Control device

Abstract

To provide a control device which suppresses occurrence of a situation that the control device cannot return to control for operating a control target even if supply power from a battery is reduced.SOLUTION: A control device has a control circuit for controlling operation of a motor. The control device includes a pre-driver which is operated on the basis of an instruction from the control circuit. Power for operation is supplied from a battery for a vehicle to the control circuit and the pre-driver. Power required for operating the control circuit is set lower than power required for operating the pre-driver. When detecting reduction of a battery voltage, the control circuit executes operation stop processing for instructing operation stop to the pre-driver before the battery voltage becomes lower than the voltage required for operating the pre-driver. During the operation stop of the pre-driver after the operation stop processing, the control circuit sets a state where an abnormality which may occur due to the operation stop of the pre-driver is not detected.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] For example, the following Patent Document 1 describes a control device having a microcomputer, a pre-driver, and an inverter. In this control device, the microcomputer, the pre-driver, and the inverter can operate by being supplied with power from a battery. For example, the pre-driver is configured to stop operating when the power supplied from the battery decreases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-109495 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when the microcomputer detects whether an abnormality has occurred in the control device, if the pre-driver stops operating, the microcomputer detects that an abnormality has occurred related to the stop of operation. However, depending on the content of the detected abnormality, even if the pre-driver can return to operation, the microcomputer may determine that the pre-driver cannot return to operation. [Means for solving the problem]

[0005] A control device that can solve the above problem has a control circuit for controlling the operation of a controlled object. The control device includes an operation processing circuit that executes processing for controlling the operation of the controlled object based on an instruction from the control circuit, the control circuit and the operation processing circuit are supplied with power for operation from a battery, the power required for the control circuit to operate is set to be lower than the power required for the operation processing circuit to operate, the control circuit is configured to execute an operation stop process for instructing the operation processing circuit to stop operation before the power supplied from the battery falls below the power required for the operation of the operation processing circuit when detecting a decrease in the power supplied from the battery while monitoring the power supplied from the battery, and the control circuit sets a state in which, after the operation stop process, while the operation of the operation processing circuit is stopped, abnormalities that may occur due to the operation processing circuit stopping are not detected.

[0006] According to the above configuration, when the power supply from the battery decreases, the control circuit can forcibly stop the operation of the operation processing circuit before the power required for the operation of the operation processing circuit can no longer be secured. When the operation processing circuit is forcibly stopped, abnormalities may occur due to the operation stop, but the control circuit sets a state in which these abnormalities are not detected. This makes it possible to create a state in which the operation processing circuit can return to operation after the operation processing circuit is forcibly stopped. Therefore, even if the power supply from the battery decreases, the occurrence of a situation in which it is not possible to return to control of operating the controlled object is suppressed.

[0007] In the above control device, it is preferable that, when the control circuit detects recovery from the drop in the power supply after the operation stop processing, the control circuit executes an operation recovery processing for instructing the operation processing circuit to resume operation.

[0008] According to the above configuration, even after the operation of the operation processing circuit is forcibly stopped, if the control circuit detects that the power supply has returned to normal, the control circuit can instruct the operation processing circuit to return to normal. This is because, when the operation of the operation processing circuit is forcibly stopped, abnormalities may occur due to the operation stop, but the control circuit sets a state in which these abnormalities are not detected. This prevents the occurrence of a situation in which the controlled object cannot be operated even if the power supply from the battery is reduced.

[0009] In the above control device, it is preferable that the condition for detecting recovery from the reduction in the power supply includes a state in which the reduction in the power supply has been resolved continuing for a specified period of time or longer. According to the above configuration, the control circuit does not immediately detect the recovery of the supply power even if the drop in the supply power is resolved. This prevents the control circuit from frequently switching between detecting the return of operation due to an unstable state of the supply power. This ensures the stability of the operation of the control circuit, more specifically, the controlled object.

[0010] In the above-mentioned control device, if the operation processing circuit cannot return to operation despite executing the operation recovery process, it is preferable that the control circuit detects an abnormality in the operation processing circuit and sets a state in which control that is possible without using the operation processing circuit is executed.

[0011] According to the above configuration, if the operation processing circuit cannot return to operation despite being instructed to return to operation, there is a high probability that an abnormality that prevents the operation from being returned to operation has occurred. Therefore, if the operation processing circuit cannot return to operation despite being instructed to return to operation, the control circuit detects an abnormality in the operation processing circuit. In this case, since it is not possible to execute control using the operation processing circuit, the control circuit executes control that is possible without using the operation processing circuit. Therefore, it is possible to realize a control circuit that can respond flexibly to circumstances, rather than continuing indefinitely a state in which the operation processing circuit is stopped.

