Motor control device

Abstract

To provide a motor control device capable of properly driving a motor at disconnection of one phase.SOLUTION: An ECU 40 that controls the drive of a motor having a three-phase motor coil 11, comprises a drive circuit 41 and a control part 50. The drive circuit 41 has switching elements 411 to 413. The control part 50 has: a drive control part 55 that controls on / off-operation of the switching elements 411 to 413 by feedback control based on a detection value of an encoder 13; and an abnormality determination part 52 that determines disconnection failures of the motor coil 11. The drive control part 55, when performing normal two-phase drive of driving a motor 10 by using normal two phases in a case where disconnection failures occur in one of three phases, performs energization by a pattern different from an energization pattern to an energization holding phase which is the energization phase at the start of the normal two-phase drive at least either at system startup and after motor stop, and then, performs a pre-start preparation process of energizing the energization holding phase.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 a wire breaks in one phase, the motor can continue to operate if it can pass the broken phase by inertia. In Patent Document 1, the energized phase that is switched to next after the broken phase is set as the first energized phase, and the motor is driven using the normal phases. However, when energization starts in one of the two normal phases, the stator salient pole of the energized phase faces the rotor recess, and the energized phase does not face the rotor tooth tip.

[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 drive a motor 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 (10) having three-phase motor windings (11), and includes a drive control unit (41) and a control unit (50). The drive circuit has switching elements (411-413) that switch on and off the supply of current to each phase of the motor winding. The control unit has a drive control unit (55) that controls the on / off operation of the switching elements 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 break fault in the motor winding.

[0007] When a wire breakage fault occurs in one of the three phases and normal two-phase drive is performed to drive the motor using the two normal phases, the drive control unit performs a pre-start preparation process at least either at system startup or after motor stop control in which current is supplied to the power-on hold phase, which is the power-on phase when normal two-phase drive begins, in a pattern different from the power-on hold phase. As a pre-start preparation process, the drive control unit switches the current phase in the following order: a first current supply process in which current is supplied to phase 1 of the normal phases, a second current supply process in which current is supplied to phase 2 of the normal phases, and a third current supply process in which current is supplied to the phase that maintains current supply for phase 1.If the motor rotates after the pre-start preparation process is completed and before the motor starts to drive, the drive control unit performs the pre-start preparation process again and then performs normal two-phase drive. This allows the motor to be driven appropriately even when one phase is broken. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a shift-by-wire system according to a first embodiment. [Figure 2] 1 is a schematic configuration diagram showing a shift-by-wire system according to a first embodiment. [Figure 3] FIG. 2 is a circuit diagram illustrating an ECU according to the first embodiment. [Figure 4] FIG. 1 is a schematic diagram showing a motor according to a first embodiment. [Figure 5] 4 is a map in which energized phase numbers are associated with energized phases according to the first embodiment. [Figure 6] 4A and 4B are explanatory diagrams illustrating a disconnected phase and a facing position according to a switching direction according to the first embodiment. [Figure 7] 4 is a schematic diagram showing an opposing state at the start of energization when the U-phase is disconnected and the rotor is driven in the forward direction in the first embodiment. FIG. [Figure 8]FIG. 2 is an explanatory diagram for explaining motor driving in normal two phases in the first embodiment. [Figure 9] FIG. 4 is an explanatory diagram illustrating switching of energized phases in pre-switching preparation processing according to the first embodiment. [Figure 10] 5A to 5C are explanatory diagrams illustrating the behavior of the rotor in the pre-switching preparation process according to the first embodiment. [Figure 11] 4 is a flowchart illustrating a range switching process according to the first embodiment. [Figure 12] 4 is a time chart illustrating a range switching process according to the first embodiment. [Figure 13] 10 is a flowchart illustrating a range switching process according to a second embodiment. [Figure 14] 10 is a flowchart illustrating a range switching process according to a third embodiment. [Figure 15] 10 is a time chart illustrating a range switching process according to a third embodiment. [Figure 16] 10 is a flowchart illustrating a range switching process according to a fourth embodiment. [Figure 17] 10 is a time chart illustrating a range switching process according to the fourth embodiment. [Figure 18] 10 is a time chart illustrating a range switching process according to the fourth embodiment. [Figure 19] 10 is a flowchart illustrating a range switching process according to a fifth embodiment. [Figure 20] 10 is a time chart illustrating a range switching process according to the fifth embodiment. [Figure 21] 10 is a time chart illustrating a range switching process according to the fifth embodiment. [Figure 22] 10 is a time chart illustrating a range switching process according to the fifth embodiment. [Figure 23] 13 is a flowchart illustrating a startup process according to the sixth embodiment. [Figure 24] 13 is a flowchart illustrating a range switching process according to the sixth embodiment. [Figure 25]13 is a time chart illustrating a range switching process according to the sixth embodiment. [Figure 26] 13 is a time chart illustrating a range switching process according to the sixth embodiment. [Figure 27] 13 is a time chart illustrating a range switching process according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A motor control device according to the present invention will be described below with reference to the accompanying drawings. In the following, substantially identical components in a plurality of embodiments will be designated by the same reference numerals, and the description thereof will be omitted.

[0010] The first embodiment is shown in Figures 1 to 12. 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, an ECU 40 as a motor control device, and the like.

[0011] The motor 10 rotates when power is supplied from a battery 90 mounted on the vehicle (not shown), and functions as a drive source for the detent mechanism 20. The motor 10 is, for example, a switched reluctance motor.

[0012] 3 and 4, the motor 10 includes a stator 101, a rotor 103, and motor windings 11. The motor windings 11 include a U-phase coil 111, a V-phase coil 112, and a W-phase coil 113, and are wound around the salient poles 102 of the stator 101. The coils 111 to 113 are connected together at a connection part 115. The connection part 115 is connected to the battery 90 via a motor relay 91 and a fuse 92.

[0013] The rotor 103 has salient poles and is rotatably provided radially inside the stator 101. The rotor 103 is rotationally driven by switching the energized phases of the coils 111 to 113. In this embodiment, the stator 101 has 12 salient poles and the rotor 103 has 8 salient poles. Hereinafter, the salient poles of the rotor 103 will be referred to as convex portions 104 and the spaces between the convex portions as concave portions 105, as appropriate.

[0014] The encoder 13 is a magnetic rotary encoder that detects the rotational position of the rotor 103. The encoder 13 is composed of Hall elements 131 and 132 for magnetic detection, a magnet 135 that rotates integrally with the rotor 103, and the like. The Hall elements 131 and 132 output pulse signals at predetermined angular intervals in synchronization with the rotation of the rotor 103. In this embodiment, the Hall elements 131 and 132 output a Lo signal when facing the N pole and a Hi signal when facing the S pole.

[0015] The magnet 135 is formed in an annular shape and is disposed coaxially with the rotor 103. The magnet 135 is magnetized so that north and south poles alternate in the circumferential direction at equal pitches. In this embodiment, the magnetization pitch is 7.5°. This magnetization pitch is the same as the rotation angle of the rotor 103 per excitation of the motor 10. That is, when the 1-2 phase excitation method switches the energized phase from U phase → UV phase → V phase → VW phase → W phase → WU phase, switching the energized phase six times to complete one cycle, the rotor 103 rotates a mechanical angle of 7.5 × 6 = 45°.

