Control System for Electric Vehicles

Abstract

To provide a technique capable of traveling an electric vehicle, when detecting defects of a processor when the electric vehicle is started.SOLUTION: A control system may include a first control device for outputting a first command value indicating target output of a motor, and a second control device for outputting a drive signal to an electric control device, on the basis of the first command value. The second control device may include a processor for processing the first command value by a program, and outputting an operation command value to the motor, and a logic circuit having a circuit structure for converting the operation command value into the drive signal while monitoring a state index indicating a state of the power control device. The first control device determines whether execution of an evacuation traveling mode is possible on the basis of the state index, when detecting defects of the processor when an electric vehicle is started, and may output a second command value based on the evacuation traveling mode to the logic circuit instead of the first command value, when determining that the execution of the evacuation traveling mode is possible.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to a control system for an electric vehicle.

Background Art

[0002] Patent Document 1 discloses an electric vehicle. This electric vehicle is a hybrid vehicle and has a control system for controlling two motors. Note that the electric vehicle in this specification broadly means a vehicle having a driving motor for driving wheels. For example, electric vehicles include battery electric vehicles, fuel cell vehicles, plug-in hybrid vehicles, etc. in addition to hybrid vehicles.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This type of control system is often composed of a plurality of control devices. For example, the control system may include a first control device that determines the target output of the motor, and a second control device that gives an operation command to a power control device such as an inverter according to a command from the first control device. In this case, the first control device and the second control device are configured to be able to communicate with each other and control the motor while cooperating with each other.

[0005] In the above control system, when a failure occurs in the second control device, even if the first control device is sound, the motor cannot be controlled. However, the failure that occurs in the second control device often occurs in a part of the configuration of the second control device, and other configurations of the second control device are still available.

[0006] As described above, when a defect occurs in a part of the second control device, it is desirable to control the motor with a limited configuration. This specification provides a technique for driving an electric vehicle when a defect in a part of the second control device is detected at the start of the electric vehicle.

Means for Solving the Problems

[0007] This specification is embodied in a control system for an electric vehicle. In a first aspect, the control system may include a power control device that adjusts the power supplied to the motor of the electric vehicle, a first control device that outputs a first command value indicating the target output of the motor, and a second control device that is configured to communicate with the first control device and outputs a drive signal to the power control device based on the first command value output from the first control device. The second control device may include a processor that is configured to communicate with the first control device, processes the first command value output from the first control device, and outputs an operation command value for the motor, and a logic circuit that has a circuit structure for converting the operation command value output from the processor into the drive signal while monitoring a state index indicating the state of the power control device. The logic circuit may be configured to communicate with the first control device without passing through the processor and may be configured to output the state index to the first control device. When the first control device detects a defect in the processor at the start of the electric vehicle, the first control device determines whether it is possible to execute an evacuation driving mode in which the electric vehicle is driven in evacuation based on the state index output from the logic circuit. If it is determined that the execution of the evacuation driving mode is possible, instead of the first command value, a second command value based on the evacuation driving mode may be output to the logic circuit.

[0008] According to the above configuration, when the first control device detects a defect in the processor at the start of the electric vehicle, it determines whether it is possible to execute an evacuation driving mode in which the electric vehicle is driven to evacuate based on the state indicator output from the logic circuit. Then, when the first control device determines that it is possible to execute the evacuation driving mode, it outputs a second command value based on the evacuation driving mode to the logic circuit instead of the first command value. Therefore, the control system can drive the electric vehicle when a defect in the processor is detected at the start of the electric vehicle.

[0009] In a second aspect, in the first aspect, the power control device may include an inverter.

[0010] In a third aspect, in the first aspect or the second aspect, the state indicator may be at least one of the temperature of the power control device, the current value of the current output by the power control device, and the power supply state of the control board of the power control device.

[0011] In a fourth aspect, in any one of the first aspect to the third aspect, the first command value may be a torque command value indicating the torque that the motor should output. Additionally, or alternatively, the operation command value may be a current command value indicating the current that the power control device should supply to the motor.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] (Circuit Configuration of Control System 2; Figure 1) The control system 2 of this embodiment is mounted on an electric vehicle (e.g., electric car, hybrid vehicle, plug-in hybrid vehicle, fuel cell vehicle, etc.) having a running motor that drives wheels. As shown in FIG. 1, the control system 2 includes a host ECU (abbreviation of Electronic Control Unit) 10, a motor ECU 20, two inverters 32a and 32b, and two running motors 34a and 34b.