[0012] In the above control device, it is preferable that the controlled object is a motor, and the operation processing circuit includes a pre-driver for controlling power supply to the motor. According to the above configuration, in the control circuit that controls the power supply to the motor, after the pre-driver is forcibly stopped, a state in which the pre-driver can be restored to operation can be created. Therefore, even if the power supply from the battery decreases, the occurrence of a situation in which the motor cannot be restored to power supply can be suppressed. In other words, the period during which the motor can be driven can be secured longer. Effect of the Invention

[0013] According to the control device of the present invention, even if the power supply from the battery drops, the occurrence of a situation in which it becomes impossible to return to control for operating the controlled object is suppressed. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle on which a control device according to a first embodiment is mounted. [Diagram 2] FIG. 2 is a diagram showing an electrical configuration of the motor device of FIG. [Diagram 3] 3 is a flowchart showing a processing procedure executed by the microcomputer in FIG. 2 when the power is turned on. [Figure 4]3 is a flowchart showing a procedure of a pre-driver abnormality detection process executed by the microcomputer of FIG. 2; [Diagram 5] 3 is a flowchart showing a procedure of inverter circuit abnormality detection processing executed by the microcomputer of FIG. 2; [Figure 6] 1A is a diagram illustrating a change in the first power supply voltage, FIG. 1B is a diagram illustrating the state of the first microcomputer, FIG. 1C is a diagram illustrating the state of the first pre-driver, and FIG. 1D is a diagram illustrating the state of the second microcomputer and the second pre-driver. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the control device will be described with reference to the drawings. As shown in FIG. 1, the vehicle steering system STG is a system mounted on the vehicle VC to perform various controls related to the vehicle VC. For example, the vehicle steering system STG performs control related to steering of the steered wheels T of the vehicle VC so as to change the traveling direction of the vehicle VC based on the operation of the steering wheel SH of the vehicle VC operated by the driver. The vehicle steering system STG is connected to the steering wheel SH via a steering shaft SS included in the components. The vehicle steering system STG is connected to the steered wheels T via a rack shaft RS included in the components. The vehicle VC is equipped with a battery B for the vehicle. The battery B for the vehicle includes a first battery B1 and a second battery B2. Each of the batteries B1 and B2 is a secondary battery that is a DC power source. Each of the batteries B1 and B2 is earthed by being individually connected to a portion of the vehicle VC. Each of the batteries B1 and B2 is connected to the vehicle steering system STG. The vehicle steering system STG is supplied with power from each of the batteries B1 and B2.

[0016] <Vehicle Steering System> As shown in Fig. 1, the vehicle steering system STG has a motor device MCU. The motor device MCU is a mechanically and electrically integrated motor device in which a control device 10 and a motor 20 are integrated. The control device 10 controls the driving of the motor 20, with the motor 20 being the control target. The motor 20 generates a motor torque for changing the traveling direction of the vehicle VC. The motor 20 is, for example, a three-phase brushless motor. The three phases are a U-phase, a V-phase, and a W-phase.

[0017] For example, the vehicle steering system STG includes an electric power steering device that applies the motor torque of the motor 20 to the steering shaft SS. In this case, the motor torque generated by the motor 20 acts as an assist force for assisting the driver in operating the steering wheel SH.

[0018] <Electrical configuration of the control device> 2, the motor 20 has a plurality of winding groups 21, each including a three-phase set consisting of a U-phase winding, a V-phase winding, and a W-phase winding. The winding groups 21 include a first winding group 21A and a second winding group 21B. When controlling the driving of the motor 20, the control device 10 independently controls the energization of the winding groups 21A and 21B. The control device 10 has a control circuit 30 for controlling the energization of the winding groups 21.

[0019] The control circuit 30 includes a first microcomputer 30A and a second microcomputer 30B. The first microcomputer 30A controls the energization of the first winding group 21A. The second microcomputer 30B controls the energization of the second winding group 21B. That is, each of the microcomputers 30A and 30B individually controls the energization of each of the winding groups 21A and 21B.

[0020] The control device 10 includes a plurality of electronic components, such as IC chips and elements, configured in combination with the microcomputers 30A and 30B. For example, the plurality of electronic components include a power supply IC 31, a pre-driver 32, and an inverter circuit 33. The power supply IC 31 includes a first power supply IC 31A and a second power supply IC 31B. The pre-driver 32 includes a first pre-driver 32A and a second pre-driver 32B. The inverter circuit 33 includes a first inverter circuit 33A and a second inverter circuit 33B.

[0021] The first power supply IC 31A, the first pre-driver 32A, and the first inverter circuit 33A, in combination with the first microcomputer 30A, constitute a first current supply system 11A. The second power supply IC 31B, the second pre-driver 32B, and the second inverter circuit 33B, in combination with the second microcomputer 30B, constitute a second current supply system 11B.

[0022] The first power supply IC31A is a chip-type integrated circuit. The first power supply IC31A is connected to the first battery B1 via the first ig power line LgA. The first power supply IC31A steps down or steps up the voltage of the first battery B1 to a voltage suitable for the operation of the first microcomputer 30A and the first pre-driver 32A, and supplies the voltage to the first microcomputer 30A and the first pre-driver 32A. Similarly, the second power supply IC31B is a chip-type integrated circuit. The second power supply IC31B is connected to the second battery B2 via the second ig power line LgB. The second power supply IC31B steps down or steps up the voltage of the second battery B2 to a voltage suitable for the operation of the second microcomputer 30B and the second pre-driver 32B, and supplies the power to the second microcomputer 30B and the second pre-driver 32B. The initial voltage or nominal voltage, i.e., the battery voltage, of each battery B1, B2 is, for example, 12V. Each of the ig power lines LgA, LgB is provided with a power switch 44. By operating the power switch 44, the conduction of each of the ig power lines LgA, LgB is turned on and off.