[0016] The Hall elements 131 and 132 are arranged on the same circumference with a phase difference of 90° electrical angle. In this embodiment, the electrical angle of 90° corresponds to a mechanical angle of 3.75°, and the Hall elements 131 and 132 are arranged with an interval of 48.75°. In this embodiment, the signal from the Hall element 131 is an A-phase signal, and the signal from the Hall element 132 is a B-phase signal. Although the encoder 13 is a two-phase encoder, it may be a three-phase encoder, or may output a Z-phase signal as a reference signal in addition to the detection signal.

[0017] Returning to Fig. 1, 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 transmits the rotation of the motor 10 to the detent mechanism 20. The output shaft sensor 16 is, for example, a potentiometer, and detects the rotational position of the output shaft 15 (see Fig. 2).

[0018] The detent mechanism 20 has 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 the parking lock mechanism 30 .

[0019] The detent plate 21 is fixed to the output shaft 15 and driven by the motor 10. On the side of the detent spring 25 of the detent plate 21, two valleys 211, 212 and a peak 215 separating the valleys 211, 212 are provided.

[0020] The detent spring 25 is an elastically deformable plate-shaped member, and has a detent roller 26 at its tip. The detent spring 25 biases the detent roller 26 toward the rotation center of the detent plate 21.

[0021] When a rotational force greater than or equal to 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 211 and 212. When the detent roller 26 fits into either of the valleys 211 and 212, the oscillation of the detent plate 21 is restricted, and the state of the parking lock mechanism 30 and the shift range of the automatic transmission 5 are determined.

[0022] The parking lock mechanism 30 has a parking rod 31, a cone 32, a parking lever 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 a cone 32. The cone 32 is formed so that its diameter decreases toward the other end 312. When the detent plate 21 rotates in a direction in which the detent roller 26 fits into the valley 211 corresponding to the P range, the cone 32 moves in the direction of arrow P.

[0023] The parking lever 33 abuts against the conical surface of the cone 32 and is provided so as to be able to swing around a shaft 34. A protrusion 331 that can mesh with the parking gear 35 is provided on the parking lever 33 on the parking gear 35 side. When the cone 32 moves in the direction of arrow P due to rotation of the detent plate 21, the parking lever 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 direction not indicated by arrow P, the meshing between the protrusion 331 and the parking gear 35 is released.

[0024] The parking gear 35 is connected to a drive shaft (not shown) and is provided so as to be able to mesh with a protrusion 331 of the parking lever 33. When the parking gear 35 meshes with the protrusion 331, rotation of the drive shaft is restricted. When the shift range is a range other than P, i.e., a not P range, the parking gear 35 is not locked by the parking lever 33, and rotation of the drive shaft is not prevented by the parking lock mechanism 30. Furthermore, when the shift range is P range, the parking gear 35 is locked by the parking lever 33, and rotation of the drive shaft is restricted.

[0025] In this embodiment, the rotation direction of the motor 10 when switching from the P range to the notP range is the forward direction, and the rotation direction of the motor 10 when switching from the notP range to the P range is the reverse direction.

[0026] 2 and 3, the ECU 40 includes a drive circuit 41, a current detection unit 45, a voltage detection circuit 46, a control unit 50, and the like. The drive circuit 41 has three switching elements 411, 412, and 413. The switching elements 411 to 413 are provided corresponding to the coils 111 to 113, respectively, and switch the energization of the corresponding phases. In this embodiment, the switching elements 411 to 413 are provided between the coils 111 to 113 and the ground. The switching elements 411 to 413 in this embodiment are MOSFETs, but may also be IGBTs or the like.

[0027] The current detection unit 45 is provided on a collective wiring that connects the sources of the switching elements 411 to 413 to the ground, and detects the sum of the currents flowing through the coils 111 to 113. Hereinafter, the current detected by the current detection unit 45 is referred to as the motor current Im. The current detection unit 45 may be provided at any location where it can detect the currents in the coils 111 to 113, and may also be provided for each phase.

[0028] The voltage detection circuit 46 is connected between the coils 111 to 113 and the switching elements 411 to 413, and detects the terminal voltage of each phase. The relay driver 48 controls the on / off operation of the motor relay 91.

[0029] 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.

[0030] The control unit 50 controls the switching of the shift range by controlling the driving 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, and the like.

[0031] The control unit 50 has, as functional blocks, a signal acquisition unit 51, an abnormality determination unit 52, a drive control unit 55, etc. The signal acquisition unit 51 acquires detection signals from the encoder 13, the output shaft sensor 16, the current detection unit 45, the voltage detection circuit 46, etc. The abnormality determination unit 52 determines an abnormality in the shift-by-wire system 1, such as a wire breakage abnormality.

[0032] The drive control unit 55 controls the on / off operation of the switching elements 411 to 413, thereby controlling the drive of the motor 10. In this embodiment, the motor 10 is driven by switching the energized phase of the motor windings 11 through feedback control based on the encoder count value.

[0033] As shown in Figure 5, the control unit 50 stores a map that associates energized phase numbers with energized phases, and rotates the motor 10 by shifting the energized phase number by one each time a pulse edge of the encoder signal is detected and switching the energized phase. When rotating the motor 10 in the forward direction, the energized phase number is increased by one each time a pulse edge of the encoder signal is detected, and when rotating the motor 10 in the reverse direction, the energized phase number is decreased by one. The energized phase number can also be considered, for example, as the remainder when the encoder count value is divided by 12.

[0034] In this embodiment, when a wire break occurs in one phase, the range is switched by energizing the two normal phases through feedback control to drive the motor 10. For example, when the U phase is broken, no torque is generated in energized phases 2 and 3, which normally only energize the U phase, but the inertia allows the motor 10 to continue driving by passing through this region.

[0035] Here, when switching ranges due to one-phase disconnection, it is desirable to start switching drive from a so-called "one-phase, one-tooth" state in which the energized phase faces the convex portion 104 of the rotor 103. Hereinafter, the state in which the U-phase salient pole 102 and the convex portion 104 of the rotor 103 face each other with one tooth per phase will be referred to as "U-phase facing," the state in which the V-phase salient pole 102 and the convex portion 104 face each other with one tooth per phase will be referred to as "V-phase facing," and the state in which the W-phase salient pole 102 and the convex portion 104 face each other with one tooth per phase will be referred to as "W-phase facing."

[0036] As shown in Figure 6, the opposing positional relationship between salient pole 102 of stator 101 and convex portion 104 of rotor 103 at the start of switching is set depending on the disconnected phase and the rotation direction of motor 10. If there is a U-phase disconnection and the switching direction is forward rotation, range switching starts from the V-phase opposing state, and if it is reverse rotation, range switching starts from the W-phase opposing state. If there is a V-phase disconnection and the switching direction is forward rotation, range switching starts from the W-phase opposing state, and if it is reverse rotation, range switching starts from the U-phase opposing state. If there is a W-phase disconnection and the switching direction is forward rotation, range switching starts from the U-phase opposing state, and if it is reverse rotation, range switching starts from the V-phase opposing state. The following explanation focuses on an example where the switching direction is forward rotation when there is a U-phase disconnection.

