Motor control unit and electric power steering unit

Abstract

The motor control device includes a temperature detection element (45a, 46a) mounted on a circuit substrate (70) on which a first power conversion circuit (42A) and a second power conversion circuit (42B) are mounted, and is arranged at a position between the first power conversion circuit (42A) and the second power conversion circuit (42B).

Description

Technical Field

[0001] The invention relates to a motor control device and an electric power steering device. Background Art

[0002] Patent Documents 1 to 3 listed below describe an electric power steering device including a temperature sensor for detecting the temperature near a circuit board that drives a motor that generates a steering assist force.

[0003] Furthermore, Patent Document 4 listed below describes an electric power steering device in which current for driving a motor is supplied from a plurality of inverters (power conversion circuits).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4135437

[0007] Patent Document 2: Japanese Patent Application Publication No. 2012-148629

[0008] Patent Document 3: Japanese Patent Application Publication No. 2020-148639

[0009] Patent Document 4: International Publication No. 2015 / 136918 Pamphlet Summary of the invention

[0010] Problems to be solved by the invention

[0011] The power conversion circuit contains heat generating components and may be damaged by overheating. A temperature detection element is provided on a circuit substrate on which the power conversion circuit is mounted. When the temperature detected by the temperature detection element exceeds the assumed temperature, the output current of the power conversion circuit is limited, thereby preventing damage to the power conversion circuit caused by overheating.

[0012] When a plurality of power conversion circuits are provided as in Patent Document 4, it is desirable to be able to appropriately detect temperature abnormalities in each power conversion circuit.

[0013] The present invention has been completed with focus on the above-mentioned problems, and its object is to improve the detection accuracy of temperature anomalies of both the first power conversion circuit and the second power conversion circuit in a motor control device in which the first power conversion circuit and the second power conversion circuit are mounted on the same circuit substrate.

[0014] Means for solving problems

[0015] In order to achieve the above-mentioned purpose, a motor control device of one embodiment of the present invention comprises: a circuit substrate; a first power conversion circuit, which is mounted on the circuit substrate and supplies current to drive a motor; a second power conversion circuit, which is mounted on the circuit substrate and supplies current to drive a motor that is the same as or different from the motor supplied with current by the first power conversion circuit; a temperature detection circuit, which has a temperature detection element; and a control circuit, which limits the current supplied by the first power conversion circuit and the current supplied by the second power conversion circuit based on the temperature detected by the temperature detection circuit, the temperature detection element being mounted on the circuit substrate on which the first power conversion circuit and the second power conversion circuit are mounted, and being arranged at a position between the first power conversion circuit and the second power conversion circuit.

[0016] An electric power steering device according to another aspect of the present invention includes the above-mentioned motor control device and a motor controlled by the motor control device, and applies a steering assist force to a steering system of a vehicle through the motor.

[0017] Effects of the Invention

[0018] According to the present invention, in a motor control device in which a first power conversion circuit and a second power conversion circuit are mounted on the same circuit board, it is possible to improve the accuracy of detecting temperature anomalies in both the first power conversion circuit and the second power conversion circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram showing an example of an electric power steering device according to an embodiment.

[0020] Figure 2 It is a schematic configuration diagram showing an example of an electronic control unit (ECU) according to the first embodiment.

[0021] Figure 3 This is a circuit diagram of an example of a temperature detection circuit.

[0022] Figure 4 This is a block diagram showing an example of the functional configuration of the temperature measuring unit according to the first embodiment.

[0023] Figure 5 This is an explanatory diagram schematically showing changes in the ECU temperature estimation value when an abnormality occurs in the temperature detection circuit.

[0024] Figure 6 This is a block diagram showing an example of the functional configuration of the control arithmetic device according to the first embodiment.

[0025] Figure 7 This is a flowchart of an example of the motor control method according to the first embodiment.

[0026] Figure 8 It is a schematic configuration diagram showing an example of an electronic control unit according to the second embodiment and the third embodiment.

[0027] Fig. 9 This is a block diagram showing an example of the functional configuration of the temperature measuring unit according to the second embodiment.

[0028] Fig.10 This is an explanatory diagram schematically showing changes in the ECU temperature estimation value when an abnormality occurs in the temperature detection circuit.

[0029] Fig.11 This is a block diagram showing an example of the functional configuration of the control arithmetic device according to the second embodiment.

[0030] Fig.12 This is a flowchart of an example of the motor control method according to the second embodiment.

[0031] Fig.13 This is a block diagram showing an example of the functional configuration of a temperature measuring unit according to a modification.

[0032] Fig.14 This is a schematic diagram showing the relative positional relationship between the power conversion circuit and the temperature detection element mounted on the circuit board.

[0033] Fig.15 This is a schematic diagram of a heat dissipation structure that releases heat generated by a power conversion circuit.

[0034] Fig.16 This is a block diagram showing an example of the functional configuration of the temperature measuring unit according to the third embodiment.

[0035] Fig.17 This is an explanatory diagram schematically showing a method of calculating an ECU temperature estimation value when a temperature detection circuit is abnormal.

[0036] Fig.18 It is a schematic structural diagram showing a first modified example of the electric power steering device.

[0037] Fig.19 It is a schematic structural diagram showing a second modified example of the electric power steering device.

[0038] Fig. 20 It is a schematic structural diagram showing a third modified example of the electric power steering device. DETAILED DESCRIPTION

[0039] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0040] In addition, the embodiments of the present invention shown below illustrate devices and methods for implementing the technical concept of the present invention, and the technical concept of the present invention does not limit the structure and configuration of the components to the following contents. The technical concept of the present invention can be modified in various ways within the technical scope specified by the technical solution described in the claims.

[0041] (First Embodiment)

[0042] (structure)

[0043] Figure 1 The present invention is a schematic structural diagram showing an example of an electric power steering (EPS) device according to an embodiment. A steering shaft (steering shaft, handle shaft) 2 of a steering wheel (steering handle) 1 is connected to steered wheels 8L, 8R via a reduction gear (worm gear) 3 constituting a reduction mechanism, universal joints 4a, 4b, a pinion rack mechanism 5, and steering tie rods 6a, 6b, and further via hub units 7a, 7b.

[0044] The rack and pinion mechanism 5 includes a pinion 5a connected to a pinion shaft that transmits steering force from the universal joint 4b and a rack 5b meshing with the pinion 5a. The rack 5b converts rotational motion transmitted to the pinion 5a into linear motion in the vehicle width direction.

[0045] The steering shaft 2 is provided with a torque sensor 10 for detecting a steering torque Th. In addition, the steering shaft 2 is provided with a steering angle sensor 14 for detecting a steering angle θh of the steering wheel 1 .

[0046] In addition, the motor 20 that assists the steering force of the steering wheel 1 is connected to the steering shaft 2 via the reduction gear 3. The motor 20 may be, for example, a multi-phase motor. In the following description, an example of a three-phase motor having a double winding in which a first system coil and a second system coil are wound in the same motor housing and a common rotor is rotated by the two system coils is described, but the motor 20 may also be a motor other than a double winding motor, and the number of phases of the motor 20 may not be three phases. A plurality of motors 20 that assist the steering force of the steering wheel 1 may also be connected to the same steering shaft 2.

[0047] An electronic control unit (ECU: Electronic Control Unit) 30 that controls the electric power steering device is supplied with electric power from the battery 13 , and an ignition key signal is inputted via the ignition switch 11 .

[0048] ECU30 calculates the current command value of the auxiliary control command based on the steering torque Th detected by the torque sensor 10, the vehicle speed Vh detected by the vehicle speed sensor 12, and the steering angle θh detected by the steering angle sensor 14, and controls the current supplied to the motor 20 (the A-phase current I1a, the B-phase current I1b, the C-phase current I1c of the first system coil, and the A-phase current I2a, the B-phase current I2b, the C-phase current I2c of the second system coil) by means of a voltage control command value obtained by applying compensation to the current command value. ECU30 is an example of a "motor control device" described in the technical proposal.

[0049] In addition, the steering angle sensor 14 is not essential, and the steering angle θh can be calculated by adding the torsion angle of the torsion bar of the torque sensor 10 to the product of the motor rotation angle θm obtained from the rotation angle sensor 23a that detects the rotation angle of the rotation shaft of the motor 20 and the gear ratio of the reduction gear 3. The rotation angle sensor 23a can be, for example, a resolver that detects the rotation position of the motor or a magnetic sensor that detects the magnetic field of a magnet attached to the rotation shaft of the motor 20. In addition, the steering angle of the steering wheels 8L and 8R can be used instead of the steering angle θh. For example, the steering angle can also be detected by detecting the displacement of the rack 5b.

[0050] The ECU 30 includes, for example, a computer including a processor and peripheral components such as a storage device. The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).

[0051] The storage device may include any of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device may include a register, a cache memory, a ROM (Read Only Memory) used as a main storage device, and a RAM (Random Access Memory) and other memories.

[0052] The functions of the ECU 30 described below are implemented, for example, by a processor of the ECU 30 executing a computer program stored in a storage device.

[0053] In addition, the ECU 30 may be formed of dedicated hardware for executing each information processing described below.

[0054] For example, the ECU 30 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the ECU 30 may include a programmable logic device (PLD: Programmable Logic Device) such as a field programmable gate array (FPGA: Field-Programmable Gate Array).

[0055] Figure 2 1 is a schematic structural diagram showing an example of the ECU 30 of the first embodiment. The ECU 30 includes a motor rotation angle detection circuit 23, a control operation device 31, a first motor current cutoff circuit 33A and a second motor current cutoff circuit 33B, a first gate drive circuit 41A, a second gate drive circuit 41B, a first power conversion circuit (first inverter) 42A, a second power conversion circuit (second inverter) 42B, a first power cutoff circuit 44A, a second power cutoff circuit 44B, and a temperature detection circuit 45.

[0056] The ECU 30 is connected to a power wiring PW that transmits power from the battery 13 via a connector CNT. The positive side line Lp of the power wiring PW is connected to the control operation device 31 via a noise filter circuit formed by a choke coil L and ceramic capacitors C1 and C2, and is branched into a first positive side line LpA and a second positive side line LpB at a branch point Pb.

[0057] The first positive electrode line LpA and the second positive electrode line LpB are power supply lines for supplying power to the first power conversion circuit 42A and the second power conversion circuit 42B, respectively, and are connected to the first power supply cutoff circuit 44A and the second power supply cutoff circuit 44B, respectively.

[0058] One end of the choke coil L is connected to the positive side line Lp and one end of the ceramic capacitor C1, the other end of the choke coil L is connected to one end of the ceramic capacitor C2, the control operation device 31 and the branch point Pb, and the other ends of the ceramic capacitors C1 and C2 are grounded. On the other hand, the negative side line of the power wiring PW is connected to the ground line of the ECU 30.

[0059] Signals of the steering torque Th detected by the torque sensor 10 , the vehicle speed Vh detected by the vehicle speed sensor 12 , and the steering angle θh detected by the steering angle sensor 14 are transmitted to the control computing device 31 via the connector CNT.