[0023] Each of the microcomputers 30A, 30B refers to the detection results of various sensors provided in the vehicle VC. Examples of the sensors include a vehicle speed sensor 41, a torque sensor 42, and a rotation angle sensor 43. The vehicle speed sensor 41 detects the vehicle speed V of the vehicle VC. The torque sensor 42 is provided on the steering shaft SS. The torque sensor 42 detects the steering torque Th input to the steering shaft SS through the operation of the steering wheel SH. The torque sensor 42 includes a first torque sensor 42A and a second torque sensor 42B. The first torque sensor 42A is provided so that the first microcomputer 30A can refer to the steering torque Th. The second torque sensor 42B is provided so that the second microcomputer 30B can refer to the steering torque Th. The rotation angle sensor 43 is provided on the motor 20. The rotation angle sensor 43 detects the rotation angle θm of the motor 20. The rotation angle sensor 43 includes a first rotation angle sensor 43A and a second rotation angle sensor 43B. The first rotation angle sensor 43A is provided so that the first microcomputer 30A can refer to the rotation angle θm. The second rotation angle sensor 43B is provided so that the second microcomputer 30B can refer to the rotation angle θm.

[0024] The first microcomputer 30A generates a first command signal SA for the first pre-driver 32A by referring to the detection results of various sensors provided in the vehicle VC. Similarly, the second microcomputer 30B generates a second command signal SB for the second pre-driver 32B by referring to the detection results of various sensors provided in the vehicle VC.

[0025] The first pre-driver 32A is a chip-type integrated circuit. The first pre-driver 32A inputs a first command signal SA from the first microcomputer 30A. The first pre-driver 32A generates a first drive signal DA for the first inverter circuit 33A based on the first command signal SA. As a result, the first pre-driver 32A performs operation processing related to the drive control of the first inverter circuit 33A. Similarly, the second pre-driver 32B is a chip-type integrated circuit. The second pre-driver 32B inputs a second command signal SB from the second microcomputer 30B. The second pre-driver 32B generates a second drive signal DB for the second inverter circuit 33B based on the second command signal SB. As a result, the second pre-driver 32B performs operation processing related to the drive control of the second inverter circuit 33B. In this embodiment, the pre-driver 32, that is, each of the pre-drivers 32A and 32B is an example of an operation processing circuit.

[0026] The first inverter circuit 33A is, for example, a drive circuit having a plurality of FETs (Field Effect Transistors) which are switching elements. The first inverter circuit 33A is connected to each phase of the first winding group 21A via three connection lines 34A. The first inverter circuit 33A is connected to the first battery B1 via the first Pig power line LpA. The first inverter circuit 33A supplies a current to the first winding group 21A by each FET performing a switching operation based on a first drive signal DA from the first pre-driver 32A. The first inverter circuit 33A converts a direct current from the first battery B1 into a three-phase alternating current. That is, the first inverter circuit 33A supplies power to the motor 20 according to a first command signal SA generated by the first microcomputer 30A. Similarly, the second inverter circuit 33B is, for example, a drive circuit having a plurality of FETs (Field Effect Transistors) which are switching elements. The second inverter circuit 33B is connected to each phase of the second winding group 21B via three connection lines 34B. The second inverter circuit 33B is connected to the second battery B2 via the second Pig power line LpB. The second inverter circuit 33B supplies current to the second winding group 21B by switching each FET based on the second drive signal DB of the second pre-driver 32B. The second inverter circuit 33B converts the DC current from the second battery B2 into a three-phase AC current. That is, the second inverter circuit 33B supplies power to the motor 20 according to the second command signal SB generated by the second microcomputer 30B.

[0027] <About the microcontroller functions> Each of the microcomputers 30A, 30B includes a central processing unit (hereinafter referred to as "CPU") and a memory. Each of the microcomputers 30A, 30B executes various processes by having the CPU execute programs stored in the memory at predetermined calculation cycles. The CPU and the memory constitute a microcomputer, which is a processing circuit. The memory includes computer-readable media such as RAM (Random Access Memory) and ROM (Read Only Memory). However, the implementation of various processes by software is one example. The processing circuit of each of the microcomputers 30A, 30B may be configured to implement at least a part of the processes by a hardware circuit such as a logic circuit.

[0028] In this embodiment, the microcomputers 30A and 30B have the same functions. In the following, only the first microcomputer 30A will be described, and a description of the second microcomputer 30B will be omitted. 3, the first microcomputer 30A executes an initial check (step 102) when the power switch 44 is switched from off to on (step 100). The initial check includes an initial setting process for initial setting to start power supply to the motor 20, and a pre-driver startup process for starting the first pre-driver 32A.

[0029] The initial setting process includes a check process related to the operation of the first microcomputer 30A. The initial setting process includes a check process related to communication with the second microcomputer 30B. The initial setting process includes an initialization process related to initialization of various variables related to power supply to the motor 20 by, for example, reading various information from a memory.