[0037] As shown in Figure 7, when switching to the forward direction due to a U-phase break, range switching begins with the V-phase energized and V-phase opposed state. In Figure 8, the upper row shows the energized phase switching, and the lower row shows the energized phases in the upper row and the corresponding motor torque. As shown in Figure 8, by switching from the V-phase energized and V-phase opposed state to the VW-phase energized and W-phase energized, the normal phase energization is switched, generating torque and rotating rotor 103.

[0038] If no U-phase breakage occurs, the W-phase is energized, followed by the WU-phase, U-phase, and UV-phase. However, if the U-phase breakage occurs, current cannot be passed through the U-phase coil 111. Therefore, in the region where the WU-phase should be energized, the W-phase continues to be energized, reducing motor torque, and in the region where the U-phase should be energized, the motor torque becomes zero. If the motor passes through this region due to inertia, current is passed through the V-phase in the UV-phase energized region, increasing motor torque, and motor 10 continues to rotate. In FIGS. 7 and 8, energized phase coils are indicated by solid lines, non-energized phase coils are indicated by dashed lines, and the U-phase coil 111 is omitted to indicate a wire breakage.

[0039] Here, if only V-phase energization is performed before range switching, there is a possibility that the recessed portion 105 of the rotor 103 and the V-phase salient pole 102 will face each other when the V-phase is energized, and in this state, it is not possible to start driving from the V-phase opposed state. When the energization phase is switched from V-phase energization to VW-phase energization from a state in which the V-phase salient pole 102 and the recessed portion 105 of the rotor 103 face each other, there is a risk that the rotor 103 will rotate in the reverse direction, or that the rotation speed will be insufficient in the region where inertia is desired to pass through, making it impossible to pass through the open-circuit phase.

[0040] Therefore, in this embodiment, a pre-switching preparation process is performed to align the positions of the stator 101 and rotor 103 so that they are reliably positioned as shown in Fig. 6. In the pre-switching preparation process, as shown in Fig. 9, one-phase energization, two-phase energization, and one-phase energization are performed in this order, so that the energized phases at the start of switching are opposed in a one-tooth-per-phase state.

[0041] Specifically, when the U-phase is broken and the switching direction is forward, W-phase energization, VW-phase energization, and V-phase energization are performed as pre-switching preparations; when the direction is reverse, V-phase energization, VW-phase energization, and W-phase energization are performed as pre-switching preparations. When the V-phase is broken and the switching direction is forward, U-phase energization, WU-phase energization, and W-phase energization are performed as pre-switching preparations; when the direction is reverse, W-phase energization, WU-phase energization, and U-phase energization are performed as pre-switching preparations. When the W-phase is broken and the switching direction is forward, V-phase energization, UV-phase energization, and U-phase energization are performed as pre-switching preparations; when the direction is reverse, U-phase energization, UV-phase energization, and V-phase energization are performed as pre-switching preparations. Hereinafter, the first one-phase energization during pre-switching preparations is referred to as energization status ST1, the next two-phase energization as energization status ST2, and the state in which one-phase, one-tooth state is maintained when one-phase energization to an energized phase at the start of switching is referred to as energization status ST3.

[0042] FIG. 10 shows the pre-switching preparations for achieving a V-phase opposing state when the U-phase is disconnected. First, by energizing the W-phase, the convex portion 104 faces the W-phase. When energizing the V-phase from this state, the rotor 103 rotates, and the convex portion 104 faces the V-phase and the W-phase, resulting in a so-called "two-phase, two-tooth" state. By switching from the two-phase, two-tooth state to the V-phase, it is possible to reliably achieve a one-phase, one-tooth state with the V-phase opposing. Note that even if the so-called "one-phase, two-tooth" state occurs when energizing the W-phase, where the concave portion 105 faces the W-phase, by energizing the V-phase after energizing the V-phase, it is possible to achieve a one-phase, one-tooth state with the V-phase opposing when energizing the V-phase.

[0043] The range switching process of this embodiment will be described with reference to the flowchart of FIG. 11. This process is executed by the control unit 50 at a predetermined cycle. In S101, the control unit 50 determines whether or not a one-phase break has been detected. If it is determined that a one-phase break has not been detected (S101: NO), the process from S102 onwards is skipped. Note that the detection of a one-phase break is performed in a process separate from that of this embodiment, and is determined, for example, based on a detection value of the voltage detection circuit 46, but the details of the detection method are not important. Furthermore, when all phases are normal, range switching is performed in a process separate from this process. If it is determined that a one-phase break has been detected (S101: YES), the process proceeds to S102.

[0044] In S102, 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 (S102: NO), the process from S103 onward is skipped and the standby mode continues. If it is determined that there is a request to switch (S102: YES), the process proceeds to S103.

[0045] In S103, the drive control unit 55 applies current in the current-carrying status ST1. For example, if the U-phase is disconnected and the switching direction is forward, the drive control unit 55 applies current to the W-phase. In S104, the drive control unit 55 determines whether the current-carrying hold time Xh1 in the current-carrying status ST1 has elapsed. If it is determined that the current-carrying hold time Xh1 has not elapsed (S104: NO), the process returns to S103, and the drive control unit 55 continues applying current in the current-carrying status ST1. If it is determined that the current-carrying hold time Xh1 has elapsed (S104: YES), the process proceeds to S105.

[0046] In S104, the drive control unit 55 performs energization in energization status ST2. For example, when the U phase is disconnected, two-phase energization is performed to the VW phase, which is the normal phase, regardless of the switching direction. In S106, the drive control unit 55 determines whether the energization hold time Xh2 in energization status ST2 has elapsed. If it is determined that the energization hold time Xh2 has not elapsed (S106: NO), the process returns to S105 and energization in energization status ST2 continues. If it is determined that the energization hold time Xh2 has elapsed (S106: YES), the process proceeds to S107.

[0047] In S107, the drive control unit 55 applies current in the current application status ST3. For example, if the U-phase is disconnected and the switching direction is forward, the drive control unit 55 applies current to the V-phase. In S108, the drive control unit 55 determines whether the current application hold time Xh3 in the current application status ST3 has elapsed. If it is determined that the current application hold time Xh3 has not elapsed (S108: NO), the process returns to S107, and the drive control unit 55 continues applying current in the current application status ST3. If it is determined that the current application hold time Xh3 has elapsed (S108: YES), the process proceeds to S109, and the pre-switching preparation completion flag is set to ON. The pre-switching preparation completion flag is set to OFF at any timing after the start of range switching.

[0048] In S110, the drive control unit 55 drives the motor 10 from a one-tooth-per-phase opposing state at a predetermined position according to the disconnected phase and rotation direction, and performs range switching by feedback control with two normal phases. In S111, the control unit 50 determines whether the range switching is complete. If it is determined that the range switching is not complete (S111: NO), the process returns to S109, and feedback control with two normal phases continues. If it is determined that the range switching is complete (S111: YES), the process transitions to standby mode, and this process ends.

[0049] The range switching process of this embodiment will be described based on the time chart of Fig. 12. In Fig. 12, the horizontal axis represents a common time axis, and from the top, the following are shown: motor control mode, one-phase open circuit detection status, pre-switching preparation completion flag, motor rotation angle, and energized phase. The motor rotation angle is a value that can be converted from the encoder count value, with the actual value indicated by a solid line and the target value indicated by a dashed line. The time when the detent roller 26 is at the bottom of the valley portion 211 is indicated as P, and the time when the detent roller 26 is at the bottom of the valley portion 212 is indicated as not P. The same applies to Fig. 15, etc., which will be described later.

