JP7760980B2 - Motor control device - Google Patents

Description

The present invention relates to a motor control device.

Motor control devices that control the drive of motors are known. For example, in Patent Document 1, an open circuit detection circuit is provided in each current-carrying line of the winding for each phase to detect open circuits.

Japanese Patent Application Laid-Open No. 2004-129450

Even if a wire breaks in one phase, the motor can continue to operate if inertia can pass the broken phase. 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 begins in one of the two normal phases, the stator salient pole of the energized phase faces the rotor recess, and the energized phase and the rotor tooth tip may not face each other.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a motor control device that can properly drive a motor even when one phase is broken.

The motor control device of the present invention controls the drive 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 power supply to each phase of the motor winding. The control unit includes a drive control unit (55) that controls the on/off operation of the switching elements through 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 whether the motor winding has an open circuit.

When a wire breakage fault occurs in one of the three phases and normal two-phase drive is performed using the two normal phases to drive the motor, the drive control unit performs a pre-start preparation process in which current is supplied to the energized hold phase in a pattern different from the current supply pattern to the energized hold phase that was the energized phase when normal two-phase drive was started.As the pre-start preparation process, the drive control unit switches the energized phases in the following order: a first energization process in which current is supplied to one of the normal phases, a second energization process in which current is supplied to two of the normal phases, and a third energization process in which current is supplied to the energized hold phase of one phase.This allows the motor to be driven appropriately when one phase is broken.

1 is a perspective view showing a shift-by-wire system according to a first embodiment; 1 is a schematic configuration diagram showing a shift-by-wire system according to a first embodiment. FIG. 2 is a circuit diagram illustrating an ECU according to the first embodiment. 1 is a schematic diagram showing a motor according to a first embodiment. FIG. 4 is a map in which energized phase numbers are associated with energized phases according to the first embodiment. 5A and 5B are explanatory diagrams illustrating a disconnection phase and a facing position depending on a switching direction according to the first embodiment. 10 is a schematic diagram showing an opposing state at the start of energization when driving in the forward direction in the event of a U-phase disconnection in the first embodiment. FIG. FIG. 4 is an explanatory diagram illustrating motor driving in normal two phases in the first embodiment. FIG. 5 is an explanatory diagram illustrating switching of energized phases in the pre-switching preparation process according to the first embodiment. 5A to 5C are explanatory diagrams illustrating the behavior of the rotor in the pre-switching preparation process according to the first embodiment. 4 is a flowchart illustrating a range switching process according to the first embodiment. 5 is a time chart illustrating a range switching process according to the first embodiment. 10 is a flowchart illustrating a range switching process according to a second embodiment. 10 is a flowchart illustrating a range switching process according to a third embodiment. 10 is a time chart illustrating a range switching process according to a third embodiment. 10 is a flowchart illustrating a range switching process according to a fourth embodiment. 10 is a time chart illustrating a range switching process according to a fourth embodiment. 10 is a time chart illustrating a range switching process according to a fourth embodiment. 13 is a flowchart illustrating a range switching process according to a fifth embodiment. 10 is a time chart illustrating a range switching process according to a fifth embodiment. 10 is a time chart illustrating a range switching process according to a fifth embodiment. 10 is a time chart illustrating a range switching process according to a fifth embodiment. 13 is a flowchart illustrating a startup process according to the sixth embodiment. 13 is a flowchart illustrating a range switching process according to a sixth embodiment. 13 is a time chart illustrating a range switching process according to a sixth embodiment. 13 is a time chart illustrating a range switching process according to a sixth embodiment. 13 is a time chart illustrating a range switching process according to a sixth embodiment.

(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.

The first embodiment is shown in Figures 1 to 12. As shown in Figures 1 and 2, the shift-by-wire system 1 includes a motor 10, a detent mechanism 20, a parking lock mechanism 30, and an ECU 40 as a motor control device.

The motor 10 rotates when power is supplied from a battery 90 installed in 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.

