Motor control device

Abstract

To provide a motor control device capable of appropriately specifying a failure state.SOLUTION: An ECU 40 controls driving of a motor 10 having a motor winding wire 11, and includes a drive circuit 41 and a control unit 50. The drive circuit 41 includes switching elements 411 to 413 that turn on and off energization to each phase of the motor winding wire 11. The control unit 50 includes a drive control unit 55 that controls on / off operations of the switching elements 411 to 413, and an abnormality determination unit 52 that determines an abnormality of an energization path to the motor winding wire 11. The abnormality determination unit 52 specifies a faulty phase based on a voltage detection value when the switching elements 411 to 413 of all phases are turned off, and specifies a constant energization failure of the faulty phase based on at least one of current detection values when the switching element of the specified faulty phase is turned on and a rotation position detection value when the switching elements 411 to 413 of one phase or the plurality of phases of normal values are turned on.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] In Patent Document 1, when the switching element is turned off, the voltage becomes high level in both the case of a wire breakage fault and a ground short-circuit fault, and it is not possible to distinguish between the two.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a motor control device that can appropriately identify a fault state. [Means for solving the problem]

[0006] The motor control device of the present invention controls the driving of a motor (10) having motor windings (11) of three or more phases, and includes a drive circuit (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, and an abnormality determination unit (52) that determines whether there is an abnormality in the current path to the motor windings.

[0007] The control unit can acquire a voltage detection value, which is a detection value of a voltage detection unit (46) that detects each phase voltage of the motor windings, a current detection value, which is a detection value of a current detection unit (45) that detects a current flowing through the motor windings, and a rotation position detection value, which is a detection value of a rotation detection unit (13) that detects the rotation position of the motor.

[0008] The abnormality determination unit identifies the faulty phase based on the voltage detection value when the switching elements of all phases are turned off. The abnormality determination unit identifies the constantly energized fault of the faulty phase based on at least one of the current detection value when the switching elements of the identified faulty phase are turned on and the rotational position detection value when the switching elements of one or more normal phases are turned on. This makes it possible to appropriately identify the fault state. [Brief explanation of the drawings]

[0009] [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] FIG. 1 is a schematic diagram showing an encoder according to a first embodiment. [Figure 6] FIG. 10 is a circuit diagram illustrating a U-phase disconnection. [Figure 7] FIG. 10 is a circuit diagram illustrating a ground short circuit. [Figure 8] FIG. 10 is a circuit diagram illustrating an incomplete ground short circuit. [Figure 9] 4 is a flowchart illustrating a faulty phase determination process according to the first embodiment. [Figure 10] FIG. 10 is an explanatory diagram illustrating a current when a switching element of a faulty phase is turned on in the event of an incomplete ground short circuit. [Figure 11]FIG. 10 is an explanatory diagram showing a current when a switching element of a faulty phase is turned on when a ground short circuit occurs. [Figure 12] FIG. 10 is an explanatory diagram illustrating the magnetic attraction force when current is applied to the V phase. [Figure 13] 4A and 4B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the first embodiment. [Figure 14] 4A and 4B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the first embodiment. [Figure 15] 4A and 4B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized fault in the first embodiment. [Figure 16] 4A and 4B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized fault in the first embodiment. [Figure 17] 5A and 5B are explanatory diagrams illustrating a rotation angle difference according to switching of an energization status according to the first embodiment. [Figure 18] 4 is a flowchart illustrating a current application process related to failure identification according to the first embodiment. [Figure 19] 4 is a flowchart illustrating a current application process related to failure identification according to the first embodiment. [Figure 20] 4 is a flowchart illustrating a failure state determination process according to the first embodiment. [Figure 21] 5 is a time chart illustrating the behavior of the rotor in the current application process according to the first embodiment. [Figure 22] 10 is a sub-flow illustrating a maximum value update process of the energization status ST13 according to the first embodiment. [Figure 23] 10 is a sub-flow illustrating a process of updating the minimum value of the energization status ST14 according to the first embodiment. [Figure 24] 4 is a time chart illustrating a range switching process according to the first embodiment. [Figure 25] 4 is a map in which energized phase numbers are associated with energized phases according to the first embodiment. [Figure 26] 5 is a time chart illustrating a process to be performed in the first embodiment when a stagnation abnormality occurs during normal two-phase motor driving. [Figure 27] 10 is a flowchart illustrating a current application process related to failure identification according to a second embodiment. [Figure 28] 10 is a flowchart illustrating a failure state determination process according to a second embodiment. [Figure 29] 10 is a time chart illustrating a range switching process according to a second embodiment. [Figure 30] 11A and 11B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the third embodiment. [Figure 31] 11A and 11B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the third embodiment. [Figure 32] 11A and 11B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized failure in the third embodiment. [Figure 33] 11A and 11B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized failure in the third embodiment. [Figure 34] 10A and 10B are explanatory diagrams illustrating a rotation angle difference according to switching of an energization status according to a third embodiment. [Figure 35] 10 is a flowchart illustrating a current application process related to failure identification according to a third embodiment. [Figure 36] 10 is a flowchart illustrating a current application process related to failure identification according to a third embodiment. [Figure 37] 10 is an explanatory diagram illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the fourth embodiment. FIG. [Figure 38] 10 is an explanatory diagram illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the fourth embodiment. FIG. [Figure 39] 13A and 13B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized failure in the fourth embodiment. [Figure 40] 13A and 13B are explanatory diagrams illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized failure in the fourth embodiment. [Figure 41] 10 is a flowchart illustrating a failure state determination process according to the fourth embodiment. [Figure 42] 13 is a time chart illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the fifth embodiment. [Figure 43] 13 is a time chart illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase break in the fifth embodiment. [Figure 44] 13 is a time chart illustrating the behavior of the rotor when the energization status is switched in the event of a U-phase constantly energized failure in the fifth embodiment. [Figure 45] 10 is a flowchart illustrating a current application process related to failure identification according to the fifth embodiment. [Figure 46] 10 is a flowchart illustrating a failure state determination process according to the fifth embodiment. [Figure 47] 13 is a sub-flow illustrating a maximum / minimum value update process in the energization status ST22 according to the fifth embodiment. [Figure 48] 13 is a sub-flow illustrating a maximum / minimum value update process in the energization status ST23 according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] (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.

[0011] The first embodiment is shown in Figures 1 to 26. 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.

[0012] 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.

[0013] 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.

[0014] 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 are referred to as convex portions 104, and the spaces between the convex portions are referred to as concave portions 105.

[0015] 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.

[0016] As shown in FIG. 5, 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 in the following order: U phase → UV phase → V phase → VW phase → W phase → WU phase, and six energized phase changes are performed to complete one cycle, the rotor 103 rotates through a mechanical angle of 7.5×6=45°.

[0017] 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.

[0018] 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).

[0019] 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 .

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] As shown in FIGS. 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 energization of the corresponding phases. In this embodiment, the switching elements 411 to 413 are provided between the coils 111 to 113 and ground. The switching elements 411 to 413 in this embodiment are MOSFETs, but may also be IGBTs or the like. In the drawings, the switching elements 411 to 413 are referred to as "MOS" where appropriate.

[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. Details of the abnormality determination will be described later. 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.

[0032] The following explanation focuses on abnormality detection, taking as an example the case where the faulty phase is the U phase. The voltage detection circuit 46 has voltage dividing resistors (not shown) corresponding to each phase, and the abnormality determination unit 52 identifies the faulty phase based on the voltage level at the intermediate connection point of the voltage dividing resistors of the voltage detection circuit 46. Hereinafter, the voltage level at the intermediate connection point of the voltage dividing resistors will be referred to as the "port level."

[0033] When coils 111-113 are normal, motor relay 91 is on, and switching elements 411-413 are off, the port level is a voltage level (hereinafter referred to as "high level") that corresponds to the battery voltage and the resistance value of the voltage-dividing resistor. On the other hand, as shown by the dashed oval in Figure 6, if there is a break in the U-phase current line, the U-phase port level becomes low. Also, as shown in Figures 7 and 8, if there is a ground short circuit in the U-phase current line, the U-phase port level becomes low.

[0034] In this embodiment, a (complete) ground short circuit is defined as a state in which the current carrying line and ground are electrically connected with resistance ≈ 0, as shown in Fig. 7, and an incomplete ground short circuit is defined as a state in which the current carrying line and ground line are electrically connected with resistance, as shown in Fig. 8. In Figs. 7 and 8 and Figs. 9 and 10 described below, the ground short circuit state is schematically depicted as a circuit surrounded by a dashed ellipse.

[0035] The faulty phase determination process based on the port level will be described with reference to the flowchart in Fig. 9. This process is executed by the control unit 50 at a predetermined cycle (e.g., 8 ms). Hereinafter, the "step" in step S101 and other steps will be omitted and simply referred to as "S".

[0036] In S101, the control unit 50 determines whether or not the power supply to all phases is turned off. If it is determined that the power supply to all phases is not turned off (S101: NO), the process from S102 onward is skipped. If it is determined that the power supply to all phases is turned off (S101: YES), the process proceeds to S102.

[0037] In S102, the abnormality determination unit 52 determines whether the U-phase port level is high. Here, if it is equal to or greater than a determination threshold set according to the battery voltage and the resistance value of the voltage dividing resistor, it is determined to be high level, and if it is less than the determination threshold, it is determined to be low level. If it is determined that the U-phase port level is low level (S102: NO), the process proceeds to S103, where the U-phase fault flag is turned on. If it is determined that the U-phase port level is high level (S102: YES), the process proceeds to S104.

[0038] In S104, the abnormality determination unit 52 determines whether the V-phase port level is high. If it is determined that the V-phase port level is low (S104: NO), the process proceeds to S105, where the V-phase failure flag is turned on. If it is determined that the V-phase port level is high (S104: YES), the process proceeds to S106.

[0039] In S106, the abnormality determination unit 52 determines whether the W-phase port level is high. If it is determined that the W-phase port level is low (S106: NO), the process proceeds to S107, where the W-phase failure flag is set to ON. If it is determined that the W-phase port level is high (S106: YES), the process proceeds to S108.

[0040] In S108, the abnormality determination unit 52 determines whether two or more phases are faulty. If it is determined that one or less phases are faulty (S108: NO), the process proceeds to S112. If it is determined that two or more phases are faulty (S108: YES), the process proceeds to S109.

[0041] In S109, the abnormality determination unit 52 turns on the two or more phase failure flag. In S110, the control unit 50 prohibits energization of all phases, and in S111, displays a warning on the instrument panel (not shown). The warning display method is not limited, and may be an audio warning or the like.

[0042] In S112, the abnormality determination unit 52 determines whether or not there is a one-phase failure. If it is determined that there is a one-phase failure (S112: YES), the process proceeds to S113, where the one-phase failure flag is set to ON. If it is determined that there is no one-phase failure (S112: NO), that is, if all phases are normal, the process proceeds to S114, where the normality flag is set to ON.

[0043] The process in Figure 9 can identify the faulty phase, but it cannot distinguish whether the fault is an open circuit fault or a constant current fault due to a ground short circuit. If the fault is a one-phase open circuit, range switching can be performed using the two normal phases.