[0030] The pre-driver startup process includes a process of instructing the first pre-driver 32A about setting information required for the operation of the first pre-driver 32A. The first pre-driver 32A can be started and start operating by executing initial settings based on the instructed setting information. The contents of the initial settings are items required for the operation of the first pre-driver 32A, such as the drive voltage of the first pre-driver 32A or on / off of various functions.

[0031] When the initial check is completed, the first microcomputer 30A starts supplying power to the motor 20 (step 104). That is, the first microcomputer 30A executes a process related to the power supply control for the first winding group 21A.

[0032] More specifically, the first microcomputer 30A includes a process of referring to the vehicle speed V, the steering torque Th, and the rotation angle θm. The first microcomputer 30A includes a process of calculating a target control amount to control the assist force based on the vehicle speed V, the steering torque Th, and the rotation angle θm. The first microcomputer 30A calculates a current command value according to the target control amount, and executes a current feedback control to make the actual first current value IA supplied to the first winding group 21A follow the current command value. The first microcomputer 30A generates a first command signal SA for the first pre-driver 32A by executing the current feedback control. The first microcomputer 30A refers to the first current value IA and the rotation angle θm when executing the current feedback control. The actual first current value IA supplied to the first winding group 21A is detected through a first current sensor 35A provided on the three connection lines 34A. The same applies to the second current value IB. That is, the second current value IB is detected through the second current sensor 35B provided on the three connection lines 34B.

[0033] The first microcomputer 30A executes a process related to a fail-safe while executing a process related to the power supply control. The process related to the fail-safe includes a pre-driver abnormality detection process and an inverter circuit abnormality detection process. The pre-driver abnormality detection process is a process related to the fail-safe of the first pre-driver 32A. The inverter circuit abnormality detection process is a process related to the fail-safe of the first inverter circuit 33A.

[0034] <Predriver abnormality detection process> As shown in FIG. 4, in the pre-driver abnormality detection process, the first microcomputer 30A judges whether the first power supply voltage VA is equal to or lower than the threshold voltage Vth (step 202). In step 202, the first microcomputer 30A judges whether the first power supply voltage VA is decreasing while monitoring the first power supply voltage VA. In this embodiment, the first power supply voltage VA is a voltage value on the downstream side of the power switch 44, i.e., the upstream side of the first power supply IC 31A, and is equivalent to the battery voltage of the first battery B1. The same is true for the second power supply voltage VB. In other words, the second power supply voltage VB is a voltage value on the downstream side of the power switch 44, i.e., the upstream side of the second power supply IC 31B, and is equivalent to the battery voltage of the second battery B2.

[0035] As expressed by the following equation (1), when the first power supply voltage VA is equal to or lower than the threshold voltage Vth, the first microcomputer 30A detects a decrease in the first power supply voltage VA, that is, a decrease in the power supplied by the first battery B1.

[0036] VA≦Vth …(1) The threshold voltage Vth is a value larger than the voltage V0 suitable for the operation of the first pre-driver 32A. The voltage V0 suitable for the operation of the first pre-driver 32A is a voltage value required to secure the power required for the operation of the first pre-driver 32A. For example, when the first power supply voltage VA falls below the voltage V0, the first pre-driver 32A becomes inoperable and stops operating by itself. When the first pre-driver 32A stops operating, even if the first microcomputer 30A tries to control the current supply to the first winding group 21A, the power supply to the first winding group 21A stops.

[0037] Moreover, the voltage V0 is a value greater than the voltage V1. That is, the threshold voltage Vth is a value greater than the voltages V0 and V1, as expressed by the following formula (2). V1 <V0<Vth …(2) The voltage V1 is a voltage value required to secure the power required for the first microcomputer 30A to operate. For example, when the first power supply voltage VA falls below the voltage V1, the first microcomputer 30A becomes inoperable and stops operating by itself. When the first microcomputer 30A stops operating, the function of the first current supply system 11A itself stops.

[0038] On the other hand, even if the first power supply voltage VA falls below the voltage V0, the first microcomputer 30A can continue to operate as long as it does not fall below the voltage V1. In other words, the first microcomputer 30A can continue to operate even if the first pre-driver 32A is inoperable.

[0039] Next, if the first power supply voltage VA is greater than the threshold voltage Vth (step 202: NO), the first microcomputer 30A determines that the first power supply voltage VA has not decreased, and repeats the process of step 202.

[0040] On the other hand, when the first power supply voltage VA is equal to or lower than the threshold voltage Vth (step 202: YES), the first microcomputer 30A determines that the first power supply voltage VA has dropped, and executes an operation stop process for stopping the operation of the first pre-driver 32A (step 204). The operation stop process includes a process of instructing the first pre-driver 32A to stop operation. When the first microcomputer 30A detects a drop in the first power supply voltage VA while monitoring the first power supply voltage VA, the first microcomputer 30A instructs the first pre-driver 32A to stop operation before the first power supply voltage VA falls below the voltage V0. Note that even when the first power supply voltage VA is equal to or lower than the threshold voltage Vth, the first microcomputer 30A can manage the operation of the first pre-driver 32A as long as the first power supply voltage VA does not fall below the voltage V1.

