Control system for electric vehicle

Abstract

To provide a technique capable of smoothly shifting to an evacuation traveling mode.SOLUTION: A control system includes a power control device, a first control device for outputting a first command value, and a second control device for outputting a driving signal to the power control device, on the basis of the first command value, where the second control device includes a processor, and a logic circuit; the first control device outputs a second command value to the logic circuit when an evacuation traveling mode is executed; and the logic circuit has: a first circuit structure; a second circuit structure; a third circuit structure to which a driving signal converted by the first circuit structure and a driving signal for evacuation traveling converted by the second circuit structure are input, and that alternatively outputs one of the signals; and a fourth circuit structure to which the output by the third circuit structure and an interruption command to the power control device are input, and that blocks the output by the third circuit structure while the interruption command is input.SELECTED DRAWING: Figure 1

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 (i.e., the torque command value), and a second control device that outputs an operation command value to a power control device such as an inverter according to the torque command value from the first control device. In this case, the first control device and the second control device are configured to be communicable with each other and control the motor while cooperating with each other.

[0005] In the above control system, if a failure occurs in the second control device, even if the first control device is healthy, the motor cannot be controlled. However, it is often the case that the failure that occurred in the second control device occurred in a part of the second control device, and other configurations of the second control device are still available. In such a case, it is assumed that the motor is controlled using other available configurations of the second control device to cause the electric vehicle to perform a retreat run.

[0006] Also, in the above control system, in order to safely run the electric vehicle, for example, in a situation where the electric vehicle should not be run (such as an abnormality in sensor values, etc.), a configuration is assumed in which a cutoff command for cutting off the operation command to the power control device is output. In the above control system, for example, a cutoff command is output from the first control device to the second control device. While the cutoff command is being output, even if a torque command value is output based on a user's instruction or the like, the operation command value from the second control device is cut off, so that the operation of the power control device is stopped. In order to safely run the electric vehicle, it is important that the operation command value is appropriately cut off while the cutoff command is input to the second control device.

[0007] For this reason, a configuration is assumed in which a cutoff confirmation is performed as to whether or not the operation command value from the second control device is cut off while the cutoff command is being output. In particular, it is assumed that the cutoff confirmation is performed independently in the normal running mode and the retreat running mode. In such a situation, when shifting from the normal running mode to the retreat running mode, the cutoff confirmation can be performed at that timing. In this case, there is a possibility that it takes a relatively long time to shift from the normal running mode to the retreat running mode. This specification provides a technique that can smoothly shift to the retreat running mode.

Means for Solving the Problems

[0008] This specification discloses a control system for an electric vehicle. In a first aspect, the control system includes 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, and a second control device configured to communicate 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. The second control device is configured to communicate with the first control device, and includes a processor that processes the first command value output from the first control device by a program and outputs an operation command value for the motor, and a logic circuit having a first circuit structure that converts the operation command value output from the processor into the drive signal. When an evacuation travel mode for causing the electric vehicle to perform evacuation travel is executed, the first control device outputs, to the logic circuit, a second command value based on the evacuation travel mode instead of the first command value. The logic circuit further includes a second circuit structure that converts the second command value output from the first control device into a drive signal for evacuation travel, a third circuit structure into which the drive signal converted by the first circuit structure and the drive signal for evacuation travel converted by the second circuit structure are input and which alternatively outputs one of them, and a fourth circuit structure into which an output from the third circuit structure and a cut-off command for the power control device are input and which cuts off the output from the third circuit structure while the cut-off command is input.

[0009] According to the above configuration, the logic circuit receives the drive signal converted by the first circuit structure and the drive signal for the retreat travel converted by the second circuit structure, and has a third circuit structure that alternatively outputs one of them. The output by the third circuit structure and the cutoff command for the power control device are input, and a fourth circuit structure that cuts off the output by the third circuit structure while the cutoff command is input. That is, the fourth circuit structure is provided in common for the drive signal converted by the first circuit structure and the drive signal converted by the second circuit structure. Therefore, when the retreat travel mode is executed, it is possible to shift to the retreat travel mode without checking the soundness of the fourth circuit structure. That is, it is possible to smoothly shift to the retreat travel mode.