[0044] On the other hand, if the fault is a constant-power fault due to a ground short circuit or the like, range switching cannot be performed using the normal two phases. Also, if the motor relay 91 remains on, current continues to flow through the faulty phase, which could cause the motor 10 to overheat. Therefore, in the event of a constant-power fault, it is desirable to turn off the motor relay 91 and stop drive control of the motor 10.

[0045] For example, after identifying the faulty phase based on the port level, two normal phases can be used to switch the power supply phase at predetermined intervals to perform range switching using open drive. The system can then determine whether the fault is a wire break or a ground short circuit based on whether the range switch was successful. However, this method can result in a delay in determining the cause. Furthermore, as shown in Figure 8, in the case of an incomplete ground short circuit, where a small amount of current flows to the ground side, range switching is possible. If this is erroneously determined to be a wire break and motor drive control continues, the motor 10 may overheat.

[0046] Therefore, in this embodiment, after the faulty phase is identified at the port level, the behavior of the switching elements 411 to 413 when they are turned on and off is used to distinguish between an open circuit fault and a ground short circuit fault.

[0047] First, the detection value of current detection unit 45 when switching element 411 of the faulty U-phase is turned on will be described. Even if switching element 411 is turned on when the U-phase is broken, no current flows in the U-phase current carrying line, so no current is detected by current detection unit 45 (see FIG. 6).

[0048] 10 and 11, when switching element 411 is turned on during a ground short circuit, a current flows through switching element 411. If the ground short circuit is incomplete and the resistance value of the shorted location is relatively high, a relatively large current flows toward current detection unit 45 (see FIG. 10). Therefore, when a U-phase fault occurs, it is possible to distinguish between an open circuit and an incomplete ground short circuit based on the detection value of current detection unit 45 when switching element 411 is turned on.

[0049] 11, when the resistance at the ground short-circuit point approaches zero, the current flowing to the current detection unit 45 side becomes very small. Therefore, when the resistance at the ground short-circuit point approaches zero, it is difficult to distinguish between an open circuit or a ground short-circuit from the detection value of the current detection unit 45 when switching element 411 is turned on. In FIGS. 10 and 11, the amount of current is schematically indicated by the thickness of the arrow.

[0050] Therefore, in this embodiment, abnormality determination is performed based on the motor rotation angle when current is applied to a normal phase, in addition to the current value when the switching element of the faulty phase is turned on. Prior to explaining abnormality determination based on the motor rotation angle, the behavior of the rotor 103 when current is applied will be described. Figure 12 shows the coil attractive force when current is applied to the V phase, with the horizontal axis representing the motor rotation angle and the vertical axis representing the coil attractive force. In Figure 12, it is assumed that the V-phase salient pole 102 of the stator 101 faces the recessed portion 105 of the rotor 103 at the circle position, and that the V-phase salient pole 102 faces the protruding portion 104 of the rotor 103 at the square position.

[0051] When switching element 412 is turned on and current is flowing only to the V-phase, a magnetic attractive force acts in a direction in which convex portion 104 moves toward V-phase salient pole 102, except when concave portion 105 faces V-phase salient pole 102 at the circled position. In Figure 12, the attractive force when current is flowing in the V-phase is schematically shown by dashed arrows, and in the region marked "+" it acts as a force that rotates rotor 103 in the positive direction, and in the region marked "-" it acts as a force that rotates rotor 103 in the negative direction.

[0052] The behavior of rotor 103 when the current supply pattern to V-phase and W-phase, which are normal phases, is switched in the event of a U-phase fault will be described with reference to Figures 13 to 16. Figures 13 and 14 show the behavior when the U-phase is broken, and Figures 15 and 16 show the behavior when the U-phase is short-circuited to ground.

[0053] 13 to 16, from the top, there are shown energization status ST11, which indicates that all phase switching elements 411 to 413 are off, energization status ST12, which indicates that V-phase switching element 412 is on, energization status ST13, which indicates that V-phase and W-phase switching elements 412 and 413 are on, and energization status ST14, which indicates that W-phase switching element 413 is on, and the description will be given assuming that the energized phases are switched in this order. Note that if U-phase switching element 411 is turned on when the U-phase is disconnected, the behavior is the same as when all phases are off.

[0054] 13 to 16 are diagrams showing the positional relationship between the stator salient poles 102 and the rotor 103 for the area enclosed by the dashed line L in FIG. 4, with the rotation direction being the left-right direction, and the left-right direction being the positive rotation direction, and the right-right direction being the negative rotation direction. In the diagrams on the left, a phase that is not energized due to a disconnection (U phase in the example of a U-phase disconnection) is marked with an "x" and the energized phase is indicated by a matte finish. Also, on the right, a rotation angle difference Δθ, which is the difference in the motor rotation angle when the energized phase is switched, is shown. The same applies to FIG. 30 and others.

[0055] 13 shows a case where the recess 105 of the rotor 103 does not face the V-phase when the U-phase is disconnected and all phases are off. When the energization status ST11 indicates all phases are off, no attractive force is generated in the motor winding 11, so the position of the rotor 103 is indefinite. Furthermore, when the U-phase is disconnected, even if the U-phase switching element 411 is turned on, the same state occurs because no current is applied to the motor winding 11.

[0056] When the current-carrying status changes from ST11 to ST12 and V-phase switching element 412 is turned on to energize the V-phase, current is passed through coil 112, generating an attractive force, causing protrusion 104 of rotor 103 to rotate to a position facing the V-phase. Because the rotor position is indefinite in current-carrying status ST11, the rotational angle difference Δθ when the current-carrying status changes from ST11 to ST12 takes a value that corresponds to the rotor position in current-carrying status ST11.

[0057] When the energization status shifts from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on to energize the VW phase, the coils 112, 113 are energized and the convex portion 104 rotates by +7.5° to a position facing the V-phase and W-phase. That is, the rotation angle difference Δθ when the energization status shifts from ST12 to ST13 is +7.5°.

[0058] When the energization status shifts from ST13 to ST14, the V-phase switching element 412 is turned off and the W-phase switching element 413 is turned on to energize the W-phase, and the coil 113 is energized, causing the protrusion 104 to rotate by +7.5° to a position facing the W-phase. That is, the rotation angle difference Δθ when the energization status shifts from ST12 to ST13 is +7.5°.

[0059] 14 shows a case where the U-phase is disconnected and the recessed portion 105 of the rotor 103 faces the V-phase when all phases are off. When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on to energize the V-phase, the coil 112 is energized. If the recessed portion 105 faces the V-phase in the energization status ST11, the left and right protrusions 104 are attracted to the V-phase, so the recessed portion 105 remains facing the V-phase and the rotor 103 does not rotate. In other words, the rotation angle difference Δθ when the energization status shifts from ST11 to ST12 is 0°.

[0060] When the energization status changes from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on, the coils 112, 113 are energized and the convex portion 104 rotates by −15° to a position facing the V-phase and W-phase. In other words, the rotation angle difference Δθ when the energization status changes from ST12 to ST13 is −15°.

[0061] When the energization status changes from ST13 to ST14, the V-phase switching element 412 is turned off, and the W-phase switching element 413 is turned on, current is passed through the coil 113, and the protrusion 104 rotates by +7.5° to a position facing the W-phase. That is, similar to Fig. 13, the rotation angle difference Δθ when the energization status changes from ST12 to ST13 is +7.5°.

[0062] 15 shows a case where, in energization status ST11, the U-phase coil 111 is energized due to a U-phase ground short circuit, and the protruding portion 104 faces the U-phase. When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on, the UV-phase is energized, and the protruding portion 104 rotates by +7.5° to a position facing the U-phase and V-phase. In other words, the rotational angle difference Δθ when the energization status shifts from ST11 to ST12 is +7.5°.

[0063] When the energization status shifts from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on, W-phase energization is applied, but the rotor 103 does not rotate because the W-phase faces the recess 105. In other words, the rotation angle difference Δθ when the energization status shifts from ST12 to ST13 is 0°.

[0064] When the energization status shifts from ST13 to ST14, the V-phase switching element 412 is turned off, and the W-phase switching element 413 is turned on, the WU-phase is energized, and the convex portion 104 rotates by −15° to a position facing the U-phase and W-phase. That is, the rotation angle difference Δθ when the energization status shifts from ST13 to ST14 is −15°.

[0065] 16 shows a case in which, in energization status ST11, the U-phase coil 111 is energized due to a U-phase ground short circuit, and the recessed portion 105 faces the U-phase. When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on, the UV-phase is energized, and the protrusion 104 rotates by −15° to a position facing the U-phase and V-phase. In other words, the rotational angle difference Δθ when the energization status shifts from ST11 to ST12 is −15°.

[0066] When the energization status shifts from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on, W-phase energization is applied, but the rotor 103 does not rotate because the W-phase faces the recess 105. In other words, the rotation angle difference Δθ when the energization status shifts from ST12 to ST13 is 0°.

[0067] When the energization status changes from ST13 to ST14, the V-phase switching element 412 is turned off, and the W-phase switching element 413 is turned on, the WU-phase is energized, and the convex portion 104 rotates by −15° to a position facing the U-phase and W-phase. That is, similar to FIG. 15 , the rotation angle difference Δθ when the energization status changes from ST13 to ST14 is −15°.

[0068] FIG. 17 is a diagram illustrating the rotation angle difference Δθ in response to switching of the energization statuses ST11 to ST14. Pattern 1 in FIG. 17 corresponds to FIG. 13, and is a pattern in which, in energization status ST11, the recess 105 does not face the phase that is energized in energization status ST12. Pattern 2 corresponds to FIG. 14, and is a pattern in which, in energization status ST11, the recess 105 faces the phase that is energized in energization status ST12. Pattern 3 corresponds to FIG. 15, and is a pattern in which, in energization status ST11, the protrusion 104 faces the phase that is constantly energized with a fault. Pattern 4 corresponds to FIG. 16, and is a pattern in which, in energization status ST11, the recess 105 faces the phase that is constantly energized with a fault.

[0069] 17, when the energization phase is switched from energization status ST11 to ST14, when the energization status changes from ST13 to ST14, regardless of the rotor position in energization status ST11, the rotation direction of rotor 103 differs between when a U-phase open circuit occurs and when a ground short circuit occurs, making it possible to distinguish between an open circuit and a ground short circuit. In particular, when there is a ground short circuit in a state where resistance is small and it is difficult to distinguish based on the current value when the faulty phase is on, the energization state when a normal one-phase switching element is turned on becomes closer to the two-phase energization state, and the encoder output tends to stabilize in a state similar to that when two-phase energization occurs, making it easy to distinguish.

[0070] When the energization status is switched from ST13 to ST14 while all phases are normal, the behavior is the same as when there is a disconnection. Therefore, the rotor rotation direction when there is a ground short circuit when the energization status is switched from ST13 to ST14 can be considered to be different from the rotation direction when all phases are normal.