[0041] In step 204, the first microcomputer 30A temporarily stops the energization control for the first winding group 21A in response to the instruction to stop the operation of the first pre-driver 32A. In this case, if the second microcomputer 30B is executing the process related to the energization control for the second winding group 21B, the motor 20 generates a motor torque corresponding to at least the second winding group 21B.

[0042] Next, the first microcomputer 30A temporarily stops the inverter circuit abnormality detection process (step 206). In step 206, the first microcomputer 30A avoids the implementation of a fail-safe of the first inverter circuit 33A, which is caused by the instruction to stop the operation of the first pre-driver 32A.

[0043] Next, the first microcomputer 30A determines whether the first power supply voltage VA is greater than the threshold voltage Vth (step 208). In step 208, the first microcomputer 30A determines whether the drop in the first power supply voltage VA has been resolved while monitoring the first power supply voltage VA.

[0044] Next, if the first power supply voltage VA is equal to or lower than the threshold voltage Vth (step 208: NO), the first microcomputer 30A determines that the drop in the first power supply voltage VA has not been resolved, and repeats the process of step 208.

[0045] On the other hand, when the first power supply voltage VA is greater than the threshold voltage Vth (step 208: YES), the first microcomputer 30A determines that the drop in the first power supply voltage VA has been eliminated, and determines whether the elapsed time TA has continued for a specified time Tth or more (step 210). In step 210, the first microcomputer 30A updates the elapsed time TA by incrementing it by a specified value. The elapsed time TA is the time that has elapsed since it was determined that the drop in the first power supply voltage VA has been eliminated, and indicates the time during which the state in which the drop in the first power supply voltage VA has been eliminated has continued. The specified time Tth is a value within a range that is experimentally determined from the viewpoint of suppressing the occurrence of a situation in which the first power supply voltage VA repeatedly goes above and below the threshold voltage Vth. The elapsed time TA is initially set to zero.

[0046] Next, if the elapsed time TA does not continue for the specified time Tth or more (step 210: NO), the first microcomputer 30A repeats the processes of steps 208 and 210. If the first microcomputer 30A determines that the first power supply voltage VA is equal to or lower than the threshold voltage Vth (step 208: NO), it resets the elapsed time TA by setting the elapsed time TA to an initial value, i.e., zero.

[0047] On the other hand, when the elapsed time TA continues for the specified time Tth or more (step 210: NO), the first microcomputer 30A determines that the first power supply voltage VA has recovered from the drop, and executes an operation recovery process for recovering the first pre-driver 32A (step 212). The operation recovery process includes a process of instructing the first pre-driver 32A to recover. Instructing the first pre-driver 32A to recover means restarting the first pre-driver 32A. As in the pre-driver startup process, the first microcomputer 30A restarts the first pre-driver 32A by instructing the first pre-driver 32A of setting information required for the first pre-driver 32A to operate.

[0048] The operation recovery process is executed in a state other than the initial check. This means that the operation recovery process is executed while the first microcomputer 30A is not executing the initial setting process. In other words, the first microcomputer 30A restarts the first pre-driver 32A in a state where various variables related to the power supply to the motor 20 are not initialized and the current state is maintained. In this way, the first microcomputer 30A avoids communication with the second microcomputer 30B being interrupted when restarting the first pre-driver 32A. In other words, the first microcomputer 30A avoids the implementation of a fail-safe in the second microcomputer 30B when restarting the first pre-driver 32A.

[0049] Next, the first microcomputer 30A determines whether the first pre-driver 32A has been successfully restarted (step 214). In step 214, the first microcomputer 30A determines whether the first pre-driver 32A has been successfully restarted by monitoring the first current value IA detected through the first current sensor 35A. For example, if the first pre-driver 32A has been successfully restarted, a current corresponding to the first command signal SA is supplied from the first inverter circuit 33A to the first winding group 21A.

[0050] Next, if the first pre-driver 32A is successfully restarted (step 214: YES), the first microcomputer 30A releases the temporary suspension of the inverter circuit abnormality detection process (step 216). In step 216, the first microcomputer 30A instructs the first pre-driver 32A to resume operation, thereby returning to a state in which the fail-safe of the first inverter circuit 33A can be detected. Thereafter, the first microcomputer 30A resumes the control of the energization of the first winding group 21, and returns to the process of step 202 to repeatedly execute the processes from step 202 onward.

[0051] On the other hand, when the first pre-driver 32A fails to restart (step 214: NO), the first microcomputer 30A performs a fail-safe. For example, the first microcomputer 30A does not resume the energization control for the first winding group 21A. In this case, the first microcomputer 30A notifies the second microcomputer 30B that it is unable to execute the energization control for the first winding group 21A. Note that while the first microcomputer 30A temporarily stops the energization control for the first winding group 21A, if the second microcomputer 30B executes the process related to the energization control for the second winding group 21B, the motor 20 generates a motor torque corresponding to at least the second winding group 21B. When the second microcomputer 30B receives the notification from the first microcomputer 30A that it is unable to execute the energization control for the first winding group 21A, it executes the energization control by, for example, supplying twice the normal current to the second winding group 21B. That is, the second microcomputer 30B executes current control to compensate for the failure of the first winding group 21A.