As shown in Figures 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 by a connection 115. The connection 115 is connected to the battery 90 via a motor relay 91 and a fuse 92.

The rotor 103 has salient poles and is rotatably mounted radially inside the stator 101. The rotor 103 is driven to rotate by switching the energized phases of the coils 111-113. 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 will be referred to as concave portions 105.

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

The magnet 135 is formed in an annular shape and is arranged coaxially with the rotor 103. The magnet 135 is magnetized with alternating north and south poles at equal pitches in the circumferential direction. 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. In other words, 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 x 6 = 45°.

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

Returning to Figure 1, the reducer 14 is located 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 Figure 2).

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.

The detent plate 21 is fixed to the output shaft 15 and driven by the motor 10. The detent plate 21 has two valleys 211, 212 and a peak 215 separating the valleys 211, 212 on the side facing the detent spring 25.

The detent spring 25 is an elastically deformable plate-shaped member with 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 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 211 and 212. When the detent roller 26 fits into either of the valleys 211 or 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.

The parking lock mechanism 30 includes 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, with one end 311 fixed to the detent plate 21. A cone 32 is provided on the other end 312 of the parking rod 31. 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.

The parking lever 33 abuts against the conical surface of the cone 32 and is pivotable around the shaft 34. A protrusion 331 that can mesh with the parking gear 35 is provided on the parking lever 33's 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 of arrow not P, the meshing between the protrusion 331 and the parking gear 35 is released.

The parking gear 35 is connected to the drive shaft (not shown) and is arranged to be able to mesh with the 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.

In this embodiment, the rotation direction of the motor 10 when switching from P range to not P range is the forward direction, and the rotation direction of the motor 10 when switching from not P range to P range is the reverse direction.

As shown in Figures 2 and 3, the ECU 40 includes a drive circuit 41, a current detection unit 45, a voltage detection circuit 46, and a control unit 50. 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 current flow to the corresponding phase. In this embodiment, the switching elements 411 to 413 are provided between the coils 111 to 113 and ground. In this embodiment, the switching elements 411 to 413 are MOSFETs, but may also be IGBTs, etc.

The current detection unit 45 is provided on the collective wiring connecting the sources of the switching elements 411-413 to ground, and detects the sum of the currents flowing through the coils 111-113. Hereinafter, the current detected by the current detection unit 45 will be 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 111-113, or may be provided for each phase.

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

The control unit 50 is primarily composed of a microcomputer 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 pre-stored in a physical memory device (i.e., a readable non-transitory tangible recording medium) such as ROM, or it may be hardware processing using dedicated electronic circuits.

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 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, the current detection unit 45, and the voltage detection circuit 46. The abnormality determination unit 52 determines abnormalities in the shift-by-wire system 1, such as a broken wire.

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

As shown in FIG. 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.

In this embodiment, if a wire break occurs in one phase, range switching is performed by driving the motor 10 by energizing the two normal phases through feedback control. For example, if the U phase is broken, no torque is generated in energized phases 2 and 3, which normally only energize the U phase, but the motor 10 can continue to be driven by passing through this region using inertia.

When switching ranges due to a single-phase disconnection, it is desirable to start the switching drive from a so-called "one-phase, one-tooth" state, where the energized phase and the convex portion 104 of the rotor 103 face each other. Hereinafter, the state in which the U-phase salient pole 102 and the rotor 103 convex portion 104 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."

As shown in Figure 6, the opposing positional relationship between the salient poles 102 of the stator 101 and the convex portions 104 of the rotor 103 at the start of switching is set depending on the broken phase and the rotational direction of the motor 10. If the U-phase is broken and the switching direction is forward, the range switching starts from the V-phase facing state, and if it is reverse, the range switching starts from the W-phase facing state. If the V-phase is broken and the switching direction is forward, the range switching starts from the W-phase facing state, and if it is reverse, the range switching starts from the U-phase facing state. If the W-phase is broken and the switching direction is forward, the range switching starts from the U-phase facing state, and if it is reverse, the range switching starts from the V-phase facing state. The following explanation focuses on an example where the switching direction is forward when the U-phase is broken.

