Control device for electric vehicles

Abstract

Provided is an electric vehicle control device capable of determining that an electric vehicle is being towed regardless of the factors involved in the towing. This electric vehicle control device is a control device mounted in an electric vehicle that includes: driving wheels; a travel motor for driving the driving wheels; an inverter for driving the travel motor; and a gearshift operation unit capable of switching a gearshift position. The control device includes: a front detector capable of detecting a distance to a vehicle in front of the vehicle body; and a controller for determining whether or not the electric vehicle is being towed. The controller determines that the electric vehicle is being towed on the basis of the fact that the gearshift position is neutral and that a change in the distance detected by the front detector is equal to or less than a change threshold.

Description

Technical Field

[0001] The present invention relates to a control device for an electric vehicle.

Background Art

[0002] Patent Document 1 describes that in an electric vehicle, when the shift position is in the N range and a short-circuited faulty element exists in the inverter, the ECU (Electronic Control Unit) determines that the vehicle is in coasting.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When an electric vehicle is towed, torque is transmitted from the tires to the drive motor, and an induced electromotive force is generated as the drive motor rotates. Therefore, it is desirable for the control device of the electric vehicle to determine that the vehicle is being towed when it is being towed and perform control to handle the induced electromotive force. On the other hand, for ordinary users, the frequency of towing is low. Therefore, it is difficult to require a special operation from the user when the electric vehicle is towed. Therefore, it is difficult to adopt means such as determining that the vehicle is being towed by the special operation.

[0005] In the above conventional technology, the ECU can only determine towing caused by a failure of the inverter.

[0006] An object of the present invention is to provide a control device for an electric vehicle that can determine whether the electric vehicle is being towed regardless of the cause of the towing.

Means for Solving the Problems

[0007] The control device for electric vehicles according to the present invention is A control device mounted on an electric vehicle comprising drive wheels, a drive motor for driving the drive wheels, an inverter for driving the drive motor, and a shift operation unit capable of switching the shift position, A forward-facing detector capable of detecting the distance to a vehicle in front of the vehicle, A controller for determining whether the electric vehicle is being towed, Equipped with, The controller determines that the electric vehicle is being towed based on the fact that the shift position is set to neutral and the change in distance detected by the forward detector is below a change threshold. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a control device for electric vehicles that can determine whether an electric vehicle is being towed, regardless of the cause. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing an electric vehicle equipped with a control device according to an embodiment of the present invention. [Figure 2] This is a side view showing an electric vehicle being towed. [Figure 3] This flowchart shows the steps of the traction control process performed by the controller. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will now be described in detail with reference to the drawings. Figure 1 is a block diagram showing an electric vehicle 1 equipped with a control device 40 according to an embodiment of the present invention. The control device 40 of this embodiment is mounted on the electric vehicle 1. The electric vehicle 1 includes drive wheels 2, a drive motor 3 that drives the drive wheels 2, a battery 4 that stores power to drive the drive motor 3, an inverter 5 that drives the drive motor 3, a shift operation unit 6 that can switch the shift position, an operation unit 7 that allows the driver to operate the vehicle, and a power switch 8 that switches the power state of the electric vehicle 1 system.

[0011] The driving motor 3 is a motor, such as a synchronous motor, in which permanent magnets are incorporated into a rotating rotor. The inverter 5 converts power between the driving motor 3 and the battery 4. The driving control unit 7 includes a steering unit 7a, such as a steering wheel, a braking control unit 7b, such as a brake pedal, and an acceleration control unit 7c, such as an acceleration pedal. The electric vehicle 1 does not have a mechanism (such as a clutch) to interrupt power transmission in the power transmission path from the rotor of the driving motor 3 to the drive wheels 2. With this configuration, when the drive wheels 2 rotate, the rotor of the driving motor 3 also rotates.

[0012] The control device 40 includes a vehicle speed sensor 41 for detecting vehicle speed, a forward detector 42 for detecting the distance to a vehicle in front of the vehicle, and a controller 43 for controlling the movement of the electric vehicle 1. The control device 40 may further include a communication device 44 to which information is sent from the towing vehicle 51 (see Figure 2) when being towed.

[0013] The vehicle speed sensor 41 is a sensor that detects the rotational speed of the drive wheels 2 or driven wheels, but any configuration that can detect vehicle speed is acceptable, such as a configuration that determines vehicle speed from measurements of a positioning system such as the Global Navigation Satellite System.