[0071] The power supply process for fault identification will be described with reference to the flowcharts of Figures 18 and 19. In S201, the control unit 50 determines whether a constant power supply fault flag FlgA, which will be described later, is on. If it is determined that the constant power supply fault flag FlgA is on (S201: YES), the process from S202 onwards is skipped. If it is determined that the constant power supply fault flag FlgA is off (S201: NO), the process proceeds to S202.

[0072] In S202, the control unit 50 determines whether the two-phase pre-switching energization processing flag FlgP is on. If it is determined that the two-phase pre-switching energization processing flag FlgP is on (S202: YES), the process proceeds to S210. If it is determined that the two-phase pre-switching switching processing flag is off (S202: NO), the process proceeds to S203.

[0073] In S203, the control unit 50 determines whether or not there is a shift range switching request. If it is determined that there is no shift range switching request (S203: NO), the process from S204 onwards is skipped. If it is determined that there is a shift range switching request (S203: YES), the process proceeds to S204.

[0074] In S204, the control unit 50 determines whether the one-phase failure flag is on. A one-phase failure is determined in the failed phase identification process of FIG. 9. If it is determined that the one-phase failure flag is off (S204: NO), the process from S205 onwards is skipped. If it is determined that the one-phase failure flag is on (S204: YES), the process proceeds to S205.

[0075] In S205, the control unit 50 determines whether the motor relay 91 is turned on. If it is determined that the motor relay 91 is not turned on (S205: NO), the control unit 50 proceeds to S206 and turns on the motor relay 91. If it is determined that the motor relay 91 is turned on (S205: YES), the control unit 50 proceeds to S207.

[0076] In S207, the control unit 50 determines whether or not the standby time has elapsed since the motor relay 91 was turned on, taking into account the delay in turning on the motor relay 91. If it is determined that the standby time has not elapsed since the motor relay 91 was turned on (S207: NO), the process from S208 onwards is skipped. If it is determined that the standby time has elapsed since the motor relay 91 was turned on (S207: YES), the process proceeds to S208.

[0077] In S208, the control unit 50 turns on the two-phase pre-switching energization process flag FlgP and turns off the two-phase pre-switching energization process completion flag FlgC. In S209, the control unit 50 sets the status to the energization status ST11.

[0078] 19, in S210, the control unit 50 determines whether the current status is the energization status ST11. If it is determined that the current status is not the energization status ST11 (S210: NO), the process proceeds to S213. If it is determined that the current status is the energization status ST11 (S210: YES), the process proceeds to S211.

[0079] In S211, the control unit 50 determines whether the duration X11 has elapsed since the start of the energization status ST11. If it is determined that the duration X11 has elapsed (S211: YES), the status is changed to energization status ST12, and the process proceeds to S215. If it is determined that the duration X11 has not continued (S211: NO), the process proceeds to S212.

[0080] In S212, the control unit 50 performs energization in energization status ST11. The energization status ST11 indicates faulty phase energization, and if the U-phase fault flag is on, the control unit 50 turns on the U-phase switching element 411, if the V-phase fault flag is on, the control unit 50 turns on the V-phase switching element 412, and if the W-phase fault flag is on, the control unit 50 turns on the W-phase switching element 413.

[0081] If it is determined that the current status is not the energization status ST11 (S210: NO), the control unit 50 proceeds to S213, where it determines whether the current status is the energization status ST12. If it is determined that the current status is not the energization status ST12 (S213: NO), it proceeds to S216. If it is determined that the current status is the energization status ST12 (S213: YES), it proceeds to S214.

[0082] In S214, the control unit 50 determines whether the duration X12 has elapsed since the start of the energization status ST12. If it is determined that the duration X12 has elapsed (S214: YES), the status is set to energization status ST13, and the process proceeds to S218. If it is determined that the duration X12 has not elapsed (S214: NO), the process proceeds to S215.

[0083] In S215, the control unit 50 performs energization in energization status ST12. The energization status ST12 indicates normal phase 1-phase energization, and if the U-phase failure flag is on, the control unit 50 turns on the V-phase switching element 412, if the V-phase failure flag is on, the control unit 50 turns on the W-phase switching element 413, and if the W-phase failure flag is on, the control unit 50 turns on the U-phase switching element 411.

[0084] If it is determined that the current status is not the energization status ST12 (S213: NO), the control unit 50 proceeds to S216, where it determines whether the current status is the energization status ST13. If it is determined that the current status is not the energization status ST13 (S216: NO), the control unit 50 proceeds to S219. If it is determined that the current status is the energization status ST13 (S216: YES), the control unit 50 proceeds to S217.

[0085] In S217, the control unit 50 determines whether the duration X13 has elapsed since the start of the energization status ST13. If it is determined that the duration X13 has elapsed (S217: YES), the status is changed to energization status ST14, and the process proceeds to S220. If it is determined that the duration X13 has not elapsed (S217: NO), the process proceeds to S218.

[0086] In S218, the control unit 50 performs energization in energization status ST13. The energization status ST13 indicates normal two-phase energization, and if the U-phase failure flag is on, the control unit 50 turns on the V-phase and W-phase switching elements 412 and 413, if the V-phase failure flag is on, the control unit 50 turns on the U-phase and W-phase switching elements 411 and 413, and if the W-phase failure flag is on, the control unit 50 turns on the U-phase and V-phase switching elements 411 and 412.

[0087] If it is determined that the power-on status is not ST13 (S216: NO), the control unit 50 proceeds to S219, where it determines whether or not duration X14 has elapsed since the start of power-on status ST14. Duration times X11 to X14 can be set arbitrarily, and at least some of them may be the same or different. If it is determined that duration X14 has elapsed (S219: NO), the control unit 50 proceeds to S221. If it is determined that duration X14 has not elapsed (S219: YES), the control unit 50 proceeds to S220.

[0088] In S220, the control unit 50 performs energization in energization status ST14. The energization status ST14 is one-phase energization to a normal phase different from the energization status ST12, and turns on the W-phase switching element 413 when the U-phase failure flag is on, turns on the U-phase switching element 411 when the V-phase failure flag is on, and turns on the V-phase switching element 412 when the W-phase failure flag is on.

[0089] In S221, which is reached after the duration X14 has elapsed since the start of the energization status ST14, the control unit 50 turns off the two-phase pre-switching energization processing flag FlgP and the two-phase pre-switching energization completion flag FlgC. In S222, the control unit 50 sets the energization status to undetermined ST0. The energized phase in normal one-phase energization in the energization statuses ST12 and ST14 can be set arbitrarily, and it is possible to determine whether there is a break or constant energization based on the rotation direction corresponding to the set energization phase.

[0090] The fault state determination process will be described with reference to the flowchart of Fig. 20. In S501, the abnormality determination unit 52 determines whether the two-phase pre-switching energization completion flag FlgC is on. If it is determined that the two-phase pre-switching energization completion flag FlgC is on (S501: YES), the process proceeds to S510. If it is determined that the two-phase pre-switching energization completion flag FlgC is off (S501: NO), the process proceeds to S502.

[0091] In S502, the abnormality determination unit 52 determines whether the current status is the energization status ST11. If it is determined that the current status is not the energization status ST11 (S502: NO), the process proceeds to S504. If it is determined that the current status is the energization status ST11 (S502: YES), the process proceeds to S503.

[0092] In S503, the abnormality determination unit 52 determines whether the state in which the motor current Im is equal to or greater than the current determination threshold Ith continues for equal to or greater than the determination time Xi. The current determination threshold Ith is set according to the current flowing through the current detection unit 45 when a ground short circuit occurs. The determination time Xi is set to a time shorter than the duration X11. If it is determined that the motor current Im is less than the current determination threshold Ith, or the duration in which the motor current Im is equal to or greater than the current determination threshold Ith is less than the determination time Xi (S503: NO), the subsequent processing is skipped. If it is determined that the state in which the motor current Im is equal to or greater than the current determination threshold Ith continues for equal to or greater than the determination time Xi (S503: YES), the process proceeds to S511.

[0093] In S504, the abnormality determination unit 52 determines whether the current status is the energization status ST13. If it is determined that the current status is not the energization status ST13 (S504: NO), the process proceeds to S507. If it is determined that the current status is the energization status ST13 (S504: YES), the process proceeds to S505.

[0094] In S505, the abnormality determination unit 52 determines whether or not a standby time Xw13 has elapsed since the start of the energization status ST13. The standby time Xw13 is set according to the time it takes for the vibration of the rotor 103 to subside to a certain extent in the energization status ST13. If it is determined that the standby time Xw13 has not elapsed since the start of the energization status ST13 (S505: NO), the subsequent processing is skipped. If it is determined that the standby time Xw13 has elapsed since the start of the energization status ST13 (S505: YES), the process proceeds to S506, where an update process for the maximum value CTmax13 in the energization status ST13 is performed. The update process for the maximum value CTmax13 will be described later.

[0095] In S507, the abnormality determination unit 52 determines whether the current status is the energization status ST14. If it is determined that the current status is not the energization status ST14 (S507: NO), the subsequent processing is skipped. If it is determined that the current status is the energization status ST14 (S507: YES), the process proceeds to S508.

[0096] In S508, the abnormality determination unit 52 determines whether or not the standby time Xw14 has elapsed since the start of the energization status ST14. The standby time Xw14 is set according to the time it takes for the vibration of the rotor 103 to subside somewhat in the energization status ST14, and may be the same as or different from the standby time Xw13. The same applies to the standby time Xw12 in the embodiments described below. If it is determined that the standby time Xw14 has not elapsed since the start of the energization status ST14 (S508: NO), the subsequent processing is skipped. If it is determined that the standby time Xw14 has elapsed since the start of the energization status ST14 (S508: YES), the process proceeds to S509, and processing to update the minimum value CTmin14 in the energization status ST14 is performed.

[0097] The update process of the maximum value CTmax13 in the energization status ST13 and the update process of the minimum value CTmin14 in the energization status ST14 will be described with reference to Figures 21 to 23. Figure 21 is a diagram illustrating the behavior of the rotor 103 in the energization statuses ST11 to ST14, with the horizontal axis representing time and the vertical axis representing the motor rotation angle. Here, the behavior when the U-phase is disconnected is shown as an example. In this embodiment, the encoder 13 is used to detect the rotation position of the rotor 103, and the rotation angle is converted from the encoder count value. Hereinafter, the rotation angle will be referred to as the encoder count value where appropriate.

[0098] After the energization status ST13 starts, update processing of the maximum value CTmax13 is performed from time xa when a waiting time Xw13 for the vibration of the rotor 103 to decrease has elapsed, until the energization status ST14 is entered. Also, after the energization status ST14 starts, update processing of the minimum value CTmin14 is performed from time xb when a waiting time Xw14 for the vibration of the rotor 103 to decrease has elapsed, until the energization status ST14 ends. The energization status ST14 is one-phase energized, and it takes longer for the vibration of the rotor 103 to decrease than the energization status ST13 is two-phase energized, so the waiting time Xw14 is set longer than the waiting time Xw13.