As shown in Figure 7, when switching to forward rotation 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 motor torque corresponding to the energized phase in the upper row. 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, a torque is generated to rotate the rotor 103.

If there is no U-phase open circuit, the W-phase is energized, followed by the WU-phase, U-phase, and UV-phase. On the other hand, when the U-phase is open circuit, 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, motor torque becomes zero. If this region is passed through inertia, current is passed through the V-phase in the UV-phase energized region, increasing motor torque, and motor 10 continues to rotate. In Figures 7 and 8, energized phase coils are indicated by solid lines, non-energized phase coils are indicated by dashed lines, and the open circuit state is indicated by omitting the U-phase coil 111.

Here, if only V-phase current is applied before range switching, the recessed portion 105 of the rotor 103 and the V-phase salient pole 102 may face each other when the V-phase is applied, and in this state, driving cannot be started from the V-phase facing state. If the current application phase is switched from V-phase current application to VW-phase current application when the V-phase salient pole 102 and the recessed portion 105 of the rotor 103 face each other, the rotor 103 may rotate in the reverse direction, or the rotation speed may be insufficient in the area where inertia is desired to pass through, preventing it from passing through the open circuit phase.

In this embodiment, therefore, 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 Figure 6. In the pre-switching preparation process, as shown in Figure 9, one-phase energization, two-phase energization, and one-phase energization are performed in sequence, so that the energized phases at the start of switching are opposed in a one-tooth, one-phase state.

Specifically, if 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. If the direction is reverse, V-phase energization, VW-phase energization, and W-phase energization are performed as pre-switching preparations. If 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. If the direction is reverse, W-phase energization, WU-phase energization, and U-phase energization are performed as pre-switching preparations. If 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. If the direction is reverse, U-phase energization, UV-phase energization, and V-phase energization are performed as pre-switching preparations. Below, the initial 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 the energized phase at the start of switching is referred to as energization status ST3.

Figure 10 shows the pre-switching preparations for achieving a V-phase opposing state when the U-phase is broken. 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 W-phase, resulting in a so-called "two-phase, two-tooth" state. By switching from the two-phase, two-tooth state to V-phase energization, 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.

The range switching process of this embodiment will be described based on the flowchart in Figure 11. This process is executed by the control unit 50 at a predetermined interval. In S101, the control unit 50 determines whether 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 detection of a one-phase break is performed in a process separate from this embodiment, and is determined, for example, based on the detection value of the voltage detection circuit 46, although 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.

In S102, the control unit 50 determines whether 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 onwards is skipped and standby mode continues. If it is determined that there is a request to switch (S102: YES), the process proceeds to S103.

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

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

In S107, the drive control unit 55 applies current in the current status ST3. For example, if the U-phase is disconnected and the switching direction is forward, the V-phase is energized. In S108, the drive control unit 55 determines whether the current hold time Xh3 in the current status ST3 has elapsed. If it is determined that the current hold time Xh3 has not elapsed (S108: NO), the process returns to S107, and current is continued in the current status ST3. If it is determined that the current 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 time after the start of range switching.

In S110, the drive control unit 55 drives the motor 10 from a one-phase, one-tooth facing state at a predetermined position corresponding to the broken phase and rotation direction, and performs range switching using 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 continues feedback control with two normal phases. If it is determined that the range switching is complete (S111: YES), the process transitions to standby mode and ends this process.

The range switching process of this embodiment will be explained based on the time chart in Figure 12. In Figure 12, the horizontal axis represents a common time axis, and from the top, the motor control mode, one-phase open circuit detection status, pre-switching preparation completion flag, motor rotation angle, and energized phase are shown. The motor rotation angle is a value that can be converted from the encoder count value, with the actual value shown as a solid line and the target value shown as a dashed line. The time when the detent roller 26 is at the bottom of the valley 211 is shown as P, and the time when it is at the bottom of the valley 212 is shown as notP. The same applies to Figure 15, etc., described below.