[0014] The forward detection device 42 includes a measuring device 42a such as a camera and distance sensor, a compound camera, or a distance sensor capable of two-dimensional scanning, and a computing device 42b that analyzes the measurement results of the measuring device 42a to determine whether or not a vehicle is positioned in front of the vehicle. The computing device 42b is a microcomputer, and another ECU (Electronic Control Unit) mounted on the electric vehicle 1 may also serve as the computing device 42b. If the measuring device 42a includes a distance sensor, various distance sensors such as LiDAR (Light Detection And Ranging) and ultrasonic sensors can be applied as the distance sensor.

[0015] The controller 43 is a microcomputer such as an ECU and operates according to a control program stored in the memory unit 43a. The controller 43 drives the drive motor 3 by controlling the inverter 5 based on the operation signals from the shift operation unit 6 and the operation signals from the driving operation unit 7.

[0016] The controller 43 controls the inverter 5 to enable the traction motor 3 to perform powered operation, zero-torque operation, and regenerative operation. In powered operation, power from the battery 4 is sent to the traction motor 3 via the inverter 5, and driving torque is output to the traction motor 3. In regenerative operation, braking torque is generated when the rotor of the traction motor 3 is rotating, and regenerative power is transmitted from the traction motor 3 to the battery 4 via the inverter 5, allowing the battery 4 to be charged. In zero-torque operation, the inverter 5 operates so that neither driving torque nor braking torque is generated when the rotor of the traction motor 3 is rotating, and so that excessive induced electromotive force is not generated in the traction motor 3 even when the rotor rotation speed is high. During zero-torque operation, the inverter 5 supplies current to the traction motor 3, so the power of the battery 4 is consumed. Hereinafter, the control of the inverter 5 by the controller 43 when the traction motor 3 is performed in zero-torque operation will be referred to as "zero-torque control".

[0017] The shift operation unit 6 can be switched to each shift position of parking, which puts the electric vehicle 1 in a state suitable for parking, drive, which enables the electric vehicle 1 to move forward, reverse, which enables the electric vehicle 1 to move backward, and neutral, in which the electric vehicle 1 does not move forward even when an acceleration operation is performed via the acceleration operation unit 7c. The driver can switch the shift position by operating the shift operation unit 6. The information on the shift position selected by the shift operation unit 6 is sent to the controller 43. The controller 43 realizes the operation of the electric vehicle 1 in each of the drive, reverse, and neutral shift positions by switching the control of the inverter 5 based on the information on the shift position.

[0018] <Towed control process> FIG. 2 is a side view showing the electric vehicle 1 during towing. "During towing" means when it is being towed. The controller 43 executes a towed control process to cope with the case where the electric vehicle 1 is towed by a tow vehicle 51. The towed control process is executed by the controller 43 during the startup of the system of the electric vehicle 1, automatically determines that the electric vehicle 1 is being towed when the electric vehicle 1 is towed by a tow vehicle, and drives the inverter 5 to appropriately respond to the towing.

[0019] FIG. 3 is a flowchart showing the procedure of the towed control process executed by the controller 43. The towed control process is started when the system of the electric vehicle 1 is started and is always executed during the startup of the system.

[0020] When the towed control process is started, the controller 43 executes a process of determining whether it is being towed (steps S1 to S3). If it is determined as NO, the controller 43 returns the process to step S1 and repeats the above determination process.

[0021] In the process of determining whether or not the vehicle is being towed, the controller 43 determines whether the shift position is neutral (step S1), whether the vehicle speed is equal to or higher than a vehicle speed threshold value (step S2), and whether the change in the distance to the vehicle ahead is equal to or less than a change threshold value (step S3).

[0022] The vehicle speed threshold value in step S2 may be a value capable of determining whether or not the electric vehicle 1 is moving, such as 1 to 5 [km / h] for example. Alternatively, the above vehicle speed threshold value may be a value set based on the towing speed allowed in a state where the inverter 5 is not operating. Specifically, it may be a value obtained by subtracting a margin value (such as 5 to 20 [km / h]) from the towing speed allowed in a state where the inverter 5 is not operating (such as 50 to 70 [km / h]), for example, a value such as 30 to 65 [km / h]. The towing speed allowed in a state where the inverter 5 is not operating means the speed at which the induced electromotive force generated by the rotation of the rotor of the traveling motor 3 via the drive wheels 2 due to towing is within the rated value, and is determined based on the specifications of the traveling motor 3, the inverter 5, and the current lines therebetween.

