Motor control device

Abstract

To provide a motor controller capable of appropriately switching a detent mechanism even when one phase is disconnected.SOLUTION: An ECU 40 comprises a driving circuit 41 and a control unit 50. The control unit 50 has: a drive control unit 55 for controlling driving of a motor 10 by feedback control on the basis of a detected value of an encoder 13 that detects a rotation position of the motor 10; and an abnormality determination unit 52 for determining a disconnection failure. In the case of one-phase disconnection, when the drive control unit 55 moves a detent roller 26 with valley portions 221 and 224 as target valley portions, valley portions being adjacent to wall portions 228 and 229, respectively, by means of normal-phase driving that drives the motor 10 using normal phases, the drive control unit performs a feedback control so that the detent roller 26 is located between a mountain portion and a wall portion on both sides of the respective target valley portions. Thereafter, the drive control unit performs a current limit switching control that sets up a current limit and drives the motor 10 so that the detent roller 26 moves toward the wall portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, motor control devices that control the driving of a motor are known. For example, in Patent Document 1, a disconnection detection circuit is provided in each current-carrying line of a winding for each phase to detect disconnection. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-129450 Summary of the Invention [Problem to be solved by the invention]

[0004] Even if one phase is broken, the motor can still be driven if the inertia can pass through the broken phase. However, when one phase is broken, the positioning variation becomes larger compared to normal operation.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a motor control device that can appropriately switch a detent mechanism even when one phase is broken. [Means for solving the problem]

[0006] The motor control device of the present invention controls the driving of a motor in a motor drive system including a motor (10) having motor windings of three or more phases and a detent mechanism (20) driven by the motor, and includes a drive circuit (41) and a control unit (50). The drive circuit has switching elements that switch the supply of current to each phase of the motor winding. The control unit has a drive control unit (55) that controls the driving 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.

[0007] The detent mechanism has a detent member (21) having a plurality of valleys (221-224) separated by peaks (225-227), an engaging member (26) that can move in the valleys by driving a motor, and a biasing member (25) that biases the engaging member in a direction that fits into the valleys, and wall portions (228, 229) that regulate the driving of the engaging member are formed on both sides of the arranged valleys.

[0008] When one phase is disconnected, 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, the control unit performs feedback control so that the engaging member is positioned between the crest portions on both sides of the target valley portion and the wall portion, and then: A value that is sufficiently farther from the wall portion even when taking into account the maximum amount of deflection of the detent mechanism is set as the target value of the rotation position, Current limit switching control is performed to limit the current and drive the motor so that the engaging member moves toward the wall, making it possible to switch the detent mechanism appropriately even in the event of one phase disconnection. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view illustrating a shift-by-wire system according to an embodiment. [Figure 2] 1 is a schematic configuration diagram illustrating a shift-by-wire system according to an embodiment. [Figure 3] 10A and 10B are schematic diagrams illustrating setting of a switching target value based on a wall reference position according to an embodiment. [Figure 4]FIG. 10 is a schematic diagram illustrating setting of a switching target value based on a valley reference position according to an embodiment. [Figure 5] 10 is a flowchart illustrating a range switching process according to an embodiment. [Figure 6] 4 is a time chart illustrating a range switching process according to an embodiment. [Figure 7] 4 is a time chart illustrating a range switching process according to an embodiment. [Figure 8] 4 is a time chart illustrating a range switching process according to an embodiment. [Figure 9] 4 is a time chart illustrating a range switching process according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (One embodiment) A motor control device according to the present invention will now be described 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.

[0011] The motor 10 rotates when supplied with power from a battery installed in the vehicle (not shown), and functions as a drive source for the detent mechanism 20. The motor 10 of this embodiment is a switched reluctance motor, and is a three-phase motor having U-phase, V-phase, and W-phase motor windings wound around a stator (not shown).

[0012] 2, encoder 13, which is a rotational position sensor, detects the rotational position of a rotor (not shown) of motor 10. Encoder 13 is, for example, a magnetic rotary encoder, and is composed of a magnet that rotates integrally with the rotor and a Hall IC for magnetic detection. Encoder 13 outputs an encoder signal, which is a pulse signal, for each predetermined angle in synchronization with the rotation of the rotor.