[0060] The control operation device 31 calculates a current command value as a control target value of the drive current of the motor 20 based on at least the steering torque Th, and outputs voltage control command values ​​V1a, V1b, V1c, V2a, V2b, and V2c obtained by performing compensation on the current command value to the first gate drive circuit 41A and the second gate drive circuit 41B. The voltage control command values ​​V1a, V1b, and V1c are respectively the A-phase voltage control command value, the B-phase voltage command value, and the C-phase voltage command value of the first system coil, and the voltage control command values ​​V2a, V2b, and V2c are respectively the A-phase voltage control command value, the B-phase voltage command value, and the C-phase voltage command value of the second system coil.

[0061] The first power supply cut-off circuit 44A has a series circuit structure in which the sources of two FETs QC1 and QC2 are connected to each other so that the parasitic diodes are reversed. The drain of FET QC1 is connected to the first positive side line LpA, and the drain of FET QC2 is connected to the drains of each FET Q1, Q3 and Q5 of the first power conversion circuit 42A. The control operation device 31 outputs a control signal SpA to control the power-on and power-off of the first power supply cut-off circuit 44A to the first gate drive circuit 41A. The first gate drive circuit 41A outputs gate signals of FET QC1 and QC2 according to the control signal SpA, so that the power supply current from the battery 13 to the first power conversion circuit 42A is turned on or off.

[0062] In addition, the second power supply cutoff circuit 44B has a series circuit structure in which the sources of the two FETs QD1 and QD2 are connected to each other so that the parasitic diodes are reversed. The drain of FET QD1 is connected to the second positive electrode side line LpB, and the drain of FET QD2 is connected to the drains of each FET Q1, Q3 and Q5 of the second power conversion circuit 42B. The control operation device 31 outputs a control signal SpB to control the power on and off of the second power supply cutoff circuit 44B to the second gate drive circuit 41B. The second gate drive circuit 41B outputs gate signals of FET QD1 and QD2 according to the control signal SpB, so that the power supply current from the battery 13 to the second power conversion circuit 42B is turned on or off.

[0063] When the voltage control command values ​​V1a, V1b, and V1c are input from the control operation device 31, the first gate drive circuit 41A generates six gate signals that are pulse width modulated (PWM) based on the voltage control command values ​​V1a, V1b, and V1c and a triangular wave carrier signal, and outputs these gate signals to the first power conversion circuit 42A.

[0064] When the voltage control command values ​​V2a, V2b, and V2c are input from the control operation device 31, the second gate drive circuit 41B generates six gate signals that are pulse width modulated (PWM) based on these voltage control command values ​​V2a, V2b, and V2c and a triangular wave carrier signal, and then outputs these gate signals to the second power conversion circuit 42B.

[0065] The first power conversion circuit 42A includes three switching arms SWAa, SWAb, and SWAc formed of FETs as switching elements, and an electrolytic capacitor CA.

[0066] The switch arms SWAa, SWAb, and SWAc are connected in parallel with each other. The switch arm SWAa of the A phase has FETQ1 and FETQ2 connected in series, the switch arm SWAb of the B phase has FETQ3 and FETQ4 connected in series, and the switch arm SWAc of the C phase has FETQ5 and FETQ6 connected in series. The gate signal output from the first gate drive circuit 41A is input to the gate of each FETQ1 to FETQ6, and through the gate signal, the A phase current I1a, the B phase current I1b, and the C phase current I1c are energized from the connection point between the FETs of each switch arm SWAa, SWAb, and SWAc to the A phase winding, the B phase winding, and the C phase winding of the first system coil of the motor 20 via the first motor current cutoff circuit 33A.

[0067] The electrolytic capacitor CA has a noise removal function and a power supply assisting function for the first power conversion circuit 42A.

[0068] The second power conversion circuit 42B includes three switching arms SWBa, SWBb, and SWBc formed of FETs as switching elements, and an electrolytic capacitor CB.

[0069] The switch arms SWBa, SWBb, and SWBc are connected in parallel with each other. The switch arm SWBa of the A phase has FETQ1 and FETQ2 connected in series, the switch arm SWBb of the B phase has FETQ3 and FETQ4 connected in series, and the switch arm SWBc of the C phase has FETQ5 and FETQ6 connected in series. The gate signal output from the second gate drive circuit 41B is input to the gate of each FETQ1 to FETQ6, and through the gate signal, the A phase current I2a, the B phase current I2b, and the C phase current I2c are energized from the connection point between the FETs of each switch arm SWBa, SWBb, and SWBc to the A phase winding, the B phase winding, and the C phase winding of the second system coil of the motor 20 via the second motor current cutoff circuit 33B.

[0070] The electrolytic capacitor CB has a noise removal function and a power supply assisting function for the second power conversion circuit 42B.

[0071] The first power conversion circuit 42A and the second power conversion circuit 42B may supply three-phase current to two different motors that respectively generate steering assist forces for assisting the steering of the steering wheel 1. For example, the two different motors may be connected to the same steering shaft 2 via a reduction gear.

[0072] Current detection circuits 39A1, 39B1, and 39C1 are provided on the source sides of the FETQ2, FETQ4, and FETQ6 forming the lower arms of the switch arms SWAa, SWAb, and SWAc of the first power conversion circuit 42A. The current detection circuits 39A1, 39B1, and 39C1 detect the downstream currents of the switch arms SWAa, SWAb, and SWAc as the A-phase current, the B-phase current, and the C-phase current of the first system coil, respectively, and output their detection values ​​I1ad, I1bd, and I1cd.

[0073] Current detection circuits 39A2, 39B2, and 39C2 are provided on the source sides of the FETQ2, FETQ4, and FETQ6 forming the lower arms of the switch arms SWBa, SWBb, and SWBc of the second power conversion circuit 42B. The current detection circuits 39A2, 39B2, and 39C2 detect the downstream side currents of the switch arms SWBa, SWBb, and SWBc as the A-phase current, the B-phase current, and the C-phase current of the second system coil, respectively, and output the detection values ​​I2ad, I2bd, and I2cd thereof.

[0074] The first motor current cutoff circuit 33A has three current cutoff FETs, FETQA1, FETQA2, and FETQA3. The source of FETQA1 is connected to the connection point of FETQ1 and FETQ2 of the switch arm SWAa of the first power conversion circuit 42A, and the drain is connected to the A-phase winding of the first system coil of the motor 20. The source of FETQA2 is connected to the connection point of FETQ3 and FETQ4 of the switch arm SWAb, and the drain is connected to the B-phase winding of the first system coil. The source of FETQA3 is connected to the connection point of FETQ5 and FETQ6 of the switch arm SWAc, and the drain is connected to the C-phase winding of the first system coil.

[0075] The control operation device 31 outputs a control signal SmA to control the energization and disconnection of the first motor current cut-off circuit 33A to the first gate drive circuit 41A. The first gate drive circuit 41A outputs gate signals of FETQA1 to FETQA3 corresponding to the control signal SmA, so as to connect or disconnect the A-phase current I1a, the B-phase current I1b, and the C-phase current I1c from the first power conversion circuit 42A to the motor 20.

[0076] The second motor current cutoff circuit 33B has three current cutoff FETs QB1, FETQB2, and FETQB3. The source of FETQB1 is connected to the connection point of FETQ1 and FETQ2 of the switch arm SWBa of the second power conversion circuit 42B, and the drain is connected to the A-phase winding of the second system coil of the motor 20. The source of FETQB2 is connected to the connection point of FETQ3 and FETQ4 of the switch arm SWBb, and the drain is connected to the B-phase winding of the second system coil. The source of FETQB3 is connected to the connection point of FETQ5 and FETQ6 of the switch arm SWBc, and the drain is connected to the C-phase winding of the second system coil.

[0077] The control operation device 31 outputs the control signal SmB for controlling the energization and disconnection of the second motor current cut-off circuit 33B to the second gate drive circuit 41B. The second gate drive circuit 41B outputs the gate signals of FETQB1 to FETQB3 corresponding to the control signal SmB, so as to connect or disconnect the A-phase current I2a, the B-phase current I2b, and the C-phase current I2c from the second power conversion circuit 42B to the motor 20.

[0078] The motor rotation angle detection circuit 23 acquires a detection value from the rotation angle sensor 23a, and detects a motor rotation angle θm, which is a rotation angle of the rotation shaft of the motor 20. The motor rotation angle detection circuit 23 outputs the motor rotation angle θm to the control calculation device 31.

[0079] The temperature detection circuit 45 includes a temperature sensor 45a disposed near the first power conversion circuit 42A and the second power conversion circuit 42B. The temperature sensor 45a is an example of a "temperature detection element". In addition, the temperature sensor 45a may not be disposed near the first power conversion circuit 42A and the second power conversion circuit 42B. The temperature sensor 45a only needs to be disposed at a portion of the ECU 30 that is prone to heat.

[0080] The temperature detection circuit 45 detects the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B based on the output of the temperature sensor 45a, and outputs a detection signal Sd1 indicating the detection result. In the following description, the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B detected by the temperature detection circuit 45 (the temperature indicated by the detection signal Sd1) is sometimes referred to as "ECU temperature detection value Te1".

[0081] For example, the temperature sensor 45a may be a thermistor. The temperature detection circuit 45 may include a thermistor processing circuit that detects the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B based on the resistance value of the thermistor.

[0082] Figure 3: is a circuit diagram of an example of the temperature detection circuit 45. The temperature detection circuit 45 has a voltage divider circuit formed by connecting a thermistor 45a as a temperature sensor and a fixed resistor R in series, and a capacitor Ct. The voltage divider circuit composed of the thermistor 45a and the fixed resistor R divides the predetermined voltage Vcc at a ratio of the resistance value of the thermistor 45a and the resistance value of the fixed resistor R, and outputs the value obtained by the voltage division as a detection signal Sd1 to the control operation device 31.

[0083] Reference Figure 2 The control operation device 31 obtains the detection values ​​I1ad, I1bd, I1cd of the A-phase current, B-phase current, and C-phase current of the first system coil, the detection values ​​I2ad, I2bd, I2cd of the A-phase current, B-phase current, and C-phase current of the second system coil, and the detection signal Sd1 of the temperature detection circuit 45 via the A / D conversion unit 31a.

[0084] The control operation device 31 includes a temperature measuring unit 31b, which measures the ECU temperature, which is the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B, and estimates the motor temperature, which is the temperature of the motor 20 (for example, the temperature of the coil winding of the motor 20). The temperature measuring unit 31b measures the ECU temperature based on the ECU temperature detection value Te1 indicated by the detection signal Sd1 of the temperature detection circuit 45. In addition, the temperature measuring unit 31b estimates the motor temperature based on the ECU temperature detection value Te1 and the detection values ​​I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd of the motor current flowing through the motor 20.

[0085] Figure 4 1 is a block diagram showing an example of the functional configuration of the temperature measuring unit 31 b according to the first embodiment. The temperature measuring unit 31 b includes an ECU temperature measuring unit 50 , a sensor abnormality determination unit 51 , an ECU temperature estimating unit 52 , an increase value estimating unit 53 , and an adder 54 .

[0086] The ECU temperature measuring unit 50 measures the ECU temperature Te, which is the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B, based on the ECU temperature detection value Te1.

[0087] The sensor abnormality determination unit 51 determines whether or not there is an abnormality in the temperature detection circuit 45. The sensor abnormality determination unit 51 outputs an abnormality determination signal Sa indicating the determination result.

[0088] The ECU 30 of the first embodiment has a single temperature detection circuit (temperature detection circuit 45). In the following description related to the first embodiment, the abnormality of the temperature detection circuit 45 is marked as "temperature detection circuit abnormality", and the situation where the temperature detection circuit 45 is not abnormal is marked as "temperature detection circuit is not abnormal".