[0023] The change threshold value in step S3 is set to a value indicating that the change in distance is almost zero. The change in distance being almost zero is not limited to the case where the change in distance is exactly zero, but includes the case where there is a small change in distance due to the looseness or play of the towing tool 52. The controller 43 calculates the above distance change based on the data on the distance to the vehicle ahead sent from the forward detector 42. In addition, in the determination process of step S3, if the detected distance is a value that cannot be the distance to the towing vehicle 51, such as 3 m or more for example, the controller 43 may make a NO determination in step S3 regardless of the change in distance.

[0024] As a result of the determination processes in steps S1 to S3, the controller 43 determines that the vehicle is being towed (i.e., is being towed) when all of steps S1 to S3 are YES (step S4). On the other hand, if any one of them is NO, the controller 43 determines that the vehicle is not being towed and returns the process to step S1.

[0025] As shown in Figure 2, when towing the electric vehicle 1, the operator connects the rear of the towing vehicle 51 to the front of the electric vehicle 1 via the towing device 52. Optionally, the operator may connect a communication line 53, through which information is transmitted from the towing vehicle 51, to the communication device 44 during the connection. Furthermore, the user or operator of the electric vehicle 1 switches the shift position to neutral so that the electric vehicle 1 moves in accordance with the towing. In this state, as the towing vehicle 51 moves, the electric vehicle 1 is pulled by the towing vehicle 51. At this time, the towing vehicle 51 is positioned at a certain distance in front of the electric vehicle 1, with the towing device 52 in between. Therefore, if the determination results of steps S1 to S3 are all YES, it can be determined that the electric vehicle is being moved by the towing vehicle 51 as described above.

[0026] The controller 43 constantly creates and saves status data indicating the control status of the electric vehicle 1 as a log, and whether or not it has determined that the vehicle is being towed can be confirmed by reading the above status data. Furthermore, since the determination that the vehicle is being towed means that the controller 43 starts zero torque control of the inverter 5, the start of zero torque control can be considered as the above determination having been made.

[0027] Furthermore, in the process of determining whether or not the vehicle is being towed, the determination process regarding vehicle speed in step S2 may be omitted. That is, the controller 43 may not perform the determination process in step S2, and may determine that the electric vehicle 1 is being towed if the determination results in steps S1 and S3 are both YES. In this case, the controller 43 may mistakenly determine that the vehicle is being towed, for example, when the driver switches the shift position to neutral during parallel parking. However, the towing determination is then canceled when the driver turns off the power to the electric vehicle 1's system in order to park, or when the driver switches the shift position to drive and attempts to start driving (see steps S7 and S8). Also, when the drive motor 3 is stopped, zero torque operation does not cause significant power consumption in the drive motor 3. Therefore, even if the determination process in step S2 is omitted and the above-mentioned erroneous determination occurs, no abnormality occurs in the electric vehicle 1.

[0028] If the process in steps S1 to S3 determines that the vehicle is being towed, the controller 43 starts zero torque control of the inverter 5 (step S5). Then, the controller 43 proceeds with the control process for when the vehicle is being towed.

[0029] When the process proceeds to control the vehicle while it is being towed, the controller 43 executes a process to drive the inverter 5 with zero torque control (step S6).

[0030] Next, the controller 43 determines whether the condition for releasing the towing determination has occurred (step S7). If it is YES, it determines that the vehicle is not being towed and terminates the zero torque control (step S8). The towing determination means that the vehicle is being towed. Then, the controller 43 returns to step S1.

[0031] The conditions for releasing the towing determination in step S7 include one or more of the following: the shift position has been switched by the operation of the shift operation unit 6; the state of the power switch 8 has been switched (for example, when it has been switched to power off); and the braking operation unit 7b has been operated. The controller 43 determines YES in step S7 if any one of the above release conditions occurs.

[0032] If the result in step S7 is NO, the controller 43 performs a process to determine whether the regenerative conditions have been met (steps S9 and S10). That is, the controller 43 determines whether the State of Charge (SOC) of the battery 4 has decreased (step S9), and if it is YES, it determines whether the electric vehicle 1 is decelerating (step S10). The order of steps S9 and S10 in Figure 3 may be reversed.

[0033] In step S9, the controller 43 can determine whether the SOC is decreasing by, for example, comparing the SOC of the battery 4 with a threshold indicating a decrease in SOC. Alternatively, the controller 43 may determine that the SOC is decreasing when the difference between the SOC at the start of towing and the current SOC exceeds a threshold.