[0099] A subflow of the process of updating the maximum value CTmax13 of the energization status ST13 (S506 in FIG. 20) is shown in FIG. 22. In S561, the abnormality determination unit 52 determines whether or not this is the first calculation after the wait time Xw13 has elapsed. If it is determined that this is the first calculation after the wait time Xw13 has elapsed (S561: YES), the process proceeds to S562, where the current encoder count value EN is set to the maximum value CTmax13. If it is determined that this is not the first calculation after the wait time Xw13 has elapsed (S561: NO), the process proceeds to S563.

[0100] In S563, the abnormality determination unit 52 determines whether the current encoder count value EN is greater than the maximum value CTmax13. If it is determined that the current encoder count value EN is equal to or less than the maximum value CTmax13 (S563: NO), the value held as the maximum value CTmax13 is not updated and this processing ends. If it is determined that the current encoder count value EN is greater than the maximum value CTmax13 (S563: YES), the processing proceeds to S564 and the maximum value CTmax13 is updated to the current encoder count value EN.

[0101] A subflow of the process of updating the minimum value CTmin14 of the energization status ST14 (S509 in FIG. 20) is shown in FIG. 23. In S591, the abnormality determination unit 52 determines whether or not this is the first calculation after the wait time Xw14 has elapsed. If it is determined that this is the first calculation after the wait time Xw14 has elapsed (S591: YES), the process proceeds to S592, where the current encoder count value EN is set to the minimum value CTmin14. If it is determined that this is not the first calculation after the wait time Xw13 has elapsed (S591: NO), the process proceeds to S593.

[0102] In S593, the abnormality determination unit 52 determines whether the current encoder count value EN is smaller than the minimum value CTmin14. If it is determined that the current encoder count value EN is equal to or greater than the minimum value CTmin14 (S593: NO), the value held as the minimum value CTmin14 is not updated and this process ends. If it is determined that the current encoder count value EN is smaller than the minimum value CTmin14 (S593: YES), the process proceeds to S594 and the minimum value CTmin14 is updated to the current encoder count value EN.

[0103] Returning to FIG. 20 , if it is determined that the two-phase pre-switching energization process completion flag FlgC is on (S501: YES), the abnormality determination unit 52 proceeds to S510, where it determines whether the value obtained by subtracting the maximum value CTmax13 of the energization status ST13 from the minimum value CTmin14 of the energization status ST14 is equal to or less than the determination threshold TH. The determination threshold TH can be set to any value that can determine whether the rotation direction differs depending on whether there is a one-phase disconnection or a ground short circuit, and is set to, for example, 0 or a value close to 0. If it is determined that the value obtained by subtracting the maximum value CTmax13 from the minimum value CTmin14 is equal to or less than the determination threshold TH (S510: YES), that is, if the rotation direction of the rotor 103 when the energization status ST13 changed to ST14 was negative, the abnormality determination unit 52 proceeds to S511. If it is determined that the value obtained by subtracting the maximum value CTmax13 from the minimum value CTmin14 is greater than the determination threshold TH (S510: NO), the abnormality determination unit 52 proceeds to S514.

[0104] If it is determined that the motor current Im in the energization status ST11 has remained equal to or greater than the current determination threshold Ith for the determination time Xi or longer (S503: YES), or if it is determined that the value obtained by subtracting the maximum value CTmax13 from the minimum value CTmin14 after the completion of the two-phase switching energization process is equal to or less than the determination threshold TH (S510: YES), the process proceeds to S511, in which the abnormality determination unit 52 determines that a constant energization fault due to a ground short circuit or the like has occurred, and turns on the constant energization fault flag FlgA. The processes of S512 and S513 are the same as those of S110 and S111 in FIG. 9, and the energization of all phases is prohibited and a warning is displayed.

[0105] If it is determined that the value obtained by subtracting the maximum value CTmax13 from the minimum value CTmin14 is greater than the determination threshold value TH (S510: NO), the abnormality determination unit 52 proceeds to S514, where it determines whether the constant-energization failure flag FlgA is off. If it is determined that the constant-energization failure flag FlgA is on (S514: NO), the process of S515 is skipped. If it is determined that the constant-energization failure flag FlgA is off (S515: YES), the process proceeds to S515, where it turns on the one-phase open circuit failure flag FlgD.

[0106] The range switching process of this embodiment will be described based on the time chart of Fig. 24. In Fig. 24, the horizontal axis represents a common time axis, and from the top, the following are shown: a one-phase failure flag, a requested shift range, the on / off state of the motor relay 91, a two-phase pre-switching energization process flag FlgP, an energization status, a constant energization failure flag FlgA, a one-phase break flag FlgD, and a two-phase pre-switching energization completion flag FlgC. This also applies to Fig. 29 in the embodiments described below.

[0107] At time x50, a one-phase failure occurs, and the one-phase failure flag is turned on in the failed phase determination process, turning off the motor relay 91. At time x51, when a range switch request occurs, the requested shift range is changed from P range to not P range, and the motor relay 91 is turned on.

[0108] At time x52, when the two-phase pre-switching energization processing flag FlgP is turned on, the energization status is set to ST11 and energization is performed to the faulty phase. At time x53, when a constant energization failure is identified based on the motor current Im, the constant energization failure flag FlgA is turned on as shown by the dashed dotted line and the motor relay 91 is turned off. Furthermore, when the energization status ST11 identifies a constant energization failure due to a ground short circuit, processing from energization status ST12 onwards and range switching using the two normal phases are not performed.

[0109] If a constant-energization failure is not identified in the energization status ST11, energization is sequentially performed in the energization statuses ST12, ST13, and ST14. Note that, for simplicity, in Fig. 24, the timing when the constant-energization failure flag FlgA is turned on and the timing when the energization status changes from ST11 to ST12 are shown to be the same, but in reality, the transition to the energization status ST12 is set to occur later.

[0110] At time x54, when the energization status ST14 ends, the two-phase pre-switching energization completion flag FlgC is turned on. If a constant energization failure is identified based on the maximum value CTmax13 of the energization status ST13 and the minimum value CTmin14 of the energization status ST14, the constant energization failure flag FlgA is turned on, as shown by the two-dot chain line, and the motor relay 91 is turned off. If a constant energization failure is not identified based on the maximum value CTmax13 and the minimum value CTmin14, the failure is identified as a one-phase open circuit, and the one-phase open circuit flag FlgD is turned on, as shown by the solid line.

[0111] If the fault occurring in the faulty phase is determined to be a one-phase break rather than a constant current due to a ground short circuit, the two phases with normal encoders are used to switch ranges using feedback control based on the encoder count value.

[0112] In shift range switching drive, the motor 10 is driven by switching the energized phase of the motor windings 11 through feedback control based on the encoder count value. Specifically, as shown in FIG. 25, the control unit 50 has a map in which energized phase numbers correspond to 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. To rotate 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. To rotate 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.

[0113] In the case where an abnormal stagnation occurs in which the encoder count value stagnates during normal operation, the motor 10 is rotated by open drive, which switches the energized phase every predetermined time. In open drive, the excitation time of each energized phase is set to a relatively long time (for example, 50 ms) in order to reliably catch the convex portion 104 of the rotor 103 with the energized phase and synchronize the rotation phase of the rotor 103 with the energized phase.

[0114] In the event of a single-phase break, the motor 10 is driven by energizing the two normal phases through feedback control, and range switching is performed. For example, if the U-phase is broken, when the energized phase numbers are "0" and "1," the W-phase is energized, and when the energized phase numbers are "4" and "5," the V-phase is energized. Furthermore, in the region of energized phase numbers "2" and "3," where no current is applied when the U-phase is broken, no torque is generated, but by passing through this region using inertia, the motor 10 can continue to be driven.

[0115] If a stagnation abnormality occurs during normal two-phase motor drive when one phase is broken, and the motor 10 is driven in open drive, which has a lower motor rotation speed than feedback control, there is a risk that the motor will not be able to pass through the region corresponding to the broken phase due to inertia. Therefore, in this embodiment, if a stagnation abnormality occurs during two-phase range switching when one phase is broken, the system does not switch to open drive, and instead determines that a range switching abnormality has occurred.

[0116] The range switching process when one phase is broken will be explained based on the time chart in Fig. 26. In Fig. 26, the horizontal axis represents a common time axis, and the encoder count value and system diagnostic flag are shown below each item in Fig. 24. The encoder count value when the detent roller 26 is fitted into the valley portion 211 is indicated as "P," and the value when the detent roller 26 is fitted into the valley portion 212 is indicated as "notP."

[0117] The processing from time x60 to time x63 is the same as the processing at time x20 to x24 in Figure 24 when one phase is broken. If a one-phase break is identified at time x63, range switching is performed with normal two phases. At time x64, the encoder count value stagnates before the detent roller 26 reaches the target valley 212. At time x65, when the stagnation determination time has elapsed, the system does not transition to open drive, but instead turns off the switching elements 411 to 413 to cut off power to the motor 10 and turn off the motor relay 91. In addition, the system diagnostic flag is turned on.

[0118] In this embodiment, the faulty phase is identified based on the port level when the switching elements 411 to 413 are turned off, and then whether the faulty phase is a wire break anomaly or a constant current anomaly due to a ground short circuit is identified based on the current detection value when the switching element of the faulty phase is turned on and the rotational position of the motor 10 when the current supply pattern to the normal phase is switched. This makes it possible to appropriately determine whether the one-phase fault is a constant current anomaly or a wire break anomaly, regardless of the degree of the ground short circuit.

[0119] As described above, ECU 40 controls the driving of motor 10 having motor windings 11 of three or more phases, and includes drive circuit 41 and control unit 50. Drive circuit 41 has switching elements 411 to 413 that switch on and off the supply of electricity to each phase of motor winding 11.

[0120] The control unit 50 has a drive control unit 55 and an abnormality determination unit 52. The drive control unit 55 controls the on / off operation of the switching elements 411 to 413. The abnormality determination unit 52 determines whether the current path to the motor windings 11 is abnormal.

[0121] The control unit 50 can acquire a voltage detection value, which is the detection value of a voltage detection circuit 46 that detects the phase voltage of the motor windings 11, a current detection unit 45 that detects the current flowing through the motor windings 11, and an encoder signal, which is the detection value of an encoder 13 that detects the rotational position of the motor 10.

[0122] The abnormality determination unit 52 identifies the faulty phase based on the voltage detection value when the switching elements 411 to 413 of all phases are turned off. The abnormality determination unit 52 identifies the constantly energized fault of the faulty phase based on at least one of the current detection value when the switching element of the identified faulty phase is turned on and the rotation position detection value when the switching elements 411 to 413 of one or more normal phases are turned on.

[0123] This allows the fault state to be properly identified. Specifically, it is possible to properly distinguish whether the fault occurring in the faulty phase is a constant current fault due to a ground short circuit or the like, or a wire break fault that disables current flow to the faulty phase.

[0124] Here, if the process of identifying a fault state based on the current detection value when the switching element of the faulty phase is turned on is called the "first fault state identification process," and the process of identifying a fault state based on the rotational position detection value when current is flowing in a normal phase is called the "second fault state identification process," then it can be said that the fault state of the faulty phase is identified by performing at least one of the first fault state determination process and the second fault state identification process.