[0089] On the other hand, the ECU 30 of the second and third embodiments described later has a plurality of temperature detection circuits (the first temperature detection circuit 45 and the second temperature detection circuit 46). In the description of the second and third embodiments described later, the case where at least one of the first temperature detection circuit 45 and the second temperature detection circuit 46 is abnormal is described as "temperature detection circuit abnormality", and the case where both the first temperature detection circuit 45 and the second temperature detection circuit 46 are not abnormal (i.e., the case where both the first temperature detection circuit 45 and the second temperature detection circuit 46 are normal) is described as "temperature detection circuit is not abnormal".

[0090] The sensor abnormality determination unit 51 can determine that the temperature detection circuit 45 is abnormal when the detection signal Sd1 is a value outside the predetermined range, and can determine that the temperature detection circuit is not abnormal (normal) when the detection signal Sd1 is a value within the predetermined range.

[0091] For example, in Figure 3 In the case of the example of the temperature detection circuit 45 shown, when the thermistor 45a is disconnected due to an abnormality, the detection signal Sd1 rises and exceeds the upper limit value of the prescribed range, thereby detecting the abnormality of the temperature detection circuit 45. In addition, when the thermistor 45a is short-circuited due to an abnormality, the detection signal Sd1 drops and falls below the lower limit value of the prescribed range, thereby detecting the abnormality of the temperature detection circuit 45.

[0092] For example, even if the detection signal Sd1 becomes a value outside the prescribed range, the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal until the state of the detection signal Sd1 being a value outside the prescribed range continues for a prescribed time TL. The sensor abnormality determination unit 51 can determine that the temperature detection circuit is abnormal when the state of the detection signal Sd1 being a value outside the prescribed range continues for more than the prescribed time TL. The prescribed time TL can be, for example, 1 [second]. In this way, it is possible to prevent the abnormality of the temperature detection circuit 45 from being erroneously detected due to temporary changes in the detection signal Sd1 caused by the influence of noise, etc.

[0093] Furthermore, when the sensor abnormality determination unit 51 detects an abnormality in the temperature detection circuit, the sensor abnormality determination unit 51 maintains the state in which the sensor abnormality determination unit 51 detects an abnormality in the temperature detection circuit until the ignition switch 11 is switched off. When the ignition switch 11 is switched off, the sensor abnormality determination unit 51 is reset to the normal state.

[0094] The ECU temperature estimation unit 52 estimates the temperatures of the first power conversion circuit 42A and the second power conversion circuit 42B based on the ECU temperature detection value Te1 indicated by the detection signal Sd1 of the temperature detection circuit 45 and the abnormality determination signal Sa output from the sensor abnormality determination unit 51 .

[0095] Hereinafter, the temperatures of the first power conversion circuit 42A and the second power conversion circuit 42B estimated by the ECU temperature estimation unit 52 are sometimes expressed as “ECU temperature estimation value Tes”. The ECU temperature estimation unit 52 is an example of a “first temperature estimation unit”, and the ECU temperature estimation value Tes is an example of a “first temperature estimation value”.

[0096] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal, the ECU temperature estimation unit 52 may output the ECU temperature detection value Te1 indicated by the detection signal Sd1 as the ECU temperature estimation value Tes.

[0097] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the ECU temperature estimation unit 52 gradually increases the ECU temperature detection value Te1 detected by the temperature detection circuit 45 before the temperature detection circuit is determined to be abnormal at a constant increase rate ΔTr [°C / second] to a specified set value Ts, and outputs it as the ECU temperature estimation value Tes.

[0098] For example, when the detection signal Sd1 of the temperature detection circuit 45 is a value within a predetermined range, the ECU temperature estimation unit 52 may temporarily hold the ECU temperature detection value Te1 detected by the temperature detection circuit 45 as the held value Thd and sequentially update it.

[0099] At time t1 when the detection signal Sd1 of the temperature detection circuit 45 becomes a value outside the prescribed range, the ECU temperature estimation unit 52 stops updating the held value Thd. And while the state in which the detection signal Sd1 continues to be a value outside the prescribed range, the held value Thd held immediately before time t1 is output as the ECU temperature estimation value Tes until the prescribed time TL has passed.

[0100] That is, the ECU temperature detection value Te1 just before the output signal of the temperature detection element becomes a value outside the specified range is maintained as the held value Thd, and while the detection signal Sd1 continues to be a value outside the specified range, the held value Thd is output as the ECU temperature estimation value Tes until the specified time TL has passed.

[0101] If the state where the detection signal Sd1 is a value outside the specified range continues even after time t2 which is a specified time TL later than time t1, then at time t2, the ECU temperature estimation value 52 will gradually increase from the maintained value Thd maintained before time t1 to the specified set value Ts at a constant increase rate ΔTr [°C / second], and will be output as the ECU temperature estimation value Tes.

[0102] If the detection signal Sd1 returns to a value within the predetermined range before time t2, the ECU temperature estimation unit 52 outputs the ECU temperature detection value Te1 indicated by the detection signal Sd1 received from the temperature detection circuit 45 as the ECU temperature estimation value Tes, and restarts updating of the held value Thd.

[0103] Figure 5 It is an explanatory diagram schematically showing changes in the ECU temperature estimation value Tes when an abnormality occurs in the temperature detection circuit.

[0104] During the period before time t1, the detection signal Sd1 of the temperature detection circuit 45 is a value within a predetermined range, and the ECU temperature estimation unit 52 outputs the ECU temperature detection value Te1 indicated by the detection signal Sd1 as the ECU temperature estimation value Tes. In addition, the ECU temperature detection value Te1 detected by the temperature detection circuit 45 is temporarily held as a held value Thd and is updated sequentially.

[0105] If the detection signal Sd1 of the temperature detection circuit 45 becomes a value outside the specified range at time t1, the updating of the held value Thd is stopped (ie, the held value Thd immediately before the detection signal Sd1 becomes a value outside the specified range is held), and the held value Thd is output as the ECU temperature estimation value Tes.

[0106] If the state where the detection signal Sd1 is a value outside the specified range continues even after time t2 which is a specified time TL later than time t1, then at time t2, the ECU temperature estimation unit 52 will gradually increase the value from the maintained value Thd to the specified set value Ts at a constant increase rate ΔTr [°C / second] and output it as the ECU temperature estimation value Tes.

[0107] Reference Figure 4. The rise value estimation unit 53 estimates the rise value Rt of the motor temperature caused by the motor current flowing through the motor 20. For example, the rise value estimation unit 53 can estimate the rise value Rt by subtracting the heat dissipation of the motor 20 from the integral value of the sum of the squares of the detected values ​​I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd of the motor current. The adder 54 calculates the value obtained by adding the rise value Rt to the ECU temperature estimation value Tes as the motor temperature estimation value Tm. The adder 54 is an example of the "second temperature estimation unit" recorded in the technical solution, and the motor temperature estimation value Tm is an example of the "second temperature estimation value" recorded in the technical solution.

[0108] Reference Figure 2 The control arithmetic device 31 limits the motor current flowing to the motor 20 when the ECU temperature Te exceeds a threshold value or when the motor temperature estimated value Tm exceeds a threshold value.

[0109] Figure 6 FIG. 1 is a block diagram of an example of the functional structure of the control operation device 31 of the first embodiment. Figure 6 Although only the functional structure of the coil of the first system driving the motor 20 is described, the functional structure of the coil of the second system driving the motor 20 also has the same structure.

[0110] The control operation device 31 includes a current command value operation unit 60, a first current limiting unit 61, subtractors 62, 63, a second current limiting unit 64, a proportional-integral (PI: Proportional-Integral) control unit 65, a two-phase / three-phase conversion unit 66, a three-phase / two-phase conversion unit 67 and an angular velocity conversion unit 68, and drives the motor 20 through vector control.

[0111] The current command value calculation unit 60 calculates a q-axis current command value Iq0 and a d-axis current command value Id0 to flow to the motor 20 based on the steering torque Th, the vehicle speed Vh, the motor rotation angle θm of the motor 20 , and the rotation angular velocity ω of the motor 20 .

[0112] The first current limiting unit 61 limits the q-axis current command value Iq0 and the d-axis current command value Id0 based on the abnormality determination signal Sa output from the temperature measuring unit 31 b, the ECU temperature Te, and the motor temperature estimated value Tm, thereby calculating the limited q-axis current command value Iq1 and the d-axis current command value Id1.

[0113] For example, when the ECU temperature Te exceeds a predetermined first threshold value Ta1, the higher the ECU temperature Te, the larger the first current limiting unit 61 limits the q-axis current command value Iq0 and the d-axis current command value Id0, thereby calculating the q-axis current command value Iq1 and the d-axis current command value Id1. That is, the q-axis current command value Iq1 and the d-axis current command value Id1 can be calculated so that they gradually decrease as the ECU temperature Te increases.

[0114] In addition, for example, when the motor temperature estimation value Tm exceeds the second threshold value Tb1, the first current limiting unit 61 may limit the q-axis current command value Iq0 and the d-axis current command value Id0 more as the motor temperature estimation value Tm increases, thereby calculating the q-axis current command value Iq1 and the d-axis current command value Id1. That is, the q-axis current command value Iq1 and the d-axis current command value Id1 may be calculated so that they gradually decrease as the motor temperature estimation value Tm increases.

[0115] In addition, for example, when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the first current limiting unit 61 may calculate the q-axis current command value Iq1 and the d-axis current command value Id1 that are smaller than the q-axis current command value Iq0 and the d-axis current command value Id0. For example, the q-axis current command value Iq1 and the d-axis current command value Id1 may be calculated by limiting the q-axis current command value Iq0 and the d-axis current command value Id0 to 50%.

[0116] For example, the first current limiting unit 61 may set a limiting gain K1 corresponding to the abnormality determination signal Sa, a limiting gain K2 corresponding to the ECU temperature Te, and a limiting gain K3 corresponding to the motor temperature estimated value Tm.

[0117] The first current limiting unit 61 may set the value of the limit gain K1 to “1” when the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal, and may set the value of the limit gain K1 to “0.5” when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal.

[0118] The first current limiting unit 61 may gradually decrease the value of the limiting gain K2 from "1" to "0" in response to the ECU temperature Te rising from the first threshold value Ta1 to the third threshold value Ta2, when the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal and the ECU temperature Te exceeds the first threshold value Ta1. The value of the limiting gain K2 may gradually decrease linearly from "1" to "0" in response to the ECU temperature Te rising from the first threshold value Ta1 to the third threshold value Ta2.

[0119] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the first current limiting unit 61 may set the value of the limit gain K2 to “1”.

[0120] The first current limiting unit 61 may also set a hysteresis characteristic for the limiting gain K2. For example, when the ECU temperature Te exceeds the first threshold value Ta1 while the limiting gain K2 value is set to "1", the limiting gain K2 value is gradually reduced from "1" in accordance with the rise of the ECU temperature Te from the first threshold value Ta1. As long as the ECU temperature Te does not reach the third threshold value Ta2 (that is, as long as the limiting gain K2 value does not become "0"), the first current limiting unit 61 decreases or increases the limiting gain K2 value in the range from "1" to "0" in accordance with the up and down fluctuation of the ECU temperature Te in the range from the first threshold value Ta1 to the third threshold value Ta2.

