Electric vehicle control device

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

Electric vehicle control device

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

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

[0003] JP 2016-165180 A

[0004] When an electric vehicle is towed, torque is transmitted from the tires to the traction motor, causing the traction motor to rotate and generating an induced electromotive force. Therefore, it is desirable for the control device of the electric vehicle to determine that the electric vehicle is being towed and to perform control to deal with the induced electromotive force when the electric vehicle is being towed. However, towing is performed infrequently by ordinary users. Therefore, it is difficult to require the user to perform a special operation when the electric vehicle is towed. Therefore, it is difficult to employ a means for determining that the electric vehicle is being towed by performing such a special operation.

[0005] In the above-described conventional technology, the ECU can only determine that towing is 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 that the electric vehicle is being towed regardless of the cause of the towing.

[0007] The control device for an electric vehicle according to the present invention is a control device mounted on an electric vehicle that has drive wheels, a traction motor that drives the drive wheels, an inverter that drives the traction motor, and a shift operation unit that can switch the shift position, and is equipped with: a forward detector that can detect the distance to a vehicle in front of the vehicle body; and a controller that determines whether or not the electric vehicle is being towed, and the controller determines that the electric vehicle is being towed based on the shift position being neutral and the change in distance detected by the forward detector being below a change threshold.

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

[0009] It is a block diagram showing an electric vehicle equipped with a control device according to an embodiment of the present invention.It is a side view showing an electric vehicle when being towed.It is a flowchart showing the procedure of towed control processing executed by a controller.

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 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 installed in the electric vehicle 1. The electric vehicle 1 includes drive wheels 2, a traction motor 3 that drives the drive wheels 2, a battery 4 that stores power for driving the traction motor 3, an inverter 5 that drives the traction motor 3, a shift operation unit 6 that can change the shift position, a driving operation unit 7 that is operated by the driver, and a power switch 8 that changes the power state of the system of the electric vehicle 1.

[0011] The traction motor 3 is a motor such as a synchronous motor with a permanent magnet built into the rotating rotor. The inverter 5 converts power between the traction motor 3 and the battery 4. The driving operation unit 7 includes a steering unit 7a such as a steering wheel, a braking operation unit 7b such as a brake pedal, and an acceleration operation unit 7c such as an accelerator pedal. The electric vehicle 1 does not have a mechanism (such as a clutch) that cuts off the transmission of power on the power transmission path from the rotor of the traction motor 3 to the drive wheels 2. With this configuration, when the drive wheels 2 rotate, the rotor of the traction motor 3 also rotates.

[0012] The control device 40 includes a vehicle speed sensor 41 that detects the vehicle speed, a forward detector 42 that detects the distance to the vehicle ahead of the vehicle, and a controller 43 that controls the traveling of the electric vehicle 1. The control device 40 may further include a communicator 44 to which information is sent from a towing vehicle 51 (see FIG. 2) when the electric vehicle 1 is being towed.

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

[0014] The forward detector 42 includes a measuring device 42a, such as a camera and distance sensor, a compound eye camera, or a distance sensor capable of two-dimensional scanning, and a calculating device 42b that determines whether a vehicle body is located in front of the vehicle body by analyzing the measurement results of the measuring device 42a. The calculating device 42b is a microcomputer, and another ECU (Electronic Control Unit) mounted on the electric vehicle 1 may also serve as the calculating device 42b. When the measuring device 42a includes a distance sensor, various distance sensors can be used, such as a LiDAR (Light Detection And Ranging) sensor or an ultrasonic sensor.

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

[0016] The controller 43 controls the inverter 5 to enable the traction motor 3 to operate in power running, zero torque running, and regenerative running. In power running, power from the battery 4 is sent to the traction motor 3 via the inverter 5, and a driving torque is output to the traction motor 3. In regenerative running, 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, thereby charging the battery 4. In zero torque running, the inverter 5 operates so that neither driving torque nor braking torque is substantially generated when the rotor of the traction motor 3 rotates, and so that excessive induced electromotive force is not generated in the traction motor 3 even when the rotor rotation speed increases. During zero torque running, the inverter 5 passes current through the traction motor 3, consuming power from the battery 4. Hereinafter, the control of the inverter 5 by the controller 43 when the traction motor 3 is operating in zero torque running will be referred to as "zero torque control."