[0125] In particular, in this embodiment, by using the first fault state identification process and the second fault state identification process in combination, it is possible to prevent a constant-power failure from being erroneously determined to be an open circuit failure, regardless of variations in the degree of current flow at the location where a constant-power failure occurs (e.g., resistance during a ground short circuit).

[0126] If the motor current Im when the switching element of the faulty phase is turned on is equal to or greater than the current determination threshold Ith, the abnormality determination unit 52 determines that a constant-energization abnormality has occurred. When the switching element of the faulty phase is turned on, by detecting the current downstream of the switching element, if a current flows, it can be determined that the faulty phase is not broken, i.e., that a constant-energization fault has occurred.

[0127] The abnormality determination unit 52 identifies a constantly energized fault based on the amount of change in the rotational position of the motor 10 when a first normal phase energization process is performed, in which current is applied to one or more normal phases, and when a second normal phase energization process is performed, in which current is applied to one or more normal phases that are at least one phase different from the first normal phase energization process. In this embodiment, the energization status ST13, in which current is applied to two normal phases, corresponds to the "first normal phase energization process," and the energization status ST14, in which current is applied to one normal phase, corresponds to the "second normal phase energization process." Specifically, the abnormality determination unit 52 identifies a constantly energized fault if the rotation direction when switching from the first normal phase energization process to the second normal phase energization process is different from when all phases are normal. This allows the constantly energized fault to be appropriately identified.

[0128] Before the first normal phase energization process, the drive control unit 55 performs a pre-energization process in which current is applied to one or more normal phases, at least one of which is different from the first normal phase energization process. In this embodiment, the energization status ST12, which energizes one normal phase, corresponds to the "pre-energization process." When current is first applied to one of the normal phases from the non-energized state, there are two positions where the rotor 103 is stationary due to balancing of attractive forces, depending on the rotor position in the non-energized state. However, the second energization can move the rotor to the intended balanced position. Therefore, in this embodiment, by performing the pre-energization process first, the first normal phase energization process and the second energized phase energization process can be performed, thereby making it possible to appropriately perform fault detection regardless of the rotor position in the non-energized state.

[0129] The motor 10 is a three-phase motor, and when the drive control unit 55 determines that the faulty phase is one phase and that the fault is not a constant-energization fault, it drives the motor 10 by energizing the motor windings 11 of the two normal phases. This allows the motor 10 to continue to be driven. In this embodiment, the system is applied to a shift-by-wire system 1, and when one phase is broken, the shift range can be switched.

[0130] If all phases are normal and a stagnation abnormality occurs in which the encoder count value stagnates, the drive control unit 55 performs open drive, which switches the energized phase without using the encoder count value, instead of feedback control based on the encoder count value.If the faulty phase is one phase and the fault is not a constant energization failure, the drive control unit 55 drives the motor 10 by energizing the motor windings 11 of the two phases that are normal in feedback control, and if a stagnation abnormality occurs, the drive control unit 55 stops drive control of the motor 10.

[0131] In the case of normal two-phase drive control when one phase is broken, the broken phase must be passed through inertia, and there is a risk that open drive, which has a relatively slow rotation speed, will cause the motor 10 to stop. Therefore, if a stagnation abnormality occurs when one phase is broken, the control is stopped without switching to open drive, thereby avoiding unnecessary current flow.

[0132] (Second embodiment) 27 to 29 show a second embodiment. As explained in FIG. 17, when the status changes from ST12 (single-phase energization) to ST13 (two-phase energization), the motor rotation angle does not change if there is a ground short circuit. Therefore, in this embodiment, if the motor rotation angle does not change when switching from single-phase energization to two-phase energization, it is determined that a constant energization fault has occurred.

[0133] The power supply process for fault identification in this embodiment is shown in the flowchart of Figure 27. Note that the first half is the same as Figure 18 of the first embodiment, so the second half corresponding to Figure 19 is shown in Figure 27. In this embodiment, power supply status ST14 is not performed, so Figure 27 omits S216, S219, and S220, and is otherwise the same as Figure 19. If a negative determination is made in S213, the process proceeds to S217, and if a positive determination is made in S217, the process proceeds to S221.

[0134] The fault state determination process will be described with reference to the flowchart in Fig. 28. S601 to S603 are the same as S501 to S503 in Fig. 20. In S604, to which the process proceeds if a negative determination is made in S602, the abnormality determination unit 52 determines whether the current status is the energization status ST12. If it is determined that the current status is not ST12 (S604: NO), the process proceeds to S607. If it is determined that the current status is ST12 (S604: YES), the process proceeds to S605.

[0135] In S605, the abnormality determination unit 52 determines whether or not the standby time Xw12 has elapsed since the start of the energization status ST12. If it is determined that the standby time Xw12 has not elapsed since the start of the energization status ST12 (S605: NO), the subsequent processing is skipped. If it is determined that the standby time Xw12 has elapsed since the start of the energization status ST12 (S605: YES), the process proceeds to S606, where the count value is smoothed and the smoothed count value CT12 is calculated (see equation (1)). The subscript (n) in the equation indicates the current value, and (n-1) indicates the previous value.

[0136] CT12 (n) =(2×CT12 (n-1) -EN) / 3 (1)

[0137] If it is determined that the current status is not the energization status ST12 (S604: NO), the process proceeds to S607, where the abnormality determination unit 52 determines whether the current status is the energization status ST13. If it is determined that the current status is not the energization status ST13 (S607: NO), the subsequent processing is skipped. If it is determined that the current status is the energization status ST13 (S607: YES), the process proceeds to S608.

[0138] In S608, the abnormality determination unit 52 determines whether or not the standby time Xw13 has elapsed since the start of the energization status ST13. If it is determined that the standby time Xw13 has not elapsed (S608: NO), the subsequent processing is skipped. If it is determined that the standby time Xw13 has elapsed (S608: YES), the process proceeds to S609, where the count value is smoothed and a smoothed count value CT13 is calculated (see equation (2)).

[0139] CT13 (n) =(2×CT13 (n-1) -EN) / 3 (2)

[0140] If it is determined that the two-phase pre-switching energization process completion flag FlgC is on (S601: YES), the abnormality determination unit 52 proceeds to S610, where it determines whether the absolute value of the difference between the count values ​​CT12 and CT13 after smoothing is equal to or greater than the difference determination threshold ΔCTth. The difference determination threshold ΔCTth is set to a value close to 0 so that it can be determined that the rotor 103 is not moving when the energization status changes from ST12 to ST13. If it is determined that the absolute value of the difference between the count values ​​CT12 and CT13 is smaller than the difference determination threshold ΔCTth (S610: NO), it determines that a continuous energization fault has occurred, and the process proceeds to S611. If it is determined that the absolute value of the difference between the count values ​​CT12 and CT13 is equal to or greater than the difference determination threshold ΔCTth (S610: YES), it determines that a wire breakage fault has occurred, not a continuous energization fault, and the process proceeds to S614. S611 to S615 are the same as the processes of S511 to S515 in FIG. 20.

[0141] The range switching process of this embodiment will be described based on the time chart of Fig. 29. When the power-on status ST11 is determined to be a constant power-on failure, the process is the same as in the first embodiment, so the description will be omitted. The process from time x60 to time x62 is the same as the process from time x50 to time x52 in Fig. 24.

[0142] After time x62, energization is performed in order in energization statuses ST11, ST12, and ST13. When energization status ST13 ends at time x63, the pre-two-phase switching energization completion flag FlgC is turned on. If a constant energization fault is identified based on the difference between count values ​​CT12 and CT13, the constant energization fault flag FlgA is turned on, as shown by the two-dot chain line, and the motor relay 91 is turned off.

[0143] If the fault is not determined to be a constant-energization fault based on the count values ​​CT12 and CT13, it is determined to be a one-phase break, and the one-phase break flag FlgD is turned on, as shown by the solid line. The processing from time x63 onwards is the same as the processing from time x54 onwards in Figure 24.

[0144] In this embodiment, when the switching elements of all normal phases are turned on as the second normal phase energization process, if the change in the encoder count value is smaller than the difference determination threshold ΔCTth, a constant energization fault is identified. In this embodiment, the energization status ST12 corresponds to the "first normal phase energization process," and the energization status ST13 corresponds to the "second normal phase energization process." This allows the constant energization fault to be identified appropriately. Furthermore, the same effects as those of the above embodiment are achieved.

[0145] (Third embodiment) A third embodiment is shown in Figures 30 to 36. In the above embodiment, when one phase fails, the energization status ST12 is set to one-phase energization, the energization status ST13 is set to two-phase energization, and the energization status ST14 is set to one-phase energization, and the faulty phase is determined to be an open circuit or a ground short-circuit based on the motor rotation angle when the energization phase is switched between one-phase energization, two-phase energization, and one-phase energization. In this embodiment, the energization statuses ST22 to ST24 are all set to one-phase energization, and the abnormal state of the faulty phase is determined based on the motor rotation angle when the energization phase is switched.

[0146] 30 to 33, from the top, there are shown energization status ST21, which indicates that the switching elements 411 to 413 of all phases are turned off, energization status ST22, which indicates that the V-phase switching element 412 is turned on, energization status ST23, which indicates that the W-phase switching element 413 is turned on, and energization status ST24, which indicates that the V-phase switching element 412 is turned on, and the energization phases are described as being switched in this order. Note that the energization statuses ST21 and ST22 are similar to the energization statuses ST11 and ST12 in the above embodiment, and therefore description thereof will be omitted where appropriate.

[0147] 30 shows a case where the U-phase is disconnected and the recessed portion 105 of the rotor 103 does not face the V-phase when all phases are off. When the energization status shifts from ST22 to ST23, the V-phase switching element 412 is turned off and the W-phase switching element 413 is turned on to shift to W-phase energization, the protruding portion 104 of the rotor 103 rotates by +15° to a position facing the W-phase. In other words, the rotational angle difference Δθ when the energization status shifts from ST22 to ST23 is +15°.

[0148] When the current-carrying status shifts from ST23 to ST24, the V-phase switching element 412 is turned on, the W-phase switching element 413 is turned off, and the V-phase current is transferred to the V-phase, and the convex portion 104 rotates by −15° to a position facing the V-phase. That is, the rotation angle difference Δθ when the current-carrying status shifts from ST23 to ST24 is −15°.

[0149] 31 shows a case where the U-phase is disconnected and the recessed portion 105 of the rotor 103 faces the V-phase when all phases are off. When the energization status shifts from ST22 to ST23, and the V-phase switching element 412 is turned off and the W-phase switching element 413 is turned on to shift to W-phase energization, the protrusion 104 rotates by −7.5° to a position facing the W-phase. In other words, the rotational angle difference Δθ when the energization status shifts from ST22 to ST23 is −7.5°.

[0150] When the current-carrying status shifts from ST23 to ST24, the V-phase switching element 412 is turned on, the W-phase switching element 413 is turned off, and the V-phase current is transferred to the V-phase, and the convex portion 104 rotates by −15° to a position facing the V-phase. That is, similar to FIG. 30 , the rotation angle difference Δθ when the current-carrying status shifts from ST23 to ST24 is −15°.