[0121] If the ECU temperature Te reaches the third threshold value Ta2 (i.e., the value of the limiting gain K2 becomes "0"), the first current limiting unit 61 does not increase the value of the limiting gain K2 from "0" even if the ECU temperature Te is less than the third threshold value Ta2. When the ECU temperature Te decreases to a value less than the fourth threshold value Ta3 which is less than the third threshold value Ta2, the first current limiting unit 61 starts to increase the limiting gain K2, and gradually increases the value of the limiting gain K2 from "0" to "1" corresponding to the ECU temperature Te decreasing to a fifth threshold value Ta4 which is less than the first threshold value Ta1. For example, the fourth threshold value Ta3 may be set to a value lower than the first threshold value Ta1, or may be set to a value higher than the first threshold value Ta1.

[0122] As long as the ECU temperature Te does not reach the fifth threshold value Ta4 (that is, as long as the value of the limiting gain K2 does not become "1"), the first current limiting unit 61 reduces or increases the value of the limiting gain K2 within the range from "0" to "1" in accordance with the up and down fluctuations of the ECU temperature Te within the range from the fourth threshold value Ta3 to the fifth threshold value Ta4.

[0123] When the motor temperature estimation value Tm exceeds the second threshold value Tb1, the first current limiting unit 61 may gradually reduce the value of the limiting gain K3 from "1" to "0" in response to the motor temperature estimation value Tm rising from the second threshold value Tb1 to the sixth threshold value Tb2. For example, the value of the limiting gain K3 may linearly decrease from "1" to "0" in response to the motor temperature estimation value Tm rising from the second threshold value Tb1 to the sixth threshold value Tb2.

[0124] In addition, the limit gain K3 may have the same hysteresis characteristic as the above-mentioned limit gain K2.

[0125] The first current limiting unit 61 calculates the q-axis current command value Iq1 and the d-axis current command value Id1 by limiting the q-axis current command value Iq0 and the d-axis current command value Id0 based on the limit gains K1 , K2 , and K3 .

[0126] For example, when the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal (i.e., the limiting gain K1 = "1"), the first current limiting unit 61 can, for example, select any smaller gain K4 = min (K2, K3) between K2 and K3, and calculate the product of multiplying the q-axis current command value Iq0 and the d-axis current command value Id0 by the gain K4 as the q-axis current command value Iq1 = K4 × Iq0 and the d-axis current command value Id1 = K4 × Id0.

[0127] Alternatively, for example, the products of the q-axis current command value Iq0 and the d-axis current command value Id0 multiplied by the gains K2 and K3 may be calculated as follows: q-axis current command value Iq1=K2×K3×Iq0 and d-axis current command value Id1=

[0128] K2×K3×Id0.

[0129] For example, when the sensor abnormality judgment unit 51 determines that the temperature detection circuit is abnormal (for example, the limiting gain K1 = "0.5"), the first current limiting unit 61 can calculate the product of multiplying the q-axis current command value Iq0 and the d-axis current command value Id0 by the limiting gains K1 and K3 as the q-axis current command value Iq1 = K1×K3×Iq0 and the d-axis current command value Id1 = K1×K3×Id0.

[0130] On the other hand, the detection values ​​I1ad, I1bd, and I1cd of the A-phase current, B-phase current, and C-phase current of the first system coil of the motor 20 detected by the current detection circuits 39A1, 39B1, and 39C1 are converted into currents id and iq of the d-q2 axis through the three-phase / two-phase conversion unit 67.

[0131] The subtractors 62 and 63 respectively subtract the fed-back currents iq and id from the limited q-axis current command value Iq1 and d-axis current command value Id1 to calculate the q-axis deviation current Δq0 and the d-axis deviation current Δd0.

[0132] The second current limiting unit 64 limits the upper limit values ​​of the q-axis deviation current Δq0 and the d-axis deviation current Δd0. The limited q-axis deviation current Δq and d-axis deviation current Δd are input to the PI control unit 65.

[0133] The PI control unit 65 calculates the voltage command values ​​vq and vd that make the q-axis deviation current Δq and the d-axis deviation current Δd respectively 0. The two-phase / three-phase conversion unit 66 converts the voltage command values ​​vd and vq into the A-phase voltage control command value V1a, the B-phase voltage command value V1b, and the C-phase voltage command value V1c of the first system of the motor 20, respectively, and outputs them to the first gate drive circuit 41A.

[0134] The angular velocity conversion unit 68 calculates the rotational angular velocity ω of the motor 20 based on the temporal change of the motor rotational angle θm. The motor rotational angle θm and the rotational angular velocity ω are input to the current command value calculation unit 60 and used for vector control.

[0135] Figure 7 This is a flowchart of an example of the motor control method according to the first embodiment.

[0136] In step S1 , the ECU temperature measuring unit 50 , the sensor abnormality determination unit 51 , and the ECU temperature estimating unit 52 obtain a detection signal Sd1 from the temperature detection circuit 45 .

[0137] In step S2 , the ECU temperature measuring unit 50 measures the ECU temperature Te based on the ECU temperature detection value Te1 .

[0138] In step S3, the first current limiting unit 61 determines whether the ECU temperature Te exceeds the first threshold value Ta1. If the ECU temperature Te exceeds the first threshold value Ta1 (step S3: Yes), the process proceeds to step S4. If the ECU temperature Te does not exceed the first threshold value Ta1 (step S3: No), the process proceeds to step S5.

[0139] In step S4, the first current limiting unit 61 limits the q-axis current command value Iq0 and the d-axis current command value Id0. Thereafter, the process proceeds to step S5.

[0140] In step S5 , the current detection circuits 39A1 , 39B1 , 39C1 , 39A2 , 39B2 , and 39C2 detect the motor currents I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd, respectively.

[0141] In step S6 , the increase value estimating unit 53 estimates the increase value Rt of the motor temperature caused by the motor current based on the motor currents I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd.

[0142] In step S7, the sensor abnormality determination unit 51 determines whether the temperature detection circuit is abnormal. If the temperature detection circuit is abnormal (step S7: Yes), the process proceeds to step S9. If the temperature detection circuit is not abnormal (step S7: No), the process proceeds to step S8.

[0143] In step S8, the ECU temperature estimation unit 52 sets the ECU temperature detection value Te1 as the ECU temperature estimation value Tes. Thereafter, the process proceeds to step S11.

[0144] In step S9, the first current limiting unit 61 limits the q-axis current command value Iq0 and the d-axis current command value Id0. In step S10, the ECU temperature estimation unit 52 gradually increases the ECU temperature estimation value Tes to a predetermined set value Ts at a constant increase rate ΔTr. For example, the ECU temperature estimation value Tes is increased by a predetermined step amount per unit time. After that, the process proceeds to step S11.

[0145] In step S11 , the adder 54 calculates a value obtained by adding the increase value Rt to the ECU temperature estimate value Tes as the motor temperature estimate value Tm.

[0146] In step S12, the first current limiting unit 61 determines whether the motor temperature estimate Tm exceeds the second threshold value Tb1. If the motor temperature estimate Tm exceeds the second threshold value Tb1 (step S12: Yes), the process proceeds to step S13. If the motor temperature estimate Tm does not exceed the second threshold value Tb1 (step S12: No), the process ends.

[0147] In step S13 , the first current limiting unit 61 limits the q-axis current command value Iq0 and the d-axis current command value Id0 . Thereafter, the process ends.

[0148] (Effects of the First Embodiment)

[0149] (1) The ECU 30 includes: a first power conversion circuit 42A and a second power conversion circuit 42B, which control the motor current flowing through the motor 20; a temperature detection circuit 45, which has a temperature sensor 45a arranged near the first power conversion circuit 42A and the second power conversion circuit 42B; an increase value estimation unit 53, which estimates the increase value Rt of the temperature of the motor 20 caused by the motor current; a sensor abnormality determination unit 51, which determines whether the temperature detection circuit 45 is abnormal; and an ECU temperature estimation unit 52, which, when the sensor abnormality determination unit 51 determines that the temperature detection circuit 45 is normal, detects the temperature of the temperature detection circuit 45. The detected temperature is output as the ECU temperature estimation value Tes. When the sensor abnormality determination unit 51 determines that the temperature detection circuit 45 is abnormal, the ECU temperature estimation unit 52 gradually increases the detected temperature detected by the temperature detection circuit 45 to a specified set value Ts at a constant increasing rate, and outputs it as the ECU temperature estimation value Tes; an adder 54, which calculates the value obtained by adding the rise value Rt to the ECU temperature estimation value Tes as the motor temperature estimation value Tm; and a first current limiting unit 61, which limits the motor current when the motor temperature estimation value Tm exceeds a specified threshold value, so that the higher the motor temperature estimation value Tm, the more gradually the motor current decreases.

[0150] The sensor abnormality determination unit 51 determines that the temperature detection circuit 45 is normal when the output signal of the temperature sensor 45a is a value within a predetermined range, and determines that the temperature detection circuit 45 is abnormal when the output signal of the temperature sensor 45a is a value outside the predetermined range.

[0151] Thus, it is possible to prevent the motor temperature estimation value Tm from increasing rapidly and the motor current from being excessively limited when an abnormality occurs in the temperature detection circuit 45. In addition, by limiting the motor current in a manner that gradually reduces the motor current even when the motor temperature estimation value Tm exceeds a predetermined threshold value, the increase in the motor temperature estimation value Tm is suppressed, and the motor current can be prevented from being excessively limited.

[0152] (2) The ECU temperature estimation unit 52 can maintain the detected temperature detected by the temperature detection circuit 45 as a holding value. When the temperature detection circuit 45 is determined to be abnormal, the value gradually increases at a constant increasing rate from the holding value maintained before the temperature detection circuit 45 is determined to be abnormal to a specified set value Ts as time passes, and outputs it as the ECU temperature estimation value Tes.

[0153] Thus, when an abnormality occurs in the temperature detection circuit 45 , it is possible to prevent the ECU temperature estimation value Tes from being calculated based on the abnormal detection value.

[0154] (3) The sensor abnormality determination unit 51 may determine that the temperature detection circuit is abnormal when the state in which the output signal of the temperature detection element is a value outside the prescribed range continues for more than a prescribed time. The ECU temperature estimation unit 52 may maintain the detected temperature detected by the temperature detection circuit 45 as a holding value, and gradually increase the value from the holding value just before the output signal of the temperature sensor 45a becomes a value outside the prescribed range at a constant increasing rate as time passes to a prescribed set value, and output it as the ECU temperature estimation value Tes.

[0155] This can prevent erroneous detection of abnormality in the temperature detection circuit 45 due to temporary fluctuations in the output signal of the temperature sensor 45 a caused by the influence of noise or the like.

[0156] (4) The electric power steering device includes an ECU 30 and a motor 20 controlled by the ECU 30, and the motor 20 provides a steering assist force to the steering system of the vehicle. The electric power steering device includes a torque sensor 10 for detecting the steering torque of the steering wheel 1, and the ECU 30 includes a current command value calculation unit 60 for setting a current command value of a motor current flowing through the motor 20 based on at least the steering torque. The current control of the motor current supplied to the electric motor can be made redundant by the first power conversion circuit 42A and the second power conversion circuit 42B. The first current limiting unit 61 can limit the motor current flowing through the motor 20 to a current smaller than the current command value when it is determined that the temperature detection circuit is abnormal. As a result, the motor current can be limited in the electric power steering device so that the temperature of the motor current control circuit is below the allowable temperature.