[0014] The host ECU 10 outputs a torque command value indicating the target output of each of the motors 34a and 34b, for example, based on the accelerator opening degree or the like. The motor ECU 20 is configured to be communicable with the host ECU 10. The motor ECU 20 outputs a drive signal to the inverters 32a and 32b based on the torque command value output from the host ECU 10.

[0015] The motor ECU 20 includes a microcomputer 22 and an ASIC (abbreviation of Application Specific Integrated Circuit) 24. The microcomputer 22 is configured to be communicable with the host ECU 10. The microcomputer 22 processes the torque command value output from the host ECU 10 by a program and outputs a current command value for the motors 34a and 34b. The microcomputer 22 includes, for example, a CPU (abbreviation of Central Processing Unit), and the CPU can process the torque command value output from the host ECU 10 by a program.

[0016] The ASIC 24 has a circuit structure that converts the current command value output from the microcomputer 22 into a drive signal. In particular, the above circuit structure of the ASIC 24 is a circuit structure for controlling the motors 34a and 34b, and includes, for example, a resolver digital converter that converts the rotation angle from the angle sensors 38a and 38b described later into a digital value. The ASIC 24 converts the current command value into a drive signal using the above rotation angle or the like. Although not shown in the figure, the microcomputer 22 and the ASIC 24 are configured to be communicable with each other.

[0017] The inverters 32a and 32b convert the DC power output from a battery (not shown) into three-phase AC power and supply it to the motors 34a and 34b. That is, each of the inverters 32a and 32b is a device that adjusts the power supplied to the motors 34a and 34b. The electric vehicle can run when the motors 34a and 34b are driven. Note that the inverters 32a and 32b can also convert the regenerative power (three-phase AC power) of each motor 34a and 34b into DC power and supply it to a battery (not shown). Since the specific circuit configurations of the inverters 32a and 32b are well known, detailed descriptions thereof are omitted.

[0018] Current sensors 36a and 36b are respectively connected to the inverters 32a and 32b. The current sensors 36a and 36b are sensors that respectively detect the current values of the output currents of the inverters 32a and 32b (that is, the currents supplied to the motors 34a and 34b). The current values detected by the current sensors 36a and 36b are output to the ASIC 24.

[0019] Angle sensors 38a and 38b are respectively connected to the motors 34a and 34b. The angle sensors 38a and 38b are, for example, resolvers. The angle sensors 38a and 38b respectively detect the rotational angles of the (rotors) of the motors 34a and 34b. The rotational angles detected by the angle sensors 38a and 38b are input to the ASIC 24.

[0020] The ASIC 24 is further configured to be communicable with the upper ECU 10 without going through the microcomputer 22. The ASIC 24 is configured to repeatedly output (for example, every time a predetermined time elapses) a state index indicating the state of the inverters 32a and 32b, such as the current values detected by the current sensors 36a and 36b. The state index includes, in addition to the current value, the temperature of the inverters 32a and 32b, the power supply state of the control boards of the inverters 32a and 32b, and the like. In this embodiment, the state index is used by the upper ECU 10 in determining whether the evacuation driving mode described later can be executed.

[0021] As described above, in the control system 2 of this embodiment, the host ECU 10 and the motor ECU 20 (i.e., the microcomputer 22 and the ASIC 24) cooperate with each other to control the inverters 32a, 32b, etc. Specifically, first, the host ECU 10 outputs a torque command value, which is the target output of the motors 34a, 34b based on the accelerator opening degree, etc., to the microcomputer 22. The microcomputer 22 processes the torque command value by a program and outputs a current command value for the motors 34a, 34b to the ASIC 24. The ASIC 24 converts the current command value into a drive signal.

[0022] In such a control system 2, assume a situation where a failure occurs in a part of the motor ECU 20 (specifically, the microcomputer 22). In such a situation, the torque command value output from the host ECU 10 is not acquired by the microcomputer 22. Therefore, the ASIC 24 cannot acquire the current command value from the microcomputer 22 and thus cannot output a drive signal. That is, normally, when the microcomputer 22 fails in such a control system 2, the control system 2 cannot drive the electric vehicle.