[0151] 32 shows a case in which, in energization status ST21, U-phase coil 111 is energized due to a U-phase ground short circuit, and convex portion 104 faces the U-phase. When the energization status shifts from ST22 to ST23, V-phase switching element 412 is turned off, and W-phase switching element 413 is turned on, a WU-phase energized state is achieved, and convex portion 104 rotates by −15° to a position facing the U-phase and W-phase. In other words, the rotation angle difference Δθ when the energization status shifts from ST22 to ST23 is −15°.

[0152] When the energization status shifts from ST23 to ST24, the V-phase switching element 412 is turned on, and the W-phase switching element 413 is turned off, the UV-phase is energized, and the convex portion 104 rotates by +15° to a position facing the U-phase and V-phase. That is, the rotation angle difference Δθ when the energization status shifts from ST23 to ST24 is +15°.

[0153] 33 shows a case in which, in energization status ST21, U-phase coil 111 is energized due to a U-phase ground short circuit, and recessed portion 105 faces the U-phase. When the energization status shifts from ST22 to ST23, V-phase switching element 412 is turned off, and W-phase switching element 413 is turned on, a WU-phase energized state is achieved, and protrusion 104 rotates by −15° to a position facing the U-phase and W-phase. In other words, the rotational angle difference Δθ when the energization status shifts from ST22 to ST23 is −15°.

[0154] When the energization status shifts from ST23 to ST24, the V-phase switching element 412 is turned on, and the W-phase switching element 413 is turned off, the UV-phase is energized, and the convex portion 104 rotates by +15° to a position facing the U-phase and V-phase. That is, similar to Fig. 32, the rotation angle difference Δθ when the energization status shifts from ST23 to ST24 is +15°.

[0155] FIG. 34 is a diagram illustrating the rotation angle difference Δθ in response to switching of the energization statuses ST21 to ST24. Pattern 1 in FIG. 34 corresponds to FIG. 30, and is a pattern in which, in energization status ST21, the recess 105 does not face the phase that is energized in energization status ST22. Pattern 2 corresponds to FIG. 31, and is a pattern in which, in energization status ST21, the recess 105 faces the phase that is energized in energization status ST22. Pattern 3 corresponds to FIG. 32, and is a pattern in which, in energization status ST21, the protrusion 104 faces the phase that is constantly energized with a fault. Pattern 4 corresponds to FIG. 33, and is a pattern in which, in energization status ST21, the recess 105 faces the phase that is constantly energized with a fault.

[0156] 34, when the energization phase is switched from energization status ST21 to ST24, regardless of the rotor position in energization status ST21, when the state transitions from energization status ST23 to ST24, the direction of rotation of rotor 103 differs between when a U-phase open circuit occurs and when a ground short circuit occurs, making it possible to distinguish between an open circuit and a ground short circuit. In particular, when there is a ground short circuit in a state where resistance is small and it is difficult to distinguish based on the current value when the faulty phase is on, the energization state when a normal one-phase switching element is turned on becomes closer to the two-phase energization state, and the encoder output tends to stabilize in a state similar to that when two-phase energization occurs, making it easy to distinguish.

[0157] The energization process for identifying the faulty phase will be described with reference to the flowcharts of Figures 35 and 36. The processes of S251 to S258 in Figure 35 are the same as the processes of S201 to S208 in Figure 18. In S259, the control unit 50 sets the status to energization status ST21.

[0158] 36, in S260, the control unit 50 determines whether the current status is the energization status ST21. If it is determined that the current status is not the energization status ST21 (S260: NO), the process proceeds to S263. If it is determined that the current status is the energization status ST21 (S260: YES), the process proceeds to S261.

[0159] In S261, the control unit 50 determines whether the duration X21 has elapsed since the start of the energization status ST21. If it is determined that the duration X21 has elapsed (S261: YES), the status is set to energization status ST22, and the process proceeds to S265. If it is determined that the duration X21 has not continued (S261: NO), the process proceeds to S262.

[0160] In S262, the control unit 50 performs energization in energization status ST21. The energization status ST11 indicates faulty phase energization, and if the U-phase fault flag is on, the control unit 50 turns on the U-phase switching element 411, if the V-phase fault flag is on, the control unit 50 turns on the V-phase switching element 412, and if the W-phase fault flag is on, the control unit 50 turns on the W-phase switching element 413.

[0161] If it is determined that the current status is not the energization status ST21 (S260: NO), the control unit 50 proceeds to S263, where it determines whether the current status is the energization status ST22. If it is determined that the current status is not the energization status ST22 (S263: NO), it proceeds to S266. If it is determined that the current status is the energization status ST22 (S263: YES), it proceeds to S264.

[0162] In S264, the control unit 50 determines whether the duration X22 has elapsed since the start of the energization status ST22. If it is determined that the duration X22 has elapsed (S264: YES), the status is set to energization status ST23, and the process proceeds to S268. If it is determined that the duration X22 has not elapsed (S264: NO), the process proceeds to S265.

[0163] In S265, the control unit 50 performs energization in energization status ST22. The energization status ST22 indicates normal phase 1 energization, and if the U-phase failure flag is on, the control unit 50 turns on the V-phase switching element 412, if the V-phase failure flag is on, the control unit 50 turns on the W-phase switching element 413, and if the W-phase failure flag is on, the control unit 50 turns on the U-phase switching element 411.

[0164] If it is determined that the current status is not the energization status ST22 (S263: NO), the control unit 50 proceeds to S266, where it determines whether the current status is the energization status ST23. If it is determined that the current status is not the energization status ST23 (S266: NO), the control unit 50 proceeds to S269. If it is determined that the current status is the energization status ST23 (S266: YES), the control unit 50 proceeds to S267.

[0165] In S267, the control unit 50 determines whether the duration X23 has elapsed since the start of the energization status ST23. If it is determined that the duration X23 has elapsed (S267: YES), the status is set to energization status ST24 and the process proceeds to S270. If it is determined that the duration X23 has not elapsed (S267: NO), the process proceeds to S268.

[0166] In S268, the control unit 50 performs energization in energization status ST23. The energization status ST23 is normal phase one-phase energization different from the energization status ST22, and turns on the W-phase switching element 413 when the U-phase failure flag is on, turns on the U-phase switching element 411 when the V-phase failure flag is on, and turns on the V-phase switching element 412 when the W-phase failure flag is on.

[0167] If it is determined that the power-on status is not ST23 (S266: NO), the control unit 50 proceeds to S269, where it determines whether or not duration X24 has elapsed since the start of power-on status ST24. Duration times X21 to X24 can be set arbitrarily, and at least some of them may be the same or different. If it is determined that duration X24 has elapsed (S269: NO), the control unit 50 proceeds to S271. If it is determined that duration X24 has not elapsed (S269: YES), the control unit 50 proceeds to S270.

[0168] In S270, the control unit 50 performs energization in energization status ST24. The energization status ST24 is the same as energization status ST22, that is, one normal phase energization, and if the U-phase failure flag is on, the control unit 50 turns on the V-phase switching element 412, if the V-phase failure flag is on, the control unit 50 turns on the W-phase switching element 413, and if the W-phase failure flag is on, the control unit 50 turns on the U-phase switching element 411. The processes of S271 and S272 are the same as S221 and S222 in FIG. 19.

[0169] The fault state determination process and range switching process are the same as those in the first embodiment if the energization statuses ST11 to ST14 are replaced with ST21 to ST24, and therefore a description thereof will be omitted. Note that in the first embodiment, the energization status ST13 was two-phase energization, and therefore the standby time Xw13 for the energization status ST13 was shorter than the standby time Xw14 for the energization status ST14, but in this embodiment, the energization statuses ST23 and ST24 are both one-phase energization, and therefore it is desirable to make the standby time Xw23 for the energization status ST23 and the standby time Xw24 for the energization status ST24 equal in length.

[0170] In this embodiment, the energization status ST23 for energizing one of the normal phases corresponds to a "first normal phase energization process," and the energization status ST24 for energizing one of the normal phases different from the energization status ST23 corresponds to a "second normal phase energization process." Also, the energization status ST22 corresponds to a "pre-energization process." Even with this configuration, the same effects as those of the above embodiment can be achieved.

[0171] (Fourth embodiment) A fourth embodiment is shown in Figures 37 to 41. In the above embodiments, whether the abnormality is a ground short circuit or a wire break is determined based on the motor rotation angle when the current conduction pattern to the normal phase is switched. In this embodiment, whether the abnormality is a ground short circuit or a wire break is determined based on the encoder output when one phase is conducting.

[0172] The left portions of Figures 37 to 40 are similar to Figures 13 to 16 of the first embodiment, and the right portions show the encoder outputs for phases A and B. Figure 37 shows a case where the U phase is broken and the recess 105 of the rotor 103 does not face the V phase when all phases are off. When all phases are off, no attractive force is generated in the motor windings 11, so the position of the rotor 103 is indefinite. Furthermore, when the U phase is broken, even if the U phase switching element 411 is turned on, no current is applied to the motor windings 11, resulting in the same state.

[0173] When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on to energize the V-phase, the protrusion 104 of the rotor 103 faces the V-phase. At this time, both the A-phase and B-phase are facing the N pole, and the encoder output becomes Lo.

[0174] When the energization status shifts from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on to energize the VW phase, the convex portion 104 faces the V-phase and W-phase. At this time, both the A-phase and B-phase face the S pole, and the encoder output becomes Hi.

[0175] When the energization status shifts from ST13 to ST14, the V-phase switching element 412 is turned off and the W-phase switching element 413 is turned on to energize the W-phase, and the convex portion 104 faces the W-phase. At this time, both the A-phase and B-phase are opposed to the N pole, and the encoder output becomes Lo.

[0176] 38 shows a case where the U-phase is disconnected and the recess 105 of the rotor 103 faces the V-phase when all phases are off. When the recess 105 faces the V-phase when all phases are off, both the A-phase and B-phase face the S pole, and the encoder output becomes Hi.

[0177] When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on to energize the V-phase, current is passed through the coil 112. When the recess 105 faces the V-phase, the left and right protrusions 104 are attracted to the V-phase, so the recess 105 remains facing the V-phase. At this time, both the A-phase and B-phase face south poles, and the encoder output becomes Hi, which is different from the encoder output when the recess 105 was not facing the V-phase when the energization was turned off.

[0178] When the energization status shifts from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on to energize the VW phase, the convex portion 104 faces the V-phase and W-phase. At this time, both the A-phase and B-phase face the S pole, and the encoder output becomes Hi.

[0179] When the energization status shifts from ST13 to ST14 and the W-phase switching element 413 is turned on to energize the W-phase, the protrusion 104 faces the W-phase. At this time, both the A-phase and B-phase are opposed to the N pole, and the encoder output becomes Lo. In other words, by energizing two phases once and then switching to one phase, one protrusion 104 faces one energized phase, regardless of the rotor position when all phases are off, a so-called "one tooth per phase" state is achieved, and the encoder output becomes Lo.

[0180] 39 shows a case where, when all phases are off, a U-phase ground short circuit causes current to flow through the U-phase coil 111, and the convex portion 104 of the rotor 103 faces the U-phase. When the convex portion 104 faces the U-phase, both the A-phase and B-phase poles face N, and the encoder output becomes Lo.

