be the switching target value θ ^* , there is a risk that it will fall outside the suction range θs. Therefore, in this embodiment, during normal phase drive with one broken phase, feedback control is followed by current limit switching control, so that the detent roller 26 can be reliably controlled to be within the suction range θs. This makes it possible to appropriately switch the detent mechanism 20 even when one phase is broken.

When all phases are normal, the switching target value θ ^* in the feedback control is set based on the wall position reference value θr learned in response to the detection value of the encoder 13 when the detent roller 26 is in contact with the wall portion 228. On the other hand, when normal phase drive is performed with one phase disconnection, the switching target value θ ^* is set based on the valley position reference value θb learned in response to the detection value of the encoder 13 when the detent roller 26 is at the bottom of the valley portion 221. That is, in this embodiment, the method of setting the switching target value θ ^* in the feedback control is different between when all phases are normal and when one phase is disconnected.

As described above, in normal phase driving when one phase is broken, the positioning variation is large, so even if the switching target value θ ^* is set based on the wall position reference value θr, the detent roller 26 may deviate from the suction range θs. Also, the variation of the learned wall position reference value θr is larger than in normal times. Therefore, in normal phase driving, the switching target value θ ^* is set without using the wall position reference value θr. This makes it possible to omit wall position learning when one phase is broken.

The motor drive system is a shift-by-wire system 1. When switching the shift range to N range in the event of one-phase disconnection, the control unit 50 performs feedback control with normal phase drive so that the detent roller 26 moves to the valley 223 corresponding to the N range, and then releases the clutch 60 provided between the vehicle's drive source, such as an engine or main motor, and the axle. This makes it possible to cut torque on the automatic transmission 5 side, allowing appropriate neutral control to be performed.

In this embodiment, the shift-by-wire system 1 corresponds to the "motor drive system," the encoder 13 corresponds to the "rotational position sensor," the detent plate 21 corresponds to the "detent member," the detent spring 25 corresponds to the "biasing member," the detent roller 26 corresponds to the "engagement member," and the ECU 40 corresponds to the "motor control device."

Other Embodiments
In the above embodiment, the rotation detection unit is an encoder. In other embodiments, a sensor capable of detecting a rotation position other than an encoder, such as a resolver, may be used. In the above embodiment, the motor is a switched reluctance motor. In other embodiments, the motor may be one other than a switched reluctance motor, such as a DC brushless motor. The number of phases of the motor windings may be four or more.

In the above embodiment, four valleys are provided on the detent plate. In other embodiments, the number of valleys is not limited to four, and for example, two valleys corresponding to the P range and the notP range may be formed. In this case, current limit switching control can be performed regardless of the required range.

The control unit and the method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method 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 described in the present disclosure may be realized by one or more dedicated computers configured by combining a processor and a memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. In addition, the computer program may be stored in a computer-readable non-transient tangible recording medium as instructions to be executed by a computer. As described above, the present disclosure is not limited to the above embodiments, and can be implemented in various forms within the scope of its spirit.

This disclosure has been described with reference to an embodiment. However, this disclosure is not limited to the embodiment and structure. This disclosure also encompasses various modifications and modifications within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one, or less than one, are within the scope and spirit of this disclosure.

Claims

A motor control device for controlling driving of a motor in a motor drive system (1) including a motor (10) having motor windings of three or more phases and a detent mechanism (20) driven by the motor, comprising:
A drive circuit (41) having a switching element for switching the energization of each phase of the motor winding;
a control unit (50) having a drive control unit (55) that controls the drive of the motor by feedback control based on a detection value of a rotational position sensor (13) that detects the rotational position of the motor, and an abnormality determination unit (52) that determines a wire breakage fault;
Equipped with
The detent mechanism includes a detent member (21) in which a plurality of valleys (221-224) separated by peaks (225-227) are formed, an engagement member (26) that is movable in the valleys by driving the motor, and a biasing member (25) that biases the engagement member in a direction in which the engagement member fits into the valleys, and wall portions (228, 229) that regulate the drive of the engagement member are formed on both sides of the arranged valleys.
The drive control unit is
When one phase is broken, in normal phase drive in which the motor is driven using a normal phase, and the engaging member is moved with the valley portion (221, 224) adjacent to the wall portion as the target valley portion, feedback control is performed so that the engaging member is between the peak portions on either side of the target valley portion and the wall portion, and then current limiting switching control is performed to drive the motor by applying current limiting so that the engaging member moves in the direction of the wall portion.
when all phases are normal, a switching target value in the feedback control is set based on a wall position reference value learned in response to a detection value of the rotational position sensor when the engagement member is in contact with the wall portion,
2. The motor control device according to claim 1, wherein, when the normal phase drive is performed, the switching target value is set based on a valley position reference value that is learned in response to a detection value of the rotational position sensor when the engagement member is at the bottom of the valley portion.
The motor drive system is a shift-by-wire system,
3. The motor control device according to claim 1, wherein when the shift range is switched to N range in the event of one phase disconnection, the control unit performs feedback control using the normal phase drive so that the engagement member moves to the valley portion corresponding to the N range, and then releases a clutch provided between a drive source and an axle of the vehicle.