Electric vehicles

Abstract

This involves combining electric vehicles equipped with manual and automatic modes with a function that allows the user to select the level of regenerative braking. [Solution] This disclosure relates to an electric vehicle that uses an electric motor as a power source for driving. The electric vehicle comprises a control device for controlling the electric vehicle and a shifter. The control device switches between an automatic mode, which drives the electric vehicle as a normal electric vehicle, and a manual mode, which accepts a virtual gear shift operation by the shifter and drives in a manner that simulates a manual transmission vehicle, in response to the operation of the driver of the electric vehicle. In manual mode, the control device switches the regenerative braking force of the electric motor in response to the virtual gear shift operation.

Description

Technical Field

[0001] The present disclosure relates to a technique for controlling an electric vehicle having an electric motor as a drive source.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2024-157909 discloses an electric vehicle that uses an electric motor as a driving power device. The electric vehicle includes a paddle shifter and a motor control device. An upshift operation, a downshift operation, and a mode switching operation are registered in the paddle shifter, and the motor control device switches the control mode between a manual mode and an automatic mode in response to the mode switching operation. The automatic mode is a control mode for driving the electric vehicle as a general electric vehicle. In the manual mode, the manual shifting operation of a manual transmission (MT) vehicle is pseudo-replicated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An electric vehicle equipped with a manual mode capable of performing a driving operation such as an MT vehicle and an automatic mode for running as a normal electric vehicle is known. In such an electric vehicle, the mode can be switched between the manual mode and the automatic mode by the operation of the driver. Also, in an electric vehicle, a function of changing the deceleration by changing the magnitude of the regenerative braking force of the electric motor is known. However, sufficient consideration has not been given so far to combining an electric vehicle equipped with a manual mode and an automatic mode with a function of selecting the magnitude of the regenerative braking force.

Means for Solving the Problems

[0005] This disclosure relates to an electric vehicle that uses an electric motor as a power source for driving. The electric vehicle comprises a control device and a shifter. The control device switches between an automatic mode, which drives the electric vehicle as a normal electric vehicle, and a manual mode, which accepts virtual gear shifting operations by the shifter and drives the electric vehicle in a manner that simulates a manual transmission vehicle, in response to the operation of the driver of the electric vehicle. In manual mode, the control device switches the regenerative braking force of the electric motor in response to the virtual gear shifting operations. [Effects of the Invention]

[0006] The electric vehicle disclosed herein features both a manual mode and an automatic mode. In manual mode, the regenerative braking force of the electric motor is switched according to a virtual gear shift operation. By replicating the switching of braking force in a manual transmission vehicle in response to gear shift operations, the realism of driving an actual manual transmission vehicle can be enhanced. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows the configuration of the control system of an electric vehicle according to this embodiment. [Figure 2] Block diagram showing the functions of the BEV ECU. [Figure 3] This graph shows the virtual transmission torque defined for each shift position in manual mode. [Figure 4] This graph shows the regenerative braking force that can be switched for each shift position in manual mode. [Figure 5] This graph shows the strength of regenerative braking force in multiple drive modes. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described with reference to the attached drawings.

[0009] 1. Configuration of the control system of an electric vehicle Figure 1 shows the configuration of the control system of an electric vehicle 100 according to an embodiment of the present disclosure. The electric vehicle 100 is a battery electric vehicle (BEV) that runs on electric energy stored in a battery. The control system of the electric vehicle 100 includes, as controlled objects, an electric motor 10 which is a power device for driving, a meter 11 which provides visual information to the driver, and a buzzer 12 and speaker 13 which provide auditory information to the driver. Furthermore, as a control device that controls these controlled objects, the electric vehicle 100 is equipped with a plurality of ECUs (Electronic Control Units) and an input device which inputs instructions from the driver to these ECUs. The ECUs include BEV (Battery Electric Vehicle)-ECU30, SBW (Shift By Wire)-ECU31, MM (Multi Media)-ECU32, MG (Motor Generator)-ECU33, meter-ECU34, and ASC (Active Sound Control)-ECU35. The input interface includes a shift range selector 20, a control mode selector switch 21, an accelerator pedal 22, a paddle shifter 23, and a multimedia system 24.

[0010] The shift range selector 20 is an input interface for the driver to select a shift range. Selectable shift ranges include, for example, parking range, reverse range, neutral range, and drive range. When the driver operates the shift range selector 20, a signal s1 corresponding to the position of the operating member of the shift range selector 20 is output from the shift range selector 20 to the SBW-ECU 31. The SBW-ECU 31 determines the shift range based on the input signal s1 and outputs a signal s2 containing information about the selected shift range to the BEV-ECU 30.