[0010] In a second aspect, in the first aspect, the cutoff command may be output from the first control device to the logic circuit.

[0011] In a third aspect, in the first or second aspect, when the power supply of the electric vehicle is turned on, the first control device outputs the first command value or the second command value to the second control device and outputs a cutoff command to the logic circuit, and by checking that the output by the third circuit structure is cut off, the process of checking the soundness of the fourth circuit structure may be executed. According to the above configuration, the first control device can check the soundness of the fourth circuit structure in advance when the power supply of the electric vehicle is turned on.

[0012] In a fourth aspect, in any one of the first to third aspects, when the first control device detects a defect in the processor, the retreat travel mode may be executed.

[0013] In the fifth aspect, in any one of the first to fourth aspects, when the power supply of the electric vehicle is turned on and a defect in the processor is detected, the first control device outputs the second command value to the logic circuit and outputs the cutoff command to the logic circuit to confirm that the output by the third circuit structure is cut off, thereby executing a process of confirming the soundness of the fourth circuit structure. According to the above configuration, the first control device can confirm the soundness of the fourth circuit structure in advance when the power supply of the electric vehicle is turned on.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0015] (Circuit Configuration of Control System 2; FIG. 1) The control system 2 of the present embodiment is mounted on an electric vehicle (for example, a battery electric vehicle, a hybrid vehicle, a fuel cell vehicle, a plug-in hybrid vehicle, etc.) having a driving motor for driving wheels. As shown in FIG. 1, the control system 2 includes an inverter 4, a motor 6, an upper ECU (abbreviation for Electronic Control Unit) 10, and a motor ECU 20.

[0016] The inverter 4 converts the DC power output from a battery (not shown) into three-phase AC power and supplies it to the motor 6. That is, the inverter 4 is a device that adjusts the power supplied to the motor 6. The electric vehicle can travel by driving the motor 6. In addition, the inverter 4 can also convert the regenerative power (three-phase AC power) of the motor 6 into DC power and supply it to a battery (not shown). Since the specific circuit configuration of the inverter 4 is well known, a detailed description thereof will be omitted.

[0017] The upper ECU 10 outputs a torque command value indicating the target output of the motor 6 based on, for example, the accelerator opening degree. The motor ECU 20 is configured to be communicable with the upper ECU 10. The motor ECU 20 outputs a drive signal to the inverter 4 based on the torque command value output from the upper ECU 10. More specifically, when the normal driving mode for normally driving the electric vehicle is executed, the upper ECU 10 outputs a torque command value for normal driving to the microcomputer 30 of the motor ECU 20. Further, when the evacuation driving mode for evacuating the electric vehicle is executed, the upper ECU 10 outputs a torque command value for evacuation driving to the ASIC 40 of the motor ECU 20. Also, the upper ECU 10 is configured to be able to output a cut-off command for the inverter 4 to the ASIC 40.

[0018] The motor ECU 20 includes a microcomputer 30 and an ASIC (abbreviation for Application Specific Integrated Circuit) 40. The microcomputer 30 is configured to be communicable with the upper ECU 10. The microcomputer 30 processes the torque command value for normal driving output from the upper ECU 10 by a program and outputs a current command value for the motor 6. The microcomputer 30 includes, for example, a CPU (abbreviation for Central Processing Unit), and the CPU can process the torque command value for normal driving output from the upper ECU 10 by a program.

[0019] The ASIC 40 is configured to be communicable with the upper ECU 10 and the microcomputer 30. In particular, the ASIC 40 is configured to be communicable with the upper ECU 10 without going through the microcomputer 30.

[0020] The ASIC 40 has a circuit structure for controlling the motor 6. For example, the ASIC 40 includes some or all of the hardware parts specialized for motor control, such as a resolver digital converter, an analog-to-digital converter, and a motor IP. More specifically, the ASIC 40 includes a first circuit structure 42, a second circuit structure 44, a third circuit structure 46, and a fourth circuit structure 48. Although not shown in the figure, the ASIC 40 also includes a circuit structure for detecting a malfunction of the microcomputer 30.