[0052] <Inverter circuit abnormality detection process> 5, in the inverter circuit abnormality detection process, the first microcomputer 30A determines whether the abnormality detection process is executable (step 302). In step 302, the first microcomputer 30A determines whether the inverter circuit abnormality detection process is temporarily stopped through the process of step 206 of the pre-driver abnormality detection process.

[0053] Next, if the first microcomputer 30A is not able to execute the abnormality detection process (step 302: NO), the first microcomputer 30A executes the process of step 302 repeatedly. On the other hand, when the first microcomputer 30A is capable of executing the abnormality detection process (step 302: YES), it determines whether or not an abnormality has occurred in the first inverter circuit 33A (step 304). In step 304, the first microcomputer 30A refers to the first current value IA detected through the first current sensor 35A, and detects an abnormality in the first inverter circuit 33A based on this first current value IA. For example, when the first microcomputer 30A generates the first command signal SA but does not supply a current corresponding to the first command signal SA from the first inverter circuit 33A to the first winding group 21A, the first microcomputer 30A determines that an abnormality has occurred in the first inverter circuit 33A.

[0054] Next, if no abnormality has occurred in the first inverter circuit 33A (step 304: YES), the first microcomputer 30A returns to the process of step 302 and repeats the process from step 302 onwards.

[0055] On the other hand, when the first microcomputer 30A determines that an abnormality has occurred in the first inverter circuit 33A (step 304: NO), it performs a fail-safe. For example, the first microcomputer 30A stops the energization control for the first winding group 21A. In this case, the first microcomputer 30A notifies the second microcomputer 30B that it is not possible to execute the energization control for the first winding group 21A, as in the case of step 214: NO in the pre-driver abnormality detection process. In other words, if the second microcomputer 30B is executing the process related to the energization control for the second winding group 21B, the motor 20 generates at least a motor torque corresponding to the second winding group 21B. In this case, the energization control for compensating for the failure of the first winding group 21A can be executed by the second microcomputer 30B.

[0056] <Action of this embodiment> 6(a) illustrates an example in which the first power supply voltage VA of "12V" starts to decrease from time t1, decreases to the threshold voltage Vth at time t2, and then further decreases to below the voltage V0 at time t3 without decreasing to the voltage V1. The figure also illustrates an example in which the first power supply voltage VA that starts to increase from time t3 and is less than the voltage V0 increases to exceed the threshold voltage Vth at time t4, and then continues to exceed the threshold voltage Vth for a specified time Tth or more.

[0057] In this case, as shown in FIGS. 6(b) and 6(c), the states of the first microcomputer 30A and the first pre-driver 32A change in response to the change in the first power supply voltage VA. More specifically, the first microcomputer 30A controls the energization of the first winding group 21A. That is, the first microcomputer 30A generates a first command signal SA for the first pre-driver 32A. The first pre-driver 32A generates a first drive signal DA for the first inverter circuit 33A.

[0058] Next, the first microcomputer 30A stops the operation of the first pre-driver 32A by determining that the first power supply voltage VA, which started to decrease at time t1, has decreased to the threshold voltage Vth at time t2. That is, the first pre-driver 32A stops operating. After stopping the operation of the first pre-driver 32A, the first microcomputer 30A temporarily stops the control of the energization of the first winding group 21A and temporarily stops the inverter circuit abnormality detection process. That is, the first microcomputer 30A stops the generation of the first command signal SA for the first pre-driver 32A and stops executing the inverter circuit abnormality detection process.

[0059] Thereafter, the first microcomputer 30A maintains the current state even if the first power supply voltage VA drops to below the voltage V0 at time t3. The first pre-driver 32A has already stopped operating. Next, the first microcomputer 30A starts counting the elapsed time TA by determining that the first power supply voltage VA, which started to rise from time t3, exceeds the threshold voltage Vth at time t4. After that, the first microcomputer 30A restores the operation of the first pre-driver 32A by determining that the first power supply voltage VA, which exceeded the threshold voltage Vth from time t4, continues for a specified time Tth or more at time t5. In other words, the first pre-driver 32A is restarted.

[0060] Thereafter, when the first microcomputer 30A restores the operation of the first pre-driver 32A, it resumes control of the current supply to the first winding group 21A by determining that the first pre-driver 32A has been successfully restarted. That is, the first microcomputer 30A generates a first command signal SA for the first pre-driver 32A. The first pre-driver 32A generates a first drive signal DA for the first inverter circuit 33A. Meanwhile, the first microcomputer 30A performs a fail-safe by determining that the first pre-driver 32A has failed to be restarted.

[0061] For example, as shown in FIG. 6(d), while the first microcomputer 30A temporarily stops the energization control for the first winding group 21A, if the second microcomputer 30B does not determine a drop in the second power supply voltage VB, the second microcomputer 30B performs the energization control for the second winding group 21B. That is, the second microcomputer 30B generates a second command signal SB for the second pre-driver 32B. The second pre-driver 32B generates a second drive signal DB for the second inverter circuit 33B. In this case, the second microcomputer 30B continues to perform the energization control after time t2, for example, by supplying a normal current to the second winding group 21B. Note that, after it is determined that the first pre-driver 32A has failed to restart, the second microcomputer 30B performs the energization control to compensate for the failure of the first winding group 21A, for example, by supplying twice the normal current to the second winding group 21B.