[0034] The determination of SOC degradation in step S9 may be replaced with a determination of whether or not there is sufficient SOC available for regenerative charging. Alternatively, if it is known that battery 4 will not reach full charge, the determination regarding SOC in step S9 may be omitted.

[0035] The deceleration determination in step S10 may include not only the determination that deceleration is in progress, but also the determination that the vehicle is in a state where it will be decelerated immediately afterward. In step S10, the controller 43 can determine deceleration based on, for example, the measured value of the vehicle speed sensor 41. Alternatively, the electric vehicle 1 may have an acceleration sensor, and the controller 43 may determine deceleration based on the measured value of the acceleration sensor. In these cases, the vehicle speed sensor 41 or the acceleration sensor described above corresponds to an example of a vehicle sensor according to the present invention. Furthermore, the controller 43 may determine deceleration based on deceleration information of the towing vehicle 51 received via the communication line 53. The deceleration information of the towing vehicle 51 may be, for example, information output based on the fact that a deceleration operation has been performed on the towing vehicle 51, or information output at the time of deceleration based on the detection of the speed or acceleration of the towing vehicle 51.

[0036] If either of the results of steps S9 and S10 is NO, the controller 43 returns to step S6 and continues the zero torque control process in step S6.

[0037] If both steps S9 and S10 result in YES, the controller 43 drives the inverter 5 so that the drive motor 3 is operated regeneratively (step S11). Then, the controller 43 returns to step S7.

[0038] As a result of the processes in steps S6 to S11 described above, if the regenerative conditions are not met during towing, the process in step S6 is repeatedly executed, thereby achieving zero-torque operation of the drive motor 3. Therefore, even if the rotor of the drive motor 3 of the electric vehicle 1 rotates at high speed during towing, it is possible to suppress the generation of excessive induced electromotive force in the drive motor 3. Thus, it is possible to suppress situations in which the electric vehicle 1 is restricted to lowering the towing speed.

[0039] Furthermore, as a result of the processes in steps S6 to S11 described above, if the regenerative conditions are met during towing, the process in step S11 is repeatedly executed, causing the drive motor 3 to perform regenerative operation. Therefore, even if the State of Charge (SOC) of the battery 4 gradually decreases due to the zero-torque control in step S6, the regenerative power generated during towing can recharge the battery 4 and restore the SOC. In addition, the regenerative conditions during towing include the condition of deceleration of the electric vehicle 1. Therefore, when the towing vehicle 51 decelerates, the regenerative operation of the electric vehicle 1 can assist in the deceleration. Furthermore, since the electric vehicle 1 is operated regeneratively when the towing vehicle 51 decelerates, the SOC of the battery 4 can be restored without reducing energy efficiency.

[0040] The towing control processing program described above is stored in a non-transient storage medium (non-transient computer-readable medium), such as the storage unit 43a of the controller 43. The controller 43 may be configured to read a program stored in a portable non-transient recording medium and execute the program. The portable non-transient storage medium described above may store the towing control processing program described above.

[0041] As described above, the control device 40 of this embodiment has a forward detector 42 capable of detecting the distance to the vehicle body in front, and the controller 43 determines that the electric vehicle 1 is being towed based on the conditions that the shift position is in neutral and the change in distance detected by the forward detector 42 is below a change threshold. Therefore, the controller 43 can determine that the electric vehicle 1 is being towed regardless of the cause of the towing. Furthermore, according to the control device 40 of this embodiment, the controller 43 also determines that the electric vehicle 1 is being towed based on the condition that the vehicle speed of the electric vehicle 1 is above a vehicle speed threshold. Therefore, it is possible to suppress the false determination that the vehicle is being towed, such as when parallel parking, and to accurately determine that the vehicle is being towed.

[0042] Furthermore, according to the control device 40 of this embodiment, the controller 43 cancels the determination that the vehicle is being towed based on at least one of the following: when the state of the power switch 8 is switched, or when the shift position is switched. Therefore, even if the controller 43 incorrectly determines that the vehicle is being towed, it can cancel the towing determination in response to the operation of the electric vehicle 1 by the driver or the like, and transition the electric vehicle 1 to a state corresponding to the operation.

[0043] Furthermore, according to the control device 40 of this embodiment, the electric vehicle 1 does not have a mechanism to interrupt power transmission in the power transmission path from the rotor of the traction motor 3 to the drive wheels 2. In such a configuration, when the drive wheels 2 rotate due to towing, the rotor of the traction motor 3 rotates, so control of the traction motor 3 in accordance with the towing is necessary. Therefore, a configuration that can determine whether or not the vehicle is being towed is particularly useful. When the controller 43 determines that the vehicle is being towed, it drives the inverter 5 to operate the traction motor 3 in zero-torque mode. As a result, it is possible to suppress the generation of excessive induced electromotive force in the traction motor 3 due to towing, and consequently, to eliminate restrictions such as having to reduce the towing speed.