[0021] The first circuit structure 42 is a circuit that receives the current command value output from the microcomputer 30 and converts the current command value into a drive signal. The second circuit structure 44 is a circuit that receives the torque command value for evacuation travel output from the upper ECU 10 and converts the torque command value for evacuation travel into a drive signal.

[0022] The third circuit structure 46 is a circuit that receives the drive signal converted by the first circuit structure 42 and the drive signal converted by the second circuit structure 44, and selectively outputs one of them. For example, the third circuit structure 46 receives whether the microcomputer 30 has a malfunction from a circuit structure for detecting a malfunction of the microcomputer 30. When the microcomputer 30 does not have a malfunction, the drive signal converted by the first circuit structure 42 is output, and when the microcomputer 30 has a malfunction, the drive signal converted by the second circuit structure 44 is output.

[0023] The fourth circuit structure 48 is configured to receive the output from the third circuit structure 46 and the output from the upper ECU 10, and block the output from the third circuit structure 46 while a shut-off command is input. That is, while the shut-off command is output from the upper ECU 10, no drive signal is output to the inverter 4, so the operation of the inverter 4 stops.

[0024] Note that the upper ECU 10 is also configured to be able to detect that the microcomputer 30 has failed. For example, the upper ECU 10 may transmit a signal to the microcomputer 30 at regular intervals and detect a failure of the microcomputer 30 when it does not receive a response to the signal.

[0025] As described above, the control system 2 of this embodiment controls the inverter 4 while the upper ECU 10 and the motor ECU 20 (i.e., the microcomputer 30 and the ASIC 40) cooperate with each other. Specifically, first, the upper ECU 10 outputs a torque command value that is the target output of the motor 6 based on the accelerator opening degree or the like to the microcomputer 30. The microcomputer 30 processes the torque command value by a program and outputs a current command value for the motor 6 to the ASIC 40. The ASIC 40 converts the current command value into a drive signal.

[0026] In such a control system 2, assume a situation where a failure occurs in a part of the motor ECU 20 (specifically, the microcomputer 30). In such a situation, the torque command value output from the upper ECU 10 is not acquired by the microcomputer 30. For this reason, the ASIC 40 cannot acquire the current command value from the microcomputer 30 and thus cannot output a drive signal. That is, normally, when the microcomputer 30 fails in such a control system 2, the control system 2 cannot run the electric vehicle.

[0027] Therefore, in the control system 2 of this embodiment, when the upper ECU 10 detects a failure of the microcomputer 30, it shifts to the evacuation running mode. In the evacuation running mode, instead of outputting the torque command value to the microcomputer 30, the upper ECU 10 outputs a torque command value for evacuation running to the second circuit structure 44 of the ASIC 40. Also, as described above, when the ASIC 40 detects a failure of the microcomputer 30, the third circuit structure 46 outputs the output from the second circuit structure 44. In this way, even when a failure of the microcomputer 30 is detected, the electric vehicle can be made to run in evacuation.

[0028] In particular, the ASIC 40 of this embodiment includes a fourth circuit structure 48 at the final stage of the ASIC 40. The drive signal converted by the first circuit structure 42 and the drive signal converted by the second circuit structure 44 are alternatively input to the fourth circuit structure 48. That is, in the configuration of this embodiment, the cutoff command for the inverter 4 is commonly given to the drive signal converted by the first circuit structure 42 (i.e., the drive signal for normal running) and the drive signal converted by the second circuit structure 44 (i.e., the drive signal for evacuation running).

[0029] Here, assume a comparative example in which the cutoff command for the inverter 4 is given independently to the signal for normal running and the drive signal for evacuation running. In this comparative example, first, at the start of the electric vehicle when the microcomputer 30 has not failed (i.e., at the start of the upper ECU 10), a cutoff confirmation for the drive signal for normal running is executed. Then, when a failure of the microcomputer 30 is detected, a cutoff confirmation for the drive signal for evacuation running is executed. Thus, in the comparative example, when shifting from the normal running mode to the evacuation running mode, a cutoff confirmation for the drive signal for evacuation running is executed. If this cutoff confirmation takes time, the shift from the normal running mode to the evacuation running mode cannot be performed smoothly. As a result, there is a possibility that the convenience for the user is reduced.