In Figure 12, the vibration components of the rotor 103 due to switching of the energization status are omitted. The energized phase numbers for the energized phases during shift switching are shown in parentheses. For simplicity, the energized phase numbers are the numbers at the time of switching. 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 progression of the motor rotation angle.

If a one-phase break occurs at time x0, the abnormality is confirmed at time x1, and then a shift range switch request is input at time x2, pre-switch preparation processing is performed. In pre-switch preparation processing, the energized phases are switched at predetermined intervals in the order of energization status ST1, ST2, and ST3. The energized phases for energization status ST1, ST2, and ST3 are set according to the broken phase and the switching direction.

Note that because the energization status ST2 indicates two-phase energization, the rotor 103 is more likely to stabilize, and the energization hold time Xh2 can be a relatively short time. Furthermore, since it is desirable for the energization status ST3 to be reliably maintained in a one-phase, one-tooth state, it is set to a relatively long time. Therefore, in this embodiment, Xh2≦Xh1≦Xh3 is set.

At time x3, when the pre-switching preparation process is completed, the pre-switching preparation complete 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. In this embodiment, stop control 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.

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 drive involves energizing one phase, then two phases, and then one phase in that order. This allows the motor 10 to start driving from a one-phase, one-tooth state in which the convex portion 104 of the rotor 103 faces the energized phase at the start of switching.

As described above, the ECU 40 controls the drive of a motor having three-phase motor windings 11 and includes a drive circuit 41 and a control unit 50. The drive circuit 41 has switching elements 411-413 that switch on and off the power supply to each phase of the motor windings 11. The control unit 50 has a drive control unit 55 that controls the on/off operation of the switching elements 411-413 through feedback control based on the detection value of the encoder 13 that detects the rotational position of the motor 10, and an abnormality determination unit 52 that determines whether the motor windings 11 have an open circuit.

When a wire breakage fault has occurred 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 energized phase after energizing it in a pattern different from the energization pattern to the energized hold phase, which is the energized phase at the start of normal two-phase drive. Here, a wire breakage fault is a fault that prevents current from flowing through the coil, and includes a wire breakage in the harness and a switching element stuck off.

By performing pre-switching preparation processing, the rotor 103 can be rotated to a position where the stator 101 and rotor 103 face each other and torque can be generated under normal two-phase drive. This allows the motor 10 to be driven appropriately even in the event of a one-phase break.

As a pre-energization preparation process, the drive control unit 55 switches the energization phase in the following order: energization status ST1, which is the first energization process for energizing one of the normal phases; energization status ST2, which is the second energization process for energizing two of the normal phases; and energization status ST3, which is the third energization process for energizing one phase that remains energized. This allows the opposing positions of the stator 101 and rotor 103 to be appropriately aligned to the specified positions.

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 in energization status ST1 is the phase that is energized before the disconnection phase in terms of the energization phase switching order. This allows the opposing positions of the stator 101 and rotor 103 to be properly aligned.

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

In S120, which occurs after energization status ST2, the control unit 50 sets the energization hold time Xh3 of energization status ST3 according to the ambient temperature H. Specifically, if the ambient temperature H is less than the first determination threshold Hth1, the energization hold time is Xp; if the ambient temperature H is equal to or greater than the first determination threshold Hth1 but less than the second determination threshold Hth2, the energization hold time is Xq; and if the ambient temperature H is equal to or greater than the second determination threshold Hth2, the energization hold time is Xr. The magnitude relationships between the values are Hth1<Hth2 and Xp<Xq<Xr. The ambient temperature H is the ambient temperature of the motor 10 and may be the temperature of the motor 10 itself, or it may be the temperature of other components located near the motor 10, such as the oil temperature in the transmission.