[0017] The shift operation unit 6 can be switched between various shift positions, including parking, which puts the electric vehicle 1 in a state suitable for parking, drive, which allows the electric vehicle 1 to move forward, reverse, which allows the electric vehicle 1 to move backward, and neutral, which prevents the electric vehicle 1 from moving 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. Information about the shift position selected by the shift operation unit 6 is sent to the controller 43. The controller 43 switches control of the inverter 5 based on the shift position information, thereby realizing operation of the electric vehicle 1 in each of the drive, reverse, and neutral shift positions.

[0018] <Towing control process> Figure 2 is a side view showing the electric vehicle 1 when being towed. When being towed means when being towed. The controller 43 executes towing control process to respond to the case where the electric vehicle 1 is towed by a towing vehicle 51. The towing control process is executed by the controller 43 while the system of the electric vehicle 1 is running, and is a process that automatically determines if the electric vehicle 1 is towed by a towing vehicle and drives the inverter 5 to respond appropriately to the towing.

[0019] 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 constantly executed while the system is running.

[0020] When the towed vehicle control process is started, the controller 43 executes a process (steps S1 to S3) to determine whether or not the vehicle is being towed. If the determination is NO, the controller 43 returns the process to step S1 and repeats the above-described determination process.

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

[0022] The vehicle speed threshold in step S2 may be a value, such as 1 to 5 km / h, that can determine whether the electric vehicle 1 is moving. Alternatively, the vehicle speed threshold may be a value that is set based on a towing speed that is allowable when the inverter 5 is not operating. Specifically, the vehicle speed threshold may be a value (e.g., 30 to 65 km / h) that is obtained by subtracting a margin (e.g., 5 to 20 km / h) from the towing speed that is allowable when the inverter 5 is not operating (e.g., 50 to 70 km / h). The towing speed that is allowable when the inverter 5 is not operating refers to a speed at which the induced electromotive force generated by the rotor of the traction motor 3 rotating via the drive wheels 2 due to towing is within a rated value, and is determined based on the specifications of the traction motor 3, the inverter 5, and the current lines between them.

[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 does not necessarily mean that the change in distance is completely zero, but also means that there is a small change in distance due to backlash or play in the towing implement 52. The controller 43 calculates the change in distance based on the data on the distance to the forward vehicle sent from the forward detector 42. Note that in the determination process of step S3, if the detected distance is an impossible value for the distance to the towing vehicle 51, such as 3 m or more, the controller 43 may make a NO determination in step S3 regardless of the change in distance.

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

[0025] As shown in FIG. 2 , when towing the electric vehicle 1, an operator couples the rear of the towing vehicle 51 to the front of the electric vehicle 1 via the towing implement 52. When coupling, the operator may optionally connect a communication line 53, which transmits information from the towing vehicle 51, to the communicator 44. 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, the towing vehicle 51 travels, and the electric vehicle 1 moves as it is pulled by the towing vehicle 51. At this time, the towing vehicle 51 is located a certain distance in front of the electric vehicle 1, with the towing implement 52 between them. Therefore, if all of the determination results in steps S1 to S3 are YES, it can be determined that the electric vehicle 1 is being towed by the towing vehicle 51 as described above.

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

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

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

[0029] When the process proceeds to the control for towing, the controller 43 executes a process for driving the inverter 5 under zero torque control (step S6).

[0030] Next, the controller 43 determines whether or not a condition for canceling the towing determination has occurred (step S7). If the determination is YES, the controller 43 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. The controller 43 then returns the process to step S1.