[0030] On the other hand, in the configuration of this embodiment, the cutoff command for the inverter 4 is commonly given to the drive signal for normal running and the drive signal for evacuation running. Therefore, if a cutoff confirmation is executed at the start of the electric vehicle (i.e., at the start of the upper ECU 10) to confirm the soundness of the fourth circuit structure 48, the electric vehicle can be appropriately run in both the normal running mode and the evacuation running mode. In particular, since it is not necessary to execute the cutoff confirmation again when shifting from the normal running mode to the evacuation running mode, a smooth shift to the evacuation running mode can be achieved. For this reason, the convenience for the user is improved.

[0031] (Processing of the upper ECU 10; Figure 2) Next, referring to FIG. 2, the processes executed by the upper ECU 10 will be described. The process in FIG. 2 is triggered and started by turning on the switch of the upper ECU 10 in response to turning on the switch of the electric vehicle.

[0032] In S10 of FIG. 2, the upper ECU 10 determines whether the microcomputer 30 has failed. For example, as described above, when the upper ECU 10 transmits a signal to the microcomputer 30 and receives a response to the signal, the upper ECU 10 determines that the microcomputer 30 has not failed (NO in S10) and proceeds to S20. On the other hand, when the upper ECU 10 transmits a signal to the microcomputer 30 and does not receive a response to the signal, the upper ECU 10 determines that the microcomputer 30 has failed (YES in S10) and proceeds to S30.

[0033] In S20, the upper ECU 10 executes a cutoff confirmation to check whether the fourth circuit structure 48 of the ASIC 40 is sound (that is, whether the output of the third circuit structure 46 can be appropriately cut off in response to the cutoff command of the upper ECU 10). Specifically, the upper ECU 10 first outputs a torque command value for normal driving to the microcomputer 30 and outputs a cutoff command to the fourth circuit structure 48. At the stage of S20, since the microcomputer 30 has not failed (NO in S10), the microcomputer 30 processes the acquired torque command value by a program and outputs a current command value to the first circuit structure 42 of the ASIC 40. The first circuit structure 42 converts the acquired current command value into a drive signal and outputs it to the third circuit structure 46. Also, at the stage of S10, since the microcomputer 30 has not failed, the third circuit structure 46 outputs the drive signal converted by the first circuit structure 42. Therefore, the drive signal converted by the first circuit structure 42 and the cutoff command are input to the fourth circuit structure 48.

[0034] As described above, while a cutoff command is input, the fourth circuit structure 48 cuts off the output from the third circuit structure 46. Therefore, if the fourth circuit structure 48 is healthy, the output of the third circuit structure 46 (i.e., the drive signal for normal driving) is cut off. The upper ECU 10 confirms that the drive signal for normal driving is cut off. Note that, if an abnormality has occurred in the fourth circuit structure 48, the drive signal for normal driving may not be cut off even though a cutoff command has been input from the upper ECU 10. In this case, although not shown in the figure, the upper ECU 10 may determine that it is impossible to drive the electric vehicle and turn off the switch of the electric vehicle.

[0035] In this embodiment, the upper ECU 10 outputs only the torque command value for normal driving. In addition to or instead of this, the torque command value for evacuation driving may be output to the second circuit structure 44 of the ASIC 40.

[0036] In S30, the upper ECU 10 performs a cutoff confirmation. Specifically, the upper ECU 10 first outputs the torque command value for evacuation driving to the second circuit structure 44 of the ASIC 40 and outputs a cutoff command to the fourth circuit structure 48. The second circuit structure 44 converts the acquired torque command value into a drive signal for evacuation driving and outputs it to the third circuit structure 46. Also, at the stage of S30, since the microcomputer 30 has failed, the third circuit structure 46 outputs the drive signal for evacuation driving converted by the second circuit structure 44. Therefore, the fourth circuit structure 48 receives the drive signal for evacuation driving converted by the second circuit structure 44 and the cutoff command. Except for the fact that the output of the third circuit structure 46 is the drive signal for evacuation driving converted by the second circuit structure 44, the subsequent processing is the same as the processing of S20.