[0013] 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. 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.

[0014] 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 reducer 14 to a manual valve 28 and a parking lock mechanism 30.

[0015] 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 a hydraulic clutch (not shown) is switched, and the engagement state of the hydraulic clutch is switched, thereby changing the shift range.

[0016] As shown in FIG. 3, four valleys 221-224 corresponding to the P (parking), R (reverse), N (neutral), and D (drive) ranges are formed on the detent spring 25 side of the detent plate 21. 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.

[0017] As shown in FIG. 1, the detent spring 25 is an elastically deformable plate-shaped member, and has a detent roller 26 attached to 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 equal to or greater than a predetermined value is applied to the detent plate 21, the detent spring 25 elastically deforms, causing the detent roller 26 to move between the valleys 221 to 224. When the detent roller 26 fits into one of the valleys 221 to 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 to 224 corresponding to the shift range.

[0018] In this embodiment, the locations where the detent roller 26 fits due to the spring force of the detent spring 25 in accordance with the shift range are defined as the bottommost portions of the valleys 221 to 224. The range over which the detent roller 26 can be dropped into the bottommost portions of the valleys 221 to 224 due to the spring force is defined as the suction range θs. The entire range on the wall portions 228 and 229 side of the bottommost portions of the valleys 221 and 224 is set to be included in the suction range θs.

[0019] The parking lock mechanism 30 includes 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 generally 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 the cone 32. The cone 32 is formed so that its diameter decreases toward the other end 312.

[0020] The parking lock pole 33 abuts against the conical surface of the cone 32 and is provided so as to be swingable around a shaft 34. A protrusion 331 that can mesh with the parking gear 35 is provided on the parking lock pole 33 on the side facing the parking gear 35. When the cone 32 moves in the P direction due to 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 Not P direction, the meshing between the protrusion 331 and the parking gear 35 is released.

[0021] The parking gear 35 is provided on an axle (not shown) and is provided so as to be able to mesh with a protrusion 331 of the parking lock pole 33. When the parking gear 35 meshes with the protrusion 331, rotation of the axle is restricted. When the shift range is a Not P range other than the P range, the parking gear 35 is not locked by the parking lock pole 33, and rotation of the axle is not prevented by the parking lock mechanism 30. Furthermore, 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 restricted.

[0022] 2, the ECU 40 includes a drive circuit 41 and a control unit 50. The drive circuit 41 has switching elements (not shown) corresponding to each phase of the motor winding. By switching the switching elements on and off, the energization of the corresponding phase is switched.

[0023] The control unit 50 is mainly composed of a microcomputer or the like, and includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (all not shown). Each process in the control unit 50 may be software processing in which the CPU executes a program stored in advance in a physical memory device (i.e., a readable non-transitory tangible recording medium) such as a ROM, or may be hardware processing using a dedicated electronic circuit.

[0024] 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 engagement and disengagement of the clutch 60 provided between the vehicle's drive source, such as the engine or main motor, and the axle.

[0025] The control unit 50 has functional blocks such as a signal acquisition unit 51, an abnormality determination unit 52, and a drive control unit 55. 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), etc. The abnormality determination unit 52 determines an abnormality in the shift-by-wire system 1, such as a wire breakage abnormality. The drive control unit 55 controls the operation of the drive circuit 41 to control the drive of the motor 10. In this embodiment, the motor 10 is driven by switching the energized 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.

[0026] 3 is a diagram showing a schematic diagram of the detent mechanism 20, with the rotation direction of the motor 10 and the 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 to 224, but FIG. 3 simply shows the detent roller 26 moving.

[0027] A reducer 14 is provided between the motor shaft 105 and the output shaft 15, and there is a "play" including gear backlash between the motor shaft 105 and the output shaft 15. 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 movable within the range of the play of the reducer 14. However, it is also acceptable to configure the motor shaft 105 and the reducer 14 as being integrated, and to configure the motor shaft 105 and the reducer 14 as being integrated, and to configure the "play" between the reducer 14 and the output shaft 15. The same applies to FIG. 4.