[0062] As described above, for example, when the first power supply voltage VA drops, the first pre-driver 32A can forcibly stop the operation of the first pre-driver 32A before the power required for the first pre-driver 32A to operate cannot be secured. When the first pre-driver 32A is forcibly stopped, abnormalities may occur due to the stop of operation, but the first microcomputer 30A sets a state in which such abnormalities are not detected. This makes it possible to create a state in which the first pre-driver 32A can return to operation after the first pre-driver 32A is forcibly stopped. The same applies to the second microcomputer 30B.

[0063] <Effects of this embodiment> (1-1) For example, the first microcomputer 30A of the control circuit 30 creates a state in which the first pre-driver 32A can return to operation after forcibly stopping the operation of the first pre-driver 32A. This is also the case with the second microcomputer 30B. Therefore, even if the power supply voltages VA and VB drop, the occurrence of a situation in which it becomes impossible to return to control for operating the motor 20 is suppressed.

[0064] (1-2) For example, the first microcomputer 30A of the control circuit 30 is capable of instructing the pre-driver 32 to resume operation if it detects recovery from a drop in the first power supply voltage VA even after forcibly stopping the operation of the first pre-driver 32A. This is because, when the first pre-driver 32A is forcibly stopped, abnormalities may occur due to the stop of operation, but the first microcomputer 30A sets a state in which such abnormalities are not detected. The same applies to the second microcomputer 30B. This prevents the motor 20 from being unable to operate even if the power supply voltages VA and VB drop.

[0065] (1-3) For example, the first microcomputer 30A in the control circuit 30 is configured not to immediately detect the recovery of the first power supply voltage VA from the drop even if the drop in the first power supply voltage VA is resolved. This prevents the first microcomputer 30A from frequently switching between detecting the recovery of operation due to the instability of the first power supply voltage VA. The same applies to the second microcomputer 30B. This ensures the stability of the operation of each microcomputer 30A, 30B, more specifically, the motor 20.

[0066] (1-4) If the pre-driver 32 cannot be restored to operation despite being instructed to do so, there is a high probability that an abnormality that prevents the pre-driver 32 from being restored to operation has occurred. Therefore, for example, the first microcomputer 30A of the control circuit 30 detects an abnormality in the first pre-driver 32A if the first pre-driver 32A cannot be restored to operation despite being instructed to do so to the first pre-driver 32A. In this case, since it is not possible to execute control using the first pre-driver 32A, the first microcomputer 30A executes control that is possible without using the first pre-driver 32A. In other words, the first microcomputer 30A implements a fail-safe to prompt the second microcomputer 30B to perform energization control to compensate for the failure of the first winding group 21A. This is also true for the second microcomputer 30B. Therefore, instead of continuing the state in which the pre-drivers 32A and 32B are stopped indefinitely, a control circuit 30 that can respond flexibly to circumstances can be realized.

[0067] (1-5) According to this embodiment, for example, in the first microcomputer 30A of the control circuit 30 that controls the power supply to the motor 20, after the first pre-driver 32A is forcibly stopped, a state in which the first pre-driver 32A can be restored to operation can be created. The same applies to the second microcomputer 30B. Therefore, even if the power supply voltages VA and VB drop, the occurrence of a situation in which the power supply to the motor 20 cannot be restored is suppressed. In other words, a period during which the motor 20 can be driven can be secured longer.

[0068] <Other embodiments> The above embodiment may be modified as follows. In addition, the following other embodiments may be combined with each other to the extent that there is no technical contradiction.

[0069] Each of the microcomputers 30A, 30B may be configured to execute current supply control by, for example, supplying a normal current to the corresponding winding group 21 even after it has been determined that the restart of the corresponding pre-driver 32 has failed.

[0070] In the control circuit 30, for example, if the first microcomputer 30A fails to restart the first pre-driver 32A, the second microcomputer 30B may also implement a fail-safe so as to stop the current control of the motor 20. This also applies to the case where the second microcomputer 30B fails to restart the second pre-driver 32B.

[0071] The power supply voltages VA, VB detected in the pre-driver abnormality detection process may be, for example, voltage values ​​downstream of the power supply ICs 31A, 31B. In this case, the power supply voltages VA, VB may be obtained by directly detecting the terminal voltages of the pre-drivers 32A, 32B. Alternatively, the power supply voltages VA, VB may be voltage values ​​upstream of the power switch 44. The power supply voltages VA, VB may be obtained by detecting the input voltages of the microcomputers 30A, 30B. In the other embodiments described herein, the threshold voltages Vth may be changed to the corresponding values.

[0072] In the pre-driver abnormality detection process, the process of step 210 may be omitted. In addition, in the pre-driver abnormality detection process, the process of step 210 may be, for example, a process of determining whether or not the first power supply voltage VA has reached the initial voltage or the nominal voltage of 12 V.