[0050] In FIG. 12, the vibration components of the rotor 103 due to the switching of the energization status are omitted. The energized phase numbers for the energized phases at the time of shift switching are written in parentheses. For simplicity, the energized phase numbers are the numbers at the time of switching. Also, for the sake of explanation, the switching of energized phases during shift switching is shown on an expanded time scale and does not correspond to the transition of the motor rotation angle.

[0051] At time x0, one phase break occurs, an abnormality is confirmed at time x1, and then a shift range switching request is input at time x2. In this pre-switching preparation process, the energized phases are switched at predetermined intervals in the order of energization status ST1, ST2, and ST3. The energized phases of energization status ST1, ST2, and ST3 are set according to the broken phase and the switching direction.

[0052] Since the energization status ST2 indicates two-phase energization, the rotor 103 is likely to be stable, and the energization hold time Xh2 can be a relatively short time. Furthermore, since it is desirable to reliably hold the one-phase, one-tooth state in the energization status ST3, the energization hold time Xh2 is set to a relatively long time. Therefore, in this embodiment, Xh2≦Xh1≦Xh3 is set.

[0053] At time x3, when the pre-switching preparation process is completed, the pre-switching preparation completion flag is turned on, and range switching is performed using feedback control using the two normal phases. At time x4, when the target attainment determination range is reached, stop control is performed. The stop control in this embodiment is fixed phase current supply to the two normal phases. At time x5, when a predetermined time has elapsed since the start of stop control, all switching elements are turned off, and the system transitions to standby mode.

[0054] In this embodiment, when one phase is broken and the motor 10 is driven by energizing the two normal phases, pre-switching preparation processing before starting driving involves energizing one phase, energizing two phases, and energizing one phase in that order. This allows the motor 10 to start driving from a one-phase, one-tooth state in which the protrusion 104 of the rotor 103 faces the energized phase at the start of switching.

[0055] As described above, ECU 40 controls the driving of a motor having three-phase motor windings 11, and includes drive circuit 41 and control unit 50. Drive circuit 41 has switching elements 411-413 that switch on and off the supply of electricity to each phase of motor windings 11. Control unit 50 has drive control unit 55 that controls the on / off operation of switching elements 411-413 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 determines whether motor windings 11 have an open circuit fault.

[0056] When a wire breakage fault occurs in one of the three phases and normal two-phase drive is performed to drive the motor 10 using the two normal phases, the drive control unit 55 performs pre-switching preparation processing to energize the energization-holding phase after energizing it in a pattern different from the energization pattern to the energized phase that was the energized phase at the start of normal two-phase drive. Here, the wire breakage fault is a fault that prevents current from flowing through the coil, and includes a wire breakage in the harness, a switching element stuck off, etc.

[0057] By performing the pre-switching preparation process, the rotor 103 can be rotated to a position where the stator 101 and the rotor 103 face each other and torque can be generated in normal two-phase driving. This allows the motor 10 to be driven appropriately even when one phase is broken.

[0058] As a pre-energization preparation process, the drive control unit 55 switches the energization phase in the order of energization status ST1, which is a first energization process for energizing one of the normal phases, energization status ST2, which is a second energization process for energizing two of the normal phases, and energization status ST3, which is a third energization process for energizing one of the normal phases to maintain energization. This allows the opposing positions of the stator 101 and rotor 103 to be appropriately aligned to a predetermined position.

[0059] The energized phase in the pre-switching preparation process is set according to the disconnection phase and the rotation direction of the motor 10, and the energized phase of the energization status ST1 is the phase that is energized before the disconnection phase in terms of the switching order of the energized phases. This allows the opposing positions of the stator 101 and the rotor 103 to be properly aligned.

[0060] (Second embodiment) A second embodiment is shown in Figure 13. The following embodiment differs from the above embodiment mainly in the pre-switching preparation processing, and this point will be mainly described. The range switching processing of this embodiment will be described based on the flowchart in Figure 13. Figure 13 differs from Figure 11 in that S120 has been added between S106 and S107.

[0061] In S120 which transitions after the energization status ST2, the control unit 50 sets the energization holding time Xh3 of the energization status ST3 according to the ambient temperature H. Specifically, when the ambient temperature H is less than the first determination threshold value Hth1, the energization holding time is Xp; when the ambient temperature H is greater than or equal to the first determination threshold value Hth1 and less than the second determination threshold value Hth2, the energization holding time is Xq; when the ambient temperature H is greater than or equal to the second determination threshold value Hth2, the energization holding time is Xr. The magnitude relationship of each value is Hth1 < Hth2, Xp < Xq < Xr. The ambient temperature H is the environmental temperature of the motor 10, which may be the temperature of the motor 10 itself, or may be the temperature of other components arranged near the motor 10, such as the oil temperature of the transmission.

[0062] The energization status ST13 is held in the state of one-phase one-tooth with one-phase energization. Here, in the case of one-phase energization, the rotor 103 is likely to vibrate. Also, when the ambient temperature H is low, the friction is large and the rotor 103 is not likely to sway. Therefore, in this embodiment, it is possible to improve the responsiveness by shortening the energization holding time Xh3 in the energization status ST3 as the ambient temperature H is lower. In this example, the energization holding time Xh3 is set in three stages using two determination threshold values Hth1 and Hth2, but the determination threshold value may be 1 or more, and the number of stages does not matter. Also, instead of threshold value determination, the energization holding time Xh3 may be set by calculation using a map or function according to the ambient temperature H. Furthermore, similar to the energization status ST3, the energization holding time Xh1 of the energization status ST1 which is one-phase energization may also be variable according to the ambient temperature H.

[0063] In this embodiment, the energization time in the pre-switching preparation process is variable according to the motor temperature. Specifically, it is set such that the energization time of the energization status ST3 becomes shorter as the motor temperature is lower. Thereby, since the energization time is appropriately set according to the motor temperature, it contributes particularly to improving the responsiveness at low temperatures. Also, it has the same effect as the above-described embodiment.

[0064] (Third Embodiment) The third embodiment is shown in Figures 14 and 15. The range switching process of this embodiment will be described based on the flowchart of Figure 14. The processes of S201 to S204 are the same as the processes of S101 to S104 in Figure 11.

[0065] In S205, which is reached after the energization hold time Xh1 in energization status ST1 has elapsed, the control unit 50 determines whether the amplitude A1 is equal to or less than the amplitude determination threshold Ath1. The amplitude A1 is, for example, the difference between the maximum and minimum values ​​of the encoder count value n units before the energization hold time Xh1 has elapsed. The details of the calculation of the amplitude A1 are not important. The amplitude determination threshold Ath1 is set to a value that allows the rotor 103 to be considered to be held in a one-phase, one-tooth state. The same applies to the amplitude A3 and amplitude determination threshold Ath3 described below. The amplitude determination thresholds Ath1 and Ath3 may be the same or different.