The energization status ST13 is maintained in a one-phase, one-tooth state with one phase energization. Here, with one phase energization, the rotor 103 is prone to vibration. Furthermore, when the ambient temperature H is low, friction is large, making the rotor 103 less likely to vibrate. Therefore, in this embodiment, the lower the ambient temperature H, the shorter the energization hold time Xh3 in the energization status ST3, thereby improving responsiveness. Note that in this example, the energization hold time Xh3 is set to three levels using two determination thresholds Hth1 and Hth2. However, the number of levels does not matter as long as the determination threshold is 1 or greater. Furthermore, instead of threshold determination, the energization hold time Xh3 may be set by calculation using a map or function corresponding to the ambient temperature H. Furthermore, similar to the energization status ST3, the energization hold time Xh1 for the energization status ST1, which is one-phase energization, may also be variable according to the ambient temperature H.

In this embodiment, the energization time in the pre-switching preparation process is variable depending on the motor temperature. Specifically, the lower the motor temperature, the shorter the energization time of energization status ST3 is set. This allows the energization time to be appropriately set depending on the motor temperature, which contributes to improved responsiveness, especially at low temperatures. It also provides the same effects as the above embodiment.

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

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.

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 begins 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. Then, the process proceeds to S207, where energization begins with energization status ST2. The processing of S207 to S210 is the same as the processing of S105 to S108.

In S211, which is reached after the energization hold time Xh3 in 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 and performs range switching in normal two-phase. 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 and extends energization in energization status ST3 by a predetermined time Xc. The extension times for energization status ST1 and ST3 may be the same or different. The processing of S213 to S215 is the same as the processing of S109 to S111 in FIG. 11.

The range switching process of this embodiment will be explained based on the time chart in Figure 15. Here, the explanation will be given assuming that the amplitude determination thresholds Ath1 and Ath3 are equal. For the sake of explanation, the vibration component with one phase current is emphasized. The process from times x10 to x12 is the same as the process from times x0 to x2 in Figure 12.

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

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 or below the amplitude determination threshold Ath3 while energization status ST3 is being extended. After extending energization status ST3 for the predetermined time Xc, range switching is performed with normal two phases. Processing from time x16 onwards is the same as the processing from time x3 onwards in Figure 12.

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 energization status ST1 and 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 rotor 103 is more likely to be unstable compared to two-phase energization. This also achieves the same effects as the above embodiment.

(Fourth embodiment)
A fourth embodiment is shown in Figures 16 to 18. Figure 16 differs from Figure 14 in that S231 and S232 replace S206, and S233 and S234 replace S212. In S205, which is performed after the current application hold time Xh1 has elapsed in the current application status ST1, if it is determined that the amplitude A1 is greater than the amplitude determination threshold Ath1 (S205: NO), the current application status ST1 is extended in S231.

In S232, the control unit 50 determines whether the timeout period Xout1 has elapsed since the start of extension of the energized status ST1. If it is determined that the timeout period has not elapsed (S232: NO), the control unit 50 continues to extend the energized status ST1 and returns to S205. If it is determined that the timeout period Xout1 has elapsed (S232: YES), the control unit 50 proceeds to S207 and switches the energized state to the energized status ST2.

In S211, which is performed after the current holding time Xh3 has elapsed in the current status ST3, if it is determined that the amplitude A3 is greater than the amplitude determination threshold Ath3 (S211: NO), the current status ST3 is extended in S233.

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

The range switching process of this embodiment will be explained based on the time charts in Figures 17 and 18. Figure 17 shows a case where vibration subsides before the 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. Because the amplitude A3 is greater than the amplitude determination threshold Ath3 at time x25, the current flow in the current flow status ST3 is extended.

At time x26, before the timeout period Xout3 has elapsed since time x25, which is the extension start time for 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 a normal two-phase range switch is performed. The processing from time x26 onwards is the same as in the example above.

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 current flow in the current flow status ST3 is extended.