[0157] (Second Embodiment)

[0158] In the ECU 30 of the second embodiment, the temperature detection circuits for detecting the temperatures of the first power conversion circuit 42A and the second power conversion circuit 42B are made redundant.

[0159] Figure 8 1 is a schematic block diagram showing an example of the ECU 30 of the second embodiment. The ECU 30 of the second embodiment includes a first temperature detection circuit 45 as the temperature detection circuit 45 of the first embodiment and a second temperature detection circuit 46. The other components of the ECU 30 of the second embodiment are the same as those of the first embodiment.

[0160] In addition, descriptions of components and functions common to the ECU 30 of the first embodiment are omitted. In the following description, the temperature sensor 45a of the first temperature detection circuit 45 is referred to as "first temperature sensor 45a".

[0161] The second temperature detection circuit 46 includes a second temperature sensor 46a disposed near the first power conversion circuit 42A and the second power conversion circuit 42B. The first temperature sensor 45a and the second temperature sensor 46a are examples of a "first temperature detection element" and a "second temperature detection element", respectively. In addition, the second temperature sensor 46a may not be disposed near the first power conversion circuit 42A and the second power conversion circuit 42B. The second temperature sensor 46a only needs to be disposed at a portion of the ECU 30 that is prone to heat.

[0162] The second temperature detection circuit 46 detects the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B based on the output of the second temperature sensor 46a, and outputs a detection signal Sd2 indicating the detection result. In the following description, the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B detected by the second temperature detection circuit 46 (the temperature indicated by the detection signal Sd2) is sometimes referred to as "ECU temperature detection value Te2".

[0163] The second temperature detection circuit 46 may have the same structure as the first temperature detection circuit 45. For example, the second temperature sensor 46a of the second temperature detection circuit 46 may be a thermistor having the same characteristics as the first temperature sensor 45a of the first temperature detection circuit 45, and the fixed resistors R of the first temperature detection circuit 45 and the second temperature detection circuit 46 may have the same resistance value.

[0164] The control operation device 31 obtains the detection signal Sd2 of the second temperature detection circuit 46 via the A / D conversion unit 31a. The temperature measurement unit 31b estimates the motor temperature based on the ECU temperature detection values ​​Te1 and Te2 indicated by the detection signals Sd1 and Sd2 of the first temperature detection circuit 45 and the second temperature detection circuit 46, and the detection values ​​I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd of the motor current flowing through the motor 20.

[0165] Fig. 9 1 is a block diagram of an example of the functional configuration of the temperature measuring unit 31b of the second embodiment. The temperature measuring unit 31b includes a sensor abnormality determination unit 51, an ECU temperature estimation unit 52, an increase value estimation unit 53, and an adder 54. Figure 4 Description will be given of the components and functions common to the temperature measuring unit 31 b of the first embodiment shown.

[0166] The sensor abnormality determination unit 51 determines whether or not at least one of the first temperature detection circuit 45 and the second temperature detection circuit 46 is abnormal, and outputs an abnormality determination signal Sa indicating the determination result.

[0167] In the description related to the second embodiment and the third embodiment, the situation where at least one of the first temperature detection circuit 45 and the second temperature detection circuit 46 is abnormal is expressed as "temperature detection circuit abnormality", and the situation where neither the first temperature detection circuit 45 nor the second temperature detection circuit 46 is abnormal (that is, the situation where both the first temperature detection circuit 45 and the second temperature detection circuit 46 are normal) is expressed as "temperature detection circuit normal".

[0168] For example, the sensor abnormality determination unit 51 may determine that the temperature detection circuit is abnormal when the difference ΔTe between the ECU temperature detection value Te1 represented by the detection signal Sd1 of the first temperature detection circuit 45 and the ECU temperature detection value Te2 represented by the detection signal Sd2 of the second temperature detection circuit 46 is greater than the specified value ΔTt. When the difference ΔTe is less than the specified value ΔTt, the sensor abnormality determination unit 51 may determine that the temperature detection circuit is not abnormal.

[0169] For example, the predetermined value ΔTt may be 5[°C]. Thus, even if there is a certain degree of error between the ECU temperature detection value Te1 and the ECU temperature detection value Te2 due to deviations in components constituting the first temperature detection circuit 45 and the second temperature detection circuit 46, erroneous detection of abnormalities in the first temperature detection circuit 45 and the second temperature detection circuit 46 can be prevented.

[0170] For example, even if the difference ΔTe becomes greater than the specified value ΔTt, the sensor abnormality determination unit 51 may determine that the temperature detection circuit is not abnormal until the state where the difference ΔTe is greater than the specified value ΔTt continues for a specified time TL. The sensor abnormality determination unit 51 may determine that the temperature detection circuit is abnormal when the state where the difference ΔTe is greater than the specified value ΔTt continues for a specified time TL or more. For example, the specified time TL may be 1 [second]. Thus, for example, it is possible to prevent the abnormality of the first temperature detection circuit 45 and the second temperature detection circuit 46 from being erroneously detected due to a temporary increase in the difference ΔTe caused by the influence of noise or the like.

[0171] The ECU temperature estimation unit 52 estimates the temperatures of the first power conversion circuit 42A and the second power conversion circuit 42B based on the ECU temperature detection value Te1 represented by the detection signal Sd1 of the first temperature detection circuit 45, the ECU temperature detection value Te2 represented by the detection signal Sd2 of the second temperature detection circuit 46, and the abnormality determination signal Sa output from the sensor abnormality determination unit 51.

[0172] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal, the ECU temperature estimation unit 52 can select either the ECU temperature detection value Te1 or the ECU temperature detection value Te2 to output as the ECU temperature estimation value Tes. For example, the ECU temperature estimation unit 52 can output the higher detection value of the ECU temperature detection value Te1 or the ECU temperature detection value Te2 as the ECU temperature estimation value Tes, or can output the lower detection value as the ECU temperature estimation value Tes.

[0173] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the ECU temperature estimation unit 52 gradually increases the ECU temperature detection value Te1 detected by the first temperature detection circuit 45 or the ECU temperature detection value Te2 detected by the second temperature detection circuit 46 at a constant increase rate ΔTr [°C / second] to a specified set value Ts and outputs it as the ECU temperature estimation value Tes.

[0174] For example, when the sensor abnormality determination unit 51 outputs the ECU temperature detection value Te1 as the ECU temperature estimation value Tes immediately before determining that the temperature detection circuit is abnormal, the ECU temperature estimation unit 52 outputs the ECU temperature detection value Te1 as the ECU temperature estimation value Tes at time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal. The ECU temperature estimation unit 52 starts increasing the ECU temperature estimation value Tes from time t1, and outputs a value gradually increasing from the ECU temperature detection value Te1 detected by the first temperature detection circuit 45 at time t1 to a predetermined set value Ts at a constant increase rate ΔTr as the ECU temperature estimation value Tes.

[0175] Similarly, when the sensor abnormality determination unit 51 outputs the ECU temperature detection value Te2 as the ECU temperature estimation value Tes immediately before determining that the temperature detection circuit is abnormal, the ECU temperature estimation unit 52 outputs the ECU temperature detection value Te2 as the ECU temperature estimation value Tes at time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal. The ECU temperature estimation unit 52 starts increasing the ECU temperature estimation value Tes from time t1, and gradually increases the value from the ECU temperature detection value Te2 detected by the second temperature detection circuit 46 at time t1 to a predetermined set value Ts at a constant increase rate ΔTr as the ECU temperature estimation value Tes.

[0176] The ECU temperature estimation unit 52 may change the increase rate ΔTr according to the ECU temperature detection value Te1 detected by the first temperature detection circuit 45 or the ECU temperature detection value Te2 detected by the second temperature detection circuit 46 at time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal.

[0177] For example, when the sensor abnormality determination unit 51 outputs the ECU temperature detection value Te1 as the ECU temperature estimated value Tes immediately before determining that the temperature detection circuit is abnormal, a lower increase rate ΔTr may be set when the ECU temperature detection value Te1 is higher than when it is lower. For example, the higher the ECU temperature detection value Te1 is, the lower the increase rate ΔTr may be set.

[0178] When the sensor abnormality determination unit 51 outputs the ECU temperature detection value Te2 as the ECU temperature estimated value Tes immediately before determining that the temperature detection circuit is abnormal, a lower increase rate ΔTr may be set when the ECU temperature detection value Te2 is higher than when it is lower. For example, the higher the ECU temperature detection value Te2 is, the lower the increase rate ΔTr may be set.

[0179] Fig.10 1 is an explanatory diagram schematically showing the change of the ECU temperature estimation value Tes when the temperature detection circuit is abnormal. Here, the case where the ECU temperature detection value Te1 is output as the ECU temperature estimation value Tes before the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal is described. When the ECU temperature detection value Te2 is output as the ECU temperature estimation value Tes, the ECU temperature detection value Te1 is replaced by the ECU temperature detection value Te2.

[0180] The solid line L1 represents the time change of the ECU temperature estimation value Tes output from the ECU temperature estimation unit 52 when the ECU temperature detection value Te1 at time t1 when the sensor abnormality judgment unit 51 judges that the temperature detection circuit is abnormal is relatively high T1, and the single-point chain line L2 represents the time change of the ECU temperature estimation value Tes output from the ECU temperature estimation unit 52 when the ECU temperature detection value Te1 at time t1 is relatively low T2.

[0181] exist Fig.10 In the example, even if the difference ΔTe becomes greater than the prescribed value ΔTt, the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal until the state where the difference ΔTe is greater than the prescribed value ΔTt continues for the prescribed time TL. Therefore, the ECU temperature estimation unit 52 outputs the ECU temperature detection value Te1 as the ECU temperature estimation value Tes until the time t1 when the state where the difference ΔTe is greater than the prescribed value ΔTt continues for the prescribed time TL. At time t1, the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal.

[0182] When the ECU temperature detection value Te1 at time t1 is temperature T1, the ECU temperature estimation unit 52 starts to increase the ECU temperature estimation value Tes from time t1 as shown by the solid line L1, gradually increases at a constant increase rate ΔTr1 [°C / second] from temperature T1, and outputs the ECU temperature estimation value Tes that reaches the specified set value Ts at time t2.

[0183] On the other hand, when the ECU temperature detection value Te1 at time t1 is temperature T2, the ECU temperature estimation unit 52 starts to increase the ECU temperature estimation value Tes from time t1 as shown by the single-dot chain line L2, and gradually increases at a constant increase rate ΔTr2 [°C / second] from temperature T2, and outputs the ECU temperature estimation value Tes that reaches the specified set value Ts at time t3.

[0184] The sensor abnormality determination unit 51 may be set to reduce the increase rate ΔTr1 when the ECU temperature detection value Te1 at time t1 is relatively high at T1, compared to the increase rate ΔTr2 when the ECU temperature detection value Te1 at time t1 is relatively low at T2. The higher the temperature of an object, the greater the heat dissipation, so the temperature rise is slower when the same amount of heat is applied. The higher the ECU temperature detection value Te1 at time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the lower the increase rate ΔTr of the ECU temperature estimation value Tes, thereby preventing the ECU temperature estimation value Tes from becoming too high.