[0181] When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on, the U-phase is short-circuited to ground, causing the UV-phase to be energized and the protruding portion 104 to face the U-phase and V-phase. At this time, both the A-phase and B-phase face south poles, and the encoder output becomes Hi. At this time, the W-phase faces the recessed portion 105.

[0182] When the current supply status shifts from ST12 to ST13 and the V-phase and W-phase switching elements 412, 413 are turned on, current is supplied to the W-phase, but since the W-phase faces the recess 105, the rotor 103 does not rotate, and both the A-phase and B-phase face the S pole, maintaining the encoder output Hi state.

[0183] When the energization status shifts from ST13 to ST14 and the W-phase switching element 413 is turned on, the U-phase is short-circuited to ground, resulting in a WU-phase energized state and the convex portion 104 facing the U-phase and W-phase. At this time, both the A-phase and B-phase are facing the S pole, and the encoder output becomes Hi.

[0184] 40 shows a case where, when all phases are off, a U-phase ground short circuit causes current to flow through the U-phase coil 111, and the recessed portion 105 of the rotor 103 faces the U-phase. When the recessed portion 105 faces the U-phase, both the A-phase and B-phase poles face the S pole, and the encoder output becomes Hi.

[0185] When the energization status shifts from ST11 to ST12 and the V-phase switching element 412 is turned on, the U-phase is short-circuited to ground, causing the UV-phase to be energized and the convex portion 104 to face the U-phase and V-phase. At this time, both the A-phase and B-phase face south poles, and the encoder output becomes Hi. The subsequent VW-phase and W-phase on states are the same as in Figure 39, so their explanation will be omitted.

[0186] When the U phase is shorted to ground, even if the normal phase is energized in one phase, energization also occurs in the U phase, resulting in a two-phase energization state, and the encoder output is different, making it possible to distinguish between a wire break and a ground short.In particular, when the resistance is low and it is difficult to distinguish from the current value when the faulty phase is on, the state is closer to two-phase energization than when there is an incomplete ground short, and the encoder output tends to stabilize in a state similar to that of two-phase energization, making it easy to distinguish.

[0187] 37 to 40, when switching between 1-phase energization, 2-phase energization, and 1-phase energization in the event of a U-phase failure, the energization status ST22 is V-phase energization, and the energization status ST24 after 2-phase energization is W-phase energization. However, the energized phase in the two 1-phase energizations is arbitrary, and the same phase may be energized, for example, V-phase energization, VW-phase energization, and V-phase energization. Also, the first 1-phase energization may be omitted, and 2-phase energization may be started first.

[0188] The current application process for identifying a faulty phase in this embodiment is the same as that in the first embodiment, and therefore will not be described further. The fault state determination process in this embodiment will be described with reference to the flowchart in Fig. 41. The processes in S701 to S703 are the same as those in S501 to S503 in Fig. 20. If a positive determination is made in S701, the process proceeds to S713.

[0189] If it is determined that the power-on status is not ST11 (S702: NO), the processing of S704 and S705 proceeds to the same as the processing of S507 and S508 in Fig. 20. If it is determined in S705 that the standby time Xw14 has not elapsed since the start of the power-on status ST14 (S705: NO), the processing proceeds to S706, where the counter Chi is cleared. If it is determined that the standby time Xw14 has elapsed (S705: YES), the processing proceeds to S707.

[0190] In S707, it is determined whether the encoder outputs for both phases A and B are Hi. A state in which the encoder outputs for both phases A and B are Hi is the signal pattern when two phases are energized and two teeth are formed. If it is determined that at least one of the encoder outputs for phases A and B is Lo (S707: NO), the subsequent processing is skipped. If it is determined that the encoder outputs for phases A and B are both Hi (S707: YES), the process proceeds to S708, and counter Chi is incremented.

[0191] In S709, the abnormality determination unit 52 determines whether the counter Chi is equal to or greater than the count determination threshold Cth. If it is determined that the counter Chi is less than the count determination threshold Cth (S709: NO), the subsequent processing is skipped. If it is determined that the counter Chi is equal to or greater than the count determination threshold Cth (S709: YES), the process proceeds to S710. The processing of S710 to S714 is the same as the processing of S511 to S515 in FIG. 20. Furthermore, the range switching processing is the same as that of the first embodiment except for the details of the failure determination.

[0192] In this embodiment, the rotation detector is the encoder 13, and the abnormality determination unit 52 determines that a constant-power-on fault has occurred if the encoder signal pattern when one of the normal phases is energized is the same as the pattern when two phases are energized. This allows the constant-power-on fault to be properly determined. This also provides the same effects as the above-described embodiment.

[0193] In this embodiment, as in the first embodiment, the energization status ST13 for energizing two normal phases corresponds to the "first normal phase energization process," and the energization status ST14 for energizing one normal phase corresponds to the "second normal phase energization process."

[0194] (Fifth embodiment) A fifth embodiment is shown in Figures 42 to 48. As explained in the above embodiments, when a single-phase fault occurs, if the switching element of one of the normal phases is turned on, the state becomes one-phase conducting if there is a wire break fault, and two-phase conducting if there is a constant conduction fault due to a ground short circuit. In the case of two-phase conducting, the convergence of rotational vibration due to switching of the conducting phase is better than in the case of one-phase conducting. Therefore, in this embodiment, the difference in vibration convergence characteristics between one-phase conducting and two-phase conducting is utilized to distinguish between a wire break fault and a ground short circuit.

[0195] The behavior of rotor 103 when the current supply pattern to V-phase and W-phase, which are normal phases, is switched in the event of a U-phase failure will be described with reference to Figures 42 to 44. In Figures 42 to 44, the horizontal axis represents time and the vertical axis represents the motor rotation angle.

[0196] 42 shows a case where the U-phase is broken and the convex portion 104 of the rotor 103 does not face the V-phase in the energization status ST21. Even if the switching element 411 of the U-phase, which is the faulty phase, is turned on in the energization status ST21, the rotor 103 does not move because no current is passed through the motor winding 11.

[0197] When the energization status shifts from ST21 to ST22, the U-phase switching element 411 is turned off, and the V-phase switching element 412 is turned on, the rotor 103 rotates to a position where the protrusion 104 faces the V-phase. At this time, because one phase is energized, the vibration is relatively large even after the standby time Xw22 has elapsed.

[0198] When the energization status shifts from ST22 to ST23, the V-phase switching element 412 is turned off, and the W-phase switching element 413 is turned on, the rotor 103 rotates to a position where the protrusion 104 faces the W-phase. At this time, because one phase is energized, the vibration is relatively large even after the standby time Xw23 has elapsed.

[0199] 43 shows a case where the U-phase is disconnected and the convex portion 104 of the rotor 103 faces the V-phase in the energization status ST21. The behavior of the energization status ST21 is the same as that in FIG.

[0200] The current conduction status shifts from ST21 to ST22, turning off the U-phase switching element 411 and turning on the V-phase switching element 412. In this example, because the convex portion 104 faces the V-phase in the current conduction status ST21, the rotor 103 does not move and the rotation angle does not change even when current is applied to the V-phase. Note that the rotation angle also does not change when the concave portion 105 faces the V-phase in the current conduction status ST21. That is, the rotor position is indefinite in the current conduction status ST21, and when the rotor 103 faces the V-phase at a position close to the convex portion 104 or the concave portion 105, vibration of the rotor 103 is small even when switching to V-phase current application.

[0201] The behavior when the current supply status changes from ST22 to ST23 is the same as in Fig. 42, and the W-phase current supply causes the rotor 103 to rotate to a position where the protrusion 104 faces the W-phase. At this time, because one phase is current supplied, the vibration is relatively large even after the standby time Xw23 has elapsed.

[0202] 44 shows the case of a U-phase constantly energized fault. In energization status ST21, when U-phase switching element 411 is turned on, U-phase coil 111 is energized, and protrusion 104, for example, faces the U-phase.

[0203] When the current conduction status shifts from ST21 to ST22, the U-phase switching element 411 is turned off, and the V-phase switching element 412 is turned on, a two-phase current conduction state for the UV phase is established, and the rotor 103 rotates to a position where the convex portion 104 faces the U-phase and V-phase.

[0204] When the energization status shifts from ST22 to ST23, the V-phase switching element 412 is turned off and the W-phase switching element 413 is turned on, a two-phase WU-phase energization state is achieved, and the rotor 103 rotates to a position where the convex portion 104 faces the U-phase and W-phase.

[0205] When a constant energization fault occurs, the energization statuses ST22 and ST23 indicate a two-phase energized state, which results in better vibration convergence than when a wire breakage fault occurs and the state is a one-phase energized state. Therefore, in this embodiment, the difference between the maximum and minimum values ​​of the energization statuses ST22 and ST23 after the waiting times Xw22 and Xw23 have elapsed is used to distinguish between a one-phase wire breakage and a ground short circuit.

[0206] 43, depending on the rotor position of the energization status ST21, the rotor 103 may not move when the energization status is switched from ST21 to ST22 even when one phase is broken, and there is a risk of erroneous determination when the energization status is switched to ST22 alone. For this reason, in this embodiment, determination is made based on the energization statuses ST22 and ST23.

[0207] The power supply process for fault identification in this embodiment is shown in the flowchart of Figure 45. Since the first half is the same as Figure 35 of the second embodiment, the second half corresponding to Figure 36 is shown in Figure 45. Figure 45 is the same as Figure 36 except that S266, S269, and S270 are omitted. If a negative determination is made in S263, the process proceeds to S267, and if a positive determination is made in S267, the process proceeds to S271.

[0208] The fault state determination process will be described with reference to the flowchart of Fig. 46. The process of S801 is the same as the process of S501 in Fig. 20, and if it is determined that the two-phase pre-switching energization completion flag FlgC is on (S801: YES), the process proceeds to S813, and if it is determined that the two-phase pre-switching energization completion flag FlgC is off (S801: NO), the process proceeds to S802.

[0209] In S802, the abnormality determination unit 52 determines whether the current status is the energization status ST21. If it is determined that the current status is ST21 (S802: YES), the process proceeds to S803. The process of S803 is the same as the process of S503 in Fig. 20, and if a positive determination is made in S803, the process proceeds to S814. If it is determined that the current status is not ST21 (S802: NO), the process proceeds to S804.

[0210] In S804, the abnormality determination unit 52 determines whether the current status is the energization status ST22. If it is determined that the current status is not the energization status ST22 (S804: NO), the process proceeds to S808. If it is determined that the current status is the energization status ST22 (S804: YES), the process proceeds to S805.

[0211] In S805, the abnormality determination unit 52 determines whether the standby time Xw22 has elapsed since the start of the energization status ST22. If it is determined that the standby time Xw22 has not elapsed (S805: NO), the subsequent processing is skipped. If it is determined that the standby time Xw22 has elapsed (S805: YES), the process proceeds to S806, where maximum and minimum values ​​in the energization status ST22 are updated.