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

The current status ST3 immediately before pre-switching preparation is complete is one-phase current, which makes it easy for the rotor 103 to vibrate and makes it difficult to determine the opposing position. 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 specified opposing position, and pre-switching preparation is completed. This allows range switching to begin appropriately.

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 extended energization. Specifically, when the timeout period Xout1 has elapsed in energization status ST1, the drive control unit 55 transitions to energization status ST2. 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 if vibrations during single-phase energization do not subside. This also provides the same effects as the above embodiment.

Fifth Embodiment
A fifth embodiment is shown in Figures 19 to 22. In this embodiment, if the preparation for starting switching is not properly performed during the pre-switching preparation, a retry is performed. The range switching process of this embodiment will be described with reference to the flowchart in Figure 19.

The processing of S301 and S302 is the same as the processing of S101 and S102 in Figure 11. If it is determined that a switch request has been made (S302: YES), the process proceeds to S303, where the retry flag described below is turned off.

The processing of S304 to S306 is the same as the processing of S203 to S205 in FIG. 14. If it is determined that the amplitude A1 is equal to or less 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 turned on.

The processing of S308 to S312 is the same as the processing 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 it 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.

In S313, the control unit 50 determines whether a voltage drop occurred between the start of current flow in current flow status ST1 and the end of current flow in current flow 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 control unit 50 determines whether a voltage drop occurred after current flow status ST3 ends. However, the control unit 50 may also perform voltage monitoring separately from this process and set the retry flag to ON when a voltage drop occurs.

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 control unit 50 proceeds to S319. If it is determined that the retry flag is on (S315: YES), the control unit 50 proceeds to S316, where it increments the retry counter Cr.

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-switch 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.

In S318, the control unit 50 determines whether the input switching request is for switching from P range to not P range. If it is determined that the request is for switching from P range to not P range (S303: YES), the processing from S319 onwards is skipped. If it is determined that the request is for switching from not P range to P range (S318: NO), the processing proceeds to S319, where the retry flag is turned off and the pre-switch 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.

In other words, 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-in side, and range switching is not performed on the P-out 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.

The range switching process of this embodiment will be explained based on the time charts in 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 from the top row showing motor control, one-phase open circuit detection status, pre-switching preparation completion flag, retry flag, retry counter, motor voltage, and current-carrying phase. The same is true for Figure 22.

The processing from time x40 to time x42 is the same as the processing from time x0 to time x2 in Figure 12. At time x43, when the motor voltage Vm falls below the voltage determination threshold Vth, the retry flag is turned on.

At time x44, when power-on 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, power is again applied with power-on statuses ST1 to ST3.

At time x45, when the current status ST3 for 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 a normal two-phase range change is performed. The processing from time x45 onwards is substantially the same as the processing from time x3 onwards in Figure 12. Note that the retry counter is reset at any timing after the start of range change. In Figure 20, the retry counter is reset when the pre-switching preparation complete flag is turned off, but this may be done at a different timing.

Figure 21 shows an example of when vibrations at energization status ST3 have not converged. The horizontal axis represents a common time axis, and from the top, it shows motor control, one-phase open circuit detection status, 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 Figure 12.

When energization status ST3 ends at time x53, amplitude A3 is greater than amplitude judgment threshold Ath3, so the retry flag is turned on and the pre-switching preparation process is retried at time x54. At time x54, the retry flag is turned off and the retry counter is incremented. Note that for the sake of explanation, time x53 is shifted to the left side of the page in Figure 21. 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.

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

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 switched from not 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.

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 complete 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.

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 vibrations do not converge in the energization status ST1, there is a risk that the opposing state will not change to two phases, two teeth, or one phase, one tooth when the energization status is switched to ST2 or ST3, 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 initiated with a normal two-phase opposing state.

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

When the number of retries reaches or exceeds the determined number, the drive control unit 55 starts normal two-phase drive. This allows the motor 10 to start driving even when there is significant vibration.