[0066] If it is determined that the amplitude A1 is equal to or less than the amplitude determination threshold Ath1 (S205: YES), the process proceeds to S207, where energization is started with energization status ST2. If it is determined that the amplitude A1 is greater than the amplitude determination threshold Ath1 (S205: NO), the process proceeds to S206, where energization with energization status ST1 is extended by a predetermined time Xa. Thereafter, the process proceeds to S207, where energization with energization status ST2 is started. The processes of S207 to S210 are the same as the processes of S105 to S108.

[0067] In S211, which is performed after the energization holding time Xh3 in the energization status ST3 has elapsed, the control unit 50 determines whether the amplitude A3 is equal to or less than the amplitude determination threshold Ath3. If it is determined that the amplitude A3 is equal to or less than the amplitude determination threshold Ath3 (S211: YES), the control unit 50 proceeds to S213, where range switching is performed in normal two phases. If it is determined that the amplitude A3 is greater than the amplitude determination threshold Ath3 (S211: NO), the control unit 50 proceeds to S211, where energization in the energization status ST3 is extended by a predetermined time Xc. The extension times for the energization statuses ST1 and ST3 may be the same or different. The processes in S213 to S215 are the same as the processes in S109 to S111 in FIG. 11.

[0068] The range switching process of this embodiment will be described based on the time chart of Fig. 15. Here, the description will be made assuming that the amplitude determination thresholds Ath1 and Ath3 are equal. For the sake of explanation, the vibration component in one-phase current application is emphasized. The process from time x10 to x12 is the same as the process from time x0 to x2 in Fig. 12.

[0069] At time x12, the rotor 103 vibrates due to one-phase energization in energization status ST1, but because the amplitude A1 at time x13 after the energization hold time Xh1 has elapsed is equal to or less than the amplitude determination threshold Ath1, the energization status ST1 is not extended and is switched to energization status ST2. In energization status ST2, two-phase energization is used, so the vibration of the rotor 103 is relatively small.

[0070] At time x14, when the energization hold time Xh2 has elapsed since the start of energization status ST2, the energization status ST2 is switched to energization status ST3, and one phase is energized, causing the rotor 103 to vibrate. Because the amplitude A3 at time x15, when the energization hold time Xh3 has elapsed, is greater than the amplitude determination threshold Ath3, energization in energization status ST3 is extended for a predetermined time Xc. In this example, the amplitude converges to less than or equal to the amplitude determination threshold Ath3 while the energization status ST3 is being extended. After the energization status ST3 is extended for the predetermined time Xc, range switching is performed with two normal phases. The processing from time x16 onwards is the same as the processing from time x3 onwards in FIG. 12.

[0071] In this embodiment, if the amplitudes A1, A3 of the motor rotation angle when the energization holding time has elapsed are greater than the amplitude determination thresholds Ath1, Ath3 in at least one of the energization status ST1 and the energization status ST3, the energization time is extended. This improves the accuracy of maintaining the opposing positions in single-phase energization, where the opposing state between the stator 101 and the rotor 103 is more likely to be unstable than in two-phase energization. This also provides the same effects as the above-described embodiments.

[0072] (Fourth embodiment) 16 to 18 show a fourth embodiment. Fig. 16 differs from Fig. 14 in that S231 and S232 replace S206, and S233 and S234 replace S212. In S205, which is performed after the energization hold time Xh1 has elapsed in energization status ST1, if it is determined that the amplitude A1 is greater than the amplitude determination threshold Ath1 (S205: NO), the energization status ST1 is extended in S231.

[0073] In S232, the control unit 50 determines whether the timeout time Xout1 has elapsed since the start of extension of the energization status ST1. If it is determined that the timeout time has not elapsed (S232: NO), the extension of the energization status ST1 continues and the process returns to S205. If it is determined that the timeout time Xout1 has elapsed (S232: YES), the process proceeds to S207, where the energization state is switched to the energization status ST2.

[0074] In S211, which is performed after the elapse of the energization holding time Xh3 in the energization status ST3, if it is determined that the amplitude A3 is greater than the amplitude determination threshold Ath3 (S211: NO), the energization status ST3 is extended in S233.

[0075] In S234, the control unit 50 determines whether the timeout time Xout3 has elapsed since the start of extension of the energization status ST3. If it is determined that the timeout time Xout3 has not elapsed (S234: NO), the control unit 50 continues to extend the energization status ST3 and returns to S205. If it is determined that the timeout time Xout3 has elapsed (S234: YES), the control unit 50 proceeds to S213.

[0076] The range switching process of this embodiment will be described based on the time charts of Figures 17 and 18. Figure 17 shows a case where vibration subsides before timeout period Xout3. The process from time x20 to time x25 is the same as the process from time x10 to time x15 in Figure 15. At time x25, amplitude A3 is greater than amplitude determination threshold Ath3, so energization in energization status ST3 is extended.

[0077] At time x26, before the timeout period Xout3 has elapsed since time x25, which is the extension start time of the energization status ST3, the amplitude A3 becomes smaller than the amplitude determination threshold Ath3, so the pre-switching preparation completion flag is turned on and range switching is performed in normal two phases. The processing from time x26 onwards is the same as in the example above.

[0078] Figure 18 shows a case where the vibration does not converge within the timeout period Xout3. The processing from time x30 to time x35 is the same as the processing from time x10 to time x15 in Figure 15. At time x35, the amplitude A3 is greater than the amplitude determination threshold Ath3, so the energization in the energization status ST3 is extended.

[0079] At time x36, when the timeout period Xout3 has elapsed since time x35, which is the start time of the energization status ST3, the amplitude A3 remains greater than the amplitude determination threshold Ath3, but the pre-switching preparation flag is turned on as a timeout, and range switching is performed in normal two phases. The processing from time x36 onwards is the same as in the example above.

[0080] The energization status ST3 immediately before the completion of pre-switching preparation is one-phase energization, so the rotor 103 is prone to vibration and the opposing position is difficult to determine. Therefore, if the timeout period Xout3 has elapsed, even if the vibration has not subsided, it is assumed that the rotor 103 has completed moving to the predetermined opposing position, and pre-switching preparation is completed. This allows the range switching to be started appropriately.

[0081] In this embodiment, the drive control unit 55 transitions to the next energization process when the timeout periods Xout1 and Xout3 have elapsed since the start of the extension of energization. Specifically, when the timeout period Xout1 has elapsed in energization status ST1, the drive control unit 55 transitions to energization status ST2, and when the timeout period Xout3 has elapsed in energization status ST3, the drive control unit 55 initiates range switching in normal two-phase drive. This allows the drive control unit 55 to appropriately switch to the next energization process even when vibrations do not subside during one-phase energization. This also provides the same effects as the above-described embodiment.

[0082] (Fifth embodiment) 19 to 22 show a fifth embodiment. In this embodiment, if the preparation for starting switching is not properly performed during the preparation before starting switching, a retry is performed. The range switching process of this embodiment will be described with reference to the flowchart in FIG.

[0083] The processes of S301 and S302 are the same as the processes of S101 and S102 in Fig. 11. If it is determined that a switch request has been made (S302: YES), the process proceeds to S303, where a retry flag, which will be described later, is turned off.