[0023] Therefore, in the control system 2 of this embodiment, when the host ECU 10 detects a failure of the microcomputer 22 at the start of the electric vehicle, it determines whether it is possible to execute an evacuation driving mode in which the electric vehicle is driven for evacuation based on the state index output from the ASIC 24. Then, when the host ECU 10 determines that the execution of the evacuation driving mode is possible, it outputs a torque command value based on the evacuation driving mode to the ASIC 24 instead of the microcomputer 22. The ASIC 24 has a control logic (i.e., circuit structure) for driving the electric vehicle for evacuation. That is, the ASIC 24 also has a circuit structure for converting the torque command value output from the host ECU 10 into a drive signal. As a result, even if a failure of the microcomputer 22 is detected at the start of the electric vehicle, the electric vehicle can be driven for evacuation. The detailed processing will be described with reference to FIGS. 2 and 3 below.

[0024] (Specific processing; FIGS. 2 and 3) Next, with reference to FIGS. 2 and 3, the specific processing of this embodiment will be described. The initial state in FIG. 2 is that the microcomputer 22 of the motor ECU 20 has failed. FIG. 2 assumes a situation where the electric vehicle is started with the microcomputer 22 failed.

[0025] In S10 of FIG. 2, the host ECU 10 receives a switch-on operation from the user to start the electric vehicle (S10 in FIG. 2). In this case, the host ECU 10 attempts to execute a startup check process with the microcomputer 22. The startup check process is a process for confirming whether the electric vehicle can run in the normal driving mode. However, in this case, since the microcomputer 22 has failed, the startup check process cannot be properly executed. Accordingly, in S12, the host ECU 10 detects the failure of the microcomputer 22.

[0026] Although not shown, when the host ECU 10 detects the failure of the microcomputer 22 in S12, it sends a shutdown request to the ASIC 24. This is because, since the microcomputer 22 has failed, the microcomputer 22 and the ASIC 24 cannot cooperate to control the motors 34a and 34b (that is, the electric vehicle cannot run in the normal driving mode). When the ASIC 24 receives the shutdown request, it shuts down the circuit for outputting the drive signals to the inverters 32a and 32b.

[0027] As described above, the ASIC 24 is configured to output the status indicator to the host ECU 10. In S14, the ASIC 24 sends the status indicator to the host ECU 10. In a modified example, when the host ECU 10 detects the failure of the microcomputer 22, it may send a status indicator transmission request to the ASIC 24. And when the ASIC 24 receives the transmission request from the host ECU 10, it may send the status indicator to the host ECU 10 in S14. Also, in addition to the status indicator, the ASIC 24 may send other information such as the temperature of components of the electric vehicle, such as the transaxle and the motor, to the host ECU 10.

[0028] When the upper ECU 10 receives the status indicator from the ASIC 24 in S16, in S20, based on the status indicator (i.e., current value, temperature, power state of the inverter), it determines whether an abnormality has occurred in each of the inverters 32a and 32b. For example, when the temperature of at least one of the inverters 32a and 32b is higher than the threshold temperature, it is detected that an abnormality has occurred in the corresponding inverter. When an abnormality is detected, the upper ECU 10 determines that it is impossible to execute the evacuation driving mode (YES in S20), proceeds to S22, and turns off the switch of the electric vehicle. This is because it is not preferable to drive the electric vehicle in a situation where an abnormality is detected. On the other hand, when the upper ECU 10 does not detect an abnormality, it determines that it is possible to execute the evacuation driving mode (NO in S20) and proceeds to S30.

[0029] In S30, the upper ECU 10 transitions to the evacuation driving mode preparation state. The evacuation driving mode preparation state is a mode in which various processes are executed between the upper ECU 10 and the ASIC 24 in order to transition the operation mode of the upper ECU 10 from the normal driving mode to the evacuation driving mode. Various processes executed between the upper ECU 10 and the ASIC 24 in order to transition to the evacuation driving mode will be described later with reference to FIG. 3.

[0030] (Continuation of FIG. 2; FIG. 3) When the upper ECU 10 transitions to the evacuation driving mode preparation state in S30 of FIG. 2, in S32 of FIG. 3, it transmits a request to transition to the evacuation driving mode to the ASIC 24. The request to transition to the evacuation driving mode is a signal for requesting the ASIC 24 to transition the state of the ASIC 24 to the evacuation driving mode.