[0031] The conditions for canceling the towing determination in step S7 include one or more of the following: a condition that the shift position is changed by operating the shift operating unit 6, a condition that the state of the power switch 8 is changed (for example, when the power is switched to off), and a condition that the brake operating unit 7b is operated. If any one of the above-mentioned multiple cancellation conditions occurs, the controller 43 makes a YES determination in step S7.

[0032] If the determination in step S7 is NO, the controller 43 performs processing to determine whether the regeneration conditions are satisfied (steps S9 and S10). That is, the controller 43 determines whether the SOC (State Of Charge) of the battery 4 is decreasing (step S9), and if the determination is YES, determines whether the electric vehicle 1 is decelerating (step S10). The order of steps S9 and S10 in FIG. 3 may be reversed.

[0033] In step S9, the controller 43 can determine whether the SOC of the battery 4 is decreasing by, for example, comparing the SOC of the battery 4 with a threshold value that indicates a decrease in the 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 is equal to or greater than the threshold value.

[0034] The determination of the decrease in SOC in step S9 may be replaced by a determination of whether there is an SOC margin that allows regenerative charging. Alternatively, if it is known that the battery 4 will not reach full charge, the determination of the SOC in step S9 may be omitted.

[0035] The determination of deceleration in step S10 may include not only a determination that the electric vehicle 1 is currently decelerating, but also a determination that the electric vehicle 1 will be decelerated immediately thereafter. In step S10, the controller 43 may determine deceleration based on, for example, the measurement 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 measurement value of the acceleration sensor. In these cases, the vehicle speed sensor 41 or the acceleration sensor 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 a deceleration operation performed by the towing vehicle 51, or information output during deceleration based on detection of the speed or acceleration of the towing vehicle 51.

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

[0037] If the determination results in both steps S9 and S10 are YES, the controller 43 drives the inverter 5 so that the traction motor 3 performs regenerative operation (step S11), and then the controller 43 returns the process to step S7.

[0038] By the processing of steps S6 to S11 described above, if the regeneration conditions are not satisfied during towing, the processing of step S6 is repeatedly executed, thereby realizing zero torque operation of the traction motor 3. Therefore, even if the rotor of the traction motor 3 of the electric vehicle 1 rotates at high speed during towing, it is possible to prevent excessive induced electromotive force from being generated in the traction motor 3. This also prevents a situation in which a restriction is imposed on the electric vehicle 1, such as requiring a low towing speed.

[0039] Furthermore, if the regeneration conditions are met during towing by the processing of steps S6 to S11 described above, the processing of step S11 is repeatedly executed, thereby causing the traction motor 3 to perform regenerative operation. Therefore, even if the SOC of the battery 4 gradually decreases due to the zero torque control of step S6, the battery 4 can be charged with the regenerative power during towing, and the SOC can be restored. Furthermore, the regeneration conditions during towing include a condition that the electric vehicle 1 decelerates. Therefore, when the towing vehicle 51 decelerates, the deceleration can be assisted by the regenerative operation of the electric vehicle 1. Furthermore, because 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 program for the towed vehicle control process described above is stored in a non-transitory computer readable medium such as the storage unit 43a of the controller 43. The controller 43 may be configured to read and execute a program stored in a portable non-transitory recording medium. The portable non-transitory recording medium may store the program for the towed vehicle control process described above.

[0041] As described above, the control device 40 of this embodiment has the 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 being satisfied that the shift position is in neutral and that the change in distance detected by the forward detector 42 is equal to or less than the 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 being satisfied that the vehicle speed of the electric vehicle 1 is equal to or greater than the vehicle speed threshold. Therefore, it is possible to prevent a false determination that the electric vehicle 1 is being towed when parallel parking, for example, and to accurately determine that the electric vehicle 1 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 and when the shift position is switched. Therefore, even if the controller 43 erroneously determines that the vehicle is being towed, it can cancel the determination that the vehicle is being towed 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 in accordance with the operation.