[0084] The processes of S304 to S306 are the same as the processes of S203 to S205 in Fig. 14. If it is determined that the amplitude A1 is equal to or smaller than the amplitude determination threshold Ath1 (S306: YES), the process proceeds to S308. If it is determined that the amplitude A1 is greater than the amplitude determination threshold Ath1 (S306: NO), the process proceeds to S307, where the retry flag is set to ON.

[0085] The processes of S308 to S312 are the same as the processes of S207 to S211 in Fig. 14. If it is determined that the amplitude A3 is greater than the amplitude determination threshold Ath3 (S312: NO), the process proceeds to S314, where the retry flag is turned on. If the retry flag is already on, the state is maintained. If it is determined that the amplitude A3 is equal to or less than the amplitude determination threshold Ath3 (S312: YES), the process proceeds to S313.

[0086] In S313, the control unit 50 determines whether a voltage drop occurred between the start of energization in the energization status ST1 and the end of energization in the energization status ST3, causing the motor voltage Vm to fall below the voltage determination threshold Vth. Instead of a voltage drop, the control unit 50 may also determine whether a current drop occurred, causing the motor current Im to fall below the current determination threshold Ith. If it is determined that a voltage drop did not occur (S313: NO), the process proceeds to S315. If it is determined that a voltage drop occurred (S313: YES), the process proceeds to S314, where the retry flag is set to ON. For the sake of explanation, the presence or absence of a voltage drop is determined after the end of the energization status ST3. However, the voltage may be monitored separately from this process, and the retry flag may be set to ON when a voltage drop occurs.

[0087] In S315, the control unit 50 determines whether the retry flag is on. If it is determined that the retry flag is off (S315: NO), the process proceeds to S319. If it is determined that the retry flag is on (S315: YES), the process proceeds to S316, where the retry counter Cr is incremented.

[0088] In S317, the control unit 50 determines whether the retry counter Cr is smaller than the count determination threshold Cth. If it is determined that the retry counter Cr is smaller than the count determination threshold Cth (S317: YES), the process returns to S303, the retry flag is turned off, and pre-switching preparation is retried. If it is determined that the retry counter Cr is equal to or greater than the count determination threshold Cth (S317: NO), the process proceeds to S318.

[0089] In S318, the control unit 50 determines whether the input switching request is a switch from P range to notP range. If it is determined that the request is a switch from P range to notP range (S303: YES), the processing from S319 onwards is skipped. If it is determined that the request is a switch from notP range to P range (S318: NO), the processing proceeds to S319, where the retry flag is turned off and the pre-switching preparation completion flag is turned on. The processing of S320 and S321 is the same as the processing of S110 and S111 in FIG. 11.

[0090] That is, in this embodiment, if the retry flag is set even after a predetermined number of retries of the pre-switching preparation process, range switching is performed using normal two-phase drive on the P-engagement side, but range switching is not performed on the P-disengagement side. Here, the state in which the retry flag is set can be considered to be a state in which the retry condition is met. Note that S318 may be omitted, and normal two-phase drive may be performed after a predetermined number of retries, regardless of the range switching direction.

[0091] The range switching process of this embodiment will be described based on the time charts of Figures 20 to 22. Figure 20 shows an example of a case where a voltage drop occurs during pre-switching preparation processing, with the horizontal axis representing a common time axis and showing, from the top, motor control, one-phase open circuit detection status, pre-switching preparation completion flag, retry flag, retry counter, motor voltage, and energized phase. Figure 22 is similar.

[0092] The process from time x40 to time x42 is the same as the process from time x0 to time x2 in Fig. 12. When the motor voltage Vm falls below the voltage determination threshold Vth at time x43, the retry flag is turned on.

[0093] At time x44 when energization status ST3 ends, the retry flag is on, so the pre-switching preparation process is retried. At time x44, the retry flag is turned off and the retry counter is incremented. From time x44 to time x45, energization is again performed with energization statuses ST1 to ST3.

[0094] At time x45, when the energization status ST3 in the retry ends, no voltage drop was detected during this retry and the retry flag is off, so the pre-switching preparation complete flag is turned on and range switching is performed with normal two phases. The processing after time x45 is substantially the same as the processing after time x3 in FIG. 12. The retry counter is reset at any timing after the start of range switching. In FIG. 20, the retry counter is reset when the pre-switching preparation complete flag is turned off, but it may be reset at a different timing.

[0095] 21 shows an example of a case where the vibration in energization status ST3 has not converged, with the horizontal axis representing a common time axis, and from the top, motor control, one-phase open circuit detection state, pre-switching preparation completion flag, retry flag, retry counter, rotation angle sensor, and energized phase. The processing from time x50 to time x52 is the same as the processing from time x0 to time x2 in FIG.

[0096] At time x53, when energization status ST3 ends, amplitude A3 is greater than amplitude judgment threshold Ath3, so the retry flag is turned on, and at time x54, the pre-switching preparation process is retried. At time x54, the retry flag is turned off, and the retry counter is incremented. Note that in FIG. 21, time x53 is shifted to the left side of the page for ease of explanation. In this example, amplitude A1 after energization status ST1 ends is less than or equal to amplitude judgment threshold Ath1, but if amplitude A1 is greater than amplitude judgment threshold Ath1, the retry flag is set when energization status ST1 ends.

[0097] At time x55, when the energization status ST3 in the retry ends, the amplitudes A1 and A3 are equal to or less than the amplitude determination thresholds Ath1 and Ath3, and the retry flag is not turned on, so range switching is performed for the normal two phases. The processing after time x55 is the same as the processing after time x3 in FIG. 12.

[0098] Figure 22 shows an example of a case where a voltage drop occurs even after a retry. In Figure 22, it is assumed that the range is not switched from P to P. The processing from time x60 to time x64 is the same as the processing from time x40 to time x44 in Figure 20. At time x65, if the motor voltage Vm falls below the voltage determination threshold Vth even during a retry, the retry flag is turned on.

[0099] At time x66, when the energization status ST3 in the retry ends, the retry flag is on, so the retry flag is turned off and the retry counter is incremented. Here, if the count determination threshold Cth is 2, a second retry is not performed, the pre-switching preparation completion flag is turned on, and range switching is performed with normal two phases. The processing from time x66 onwards is substantially the same as the processing from time x3 onwards in Figure 12.

[0100] In this embodiment, if there is a risk that the pre-switching preparation process has failed due to a voltage drop during the pre-switching preparation process, the pre-switching preparation process is retried. Furthermore, if the vibration does not converge in the energization status ST1, when the energization status is switched to ST2 or ST3, there is a risk that the opposing state will not change to two phases, two teeth, or one phase, one tooth, for example, due to a recessed portion being opposed. Therefore, the pre-switching preparation process is retried. Furthermore, if the amplitude A3 is greater than the amplitude determination threshold Ath3 even after the energization hold time Xh3 has elapsed since the start of the pre-switching preparation process in energization status ST3, and the rotor 103 is not in the specified opposing state, the pre-switching preparation process is retried. This allows range switching to be started with the correct two-phase opposing state.