[0031] When the ASIC 24 receives a retreat driving mode transition request from the upper ECU 10 at S34, it transitions to the retreat driving mode at S36 and transmits a retreat driving mode state indicating that the ASIC 24 has transitioned to the retreat driving mode to the upper ECU 10 at S38. The ASIC 24 is configured to convert the torque command value output from the upper ECU 10 into a drive signal in the retreat driving mode. In particular, in the retreat driving mode, the output is restricted compared to the normal driving mode.

[0032] Also, after transmitting a retreat driving mode transition request to the ASIC 24 at S32, the upper ECU 10 determines at S42 whether the ASIC 24 has transitioned to the retreat driving mode. Specifically, the upper ECU 10 determines whether it has received the retreat driving mode state from the ASIC 24. When the upper ECU 10 has received the retreat driving mode state from the ASIC 24, it determines that the ASIC 24 has transitioned to the retreat driving mode (YES at S42) and proceeds to S50. On the other hand, when the upper ECU 10 has not received the retreat driving mode state from the ASIC 24, it determines that the ASIC 24 has not transitioned to the retreat driving mode (NO at S42) and executes the process of S32 again. For example, when the retreat driving mode transition request is not properly transmitted from the upper ECU 10 to the ASIC 24, or when there is a relatively long time lag from when the retreat driving mode transition request is transmitted until the retreat driving mode state is received, it may be determined as NO at S42.

[0033] The upper ECU 10 transmits a shutdown release request to the ASIC 24 at S50. As described above, the upper ECU 10 has already transmitted a shutdown request to the ASIC 24 due to the failure of the microcomputer 22. However, in this case, even if the microcomputer 22 has failed, the electric vehicle can be retreated in the retreat driving mode. Therefore, the upper ECU 10 transmits a shutdown release request to the ASIC 24 in order to retreat the electric vehicle in the retreat driving mode.

[0034] When the ASIC 24 receives a shutdown release request from the upper ECU 10 at S52, it releases the shutdown at S54. That is, the ASIC 24 releases the shutdown of the circuit for outputting drive signals to the inverters 32a and 32b. For this reason, the ASIC 24 becomes in a state where it can output drive signals based on the retreat running mode to the inverters 32a and 32b.

[0035] Also, at S56, the ASIC 24 transmits a shutdown release state indicating that the ASIC 24 has released the shutdown to the upper ECU 10.

[0036] Also, after transmitting a shutdown release request to the ASIC 24 at S50, the upper ECU 10 determines at S60 whether the ASIC 24 has completed releasing the shutdown. Specifically, the upper ECU 10 determines whether it has received a shutdown release state from the ASIC 24. When the upper ECU 10 has received a shutdown release state from the ASIC 24, it determines that the ASIC 24 has completed releasing the shutdown (YES at S60) and proceeds to S62. On the other hand, when the upper ECU 10 has not received a shutdown release state from the ASIC 24, it determines that the ASIC 24 has not completed releasing the shutdown (NO at S60) and executes the process of S50 again. For example, when the shutdown release request is not properly transmitted from the upper ECU 10 to the ASIC 24, or when there is a relatively long time lag from when the shutdown release request is transmitted until the shutdown release state is received, it may be determined as NO at S60.

[0037] The upper ECU 10 shifts to the evacuation driving mode in S62. In the evacuation driving mode, the upper limit value of the torque command value is set lower than that in the normal driving mode. When the upper ECU 10 shifts to the evacuation driving mode, it outputs a torque command value based on the evacuation driving mode to the ASIC 24 instead of the microcomputer 22 based on the accelerator opening degree or the like. As a result, the ASIC 24 converts the torque command value output from the upper ECU 10 into a drive signal and supplies it to the inverters 32a and 32b. As a result, even when the microcomputer 22 of the motor ECU 20 has failed, the electric vehicle can be driven in the evacuation driving mode.