[0043] Furthermore, according to the control device 40 of this embodiment, the electric vehicle 1 does not have a mechanism for cutting off power transmission on the power transmission path from the rotor of the traction motor 3 to the drive wheels 2. In this configuration, when the drive wheels 2 rotate due to towing, the rotor of the traction motor 3 rotates, and therefore control of the traction motor 3 in accordance with towing is necessary. Therefore, the configuration described above that can determine whether towing is occurring is particularly useful. When it is determined that towing is occurring, the controller 43 drives the inverter 5 to operate the traction motor 3 at zero torque. This prevents excessive induced electromotive force from being generated in the traction motor 3 due to towing, thereby eliminating restrictions such as the need to reduce the towing speed.

[0044] Furthermore, according to the control device 40 of this embodiment, when the electric vehicle 1 is being towed, if a regeneration condition is satisfied, the controller 43 switches the traction motor 3 from zero torque operation to regenerative operation. The regenerative condition includes a condition that the electric vehicle 1 is decelerating. Therefore, the regenerative operation can assist in deceleration of the towing vehicle 51, and further, the regenerative operation can improve the power balance of the battery 4. Furthermore, the regenerative condition includes a condition based on the SOC of the battery 4. Therefore, the regenerative operation can maintain 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 determining the deceleration of the electric vehicle 1 as a regeneration condition, the controller 43 determines the deceleration based on the detected values ​​of vehicle sensors such as the vehicle speed sensor 41 or an acceleration sensor. Therefore, the controller 43 can make the deceleration determination even when information about the driving operation of the towing vehicle 51 cannot be obtained. This eliminates the need to connect the towing vehicle 51 and the control device 40 via the communication line 53. Furthermore, the controller 43 can also make the deceleration determination based on deceleration information sent from the towing vehicle 51 via the communicator 44. In this case, the controller 43 can perform regenerative operation of the traction motor 3 in synchronization with the timing at which deceleration begins, thereby enabling the regenerative operation of the electric vehicle 1 to be used to assist in deceleration while maintaining good driving operability of the towing vehicle 51.

[0046] The above describes an embodiment of the present invention. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, the processing of steps S6 to S11 in FIG. 3 is performed as a specific example of control when the vehicle is being towed after determining that the vehicle is being towed. However, if the focus is on the method of determining whether or not the vehicle is being towed, any control may be performed when the vehicle is being towed. Furthermore, in the above embodiment, the processing of steps S1 to S5 in FIG. 3 is described as a specific example of the process for determining that 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 to determine that the vehicle is being towed. Other details shown in the embodiment may be modified as appropriate without departing from the spirit of the invention.

[0047] The present invention can be used in a control device for an electric vehicle.

[0048] REFERENCE SIGNS LIST 1 Electric vehicle 2 Drive wheels 3 Traction motor 4 Battery 5 Inverter 6 Shift operation unit 7 Driving operation unit 7a Steering unit 7b Braking operation unit 7c Acceleration operation unit 8 Power switch 40 Control device 41 Vehicle speed sensor 42 Forward detector 42a Measuring device 42b Calculating device 43 Controller 44 Communication device 51 Towing vehicle 52 Towing equipment 53 Communication line

Claims

1. A control device mounted on an electric vehicle having drive wheels, a traction motor that drives the drive wheels, an inverter that drives the traction motor, and a shift operation unit that can switch the shift position, the control device comprising: a forward detector that can detect the distance to a vehicle in front of the vehicle body; and a controller that determines whether the electric vehicle is being towed, wherein the controller determines that the electric vehicle is being towed when the shift position is in neutral and the change in distance detected by the forward detector is equal to or less than a change threshold.

2. A control device for an electric vehicle as described in claim 1, further comprising a vehicle speed sensor that detects vehicle speed, wherein the controller determines that the electric vehicle is being towed when the shift position is in neutral, the change in distance detected by the forward detector is less than the change threshold, and the vehicle speed is greater than or equal to the vehicle speed threshold.

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

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

5. The control device for an electric vehicle according to claim 1, wherein the controller drives the inverter so as to operate the traction motor at zero torque when it is determined that the electric vehicle is being towed.

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