[0044] Furthermore, according to the control device 40 of this embodiment, when the electric vehicle 1 is being towed and the regenerative conditions are met, the controller 43 switches the drive motor 3 from zero-torque operation to regenerative operation. The regenerative conditions include the deceleration of the electric vehicle 1. Therefore, the regenerative operation can assist in the deceleration of the towing vehicle 51, and furthermore, the regenerative operation can improve the power balance of the battery 4. Moreover, the regenerative conditions include conditions based on the state of charge (SOC) of the battery 4. Therefore, the regenerative operation can keep the SOC of the battery 4 within an appropriate range, and can prevent, for example, the battery 4 from approaching full charge.

[0045] Furthermore, according to the control device 40 of this embodiment, when the controller 43 determines the deceleration of the electric vehicle 1 as a regenerative condition, it determines the deceleration based on the detected values ​​of vehicle sensors such as the vehicle speed sensor 41 or the acceleration sensor. Therefore, even if information on the driving operation of the towing vehicle 51 cannot be obtained, the controller 43 can still make the deceleration determination. Consequently, the effort of connecting the towing vehicle 51 and the control device 40 via the communication line 53 is eliminated. Furthermore, the controller 43 can also make the deceleration determination based on the deceleration information sent from the towing vehicle 51 via the communication device 44. In this case, the controller 43 can regenerate the driving motor 3 in synchronization with the timing of the start of deceleration, and can use the regenerative operation of the electric vehicle 1 as an aid for deceleration while maintaining good drivability of the towing vehicle 51.

[0046] Embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. For example, in the above embodiments, after determining that the vehicle is being towed, the process of steps S6 to S11 in Figure 3 was described as a specific example of control when the vehicle is being towed. However, if the focus is on the method for determining whether or not the vehicle is being towed, any control may be performed when the vehicle is being towed. Also, in the above embodiments, the process of steps S1 to S5 in Figure 3 was described as a specific example of the process for determining whether or not the vehicle is being towed. However, if the focus is on the control method when the vehicle is being towed, any method may be used as the method for determining whether or not the vehicle is being towed. Furthermore, details shown in the embodiments can be modified as appropriate without departing from the spirit of the invention. [Industrial applicability]

[0047] This invention can be used in control devices for electric vehicles. [Explanation of Symbols]

[0048] 1. Electric Vehicle 2 drive wheels 3. Motor for driving 4 Batteries 5 Inverter 6 Shift operation section 7. Operation Unit 7a Steering section 7b Brake operation section 7c Acceleration operation section 8 Power switch 40 Control device 41. Vehicle speed sensor 42 Forward-facing detectors 42a Measuring device 42b Computing equipment 43 Controllers 44 Communication devices 51 Towing vehicle 52 Towing equipment 53 Communication lines

Claims

1. A control device mounted on an electric vehicle comprising drive wheels, a drive motor for driving the drive wheels, an inverter for driving the drive motor, and a shift operation unit capable of switching the shift position, A forward-facing detector capable of detecting the distance to a vehicle in front of the vehicle, A controller for determining whether the electric vehicle is being towed, Equipped with, The control device for an electric vehicle is characterized in that the controller determines that the electric vehicle is being towed based on the fact that the shift position is set to neutral and the change in distance detected by the forward detector is below a change threshold.

2. It is further equipped with a vehicle speed sensor that detects vehicle speed, The control device for an electric vehicle according to claim 1, characterized in that the controller determines that the electric vehicle is being towed based on the fact that the shift position is in neutral, the change in distance detected by the forward detector is less than or equal to the change threshold, and the vehicle speed is greater than or equal to the vehicle speed threshold.

3. The controller cancels the determination that the vehicle is being towed based on at least one of the following: when the state of the electric vehicle's power switch is changed, and when the shift position is changed. The control device for an electric vehicle according to claim 1.

4. The control device for an electric vehicle according to claim 1, characterized in that the electric vehicle does not have a mechanism for interrupting power transmission in the power transmission path from the rotor of the driving motor to the drive wheels.

5. The control device for an electric vehicle according to claim 1, characterized in that the controller drives the inverter to operate the drive motor in zero torque mode when it determines that the electric vehicle is being towed.

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