[0037] In S40, the upper ECU 10 starts control in the normal driving mode. That is, the upper ECU 10 starts the process of outputting a torque command value to the microcomputer 30 based on an instruction from the user such as the accelerator opening. The processing of S42 is the same as the processing of S10.

[0038] In S50, the upper ECU 10 starts control in the evacuation driving mode. That is, the upper ECU 10 starts the process of outputting a torque command value for evacuation driving to the second circuit structure 44 of the ASIC 40 based on an instruction from the user such as the accelerator opening degree.

[0039] As described above, according to the configuration of this embodiment, when starting the electric vehicle (i.e., when starting the upper ECU 10), if the upper ECU 10 performs a disconnection check to confirm the soundness of the fourth circuit structure 48, the electric vehicle can be appropriately driven in both the normal driving mode and the evacuation driving mode. Therefore, it is not necessary to execute the disconnection check again when shifting from the normal driving mode to the evacuation driving mode, so the shift to the evacuation driving mode can be made smoothly. As a result, the convenience for the user is improved.

[0040] 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 30 and the ASIC 40 are examples of the "processor" and the "logic circuit" of the present technology, respectively. The inverter 4 is an example of the "power control device" of the present technology. The torque command value output from the upper ECU 10 to the microcomputer 30 and the torque command value output from the upper ECU 10 to the ASIC 40 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 30 to the ASIC 40 is an example of the "operation command value" of the present technology.

[0041] A modification of the above embodiment will be described. The upper ECU 10 can omit the processes of S10 and S30. In this case, when the switch of the electric vehicle is turned on, the upper ECU 10 may execute the disconnection check by outputting at least one of the torque command value for normal driving and the torque command value for evacuation driving and the disconnection command in S20.

[0042] 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 of the specific examples exemplified 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 exemplified in this specification or the drawings can achieve multiple purposes simultaneously, and achieving one of those purposes itself has technical utility.

Description of Reference Numerals

[0043] 2: Control system, 4: Inverter, 6: Motor, 10: Upper ECU, 20: Motor ECU, 30: Microcomputer, 40: ASIC, 42: First circuit structure, 44: Second circuit structure, 46: Third circuit structure, 48: Fourth circuit structure

Claims

1. A control system for an electric vehicle, comprising: 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 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, process the first command value output from the first control device by a program, and output an operation command value for the motor; a logic circuit having a first circuit structure that converts the operation command value output from the processor into the drive signal; wherein when a retreat running mode for causing the electric vehicle to perform retreat running is executed, the first control device outputs, instead of the first command value, a second command value based on the retreat running mode to the logic circuit; the logic circuit further comprises: a second circuit structure that converts the second command value output from the first control device into a drive signal for retreat running; a third circuit structure into which the drive signal converted by the first circuit structure and the drive signal for retreat running converted by the second circuit structure are input, and one of them is selectively output; a fourth circuit structure into which the output by the third circuit structure and a cutoff command for the power control device are input, and the output by the third circuit structure is cut off while the cutoff command is input; and the control system has the above structures.

2. The control system according to claim 1, wherein the cutoff command is output from the first control device to the logic circuit.

3. The control system according to claim 1, wherein when the power supply of the electric vehicle is turned on, the first control device outputs the first command value or the second command value to the second control device, and outputs the cutoff command to the logic circuit, and executes a process of confirming the soundness of the fourth circuit structure by confirming that the output by the third circuit structure is cut off.

4. The control system according to claim 1, wherein when the first control device detects a defect in the processor, the first control device executes the retreat running mode.

5. ​ ​ The control system according to claim 1, wherein when the power supply of the electric vehicle is turned on and a defect in the processor is detected, the first control device outputs the second command value to the logic circuit and outputs the cutoff command to the logic circuit to confirm that the output by the third circuit structure is cutoff, thereby executing a process of confirming the soundness of the fourth circuit structure.

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