[0028] 3, under normal circumstances, the encoder count value when the detent roller 26 is in contact with the wall portion 228 is learned as the wall position reference value θr. When the shift range is switched, the switching target value θr is calculated based on the learned wall position reference value θr and the wall-to-wall valley angle θrb. * and controls the drive of the motor 10 by feedback control based on the encoder count value. This allows the detent roller 26 to fall into a valley corresponding to the required shift range with high precision. While 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.

[0029] For example, if a wire breakage occurs in the U phase, no torque is generated in the region where current is normally supplied only to the U phase, but inertia allows the motor 10 to pass through this region and continue to drive. In this embodiment, when one phase is broken, the shift range is switched by normal two-phase drive, in which current is supplied to the two normal phases to drive the motor 10.

[0030] In normal two-phase drive, the torque variation is large, so when reference position learning is performed by hitting a wall, the variation in the learned value becomes large. Therefore, the switching target value θ * If the range is switched with this setting, 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.

[0031] Therefore, as shown in Figure 4, when one phase is disconnected and it is difficult to perform accurate control based on the wall position reference value θr, 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 initial driving, 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 turned on is 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.

[0032] The valley position reference value θb is the encoder count value when the motor shaft 105 is at any position within the backlash, and therefore the value varies by the amount of the backlash width θg. Therefore, when switching to the P range, the valley position reference value θb is set to the switching target value θ * After driving the motor 10 by feedback control as above, current limiting switching control is performed to drive the motor 10 by applying current limiting 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. Also, when switching to the D range, a switching target value θ is set based on the valley position reference value θb and the angle between the valley portions 221 and 224. * After setting and performing feedback control, current limit 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.

[0033] The range switching process of this embodiment will be described with reference to the flowchart of 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 simply referred to as the symbol "S".

[0034] 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.

[0035] 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.

[0036] In S103, the drive control unit 55 calculates the switching target value θ * For example, when switching to the P range, the switching target value θ is set based on the wall position reference value θr and the angle between the wall portion 228 and the valley portion corresponding to the required shift range, such as by adding the wall valley angle θrb to the learned wall position reference value θr. * Set.

[0037] In S104, the drive control unit 55 drives the motor 10 by feedback control based on the encoder count value. Here, since the three phases are normal, the motor 10 is driven using the three phases.

[0038] In S105, the drive control unit 55 determines the switching target value θ * Here, it is determined whether the encoder count value has reached the set switching target value θ * If the rotational position of the motor 10 is within a predetermined range including the switching target value θ * If it is determined that the rotational position of the motor 10 has not reached the switching target value θ (S105: NO), the process returns to S104 and the feedback control is continued. * If it is determined that the count value has reached the predetermined value (S105: YES), the process proceeds to S106, where a stop control is performed to stop the motor 10 by energizing the two phases according to the encoder count value. Then, the process proceeds to S119.

[0039] If it is determined that at least some of the current paths are abnormal (S102: NO), the control unit 50 proceeds to S107, where it determines whether the abnormality that has occurred is a one-phase break. If it is determined that the abnormality that has occurred is not a one-phase break (S107: NO), that is, if there are two or more broken phases or if there is a short-circuit abnormality other than a break, the range cannot be switched in normal two-phase drive, and the processing from S108 onwards is skipped. If it is determined that the abnormality that has occurred is a one-phase break (S107: YES), the processing proceeds to S108.

[0040] In S108, the drive control unit 55 calculates the switching target value θ * For example, when switching to P range, the learned valley position reference value θb is set as the switching target value θ * In addition, when switching to a range other than the P range, the switching target value θ is calculated 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. * Set.

[0041] In S109, the drive control unit 55 performs pre-switching preparation processing. In normal two-phase drive, it is necessary to pass through the region 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 between them.