[0011] The control mode selector switch 21 is an input interface for switching the control mode of the electric vehicle 100 between automatic mode and manual mode. Automatic mode is a mode in which the electric motor 10 is controlled with normal output characteristics in response to output requests from the driver. Manual mode is a mode for operating the electric vehicle 100 like an engine vehicle (manual transmission vehicle / MT vehicle) capable of manual gear shifting. In manual mode, the output characteristics of the electric motor 10 can be switched in multiple stages by operating the paddle shifter 23, which will be described later. The control mode selector switch 21 may be an alternate switch or a momentary switch. When the driver operates the control mode selector switch 21, a signal s3 corresponding to the control mode specified by that operation is output from the control mode selector switch 21 to the BEV-ECU 30.

[0012] The accelerator pedal 22 is an input interface that acquires the amount of depression the driver makes when they press it, as the driver's acceleration request. When the driver presses the accelerator pedal 22, a signal s4 corresponding to the amount of depression is output from the accelerator pedal stroke sensor to the BEV-ECU 30.

[0013] The paddle shifter 23 is an input interface consisting of a pair of left and right paddles mounted on the steering wheel or steering column. When the driver pulls a paddle towards them, a signal s5 corresponding to the pulled paddle is output from the paddle shifter 23 to the BEV-ECU 30. When manual mode is selected, the paddle shifter 23 becomes an input interface for switching between multiple shift positions. However, the electric vehicle 100 does not have a physical transmission. The shift position referred to here is not the shift position of an actual transmission, but one of the parameters of the physical model used to calculate engine torque, as described later. In manual mode, the signal s5 output when the right paddle is pulled is a signal requesting an upshift, and the signal s5 output when the left paddle is pulled is a signal requesting a downshift. On the other hand, when automatic mode is selected, the paddle shifter 23 becomes an input interface for switching between multiple strengths of regenerative braking force. In automatic mode, when the right paddle is pulled, signal s5 is output, which requests a reduction in regenerative braking force, and when the left paddle is pulled, signal s5 is output, which requests an increase in regenerative braking force.

[0014] The multimedia system 24 is an input interface equipped with a touchscreen that displays various information such as navigation and audio settings and accepts touch operations from the driver. The driver can make various settings for the electric vehicle 100 by operating the touchscreen. When the driver operates the touchscreen, a signal s6 corresponding to the operation is output from the multimedia system 24 to the MM-ECU 32. The MM-ECU 32 determines the setting requested by the driver based on the input signal s6. If the setting requested by the driver is a driving mode, the MM-ECU 32 outputs a signal s7 containing information about the driving mode selected by the driver to the BEV-ECU 30. The driving mode can be set in manual mode, and the driver can select a driving mode that suits their preference from among several driving modes. If the setting requested by the driver is to turn the speaker 13 on / off or the volume, the MM-ECU 32 outputs a signal s8 containing information about turning the speaker 13 on / off or the volume to the ASC-ECU 35.

[0015] The BEV-ECU30 calculates the torque (hereinafter referred to as motor torque) to be output by the electric motor 10 based on the input signals s2, s3, s4, s5, and s7. However, in addition to these signals, other information, including at least the vehicle speed, is also used in the calculation of motor torque. The vehicle speed is measured using speed sensors provided on each wheel. The BEV-ECU30 calculates the motor torque in a manner corresponding to the control mode specified by signal s3. In automatic mode, the BEV-ECU30 calculates the motor torque mainly based on signal s4 and the vehicle speed. In manual mode, the BEV-ECU30 calculates the motor torque mainly based on signals s4, s5, s7, and the vehicle speed. Details of the motor torque calculation method in each control mode will be described later. The BEV-ECU30 outputs a signal s9 containing the motor torque information obtained in the calculation to the MG-ECU33. The MG-ECU33 generates a signal s12 for PWM control of the electric motor 10 based on signal s9, and controls the electric motor 10 with signal s12.

[0016] The BEV-ECU30 outputs a signal s10 to the meter-ECU34 that includes information to be displayed on the meter 11 and a request to sound the buzzer. The information to be displayed on the meter 11 includes, for example, the selected control mode, the shift position if manual mode is selected, and the virtual engine speed. The virtual engine speed is one of the parameters of the physical model used to calculate motor torque in manual mode. The meter-ECU34 generates a signal s13 to display this information and controls the meter 11 with signal s13. A request to sound the buzzer is output, for example, to inform the driver of the timing of a downshift or upshift. If the signal s10 includes a request to sound the buzzer, the meter-ECU34 generates a signal s14 and sounds the buzzer 12 with signal s14.