[0073] In the pre-driver abnormality detection process, the pre-driver 32 may be restarted by itself. For example, in step 204, when the first microcomputer 30A determines that the first power supply voltage VA has dropped and stops the operation of the first pre-driver 32A, the process may include a process of instructing the first pre-driver 32A not to restart. After that, in step 212, when the first microcomputer 30A determines that the first power supply voltage VA has recovered from the drop and returns the first pre-driver 32A to operation, the process may include a process of stopping the instruction not to restart to the first pre-driver 32A. In this way, the first pre-driver 32A can restart by itself on the condition that the instruction not to restart from the first microcomputer 30A is stopped.

[0074] In the pre-driver abnormality detection process, when the pre-driver 32 is restarted, the corresponding microcomputer may also be restarted. In this case, for example, the microcomputer that is restarted together with the pre-driver 32 may notify the other microcomputer of the restart, so that the other microcomputer may take measures to prevent the detection of an abnormality due to a communication interruption or the like.

[0075] In the pre-driver abnormality detection process, the process of step 210 may be a process of updating the elapsed time TA by subtracting a predetermined value at a time. In this case, the elapsed time TA may be set to the specified time Tth as an initial value. Then, in the process of step 210, it is determined whether the elapsed time TA is zero. In the other embodiments described herein, the elapsed time TA being zero corresponds to the elapse of the specified time Tth.

[0076] The inverter circuit abnormality detection process may be any process that detects an abnormality that may occur due to the operation of the pre-driver 32 being stopped. For example, the inverter circuit abnormality detection process may be modified as appropriate, such as determining whether or not an abnormality has occurred in the inverter circuit 33 based on the magnitude of the deviation in the current feedback control.

[0077] The control device 10 may be a device that configures a single current supply system. Alternatively, the control device 10 may be a device that configures three or more current supply systems. The control device 10 may share a single battery between the current supply systems 12A and 12B. Alternatively, the control device 10 may share a single microcomputer, a single pre-driver, or a single inverter circuit between the current supply systems 12A and 12B. On the other hand, the control device 10 may share a single winding group, a single pre-driver, a single inverter circuit, or a single torque sensor between the microcomputers 30A and 30B. In addition, when a single winding group is shared, a rotation angle sensor may be shared between the microcomputers 30A and 30B.

[0078] The vehicle steering system STG may include a steer-by-wire steering device. In this case, the motor device MCU is used as a drive source for a reaction mechanism or a steering mechanism in the steer-by-wire steering device. That is, the motor 20 functions as a reaction motor that generates a steering reaction force, or a steering motor that generates a steering force for steering the steered wheels T of the vehicle VC. The control device 10 controls the motor 20 as a reaction motor or a steering motor.

[0079] The motor device MCU is not limited to use in vehicles. The control device 10 of the above embodiment is effective regardless of the use of the motor device MCU in that it suppresses the occurrence of a situation in which it is not possible to return to control for operating the controlled object even if the power supply from the battery, which is the power source, decreases.

[0080] The above embodiment is not limited to a mechanically and electrically integrated type that is integrated with the motor 20, but may also be applied to a control device that is used separately from the motor 20, for example. The control device 10 of the above embodiment is not limited to controlling the operation of the motor 20, i.e., the pre-driver 32 and the inverter circuit 33, but may be applied to controlling the operation of IC chips for other purposes, for example. In other words, when the control device 10 controls the operation of the power supply IC 31, the above embodiment may be applied to the power supply IC 31. [Explanation of symbols]

[0081] 10...Control device 20...Motor (control object) 30...Control circuit 30A…First microcomputer 30B…Second microcomputer 32...Pre-driver (operation processing circuit) 32A…First pre-driver 32B…Second pre-driver 33...Inverter circuit 33A…First inverter circuit 33B…Second inverter circuit B: Vehicle battery B1…First battery B2: Second battery

Claims

1. A control device having a control circuit for controlling an operation of a control target, an operation processing circuit that executes an operation process for controlling an operation of the controlled object based on an instruction from the control circuit; The control circuit and the operation processing circuit are supplied with power for operation from a battery, The power required for the control circuit to operate is set lower than the power required for the operation processing circuit; the control circuit is configured to, when detecting a decrease in the power supply from the battery while monitoring the power supply from the battery, execute an operation stop process for instructing the operation processing circuit to stop operation before the power supply falls below a power required for the operation of the operation processing circuit; The control circuit is a control device that sets a state such that, after the operation stop processing, while the operation processing circuit is stopped, any abnormalities that may occur due to the operation processing circuit being stopped are not detected.

2. The control device according to claim 1 , wherein the control circuit, when detecting recovery from the drop in the power supply after the operation stop process, executes an operation recovery process for instructing the operation processing circuit to resume operation.

3. The control device according to claim 2 , wherein the condition for detecting recovery from the reduction in the power supply includes a condition in which the reduction in the power supply has been eliminated and continues for a specified period of time or longer.

4. The control device according to claim 3, wherein, if the operation processing circuit cannot return to operation despite having executed the operation recovery process, the control circuit detects an abnormality in the operation processing circuit and sets a state in which control that is possible without using the operation processing circuit is executed.

5. the controlled object is a motor, 5. The control device according to claim 1, wherein the operation processing circuit includes a pre-driver for controlling power supply to the motor.

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