[0212] A subflow of the maximum / minimum value update process in the energization status ST22 is shown in Figure 47. In S861, the abnormality determination unit 52 determines whether or not this is the first calculation after the wait time Xw22 has elapsed. If it is determined that this is the first calculation after the wait time Xw22 has elapsed (S861: YES), the process proceeds to S862, where the current encoder count value EN is set to the maximum value CTmax22 and the minimum value CTmin22. If it is determined that this is not the first calculation after the wait time Xw22 has elapsed (S861: NO), the process proceeds to S863.

[0213] In S863, the abnormality determination unit 52 determines whether the current encoder count value EN is greater than the maximum value CTmax22. If it is determined that the current encoder count value EN is equal to or less than the maximum value CTmax22 (S863: NO), the value held as the maximum value CTmax22 is not updated, and the process proceeds to S865. If it is determined that the current encoder count value EN is greater than the maximum value CTmax22 (S863: YES), the process proceeds to S864, and the maximum value CTmax22 is updated to the current encoder count value EN.

[0214] In S865, the abnormality determination unit 52 determines whether the current encoder count value EN is smaller than the minimum value CTmin22. If it is determined that the current encoder count value EN is equal to or greater than the minimum value CTmin22 (S865: NO), the value held as the minimum value CTmin22 is not updated and this process ends. If it is determined that the current encoder count value EN is smaller than the minimum value CTmin22 (S865: YES), the minimum value CTmin22 is updated to the current encoder count value EN.

[0215] 46, in S807, which is performed following the maximum / minimum value update process for the energization status ST22, the abnormality determination unit 52 determines whether the vibration amplitude A22 (see equation (3)) is equal to or greater than the amplitude determination threshold Ath. If it is determined that the vibration amplitude A22 is smaller than the amplitude determination threshold Ath (S807: NO), the subsequent processes are skipped. If it is determined that the vibration amplitude A22 is equal to or greater than the amplitude determination threshold Ath (S807: YES), the process proceeds to S812.

[0216] A22=CTmax22-CTmin22 (3)

[0217] If it is determined that the current status is not the energization status ST22 (S804: NO), the abnormality determination unit 52 proceeds to S808, where it determines whether the current status is the energization status ST23. If it is determined that the current status is not the energization status ST23 (S808: NO), the subsequent processing is skipped. If it is determined that the current status is the energization status ST23 (S808: YES), the processing proceeds to S809.

[0218] In S809, the abnormality determination unit 52 determines whether or not the standby time Xw23 has elapsed since the start of the energization status ST23. If it is determined that the standby time Xw23 has not elapsed (S809: NO), the subsequent processing is skipped. If it is determined that the standby time Xw23 has elapsed (S809: YES), the process proceeds to S810, where maximum and minimum values ​​in the energization status ST23 are updated.

[0219] A subflow of the maximum / minimum value update process in the energization status ST23 is shown in Figure 48. In S891, the abnormality determination unit 52 determines whether or not this is the first calculation after the wait time Xw23 has elapsed. If it is determined that this is the first calculation after the wait time Xw23 has elapsed (S891: YES), the process proceeds to S892, where the current encoder count value EN is set to the maximum value CTmax23 and the minimum value CTmin23. If it is determined that this is not the first calculation after the wait time Xw23 has elapsed (S891: NO), the process proceeds to S893.

[0220] In S893, the abnormality determination unit 52 determines whether the current encoder count value EN is greater than the maximum value CTmax23. If it is determined that the current encoder count value EN is equal to or less than the maximum value CTmax23 (S893: NO), the value held as the maximum value CTmax23 is not updated, and the process proceeds to S895. If it is determined that the current encoder count value EN is greater than the maximum value CTmax23 (S893: YES), the process proceeds to S894, and the maximum value CTmax23 is updated to the current encoder count value EN.

[0221] In S895, the abnormality determination unit 52 determines whether the current encoder count value EN is smaller than the minimum value CTmin23. If it is determined that the current encoder count value EN is equal to or greater than the minimum value CTmin23 (S895: NO), the value held as the minimum value CTmin23 is not updated and this process ends. If it is determined that the current encoder count value EN is smaller than the minimum value CTmin23 (S895: YES), the minimum value CTmin23 is updated to the current encoder count value EN.

[0222] Returning to FIG. 46, in S811, which is performed following the maximum / minimum value update process in the energization status ST23, it is determined whether the vibration amplitude A23 (see equation (4)) is equal to or greater than the amplitude determination threshold Ath. The amplitude determination threshold Ath is the same as the value used in S807, but may be different. If it is determined that the vibration amplitude A23 is smaller than the amplitude determination threshold Ath (S811: NO), the subsequent processes are skipped. If it is determined that the vibration amplitude A23 is equal to or greater than the amplitude determination threshold Ath (S811: YES), the process proceeds to S812.

[0223] A23=CTmax23-CTmin23 (4)

[0224] In S812, which is reached when it is determined that the vibration amplitudes A22 and A23 are equal to or greater than the amplitude determination threshold Ath (S807: YES or S811: YES), the abnormality determination unit 52 determines that the fault occurring in the faulty phase is an open circuit fault and turns on the one-phase open circuit fault flag FlgD.

[0225] In S813, which is performed when it is determined that the two-phase pre-switching energization completion flag FlgC is on (S801: YES), the abnormality determination unit 52 determines whether the one-phase open circuit fault flag FlgD is off. If it is determined that the one-phase open circuit fault flag FlgD is on (S813: NO), the subsequent processing is skipped. If it is determined that the one-phase open circuit fault flag FlgD is off (S813: YES), the abnormality occurring in the faulty phase is identified as a constant energization fault, and the processing proceeds to S814. The processing of S814 to S816 is the same as the processing of S511 to S513 in FIG. 20.

[0226] In this embodiment, the abnormality determination unit 52 applies current to one of the normal phases, and if the amplitudes A22 and A23 of the encoder count value after the standby time has elapsed from the start of current application are smaller than the amplitude determination threshold Ath, the abnormality determination unit 52 determines that a constant-power-on fault has occurred. This allows the constant-power-on fault to be properly identified. This also provides the same effects as the above-described embodiment.

[0227] In the above embodiment, the encoder 13 corresponds to the "rotational position detection unit," the ECU 40 corresponds to the "motor control device," and the voltage detection circuit 46 corresponds to the "voltage detection unit." The port level corresponds to the "voltage detection value," and the motor current Im corresponds to the "current detection value." Furthermore, the encoder signal including the A-phase signal and the B-phase signal corresponds to the "rotational position detection value," the encoder count value corresponds to the "motor rotational position," and the vibration amplitudes A22 and A23 correspond to the "rotational position amplitude."

[0228] (Other embodiments) In the above embodiment, a first fault state identification process based on the motor current and a second fault state identification process based on the motor rotational position are performed to identify a constantly energized fault. In other embodiments, a constantly energized fault may be identified by either the first fault state identification process or the second fault state identification process.

[0229] In the first embodiment and the like, the energization status ST12, which is a preliminary energization process, is performed before the energization status ST13, which is a first normal phase energization process. In other embodiments, the preliminary energization process may be omitted.

[0230] 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. The current detection unit and the voltage detection unit may also have different configurations from those in the above embodiment.

[0231] 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.

[0232] 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.

[0233] 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.

[0234] The features of the present invention may be, for example, "a motor control device according to claim 3 or 4, wherein the drive control unit performs a pre-energization process of energizing one or more normal phases that are different in at least one phase from the first normal phase energization process before the first normal phase energization process" or "a motor control device according to any one of claims 1 to 8, wherein the motor is a three-phase motor, and the drive control unit drives the motor by energizing the motor windings of the two normal phases when it is determined that the faulty phase is one phase and is not a constantly energized fault."

[0235] 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]

[0236] 1. Shift-by-wire system 10 Motor 11 Motor winding 13 Encoder (rotation detection unit) 40···ECU (motor control unit) 41: Drive circuit 411 to 413: Switching elements 45 Current detection unit 46 Voltage detection circuit (voltage detection unit) 50: Control unit 51: Signal acquisition unit 52... Abnormality determination section 55 Drive control unit

Claims

1. A motor control device for controlling the driving of a motor (10) having motor windings (11) of three or more phases, 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 and an abnormality determination unit (52) that determines an abnormality in a current path to the motor winding; Equipped with the control unit is capable of acquiring a voltage detection value that is a detection value of a voltage detection unit (46) that detects each phase voltage of the motor winding, a current detection value that is a detection value of a current detection unit (45) that detects a current flowing through the motor winding, and a rotation position detection value that is a detection value of a rotation detection unit (13) that detects a rotation position of the motor, The abnormality determination unit Identifying the faulty phase based on the voltage detection value when the switching elements of all phases are turned off; A motor control device that identifies a constantly energized fault in the identified faulty phase based on at least one of the current detection value when the switching element of the identified faulty phase is turned on and the rotational position detection value when the switching elements of one or more normal phases are turned on.

2. The motor control device according to claim 1 , wherein the abnormality determination unit determines that the fault is a constantly energized fault when the current detection value when the switching element of the faulty phase is turned on is equal to or greater than a current determination threshold value.

3. 3. The motor control device according to claim 1, wherein the abnormality determination unit identifies the constantly energized fault based on the amount of change in rotational position of the motor when a first normal phase energization process is performed in which current is applied to one or more normal phases, and when a second normal phase energization process is performed in which current is applied to one or more normal phases that are at least one phase different from the first normal phase energization process.

4. 4. The motor control device according to claim 3, wherein the abnormality determination unit determines that the constant current failure has occurred when the rotation direction when switching from the first normal phase energization process to the second normal phase energization process is different from that when all phases are normal.

5. 4. The motor control device according to claim 3, wherein the drive control unit performs a pre-energization process before the first normal phase energization process, in which energization is performed on one or more normal phases that are at least one phase different from the first normal phase energization process.

6. 4. The motor control device according to claim 3, wherein the abnormality determination unit determines that the motor has a constant-energization fault if, when the switching elements of all normal phases are turned on as the second normal phase energization process, the amount of change in the rotational position of the motor is smaller than a determination threshold value.

7. 3. The motor control device according to claim 1, wherein the abnormality determination unit determines that a constant-power-on fault has occurred when current is applied to one of the normal phases and the amplitude of the rotational position of the motor after a standby time has elapsed since the start of current application is smaller than an amplitude determination threshold.

8. the rotation detection unit is an encoder, 3. The motor control device according to claim 1, wherein the abnormality determination unit determines that the motor has a constantly energized fault when an encoder signal pattern obtained when one of the normal phases is energized is the same as a pattern obtained when two phases are energized.

9. The motor is a three-phase motor, 2. The motor control device according to claim 1, wherein when it is determined that the faulty phase is one phase and the fault is not a constantly energized fault, the drive control unit drives the motor by energizing the motor windings of the two normal phases.

10. The drive control unit When all phases are normal and a stagnation abnormality occurs in which the rotational position detection value stagnates, open drive is performed to switch the energized phase without using the rotational position detection value, instead of feedback control based on the rotational position detection value.

10. The motor control device according to claim 9, wherein, when the faulty phase is one phase and the fault is not a constantly energized fault, the motor is driven by energizing the motor windings of the two phases that are normal in the feedback control, and when the stagnation abnormality occurs, drive control of the motor is stopped.

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