[0185] Fig.11 FIG. 1 is a block diagram of an example of the functional structure of the control operation device 31 of the second embodiment. Fig.11 In the embodiment, only the functional structure for driving the coils of the first system of the motor 20 is described, but the functional structure for driving the coils of the second system also has the same structure. Figure 6 Description will be given of the components and functions common to the control arithmetic device 31 of the first embodiment shown.

[0186] The first current limiting unit 61 limits the q-axis current command value Iq0 and the d-axis current command value Id0 based on the abnormality determination signal Sa output from the temperature measuring unit 31 b and the motor temperature estimated value Tm, thereby calculating the limited q-axis current command value Iq1 and the d-axis current command value Id1 .

[0187] For example, when the motor temperature estimation value Tm exceeds the second threshold value Tb1, the first current limiting unit 61 may calculate the q-axis current command value Iq1 and the d-axis current command value Id1 by limiting the q-axis current command value Iq0 and the d-axis current command value Id0 more as the motor temperature estimation value Tm is higher. That is, the q-axis current command value Iq1 and the d-axis current command value Id1 may be calculated so that they gradually decrease as the motor temperature estimation value Tm is higher.

[0188] In addition, for example, the first current limiting unit 61 may calculate the q-axis current command value Iq1 and the d-axis current command value Id1 which are smaller than the q-axis current command value Iq0 and the d-axis current command value Id0 when the sensor abnormality determining unit 51 determines that the temperature detection circuit is abnormal. For example, the q-axis current command value Iq1 and the d-axis current command value Id1 may be calculated by limiting the q-axis current command value Iq0 and the d-axis current command value Id0 to 50%.

[0189] In addition, when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the first current limiting unit 61 can calculate the q-axis current command value Iq1 and the d-axis current command value Id1 that are smaller than the q-axis current command value Iq0 and the d-axis current command value Id0 (for example, the q-axis current command value Iq0 and the d-axis current command value Id0 are set to 50%, respectively) even when the motor temperature estimated value Tm does not exceed the second threshold value Tb1.

[0190] For example, the first current limiting unit 61 may set the limit gain K1 corresponding to the abnormality determination signal Sa and the limit gain K3 corresponding to the motor temperature estimated value Tm.

[0191] For example, the first current limiting unit 61 may also set a hysteresis characteristic for the limiting gain K3. For example, if the value of the limiting gain K3 becomes "1", then when the motor temperature estimation value Tm exceeds the second threshold value Tb1, the value of the limiting gain K3 is gradually reduced from "1" in correspondence with the increase of the motor temperature estimation value Tm from the second threshold value Tb1. As long as the motor temperature estimation value Tm does not reach the sixth threshold value Tb2 (that is, as long as the value of the limiting gain K2 does not become "0"), the first current limiting unit 61 reduces or increases the value of the limiting gain K3 in the range from "1" to "0" in correspondence with the motor temperature estimation value Tm fluctuating up and down within the range from the second threshold value Tb1 to the sixth threshold value Tb2.

[0192] If the estimated motor temperature value Tm reaches the sixth threshold value Tb2 (that is, the value of the limiting gain K3 becomes "0"), the first current limiting unit 61 does not increase the value of the limiting gain K3 from "0" even if the estimated motor temperature value Tm is less than the sixth threshold value Tb2. When the estimated motor temperature value Tm decreases to a value less than the seventh threshold value Tb3 which is less than the sixth threshold value Tb2, the first current limiting unit 61 may start to decrease the limiting gain K3, and gradually increase the value of the limiting gain K3 from "0" to "1" corresponding to the decrease of the estimated motor temperature value Tm to an eighth threshold value Tb4 which is less than the second threshold value Tb1. For example, the seventh threshold value Tb3 may be set to a value lower than the second threshold value Tb1, or may be set to a value higher than the second threshold value Ttb1.

[0193] As long as the motor temperature estimation value Tm does not reach the eighth threshold value Tb4 (that is, as long as the value of the limiting gain K3 does not become "1"), the first current limiting unit 61 reduces or increases the value of the limiting gain K3 within the range from "0" to "1" in response to the up and down fluctuations of the motor temperature estimation value Tm within the range from the seventh threshold value Tb3 to the eighth threshold value Tb4.

[0194] The first current limiting unit 61 calculates the products of multiplying the q-axis current command value Iq0 and the d-axis current command value Id0 by the limit gains K1 and K3 as q-axis current command value Iq1=K1×K3×Iq0 and d-axis current command value Id1=K1×K3×Id0.

[0195] In addition, the temperature measuring unit 31 b of the second embodiment may also output the ECU temperature Te in the same manner as the temperature measuring unit 31 b of the first embodiment.

[0196] In addition, in the first current limiting unit 61 of the second embodiment, the q-axis current command value Iq0 and the d-axis current command value Id0 can be limited based on the abnormality determination signal Sa output from the temperature measuring unit 31b, the ECU temperature Te and the motor temperature estimated value Tm, and the q-axis current command value Iq1 and the d-axis current command value Id1 after the limitation can be calculated, as in the first current limiting unit 61 of the first embodiment.

[0197] Fig.12 This is a flowchart of an example of the motor control method according to the second embodiment.

[0198] The processing of step S20 is Figure 7 The processing of steps S21 to S29 is the same as that of step S1. Figure 7 The processing of steps S5 to S13 is the same.

[0199] Fig.13FIG. 2 is a block diagram showing an example of the functional configuration of the temperature measuring unit 31 b of the modified example. Fig. 9 In addition to the structure of the temperature measuring unit 31 b of the second embodiment shown, an ECU temperature measuring unit 50 is further provided.

[0200] The ECU temperature measuring unit 50 measures the ECU temperature Te, which is the temperature of the first power conversion circuit 42A and the second power conversion circuit 42B, based on the ECU temperature detection value Te1 and the ECU temperature detection value Te2. The ECU temperature measuring unit 50 can select either the ECU temperature detection value Te1 or the ECU temperature detection value Te2 as the ECU temperature Te output. For example, the ECU temperature measuring unit 50 can output the higher detection value of the ECU temperature detection value Te1 and the ECU temperature detection value Te2 as the ECU temperature Te, or can output the lower detection value as the ECU temperature Te.

[0201] (Effects of the Second Embodiment)

[0202] (1) The ECU 30 includes: a first power conversion circuit 42A and a second power conversion circuit 42B, which control the motor current flowing through the motor 20; temperature detection circuits 45 and 46, which have temperature sensors 45a and 46a arranged near the first power conversion circuit 42A and the second power conversion circuit 42B; an increase value estimation unit 53, which estimates the increase value Rt of the temperature of the motor 20 caused by the motor current; a sensor abnormality determination unit 51, which determines whether the temperature detection circuit is abnormal; and an ECU temperature estimation unit 52, which, when the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal, determines that the temperature detection circuit 45 is abnormal. , and 46 are output as the ECU temperature estimation value Tes. When the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the ECU temperature estimation unit 52 gradually increases the detection temperature detected by the temperature detection circuits 45 and 46 to a specified set value Ts at a constant increase rate ΔTr and outputs it as the ECU temperature estimation value Tes; an adder 54, which calculates a value obtained by adding the increase value Rt to the ECU temperature estimation value Tes as the motor temperature estimation value Tm; and a first current limiting unit 61, which limits the motor current in a manner that gradually decreases as the motor temperature estimation value Tm increases when the motor temperature estimation value Tm exceeds a specified threshold value.

[0203] Thus, it is possible to prevent the motor temperature estimation value Tm from rising sharply and the motor current from being excessively limited when an abnormality occurs in the temperature detection circuit. In addition, by limiting the motor current in a gradually decreasing manner even when the motor temperature estimation value Tm exceeds a predetermined threshold, it is possible to suppress the increase in the motor temperature estimation value Tm and prevent the motor current from being excessively limited.

[0204] (2) The temperature detection circuits 45 and 46 may include temperature sensors 45a and 46a, respectively, and output a detection signal indicating an ECU temperature detection value Te1 corresponding to the output of the temperature sensor 45a and a detection signal indicating an ECU temperature detection value Te2 corresponding to the output of the temperature sensor 46a. The sensor abnormality determination unit 51 may determine that the temperature detection circuit is abnormal when the difference ΔTe between the higher first detection temperature and the lower second detection temperature of the ECU temperature detection values ​​Te1 and Te2 is greater than a predetermined value ΔTt. The ECU temperature estimation unit 52 may output the first detection temperature as the ECU temperature estimation value Tes when it is determined that the temperature detection circuit is normal.

[0205] In this way, by determining whether the temperature detection circuit is abnormal based on the ECU temperature detection values ​​Te1 and Te2 of the plurality of temperature detection circuits 45 and 46, it is possible to determine abnormality of the temperature detection circuit more accurately and quickly than when a single temperature detection circuit is provided.

[0206] (3) The sensor abnormality determination unit 51 may determine that the temperature detection circuit is abnormal when the difference ΔTe between the first detected temperature and the second detected temperature is greater than or equal to the prescribed value ΔTt for a period of time TL or longer. The ECU temperature estimation unit 52 may output, as the ECU temperature estimation value Tes, a value which gradually increases at a constant increasing rate ΔTr from the first detected temperature output by the temperature detection circuit 45 or 46 to a prescribed set value Ts as time passes when the difference ΔTe is greater than or equal to the prescribed value ΔTt for a period of time TL.

[0207] This can prevent erroneous detection of abnormality in the temperature detection circuit due to, for example, a temporary increase in the difference ΔTe caused by the influence of noise or the like.

[0208] (4) When it is determined that the temperature detection circuit is abnormal, the ECU temperature estimation unit 52 may output the ECU temperature estimation value Tes that gradually increases at a lower increase rate ΔTr when the temperature detected by the temperature detection circuit 45 or 46 is higher than when it is lower.

[0209] Thus, when it is determined that the temperature detection circuit is abnormal, if the temperature detected by the temperature detection circuit 45 or 46 is high, it is possible to prevent the ECU temperature estimation value Tes from becoming excessively high.

[0210] (Third Embodiment)

[0211] The configuration of the ECU 30 of the third embodiment is similar to that of the reference ECU 30. Figure 8 The configuration of the control computing device 31 of the third embodiment is the same as that of the ECU 30 of the second embodiment described above. Figure 6 The control arithmetic device 31 of the first embodiment described above has the same structure. In addition, the description of the components and functions common to the ECU 30 of the second embodiment and the control arithmetic device 31 of the first embodiment will be omitted.

[0212] Reference Figure 8 The first temperature sensor 45a of the first temperature detection circuit 45 and the second temperature sensor 46a of the second temperature detection circuit 46 are mounted on the same circuit board as the FETQ1 to FETQ6 of the first power conversion circuit 42A and the FETQ1 to FETQ6 of the second power conversion circuit 42B, which are heat generating components.

[0213] Fig.14 It is a schematic diagram of the relative positional relationship between the power conversion circuit (first power conversion circuit 42A, second power conversion circuit 42B) and the temperature sensor (first temperature sensor 45a, second temperature sensor 46a) mounted on the circuit substrate 70. In the following description, the two orthogonal axial directions parallel to the component mounting surface of the circuit substrate 70 are respectively expressed as the first direction D1 and the second direction D2.