[0017] The BEV-ECU30 outputs a signal s11 to the ASC-ECU35 that contains information used to generate a simulated engine sound. The simulated engine sound is a sound that simulates the exhaust sound of an engine vehicle emitted from speaker 13 when manual mode is selected. The information used to generate the simulated engine sound includes, for example, virtual engine speed, virtual engine torque, and virtual shift position. Virtual engine torque is one of the parameters of the physical model used to calculate motor torque in manual mode. Based on this information, the ASC-ECU35 generates a signal s15 that generates a simulated engine sound and controls speaker 13 with signal s15.

[0018] 2. Functions of the BEV-ECU Next, the functions of the BEV-ECU30 will be described. The BEV-ECU30 is equipped with at least a processor (processing circuit) and memory. The memory includes RAM for temporarily recording data and ROM for storing programs that can be executed by the processor and various data related to the programs. The program consists of multiple instructions. The processor reads the program and data from memory and executes them, generating signals s9 to be output to the MG-ECU33, signals s10 to be output to the meter-ECU34, and signals s11 to be output to the ASC-ECU35.

[0019] FIG. 2 is a block diagram showing the functions of the BEV-ECU 30. The BEV-ECU 30 has functions as a control mode switching unit 310, an automatic mode parameter calculation unit 320, and a manual mode parameter calculation unit 330. These functions are realized by one or more programs stored in the memory of the BEV-ECU 30 being executed by a processor.

[0020] The control mode switching unit 310 switches the output control mode of the electric motor 10 with respect to an operation input from the driver. The control modes that can be switched by the control mode switching unit 310 are the automatic mode and the manual mode described above. The control mode switching unit 310 switches the control mode according to the signal s3 input from the control mode switching switch 21.

[0021] When the control mode is switched to the automatic mode by the control mode switching unit 310, the BEV-ECU 30 functions as the automatic mode parameter calculation unit 320. The automatic mode parameter calculation unit 320 performs output control according to the shift range selected by the shift range selector 20. For example, when the selected shift range is the D range, the automatic mode parameter calculation unit 320 acquires the accelerator opening from the signal s4 of the accelerator pedal 22 and acquires the vehicle speed from the signal of a speed sensor (not shown). The automatic mode parameter calculation unit 320 has a motor torque map using the accelerator opening and the vehicle speed as parameters. The automatic mode parameter calculation unit 320 calculates the motor torque to be generated in the electric motor 10 by inputting the accelerator opening and the vehicle speed into the motor torque map, and outputs a signal s9 including the information of the calculated motor torque to the MG-ECU 33.

[0022] In the motor torque map described above, the motor torque is specified to be a negative value when the accelerator opening is zero. In other words, when the accelerator opening is zero, the regenerative braking force of the electric motor 10 is activated, decelerating the electric vehicle 100. In automatic mode, the driver can switch the strength of the regenerative braking force by operating the paddle shifter 23. At this time, the strength of the regenerative braking force may be switched by multiplying the motor torque calculated by the motor torque map by a predetermined value, or multiple motor torque maps with different regenerative braking forces may be prepared in advance, and the strength of the regenerative braking force may be switched by switching between motor torque maps.

[0023] When the control mode is switched to manual mode by the control mode switching unit 310, the BEV-ECU 30 functions as a manual mode parameter calculation unit 330. The manual mode parameter calculation unit 330 performs the process of calculating the drive wheel torque to be generated by the drive wheels and the process of calculating the motor torque based on the drive wheel torque.

[0024] The manual mode parameter calculation unit 330 calculates the drive wheel torque using a physical model of the engine vehicle. The physical model includes a virtual engine 331 that models the engine and a virtual transmission 332 that models a transmission capable of manual shifting. The virtual transmission 332 also includes a model of an automated clutch.

[0025] In the virtual engine 331, the relationship between virtual engine speed and virtual engine torque is defined for each accelerator opening. The speed-torque characteristics of the virtual engine 331 can be set to those of a gasoline engine, a diesel engine, a naturally aspirated engine, or a turbocharged engine. The virtual engine speed is calculated based on the virtual gear ratio calculated by the virtual transmission 332, the virtual reduction ratio from the virtual transmission 332 to the drive wheels, and the vehicle speed. The virtual engine torque calculated by the virtual engine 331 is input to the virtual transmission 332.