[0042] In this embodiment, as a pre-switching preparation process, the energized phases are switched in the order of 1-phase energization → 2-phase energization → 1-phase energization. The initial 1-phase energization is the phase that is energized before the disconnected phase, based on the order of energized phase switching 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, when the U phase is disconnected and the motor is rotating forward, as a pre-switching preparation process, energization is performed in the order of W phase → VW phase → V phase, and range switching begins from a so-called "1 phase, 1 tooth" state in which the salient pole of the V phase faces the salient pole of the rotor.

[0043] In S110, the drive control unit 55 drives the motor 10 by a feedback control unit based on the encoder count value. Here, since one phase disconnection has occurred, the motor 10 is driven using two normal phases.

[0044] The process of S111 is the same as the process of S105, and the motor rotation position is set to the switching target value θ * If it is determined that the switching target value θ has not been reached (S111: NO), the process returns to S110, the feedback control is continued, and the switching target value θ * If it is determined that the motor 10 has reached the predetermined value (S111: YES), the process proceeds to S112, and a stop control is performed to stop the motor 10 by energizing the two normal phases.

[0045] In S113, the control unit 50 determines whether or not the range is being switched to the R range. If it is determined that the range is being switched to the R range (S113: YES), the process proceeds to S119. If it is determined that the range is being switched to a range other than the R range (S113: NO), the process proceeds to S114.

[0046] In S114, the control unit 50 determines whether or not the range is to be switched to N. If it is determined that the range is to be switched to N (S114: YES), the process proceeds to S115, where the clutch 60 is disengaged, and then to S119. The processing of S115 may be omitted. If it is determined that the range is not to be switched to N (S114: NO), that is, if the range is to be switched to P or D, the process proceeds to S116. Note that switching to P or D range can be considered to be switching to a range adjacent to the wall portions 228 and 229, and switching to R or N range can be considered to be switching to an intermediate range that is not adjacent to the wall portions 228 and 229. In addition, the allocation of control based on the range determination may be performed before the start of driving of the motor 10, for example, following S107.

[0047] The control unit 50 performs current limiting control in S116 and performs 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.

[0048] The range switching process of this embodiment will be described based on the time charts of 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." When it is in a state where there is no deflection or the like and it is in contact with the wall portion 228, it is called a "P wall." The same applies to Figures 7 and 8.

[0049] FIG. 6 shows an example of shifting from D range to P range when the three phases are normal. At time x10, it is confirmed that the three phases are normal. When a shift request to P range is acquired at time x11, the shift target value θ is calculated based on the learned wall position reference value θr and wall-to-wall valley angle θrb. * The drive control unit 55 sets the switching target value θ * The motor 10 is driven by feedback control so that

[0050] At time x12, the encoder count value reaches the switching target value θ * When the time reaches x13, the motor 10 is stopped, and at time x13 when the stop control time has elapsed, the motor 10 is turned off and the system transitions to standby mode.

[0051] When the three phases are normal, the positioning accuracy θa is smaller than the suction range θs, so the switching target value θ * is set so that the positioning accuracy θa falls within the suction range θs. For example, the center value of the suction range θs is set as the switching target value θ * This allows the detent roller 26 to be reliably dropped into the valley portion according to the required range.

[0052] Figure 7 shows an example of switching from D range to P range when one phase is disconnected. In Figure 7 and other figures, the P valley area is enlarged to explain the current limit switching, and the ratio of the PD angle to the P valley wall angle, for example, differs from the actual ratio.

[0053] When a one-phase break occurs at time x20, the one-phase break is confirmed at time x21, and a range switch request is acquired at time x22, pre-switch preparation processing for normal two-phase drive is performed. In the example of Figure 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, pre-switch preparation processing is performed by energizing the V phase → VW phase → W phase, resulting in a one-phase, one-tooth state opposite the W phase.

[0054] At time x23, when the pre-switching preparation process is completed, the valley position reference value θb is set to the switching target value θ * At time x24, the encoder count value reaches the switching target value θ * When it reaches this point, the system performs stop control.

[0055] During normal two-phase drive when one phase is disconnected, 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 fall into the valley portion corresponding to the required range.

[0056] Therefore, in this embodiment, when the requested range is the P range or D range adjacent to the wall portions 228, 229, current limit switching control is performed to place the detent roller 26 in the suction range θs after feedback control is completed.