[0214] like Fig.14 As shown, the circuit board 70 has a semi-elliptical shape obtained by dividing the elliptical shape along the minor axis in a plan view, and one edge e1 of the two edges e1 and e2 in the first direction D1 is formed in an arc shape, and the other edge e2 is formed in a straight line shape.

[0215] The first power conversion circuit 42A and the second power conversion circuit 42B are arranged along the second direction D2, and the first temperature sensor 45a and the second temperature sensor 46a are arranged between the first power conversion circuit 42A and the second power conversion circuit 42B in the second direction D2. In this way, by arranging the first temperature sensor 45a and the second temperature sensor 46a between the first power conversion circuit 42A and the second power conversion circuit 42B, the temperature abnormality of both the first power conversion circuit 42A and the second power conversion circuit 42B can be well detected without biasing to either the first power conversion circuit 42A or the second power conversion circuit 42B.

[0216] For example, the first temperature sensor 45a and the second temperature sensor 46a may be disposed between the positive electrode side line Lp (see Figure 8 ) is branched into the first positive electrode side line LpA and the second positive electrode side line LpB. For example, the first temperature sensor 45a and the second temperature sensor 46a may be arranged at a position on the side of the power conversion circuits 42A and 42B near the branch point Pb and between the first positive electrode side line LpA and the second positive electrode side line LpB.

[0217] By arranging the first temperature sensor 45a and the second temperature sensor 46a near the branch point Pb where the power lines for the first power conversion circuit 42A and the second power conversion circuit 42B branch, it is easy to arrange the first temperature sensor 45a and the second temperature sensor 46a between the first power conversion circuit 42A and the second power conversion circuit 42B.

[0218] For example, the first temperature sensor 45a and the second temperature sensor 46a may be arranged on a center line CL passing through the approximate center of the circuit substrate 70 in the second direction D2 (i.e., the center line CL along the first direction D1). By arranging the first temperature sensor 45a and the second temperature sensor 46a on the center line CL, it is easy to arrange the first temperature sensor 45a and the second temperature sensor 46a between the first power conversion circuit 42A and the second power conversion circuit 42B. In addition, heat is easily accumulated in the center of the circuit substrate 70, so by arranging the first temperature sensor 45a and the second temperature sensor 46a at a position that is likely to become high temperature, it is easy to detect overheating of the ECU 30.

[0219] Furthermore, the first temperature sensor 45a and the second temperature sensor 46a may also be arranged close to each other. By arranging the first temperature sensor 45a and the second temperature sensor 46a close to each other, the thermal coupling between the first temperature sensor 45a and the second temperature sensor 46a can be made tight. As a result, the detected temperature of the first temperature sensor 45a and the detected temperature of the second temperature sensor 46a can be made close to each other.

[0220] Thus, it is possible to detect abnormality occurring in the first temperature detection circuit 45 and the second temperature detection circuit 46 based on the difference between the detected temperatures of the first temperature sensor 45 a and the second temperature sensor 46 a .

[0221] Alternatively, the first temperature sensor 45a and the second temperature sensor 46a may be mounted on the circuit board 70 so as to be oriented in different directions from each other. Figure 4In the figure, reference numerals 45b and 45c denote electrodes at both ends of a first temperature sensor 45a as a thermistor, and reference numerals 46b and 46c denote electrodes at both ends of a second temperature sensor 46a as a thermistor.

[0222] exist Fig.14 In the example, the electrodes 45b and 45c at both ends of the first temperature sensor 45a are arranged along the second direction D2, and the electrodes 46b and 46c at both ends of the second temperature sensor 46a are arranged along the first direction D1, and the orientation of the first temperature sensor 45a is orthogonal to the orientation of the second temperature sensor 46a.

[0223] In this way, by orienting the first temperature sensor 45 a and the second temperature sensor 46 a in different directions, it is possible to avoid the first temperature sensor 45 a and the second temperature sensor 46 a being damaged at the same time when stress is applied to the circuit board 70 .

[0224] As described above, when the abnormality of the first temperature detection circuit 45 and the second temperature detection circuit 46 is detected based on the difference in the detected temperatures of the first temperature sensor 45a and the second temperature sensor 46a, when the same abnormality occurs in both sensors and there is no difference in the detected temperatures, the abnormality may not be detected. By preventing both sensors from being damaged at the same time due to the stress applied to the circuit board 70, it is possible to suppress the occurrence of the same abnormality in both sensors due to damage caused by the stress.

[0225] The FETQ1 to FETQ6 and the temperature sensors (the first temperature sensor 45a and the second temperature sensor 46a) included in the first power conversion circuit 42A and the second power conversion circuit 42B may be thermally connected to the same heat dissipation component (heat sink). Since the heat dissipation component is made of a material with good thermal conductivity, it is easier to detect temperature abnormalities in the first power conversion circuit 42A and the second power conversion circuit 42B by thermally connecting the FETQ1 to FETQ6 and the first temperature sensor 45a and the second temperature sensor 46a as heat dissipation components to the same heat dissipation component.

[0226] In addition, by thermally connecting the first temperature sensor 45a and the second temperature sensor 46a to the same heat dissipation component, the thermal coupling between the first temperature sensor 45a and the second temperature sensor 46a becomes tighter, and the detection temperature of the first temperature sensor 45a can be closer to the detection temperature of the second temperature sensor 46a.

[0227] Fig.15 Schematic diagram of a heat dissipation structure for dissipating heat generated by the first power conversion circuit 42A and the second power conversion circuit 42B. The heat dissipation member 72 may be a heat sink formed of a metal having good thermal conductivity, such as an aluminum alloy.

[0228] The surfaces f1 of the FETQ1 to FETQ6 included in the first power conversion circuit 42A and the second power conversion circuit 42B, which are on the opposite side to the circuit substrate 70, and the surfaces f2 of the first temperature sensor 45a and the second temperature sensor 46a, which are on the opposite side to the circuit substrate 70, are thermally connected to the same heat sink 72. For example, the surfaces f1 and f2 are in contact with the heat sink 72 via thermal interface materials (TIM) 73 and 74 such as conductive paste (for example, heat dissipation paste), respectively.

[0229] FETQ1 to FETQ6 may be, for example, switch elements having a top surface (upper surface) heat dissipation structure. For example, FETQ1 to FETQ6 may be switch elements in which a heat conductive pad connected to a source pad is exposed from a resin package (mold) in which a chip is sealed on the surface (upper surface) opposite to the surface (bottom surface) on which a drain pad is provided. In addition, for example, FETQ1 to FETQ6 may be switch elements having a mold formed of a resin with high thermal conductivity, and the mold on the surface opposite to the surface on which a drain pad is provided is thinned.

[0230] Fig.16 This is a block diagram of an example of the functional structure of the temperature measuring unit 31b of the third embodiment. The temperature measuring unit 31b includes a sensor abnormality determination unit 51, an ECU temperature measuring unit 50, and a motor temperature estimation unit 55. The function of the sensor abnormality determination unit 51 of the third embodiment is the same as that of the sensor abnormality determination unit 51 of the second embodiment, and the function of the ECU temperature measuring unit 50 of the third embodiment is the same as that of the ECU temperature measuring unit 50 of the modified example of the second embodiment, so the description is omitted.

[0231] The motor temperature estimation unit 55 estimates the motor temperature of the motor 20. Specifically, the motor temperature estimation unit 55 estimates the ECU temperature based on the ECU temperature detection value Te1, the ECU temperature detection value Te2, and the abnormality determination signal Sa output from the sensor abnormality determination unit 51 (i.e., calculates the ECU temperature estimation value Tes), and estimates the motor temperature based on the ECU temperature estimation value Tes and the motor current detection values ​​I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd.

[0232] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is not abnormal, the motor temperature estimation unit 55 selects either the ECU temperature detection value Te1 or the ECU temperature detection value Te2 as the ECU temperature estimation value Tes. For example, the motor temperature estimation unit 55 may select the higher detection value of the ECU temperature detection value Te1 or the ECU temperature detection value Te2 as the ECU temperature estimation value Tes, or may select the lower detection value as the ECU temperature estimation value Tes.

[0233] When the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the motor temperature estimation unit 55 calculates a value that gradually increases from the ECU temperature detection value Te1 or the ECU temperature detection value Te2 at a constant increase rate ΔTr [° C. / sec] to a predetermined set value Ts as the ECU temperature estimation value Tes.

[0234] Fig.17 This is an explanatory diagram schematically showing a method for calculating the ECU temperature estimation value Tes when the temperature detection circuit is abnormal. For example, when the ECU temperature detection value Te1 is selected as the ECU temperature estimation value Tes immediately before the time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the motor temperature estimation unit 55 sets the ECU temperature detection value Te1 as the ECU temperature estimation value Tes at the time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal. The motor temperature estimation unit 55 starts to increase the ECU temperature estimation value Tes from the time t1, and calculates a value that gradually increases from the ECU temperature detection value Te1 detected by the first temperature detection circuit 45 at the time t1 to the predetermined set value Ts at a constant increase rate ΔTr as the ECU temperature estimation value Tes.

[0235] On the other hand, when the ECU temperature detection value Te2 is selected as the ECU temperature estimation value Tes immediately before the time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal, the motor temperature estimation unit 55 sets the ECU temperature detection value Te2 as the ECU temperature estimation value Tes at the time t1 when the sensor abnormality determination unit 51 determines that the temperature detection circuit is abnormal. The motor temperature estimation unit 55 starts to increase the ECU temperature estimation value Tes from the time t1, and calculates a value that gradually increases from the ECU temperature detection value Te2 detected by the first temperature detection circuit 45 at the time t1 to the predetermined set value Ts at a constant increase rate ΔTr as the ECU temperature estimation value Tes.

[0236] Reference Fig.16The motor temperature estimating unit 55 estimates the increase value Rt of the motor temperature caused by the motor current flowing through the motor 20. For example, the motor temperature estimating unit 55 can estimate the increase value Rt by subtracting the heat dissipation of the motor 20 from the integral value of the sum of the squares of the motor current detection values ​​I1ad, I1bd, I1cd, I2ad, I2bd, and I2cd.

[0237] The motor temperature estimating unit 55 calculates a value obtained by adding the increase value Rt to the ECU temperature estimated value Tes as the motor temperature estimated value Tm.

[0238] In addition, the motor control method of the third embodiment is similar to the reference Figure 7 The motor control method is the same as the flowchart of FIG.

[0239] (Effects of the Third Embodiment)

[0240] (1) The ECU 30 includes: a circuit board 70; a first power conversion circuit 42A mounted on the circuit board 70 and supplying current to drive the motor 20; a second power conversion circuit 42B mounted on the circuit board 70 and supplying current to drive the same motor 20 as or a different motor 20 supplied with current by the first power conversion circuit 42A; temperature detection circuits 45 and 46 having temperature sensors 45a and 46a; and a first current limiting unit 61 that limits the current supplied by the first power conversion circuit 42A and the current supplied by the second power conversion circuit 42B based on the temperature detected by the temperature detection circuits 45 and 46. The temperature sensors 45a and 46a are mounted on the circuit board 70 on which the first power conversion circuit 42A and the second power conversion circuit 42B are mounted, and are arranged at a position between the first power conversion circuit 42A and the second power conversion circuit 42B.

[0241] Thus, the temperature abnormality of both the first power conversion circuit 42A and the second power conversion circuit 42B can be detected favorably without biasing to either the first power conversion circuit 42A or the second power conversion circuit 42B.