[0038] According to the configuration of this embodiment, when the upper ECU 10 detects a failure of the microcomputer 22 of the motor ECU 20 at the start of the electric vehicle, it determines whether it is possible to execute the evacuation driving mode in which the electric vehicle is driven in evacuation based on the state indicator (S14 in FIG. 2) output from the ASIC 24 (S20). Then, when the upper ECU 10 determines that the execution of the evacuation driving mode is possible, it outputs a torque command value based on the evacuation driving mode to the ASIC 24 instead of the torque command value output from the upper ECU 10 to the microcomputer 22. Therefore, the control system 2 can drive the electric vehicle when a failure of the microcomputer 22 is detected at the start of the electric vehicle.

[0039] The upper ECU 10 and the motor ECU 20 are examples of the "first control device" and the "second control device" of the present technology, respectively. The microcomputer 22 and the ASIC 24 are examples of the "processor" and the "logic circuit" of the present technology, respectively. The inverters 32a and 32b are examples of the "power control device" of the present technology. The torque command value output from the upper ECU 10 to the microcomputer 22 and the torque command value output from the upper ECU 10 to the ASIC 24 are examples of the "first command value" and the "second command value" of the present technology, respectively. The current command value output from the microcomputer 22 to the ASIC 24 is an example of the "operation command value" of the present technology.

[0040] Modifications of the above embodiments are described below. The processes of S38, S40, S56, and S58 in FIG. 3 can be omitted. As described above, the ASIC 24 repeatedly outputs the status indicators to the upper ECU 10. The ASIC 24 may transmit, to the upper ECU 10, information (such as the output upper limit value of the ASIC 24) that enables the upper ECU 10 to determine its own status (for example, the standby driving mode state, the shutdown release state) together with the status indicators. The upper ECU 10 may execute processes such as S42 and S60 based on this information.

[0041] In the control system 2 of this embodiment, the upper ECU 10 is configured to output a torque command value to the motor ECU 20. The torque command value in this embodiment is an example of a first command value indicating the target output of the motors 34a and 34b. However, in other embodiments, the upper ECU 10 may output, as the first command value, another indicator indicating the target output of the motors 34a and 34b to the motor ECU 20 instead of the torque command value.

[0042] In the control system 2 of this embodiment, the microcomputer 22 of the motor ECU 20 is programmed to output a current command value to the ASIC 24 based on the torque command value (or another first command value). However, the current command value in this embodiment is an example of an operation command value for the motors 34a and 34b and does not limit the operation command value. In other embodiments, the microcomputer 22 may be programmed to determine another operation command value for the motors 34a and 34b based on the torque command value (or another first command value) and output it to the ASIC 24.

[0043] As described above, specific examples of the technology disclosed in this specification have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of these purposes itself has technical utility.

Description of Reference Numerals

[0044] 2: Control system 10: Host ECU 20: Motor ECU 22: Microcomputer 24: ASIC 32a, 32b: Inverter 34a, 34b: Motor 36a, 36b: Current sensor 38a, 38b: Angle sensor

Claims

1. A control system for an electric vehicle, comprising: a power control device that adjusts the power supplied to a motor of the electric vehicle; a first control device that outputs a first command value indicating a target output of the motor; a second control device configured to be communicable with the first control device and output a drive signal to the power control device based on the first command value output from the first control device; wherein the second control device comprises: a processor configured to be communicable with the first control device and process the first command value output from the first control device by a program to output an operation command value for the motor; a logic circuit having a circuit structure that monitors a state index indicating a state of the power control device and converts the operation command value output from the processor into the drive signal; wherein the logic circuit is configured to be communicable with the first control device without passing through the processor and output the state index to the first control device; wherein the first control device, when detecting a defect in the processor at startup of the electric vehicle, determines whether it is possible to execute an evacuation travel mode for causing the electric vehicle to perform an evacuation travel based on the state index output from the logic circuit; and when determining that it is possible to execute the evacuation travel mode, outputs a second command value based on the evacuation travel mode to the logic circuit instead of the first command value. A control system.

2. The control system according to claim 1, wherein the power control device includes an inverter.

3. The control system according to claim 1, wherein the state index is at least one of a temperature of the power control device, a current value of a current output by the power control device, and a power supply state of a control board of the power control device.

4. The control system according to claim 1, wherein the first command value is a torque command value indicating a torque to be output by the motor, and the operation command value is a current command value indicating a current to be supplied by the power control device to the motor. ​ ​ ​

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