[0057] In the current limit switching control when switching the P range, the switching target value θ *is set to an arbitrary value that is sufficiently farther from the wall 228 even when taking into account the maximum deflection θd of the wall 228, and the motor 10 is driven so that the detent roller 26 moves toward the wall 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 torque is greater 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, which is set depending on, for example, the durability of the detent mechanism.

[0058] 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 detent roller 26 has moved from the bottom of valley portion 221 to the wall portion 228 side under feedback control, there is a possibility that detent roller 26 may push wall portion 228 further than its intended position due to the deflection of detent mechanism 20.

[0059] At time x26 when the current limit switching time has elapsed, the wall portion 228 is pushed inward 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 state, which may cause the detent roller 26 to exceed the suction range θs and be pushed back toward the peak portion 225.

[0060] Therefore, after the current limit switching control, wall return control is performed to return the detent roller 26 by 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.

[0061] At time x27 when the wall return control is completed, stop control is performed by energizing normal two-phase current. At time x28, the power supply to the motor 10 is turned off and the system transitions to standby mode. When the power supply 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.

[0062] 7, the detent roller 26 is driven by the current limit switching control to a position where it bends the wall portion 228. However, 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 the detent roller 26 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 acceptable if the detent roller 26 does not reach the wall portion 228.

[0063] The control from time x30 to time x38 in Figure 8 corresponds to the control from time x20 to time x28 in Figure 7. When 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 Figure 7, or the backlash width θg. In the example of Figure 8, the detent roller 26 moves to the bottom of the valley 221 during the wall-return control, but the behavior when power to the motor 10 is turned off at time x38 is determined by 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 spring force of the detent spring 25 will move the detent roller 26 toward the valley 221 when power to the motor 10 is turned off.

[0064] FIG. 9 shows an example of switching from D range to N range when one phase is disconnected. In FIG. 9, the horizontal axis represents a common time axis, and from the top to bottom, the graphs show motor control, one-phase disconnection state, shift request, state of clutch 60, and motor rotation angle. The motor rotation angle is defined as the "N valley" when detent roller 26 is at the bottom of valley portion 223. 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.

[0065] At time x43, when the pre-switching preparation process is completed, the switching target value θ is calculated based on the valley position reference value θb. * is set, and the motor 10 is driven by feedback control using the normal two phases. *Specifically, is set based on the valley position reference value θb and the angle between the valleys 221 and 223.

[0066] At time x44, the encoder count value reaches the switching target value θ * When the detent roller 26 reaches the suction range θs_N of the N range, stop control is performed. Here, the suction range θs_N of the N range is relatively small, and the positioning accuracy θa_N is greater than the suction range θs_N. Furthermore, since the N range is an intermediate range that is not adjacent to the wall portions 228, 229, current limiting switching control that moves the detent roller 26 toward the wall, as when switching to the P range or D range, cannot be performed. Therefore, if the position of the detent roller 26 at the end of feedback control is outside the suction range θs_N of the N range, there is a risk that the automatic transmission 5 will not be properly put into neutral.

[0067] Therefore, in this embodiment, when the shift range is switched to N range using normal two-phase drive during 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 to prevent power from being transmitted to the axle side. At time x45, power supply to the motor 10 is turned off and the system transitions to standby mode.

[0068] As described above, in the shift-by-wire system 1 including the motor 10 having motor windings of three or more phases and the 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.

[0069] Drive circuit 41 has switching elements that switch the power supply to each phase of the motor winding. Control unit 50 has drive control unit 55 that controls the drive of motor 10 by feedback control based on the detection value of encoder 13 that detects the rotational position of motor 10, and abnormality determination unit 52 that detects open circuit faults. Here, an "open circuit fault" is a fault that prevents power from being supplied to each phase coil of the motor winding, and includes not only a break in the motor winding itself but also a break in the harness or a switching element stuck off.

[0070] The detent mechanism 20 has a detent plate 21 having a plurality of valleys 221-224 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, and wall portions 228, 229 that regulate the drive of the detent roller 26 are formed on both sides of the arranged valleys 221-224.