[0101] In this embodiment, if a retry condition is met in the pre-switching preparation process, the pre-switching preparation process is performed again. The control unit 50 determines that the retry condition is met if the amplitudes A1 and A3 of the motor rotation angle when the current hold times Xh1 and Xh3 have elapsed are greater than the amplitude determination thresholds Ath1 and Ath3 in at least one of the energization status ST1 and the energization status ST3. The control unit 50 also determines that the retry condition is met if the motor voltage Vm or the motor current Im becomes smaller than the determination threshold during pre-start switching preparation. This improves the accuracy of the pre-switching preparation process.

[0102] When the number of retries reaches or exceeds the determination number, the drive control unit 55 starts normal two-phase drive, thereby enabling the drive of the motor 10 to start even when vibration is large.

[0103] The ECU 40 is applied to a shift-by-wire system, and when the number of retries is equal to or greater than the number of determinations and the retry condition is met, the ECU 40 allows switching from a range other than the P range to the P range by normal two-phase drive, and prohibits switching from the P range to a range other than the P range. This allows the shift range to be switched appropriately. The same effects as those of the above embodiment are also achieved.

[0104] (Sixth embodiment) 23 to 27 show the sixth embodiment. In the above-described embodiments, when a request to switch the shift range is made, pre-switching preparation processing is performed. In this embodiment, the pre-switching preparation processing is performed in advance before a range switching request is made.

[0105] The startup process of this embodiment will be described with reference to the flowchart of Fig. 23. This process is executed when a vehicle start switch, such as an ignition switch, is turned on. In S401, the control unit 50 determines whether or not initial drive has been completed. The initial drive process is a current application process for matching the relative positions of the encoder 13 and the rotor 103. If it is determined that initial drive has not been completed (S401: NO), this determination process is repeated. If it is determined that initial drive has been completed (S401: YES), the process proceeds to S402.

[0106] The processing of S402 is the same as the processing of S101 in FIG. 11. If it is determined that no one-phase break has been detected (S402: NO), the subsequent processing is skipped, and if it is determined that one-phase break has been detected (S402: YES), the processing proceeds to S403.

[0107] S403 to S408 are pre-switching preparation processes similar to S103 to S108 in Fig. 11. When the pre-switching preparation process is completed, the control unit 50 turns on a pre-switching preparation completion flag in S409, transitions to standby mode in S410, and ends this process. In this embodiment, the encoder count value when the pre-switching preparation process is completed is stored as an initial value ENi in a storage unit such as a RAM (not shown).

[0108] The range switching process of this embodiment will be described with reference to the flowchart of Fig. 24. The processes of S501 and S502 are the same as the processes of S101 and S102 in Fig. 11. If it is determined that a switching request has been made (S502: YES), the process proceeds to S505, and if it is determined that a switching request has not been made (S502: NO), the process proceeds to S503.

[0109] In S503, the control unit 50 determines whether the rotation amount ΔEN, which is the difference between the current encoder count value EN and the initial value ENi, is 0. If it is determined that the rotation amount ΔEN is 0 (S503: YES), that is, if the rotor 103 has not moved since the pre-switching preparation process was completed, the control unit 50 skips the subsequent processes. If it is determined that the rotation amount ΔEN is not 0 (S503: NO), that is, if the rotor 103 has moved since the pre-switching preparation was completed, the control unit 50 proceeds to S504 and turns off the pre-switching preparation completion flag.

[0110] If it is determined that a range switching request has been made (S502: YES), the control unit 50 proceeds to S505, where it determines whether the pre-switching preparation completion flag is on. If it is determined that the pre-switching preparation completion flag is on (S505: YES), it proceeds to S516. If it is determined that the pre-switching preparation completion flag is off (S505: NO), it proceeds to S506.

[0111] In S506, the control unit 50 determines whether the rotation amount ΔEN is smaller than the rotation amount determination threshold ENth. The rotation amount determination threshold ENth is a value corresponding to the rotation amount when one energized phase is switched, and is set to, for example, two counts of the encoder count value. If it is determined that the rotation amount ΔEN is smaller than the rotation amount determination threshold ENth (S507: YES), the process proceeds to S507. If it is determined that the rotation amount ΔEN is equal to or greater than the rotation amount determination threshold ENth (S507: NO), the process proceeds to S509.

[0112] The processes of S508 and S509 are the same as the processes of S107 and S108 in Fig. 11, and energization is performed in the energization status ST3 for the energization holding time Xh3. If it is determined that the energization holding time Xh3 has elapsed in the energization status ST3 (S508: YES), the process proceeds to S515.

[0113] 11, and when the rotation amount ΔEN is equal to or greater than the rotation amount determination threshold ENth, the pre-switching preparation process is performed by switching the energization status between ST1, ST2, and ST3. When it is determined that the energization hold time Xh3 has elapsed in the energization status ST3 (S514: YES), the process proceeds to S515.

[0114] The processing of S515 to S517 is the same as the processing of S109 to S111 in FIG. 11, and range switching is performed in normal two phases. If it is determined that range switching is complete (S517: YES), the process proceeds to S518, where pre-switching preparation processing is performed. In S518, pre-switching preparation processing is performed by switching the energization status between ST1, ST2, and ST3, as in S509 to S515. After the energization hold time Xh3 has elapsed in energization status ST3, the pre-switching preparation completion flag is turned on, and the system enters standby mode in S519. In addition, the encoder count value EN at the time pre-switching preparation is complete is held as the initial value ENi.

[0115] The range switching process of this embodiment will be described with reference to the time charts of Figures 25 to 27. As shown in Figure 25, the IG is turned on at time x70, and when a one-phase break is detected by an initial diagnosis or the like, pre-switching preparation processing is performed from time x72 when the initial drive is completed, in which the energized phases are switched in the order of energization status ST1, ST2, and ST3. At time x73 when the pre-switching preparation processing is completed, the pre-switching preparation completion flag is turned on and the system enters standby mode.

[0116] 25, the rotor 103 is not moving during standby, and the pre-switching preparation completion flag remains on. When a shift range switching request is input at time x74, the pre-switching preparation completion flag is on, so range switching is performed from this state using feedback control using the normal two phases.

[0117] At time x75, when the target attainment judgment range is reached, stop control is performed. When stop control ends at time x76, pre-switch preparation processing is performed in preparation for the next range switch. Since the rotation direction will be reversed in the next range switch, if there is a U-phase break, current is supplied in the order V-phase → VW-phase → W-phase. At time x77 when pre-switch preparation processing is completed, the pre-switch preparation complete flag is turned on and the system transitions to standby mode.

[0118] In Figure 26, the processing from time x80 to time x83 is the same as the processing from time x70 to time x73 in Figure 25. At time x84, when the rotor 103 moves from the stop position at the time of completion of pre-switching preparation due to, for example, vibration, the pre-switching preparation completion flag is turned off.

[0119] At time x85, when a shift range switching request is input, the pre-switching preparation completion flag is off, so the pre-switching preparation process is performed again. In the example of Fig. 26, the rotation amount ΔEN from the pre-switching preparation completion is smaller than the rotation amount determination threshold ENth, so as the pre-switching preparation process, only the energization status ST3, that is, if the U-phase is disconnected and the rotation is forward, the V-phase is energized.

[0120] At time x86, when the pre-switching preparation process is completed, the pre-switching preparation completion flag is turned on and range switching is performed under feedback control using the two normal phases. The process from time x86 onwards is the same as the process from time x74 onwards in Figure 25.