When applied to a shift-by-wire system, the ECU 40 allows shifting from a range other than P range to P range using normal two-phase drive when the number of retries is equal to or greater than the number of determinations and the retry conditions are met, and prohibits shifting from P range to a range other than P range. This allows the shift range to be switched appropriately, and also achieves the same effects as the above embodiment.

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

The startup process of this embodiment will be described based on the flowchart in Figure 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 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.

The processing of S402 is the same as the processing of S101 in Figure 11. If it is determined that a one-phase break has not been detected (S402: NO), the subsequent processing is skipped. If it is determined that a one-phase break has been detected (S402: YES), the processing proceeds to S403.

S403 to S408 are pre-switching preparation processes similar to S103 to S108 in Figure 11. When the pre-switching preparation process is completed, the control unit 50 turns on the 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 set as the initial value ENi and is stored in a storage unit such as RAM (not shown).

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

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.

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

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, 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.

The processing of S508 and S509 is the same as the processing of S107 and S108 in Figure 11, and energization is performed in energization status ST3 for the energization hold time Xh3. If it is determined that the energization hold time Xh3 has elapsed in energization status ST3 (S508: YES), the process proceeds to S515.

The processing of S509 to S514 is the same as the processing of S103 to S108 in Figure 11. If the rotation amount ΔEN is equal to or greater than the rotation amount determination threshold ENth, the pre-switching preparation processing is performed by switching the current status between ST1, ST2, and ST3. If it is determined in current status ST3 that the current hold time Xh3 has elapsed (S514: YES), the processing proceeds to S515.

The processing of S515 to S517 is the same as the processing of S109 to S111 in Figure 11, and performs range switching with normal two phases. If it is determined that range switching is complete (S517: YES), proceed to S518 and perform pre-switching preparation processing. In S518, pre-switching preparation processing is performed by switching the current status between ST1, ST2, and ST3, just like in S509 to S515. After the current hold time Xh3 has elapsed in current status ST3, the pre-switching preparation complete flag is turned on, and standby mode is entered in S519. In addition, the encoder count value EN at the time pre-switching preparation is complete is retained as the initial value ENi.

The range switching process of this embodiment will be explained based on the time charts in Figures 25 to 27. As shown in Figure 25, when the IG is turned on at time x70 and a one-phase break is detected through 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.

In the example of Figure 25, the rotor 103 is not moving during standby, and the pre-switch preparation complete flag remains on. When a shift range switch request is input at time x74, the pre-switch preparation complete flag is on, so range switching is performed using feedback control using the normal two phases from this state.

At time x75, when the target attainment determination 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 for the next range switch, if there is a U-phase break, current is applied in the order V-phase → VW-phase → W-phase. At time x77 when pre-switch preparation processing ends, the pre-switch preparation complete flag is turned on and the system transitions to standby mode.

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, if the rotor 103 moves from the stop position at which it was stopped when pre-switching preparation was complete, for example due to vibration, the pre-switching preparation completion flag is turned off.

When a shift range switch request is input at time x85, the pre-switch preparation complete flag is off, so pre-switch preparation processing is performed again. In the example of Figure 26, the rotation amount ΔEN from pre-switch preparation complete is less than the rotation amount determination threshold ENth, so as pre-switch preparation processing, V-phase current is applied if only energization status ST3 is present, i.e., forward rotation with U-phase disconnection.

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 using 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.

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 pre-switching preparation is complete due to vibration or the like, the pre-switching preparation completion flag is turned off.

When a shift range switch request is input at time x95, the pre-switch preparation completion flag is off, so pre-switch preparation processing is performed again. In the example of Figure 27, the rotation amount ΔEN since pre-switch 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, and ST3, as in the pre-switch preparation processing from time x92 to time x93, etc.

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 using 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.

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

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

If the amount of rotation of the rotor 103 after pre-switching preparation is complete is small and the opposing state at the time of pre-switching preparation completion can be restored in energization status ST3, the pre-switching preparation process can be limited to energization status ST3, thereby shortening the time required for the pre-switching preparation process compared to when energization is performed from energization status ST1. Furthermore, if the amount of rotation ΔEN of the rotor 103 is equal to or greater than the rotation amount determination threshold ENth, energization in energization statuses ST1 to ST3 can be performed to start range switching from the specified opposing state.