[0071] When one phase is disconnected and the detent roller 26 is moved to the target valleys 221, 224 adjacent to the walls 228, 229 using normal phase drive, the drive control unit 55 performs feedback control so that the detent roller 26 is positioned between the peaks on both sides of the target valley and the wall, and then performs current limiting switching control to drive the motor 10 while applying current limiting so that the detent roller 26 moves toward the wall. When the target valley is the valley 221, the drive control unit 55 performs feedback control so that the detent roller 26 is positioned between the peaks 225 on both sides 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.

[0072] In the case of normal phase drive with one phase disconnection, the positioning variation becomes larger compared to when all phases are normal, so the encoder count value is set to the switching target value θ * Even if control is performed so that the detent roller 26 falls within the suction range θs, there is a risk that the detent roller 26 will fall outside the suction range θs. Therefore, in this embodiment, when normal phase drive is performed with one phase disconnection, current limiting switching control is performed after feedback control, thereby ensuring that the detent roller 26 falls within the suction range θs. This makes it possible to appropriately switch the detent mechanism 20 even when one phase is disconnected.

[0073] When all phases are normal, the switching target value θ *is set based on the wall position reference value θr learned in accordance with 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 driving is performed in the case of one phase disconnection, the switching target value θ * is set based on the valley position reference value θb learned in accordance with 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 switching target value θ in the feedback control is set based on the detection value θb learned in accordance with the detection value of the encoder 13 when the detent roller 26 is at the bottom of the valley portion 221. * The setting method is different.

[0074] As mentioned above, when one phase is disconnected, the normal phase drive has large positioning variations, so the switching target value θ is set based on the wall position reference value θr. * Even if the wall position reference value θr is set, there is a possibility that the detent roller 26 may deviate from the suction range θs. Also, the variation of the learned wall position reference value θr becomes larger than that in the normal state. Therefore, in the normal phase drive, the switching target value θr is set without using the wall position reference value θr. * This makes it possible to omit wall position learning when one phase is disconnected.

[0075] 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 axle and the vehicle drive source, such as the engine or main motor. This allows torque to be cut on the automatic transmission 5 side, enabling appropriate neutral control.

[0076] In the 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."

[0077] (Other embodiments) In the above embodiment, the rotation detection unit is an encoder. In other embodiments, a sensor capable of detecting rotational 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 a motor other than a switched reluctance motor, such as a DC brushless motor. The number of phases of the motor winding may be four or more.

[0078] 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 not P range may be formed. In this case, current limit switching control can be performed regardless of the required range.

[0079] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to execute one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer. As described above, the present invention is not limited to the above embodiments and can be embodied in various forms without departing from the spirit of the invention. [Explanation of symbols]

[0080] 1. Shift-by-wire system (motor drive system) 10 Motor 13 Encoder (rotational position sensor) 20: Detent mechanism 21: Detent plate (detent member) 25 Detent spring (biasing member) 26 Detent roller (engagement member) 40···ECU (motor control unit) 41 Drive circuit 50 Control unit 52: Abnormality determination unit 55: Drive control unit

Claims

1. A motor control device for controlling the 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) having a plurality of valleys (221-224) separated by peaks (225-227), an engaging member (26) that is movable along the valleys by driving the motor, and a biasing member (25) that biases the engaging member in a direction to fit into the valleys, and wall portions (228, 229) that restrict the drive of the engaging member are formed on both sides of the arranged valleys. The drive control unit When one phase is broken, in normal phase drive that drives the motor 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 wall portion and the peak portions on both sides of the target valley portion, and then a value that is sufficiently farther back than the wall portion even when taking into account the maximum amount of deflection of the detent mechanism is set as the target value of the rotational position, and current limit switching control is performed to drive the motor by applying current limit so that the engaging member moves in the direction of the wall portion.

2. when all phases are normal, a switching target value in the feedback control is set based on a wall position reference value learned in accordance with 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 accordance with the detection value of the rotational position sensor when the engagement member is at the bottom of the valley portion.

3. 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 the drive source and the axle of the vehicle.

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