[0121] In Figure 27, the processing from time x90 to time x93 is the same as the processing from x70 to x73 in Figure 25. At time x94, when the rotor 103 moves from the stop position at the time of completion of pre-switching preparation due to vibration or the like, the pre-switching preparation completion flag is turned off.

[0122] At time x95, when a shift range switching request is input, the pre-switching preparation completion flag is off, so the pre-switching preparation process is performed again. In the example of Figure 27, the rotation amount ΔEN from the pre-switching preparation completion is equal to or greater than the rotation amount determination threshold ENth, so the energized phases are switched in the order of energization status ST1, ST2, ST3, as in the pre-switching preparation process from time x92 to time x93, etc.

[0123] At time x96, when the pre-switching preparation process is completed, the pre-switching preparation completion flag is turned on and range switching is performed under feedback control using the two normal phases. The process from time x96 onwards is the same as the process from time x74 onwards in Figure 25.

[0124] In this embodiment, by performing pre-switching preparation processing after the initial drive is completed and when the range switching is completed, the time required for range switching can be shortened compared to when the pre-switching preparation processing is performed after a shift request.

[0125] Furthermore, when pre-switching preparation processing is performed in advance, there is a risk that the rotor 103 may move due to vibration or the like before a shift range switching request is input, which may change the opposing state between the stator 101 and the rotor 103. Therefore, if the rotor 103 moves after the pre-switching preparation processing is completed, the pre-switching preparation processing is performed again before the range switching.

[0126] If the amount of rotation of the rotor 103 after completion of pre-switching preparation is small and the opposing state at the time of completion of pre-switching preparation can be returned to with the energization status ST3, the pre-switching preparation process can be performed only with the energization status ST3, thereby shortening the time required for the pre-switching preparation process compared to when energization is performed from the energization status ST1. Also, if the amount of rotation ΔEN of the rotor 103 is equal to or greater than the rotation amount determination threshold ENth, energization of the energization statuses ST1 to ST3 can be performed, thereby starting range switching from a predetermined opposing state.

[0127] Here, the response time is the time from the input of the shift range switching request to the start of the stop control, the response time when the rotor 103 does not move from the completion of pre-switching preparation until the input of the shift range switching request is Xr1, the response time when the rotation amount ΔEN until the input of the shift range switching request is smaller than the rotation amount determination threshold ENth is Xr2, and the response time when the rotation amount ΔEN until the input of the shift range switching request is equal to or greater than the rotation amount determination threshold ENth is Xr3. <Xr2<Xr3である。

[0128] In this embodiment, when a wire breakage fault occurs in one of the three phases and normal two-phase drive is performed in which the motor is driven using the two normal phases, the drive control unit 55 performs pre-switching preparation processing to energize the energization-holding phase after energizing it in a different energization pattern from the energization to the energization-holding phase at the start of normal two-phase drive at least one of the system startup and after the motor 10 has stopped. In this embodiment, the period after initial drive corresponds to "system startup," and the period after stop control corresponds to "after the motor has stopped." This allows for improved responsiveness compared to when pre-switching preparation processing is performed at the start of motor 10 startup.

[0129] If the motor 10 rotates between the completion of the pre-switching preparation process and the start of driving the motor 10, the drive control unit 55 performs the pre-switching preparation process again and then performs normal two-phase drive. As a result, if the rotor 103 moves due to vibration or the like between the completion of the pre-switching preparation process and the start of driving the motor, normal two-phase drive can be started from an appropriate opposing state by performing the pre-switching preparation process again.

[0130] Furthermore, if the rotation amount ΔEN of the motor 10 from the completion of the pre-switching preparation process until the start of driving the motor 10 is smaller than the rotation amount determination threshold ENth, the drive control unit 55 omits energization to phases other than the energization hold phase in the pre-switching preparation process before starting motor driving. This shortens the pre-switching preparation process time before starting motor driving. This also provides the same effects as the above embodiment.

[0131] In the embodiment, the encoder 13 corresponds to the "rotational position sensor," the encoder count value corresponds to the "detection value of the rotational position sensor," and the ECU 40 corresponds to the "motor control device." Also, the pre-switching preparation process corresponds to the "pre-start preparation process," the energization status ST1 corresponds to the "first energization process," the energization status ST2 corresponds to the "second energization process," the energization status ST3 corresponds to the "third energization process," and the energization phase in the energization status ST3 corresponds to the "energization holding phase."

[0132] (Other embodiments) In the first to sixth embodiments, the processing of each embodiment can be implemented in an appropriate combination, for example, by varying the power-on hold time depending on the ambient temperature regardless of the timing of the pre-switching preparation process, extending the power-on status before performing a retry, or allowing P-on and prohibiting P-off if a timeout occurs.

[0133] In the above embodiment, the energized phase is switched in the order of energization status ST1, ST2, and ST3 as the pre-energization preparation process. In other embodiments, one of the energization statuses ST1 and ST2 may be omitted.

[0134] 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.

[0135] In the above embodiment, two valleys are provided on the detent plate. In other embodiments, the number of valleys is not limited to two, and for example, four valleys corresponding to the P, R, N, and D ranges may be formed. Also, the detent mechanism, parking lock mechanism, etc. may be different from those in the above embodiment.

[0136] In the above embodiment, the motor control device is applied to a shift-by-wire system. In other embodiments, the motor control device may be applied to an in-vehicle system other than a shift-by-wire system, or a motor drive system other than an in-vehicle system.

[0137] 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]

[0138] 1. Shift-by-wire system 10. Motor 11. Motor winding 40···ECU (motor control unit) 41 Drive circuit 411~413 Switching elements 50 Control unit 52...Abnormality determination section 55 Drive control unit

Claims

1. A motor control device for controlling the driving of a motor (10) having three-phase motor windings (11), comprising: a drive circuit (41) having switching elements (411 to 413) for switching on and off the energization of each phase of the motor winding; a control unit (50) having a drive control unit (55) that controls the on / off operation of the switching element by feedback control based on the 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 in the motor winding; Equipped with The drive control unit When a wire breakage fault occurs in one of the three phases and normal two-phase drive is performed by using the two normal phases to drive the motor, a pre-start preparation process is performed at least either at system startup or after the motor has stopped, in which current is supplied to the energization hold phase in a different current supply pattern from that used to supply current to the energization hold phase at the start of the normal two-phase drive, and then current is supplied to the energization hold phase; As the pre-start preparation process, the energized phases are switched in the order of a first energization process for energizing one of the normal phases, a second energization process for energizing two of the normal phases, and a third energization process for energizing the energization-maintaining phase of one phase; If the motor rotates after the pre-start preparation process is completed and before the motor starts to be driven, the motor control device performs the pre-start preparation process again and then performs the normal two-phase drive.

2. The energized phase in the pre-start preparation process is set according to the disconnection phase and the rotation direction of the motor, 2. The motor control device according to claim 1, wherein the energized phase of the first energization process is a phase that is energized before the disconnection phase in terms of the energization phase switching order.

3. 3. The motor control device according to claim 1, wherein the drive control unit omits energization to phases other than the energization holding phase during the pre-start preparation process before starting to drive the motor if the amount of rotation of the motor from the completion of the pre-start preparation process to the start of driving the motor is smaller than a rotation amount determination threshold.

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