Here, the response time is the time from the input of the shift range switch request to the start of stop control, the response time when the rotor 103 does not move from the completion of pre-switch preparation until the input of the shift range switch request is Xr1, the response time when the rotation amount ΔEN until the input of the shift range switch request is less 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 switch request is greater than or equal to the rotation amount determination threshold ENth is Xr3, where Xr1 < Xr2 < Xr3.

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 energized phase after energizing it using a different energization pattern than the energization to the energized phase at the start of normal two-phase drive, at least either at system startup or after motor 10 stop control. This allows for improved responsiveness compared to when pre-switching preparation processing is performed at the start of motor 10 startup.

If the motor 10 rotates after the pre-switching preparation process is completed and before the motor 10 starts to drive, the pre-switching preparation process is performed again, and then normal two-phase drive is performed. 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 motor drive, the pre-switching preparation process can be performed again, allowing normal two-phase drive to start from the appropriate opposing state.

Furthermore, if the rotation amount ΔEN of the motor 10 from the completion of the pre-switching preparation process to the start of driving the motor 10 is smaller than the rotation amount determination threshold ENth, energization to phases other than the energization hold phase is omitted in the pre-switching preparation process before motor driving starts. This shortens the pre-switching preparation process time before motor driving starts, and also achieves the same effects as the above embodiment.

In this 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." Furthermore, 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."

(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.

In the above embodiment, the pre-energization preparation process involves switching the energized phase in the order of energization status ST1, ST2, and ST3. In other embodiments, one of energization status ST1 and ST2 may be omitted.

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 something other than a switched reluctance motor, such as a DC brushless motor. The number of phases of the motor winding may also be four or more.

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 may be formed corresponding to the P, R, N, and D ranges. Furthermore, the detent mechanism, parking lock mechanism, etc. may differ from those in the above embodiment.

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 to a motor drive system other than an in-vehicle system.

A feature of the present invention may be, for example, "the motor control device according to any one of claims 1 to 5, wherein the energization time during the pre-start preparation process is variable depending on the temperature of the motor."

The control unit and method described in the present disclosure 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 method described in the present disclosure 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 method described in the present disclosure 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 on a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer. As described above, the present invention is in no way limited to the above embodiments, and various forms may be implemented within the scope of the invention.

1... Shift-by-wire system 10... Motor 11... Motor winding 40... ECU (motor control unit)
41: Drive circuit 411 to 413: Switching elements 50: Control unit 52: Abnormality determination unit 55: Drive control unit

Claims (5)

A motor control device for controlling the driving of a motor (10) having a three-phase motor winding (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
when a wire breakage fault has occurred in one of the three phases and normal two-phase drive is to be performed in which the motor is driven using the two normal phases, the drive control unit performs a pre-start preparation process in which current is supplied to the energization hold phase, which is the energized phase at the start of the normal two-phase drive, in a pattern different from the current supply pattern to the energization hold phase ,
The drive control unit is a motor control device that switches the current flow phase in the following order as the pre-start preparation process: a first current flow process in which current is flowed through one of the normal phases, a second current flow process in which current is flowed through two of the normal phases, and a third current flow process in which current is flowed through the current-maintaining phase of one phase . 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. The motor control device according to claim 1, wherein the drive control unit extends the current flow time when the amplitude of the motor rotation angle when the current flow holding time has elapsed is greater than an amplitude determination threshold during at least one of the first current flow process and the third current flow process. The motor control device according to claim 3 , wherein the drive control unit proceeds to a next energization process when a timeout period has elapsed since the start of the extension of energization. 2. The motor control device according to claim 1 , wherein the power supply time in the pre-start preparation process is variable depending on the temperature of the motor.