[0242] (2) The surface of the switching element included in the first power conversion circuit 42A opposite to the circuit substrate 70, the surface of the switching element included in the second power conversion circuit 42B opposite to the circuit substrate 70, and the surfaces of the temperature sensors 45a and 46a opposite to the circuit substrate 70 can also be thermally connected to the same heat dissipation component 72.

[0243] This makes it easier to detect temperature abnormalities in the first power conversion circuit 42A and the second power conversion circuit 42B.

[0244] (3) The temperature sensors 45 a and 46 a may be arranged substantially at the center of the circuit board 70 in the arrangement direction of the circuit board 70 in which the first power conversion circuit 42A and the second power conversion circuit 42B are arranged.

[0245] Thus, it is easy to dispose the first temperature sensor 45a and the second temperature sensor 46a between the first power conversion circuit 42A and the second power conversion circuit 42B. In addition, heat is easily accumulated in the center of the circuit substrate 70, so by disposing the first temperature sensor 45a and the second temperature sensor 46a at a position that is prone to high temperature, it is easy to detect overheating of the ECU 30.

[0246] (4) The sensor abnormality determination unit 51 may determine whether the temperature detection circuits 45 and 46 are abnormal based on the difference between the detected temperature corresponding to the output of the first temperature sensor 45a and the detected temperature corresponding to the output of the second temperature sensor 46a, and configure the first temperature sensor 45a and the second temperature sensor 46a close to each other.

[0247] Thus, the thermal coupling between the first temperature sensor 45a and the second temperature sensor 46a can be made tight. As a result, the detected temperature of the first temperature sensor 45a and the detected temperature of the second temperature sensor 46a can be made close to each other, and an abnormality generated in the temperature detection circuit 45 and the temperature detection circuit 46 can be detected with high accuracy based on the difference between the detected temperatures of the first temperature sensor 45a and the second temperature sensor 46a.

[0248] (5) The sensor abnormality determination unit 51 can also determine whether the temperature detection circuits 45 and 46 are abnormal based on the difference between the detection temperature corresponding to the output of the first temperature sensor 45a and the detection temperature corresponding to the output of the second temperature sensor 46a, and the surface of the first temperature detection element on the opposite side of the circuit substrate 70 and the surface of the second temperature detection element on the opposite side of the circuit substrate 70 are thermally connected to the same heat dissipation component 72.

[0249] As a result, the thermal coupling between the first temperature sensor 45 a and the second temperature sensor 46 a becomes closer, and the detected temperature of the first temperature sensor 45 a and the detected temperature of the second temperature sensor 46 a can be made closer.

[0250] (6) The first temperature sensor 45 a and the second temperature sensor 46 a may be temperature detection elements having the same structure, or the first temperature sensor 45 a and the second temperature sensor 46 a may be oriented in different directions and mounted on the circuit board 70 .

[0251] This can prevent the first temperature sensor 45a and the second temperature sensor 46a from being damaged simultaneously when stress is applied to the circuit board 70. Therefore, it is possible to suppress the first temperature sensor 45a and the second temperature sensor 46a from failing simultaneously.

[0252] (Variation Example)

[0253] In the above description, an example of applying the rotation angle detection device of the present invention to an electric power steering device of a steering column assist type, which is called an upstream assist type, is described, but the rotation angle detection device of the present invention can also be applied to an electric power steering device of a so-called downstream assist type. Hereinafter, as an example of an electric power steering device of a downstream assist type, a structural example of applying the rotation angle detection device of the present invention to an electric power steering device of a single pinion assist type, a rack assist type, and a double pinion assist type will be described.

[0254] In the case of the downstream assist mode, the motor 20, the rotation angle sensor 23a, and the ECU 30 may not be separate structures, but may be combined as shown in FIG. Figure 18 to Figure 20 The dotted line shows the integrated MCU (Motor Control Unit).

[0255] Fig.18 The following is a structural example of a rotation angle detection device of the present invention applied to a single pinion assist type electric power steering device. A steering wheel 1 is connected to a universal joint 4a on one side of an intermediate shaft via a steering shaft 2. In addition, an input side shaft 4c of a torsion bar (not shown) is connected to the universal joint 4b on the other side.

[0256] The pinion rack mechanism 5 includes a pinion (gear) 5a, a rack bar (rack) 5b, and a pinion shaft 5c. The input side shaft 4c and the pinion rack mechanism 5 are connected by a torsion bar (not shown), and the torsion bar is twisted due to the deviation of the rotation angle between the input side shaft 4c and the pinion rack mechanism 5. The torque sensor 10 electromagnetically measures the torsion angle of the torsion bar as the steering torque Th of the steering wheel 1.

[0257] The motor 20 that assists the steering force of the steering wheel 1 is connected to the pinion shaft 5 c via the reduction gear 3 , and the rotation angle sensor 23 a calculates the rotation angle information of the motor rotation shaft of the motor 20 similarly to the above-mentioned embodiment.

[0258] Fig.19The following is a structural example of an electric power steering device of a rack-assisted type in which the rotation angle detection device of the present invention is applied. A spiral groove (not shown) is formed on the outer peripheral surface of the rack bar 5b, and a spiral groove (not shown) with the same lead is also formed on the inner peripheral surface of the nut 81. A ball screw is formed by arranging a plurality of rolling elements in the rolling path formed by these spiral grooves.

[0259] A belt 84 is wound around a driving pulley 82 connected to a rotating shaft 20a of a motor 20 that assists the steering force of the steering wheel 1 and a driven pulley 83 connected to a nut 81, and the rotational motion of the rotating shaft 20a is converted into a linear motion of the rack bar 5b. The rotation angle sensor 23a calculates the rotation angle information of the motor rotating shaft of the motor 20 in the same manner as in the above embodiment.

[0260] Fig. 20 The following is a structural example of the rotation angle detection device of the present invention applied to an electric power steering device of a dual pinion assist type. The electric power steering device of the dual pinion assist type has a second pinion shaft 85 and a second pinion 86 in addition to the pinion shaft 5c and the pinion 5a, and the rack bar 5b has a first rack tooth (not shown) meshing with the pinion 5a and a second rack tooth (not shown) meshing with the second pinion 86.

[0261] The motor 20 that assists the steering force of the steering wheel 1 is connected to the second pinion shaft 85 via the reduction gear 3 , and the rotation angle sensor 23 a calculates the rotation angle information of the motor rotation shaft of the motor 20 similarly to the above-mentioned embodiment.

[0262] Description of Reference Numerals

[0263] 1: Steering wheel; 2: Steering shaft; 3: Reduction gear; 4a, 4b: Universal joint; 4c: Input shaft; 5: Pinion rack mechanism; 5a: Pinion (gear); 5b: Rack bar (rack); 5c: Pinion shaft; 6a, 6b: Steering tie rod; 7a, 7b: Wheel hub unit; 8L, 8R: Steering wheels; 10: Torque sensor; 11: Ignition switch; 12: Vehicle speed sensor; 13: Battery; 14: Steering angle sensor; 20: Motor; 23: Motor rotation angle detection circuit; 30: Electronic control unit; 31: Control operation device; 31a: A / D conversion unit; 31b: Temperature measurement unit; 33A: First motor current cutoff circuit; 33B: Second motor current cutoff circuit; 39A1, 39A2, 39B1, 39B2, 39C1, 39C2: Current detection circuit; 41A: First gate drive circuit; 41B: Second gate drive circuit; 42A: First power conversion circuit; 42B: Second power conversion circuit; 44A: First power cutoff circuit; 44B: Second power cutoff circuit; 45: Temperature detection circuit, first temperature detection circuit; 45a: Temperature sensor, first temperature sensor; 46: Second temperature detection circuit; 46a: Second temperature sensor; 50: ECU temperature measurement unit; 51: Sensor abnormality determination unit; 52: ECU temperature estimation unit; 53: Rise value estimation unit; 54: Adder; 55: Motor temperature estimation unit; 60 : Current command value calculation unit; 61: First current limiting unit; 62, 63: Subtractor; 64: Second current limiting unit; 65: PI control unit; 66: Two-phase / three-phase conversion unit; 67: Three-phase / two-phase conversion unit; 68: Angular velocity conversion unit; 70: Circuit substrate; 72: Heat dissipation component; 73, 74: Thermal interface material (TIM); 81: Nut; 82: Driving pulley; 83: Driven pulley; 84: Belt; 85: Second pinion shaft; 86: Second pinion.

Claims

1. A motor control device, characterized in that: The motor control device comprises: Circuit board; a first power conversion circuit mounted on the circuit substrate and supplying current for driving the motor; a second power conversion circuit mounted on the circuit substrate and supplying current for driving the same motor as or a different motor from the motor supplied with current by the first power conversion circuit; A temperature detection circuit having a temperature detection element; as well as a control circuit that limits the current supplied by the first power conversion circuit and the current supplied by the second power conversion circuit based on the temperature detected by the temperature detection circuit, The temperature detection element is mounted on the circuit substrate on which the first power conversion circuit and the second power conversion circuit are mounted, and is arranged at a position between the first power conversion circuit and the second power conversion circuit.

2. The motor control device according to claim 1, characterized in that: The surface of the switching element included in the first power conversion circuit opposite to the circuit substrate, the surface of the switching element included in the second power conversion circuit opposite to the circuit substrate, and the surface of the temperature detection element opposite to the circuit substrate are thermally connected to the same heat dissipation component.

3. The motor control device according to claim 1, characterized in that: The temperature detection element is arranged substantially at the center of the circuit substrate in the direction in which the first power conversion circuit and the second power conversion circuit are arranged on the circuit substrate.

4. The motor control device according to claim 1, characterized in that: The motor control device includes a first temperature detection element and a second temperature detection element as the temperature detection element. The control circuit determines whether the temperature detection circuit is abnormal based on a difference between a detected temperature corresponding to an output of the first temperature detection element and a detected temperature corresponding to an output of the second temperature detection element. The first temperature detection element and the second temperature detection element are arranged close to each other.

5. The motor control device according to claim 1, characterized in that: The motor control device includes a first temperature detection element and a second temperature detection element as the temperature detection element. The control circuit determines whether the temperature detection circuit is abnormal based on a difference between a detected temperature corresponding to an output of the first temperature detection element and a detected temperature corresponding to an output of the second temperature detection element. A surface of the first temperature detection element on the opposite side to the circuit substrate and a surface of the second temperature detection element on the opposite side to the circuit substrate are thermally connected to the same heat dissipation member.

6. The motor control device according to claim 5, characterized in that: The surface of the switching element included in the first power conversion circuit opposite to the circuit substrate, the surface of the switching element included in the second power conversion circuit opposite to the circuit substrate, the surface of the first temperature detection element opposite to the circuit substrate, and the surface of the second temperature detection element opposite to the circuit substrate are thermally connected to the same heat dissipation component.

7. The motor control device according to claim 4 or 5, characterized in that: The first temperature detection element and the second temperature detection element are temperature detection elements of the same structure, and are mounted on the circuit board with the first temperature detection element and the second temperature detection element oriented in different directions.

8. An electric power steering device, characterized in that: The electric power steering device comprises: The motor control device according to any one of claims 1, 4, and 5; and a motor controlled by the motor control device, The motor provides a steering assist force to a steering system of the vehicle.

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