[0026] In the virtual transmission 332, a virtual gear ratio is set for each shift position. For example, if there are shift positions from 1st to 6th gear, the largest virtual gear ratio is set for 1st gear, and the virtual gear ratios decrease in the order of 2nd, 3rd, 4th, 5th, and 6th gear. The virtual transmission torque is calculated using the virtual gear ratio calculated by the virtual transmission 332 and the virtual engine torque input from the virtual engine 331. The manual mode parameter calculation unit 330 calculates the drive wheel torque from the virtual transmission torque and reduction ratio.

[0027] The manual mode parameter calculation unit 330 calculates the motor torque by multiplying the drive wheel torque by the actual reduction ratio from the output shaft of the electric motor 10 to the drive wheel, and outputs a signal s9 containing the calculated motor torque information to the MG-ECU 33. However, if the electric vehicle 100 is equipped with electric motors 10 on both the front and rear wheel sides, the manual mode parameter calculation unit 330 calculates the motor torque of the front electric motor based on the torque distribution of the drive wheel torque to the front wheel, and calculates the motor torque of the rear electric motor based on the torque distribution of the drive wheel torque to the rear wheel.

[0028] 3. Regenerative braking force in manual mode In manual mode, the virtual transmission torque is calculated using a physical model of the engine vehicle. In the physical model used in the manual mode parameter calculation unit 330, the relationship between vehicle speed and virtual transmission torque is defined by a torque map. Figure 3 shows the relationship between vehicle speed and virtual transmission torque at maximum accelerator opening for each virtual gear ratio. The virtual transmission torque calculated from the torque map is switched accordingly when the virtual gear ratio is switched.

[0029] Furthermore, when the accelerator opening is zero, the virtual transmission torque is a negative value. This negative virtual transmission torque is reproduced by the regenerative braking force of the electric motor 10. This corresponds to engine braking in a manual transmission vehicle. Figure 4 shows the relationship between vehicle speed and virtual transmission torque for each virtual gear ratio. The virtual transmission torque calculated from the torque map is switched accordingly when the virtual gear ratio is switched. That is, in manual mode, the regenerative braking force of the electric motor 10 is switched according to the virtual gear shift operation using the paddle shifter 23.

[0030] In manual mode, the regenerative braking characteristics, specifically the regenerative braking force for each virtual gear ratio defined by the torque map, are designed to replicate the engine braking of a manual transmission (MT) vehicle. On the other hand, the regenerative characteristics of the electric motor 10 in automatic mode do not replicate the engine braking of an MT vehicle. Therefore, the regenerative characteristics in manual mode differ from those in automatic mode. In manual mode, the drive characteristics of the electric motor 10 are controlled to replicate the drive characteristics of an MT vehicle. Furthermore, by making the regenerative characteristics of the electric motor 10 specific to manual mode that replicate engine braking, the sense of realism, as if driving an actual MT vehicle, can be enhanced.

[0031] In addition, the manual mode parameter calculation unit 330 may switch torque maps for each virtual gear ratio and calculate virtual transmission torque from the torque map for each virtual gear ratio. Alternatively, it may calculate virtual engine torque from a single torque map and calculate virtual transmission torque from the virtual engine torque and virtual gear ratio.

[0032] 4. Operating member for switching regenerative braking force The paddle shifter 23 is used as an operating element for performing virtual gear changes in manual mode, and as a deceleration selector for switching the strength of the regenerative braking characteristic, i.e., deceleration, in automatic mode. By using the paddle shifter 23 according to each mode, the operating elements installed in the electric vehicle 100 can be effectively utilized, eliminating the need to install different operating elements for manual and automatic modes.

[0033] Furthermore, in automatic mode, the driver can increase the strength of regenerative braking by performing the same operation as downshifting in manual mode, and decrease the strength of regenerative braking by performing the same operation as upshifting in manual mode. In manual transmission vehicles, downshifting increases engine braking, and upshifting decreases engine braking. Therefore, by making the operation to increase regenerative braking in automatic mode the same as downshifting in manual mode, and the operation to decrease regenerative braking the same as upshifting in manual mode, the operation can be made more intuitive to understand, and errors can be reduced.

[0034] 5. Multiple drive modes The automatic mode may include multiple drive modes with different strengths of regenerative braking force. In the automatic mode, the strength of the regenerative braking force may be switched by switching the drive mode in response to the driver's operation of the paddle shifter 23.

[0035] Figure 4 shows examples of multiple drive modes. The vertical axis of the graph represents the torque of the electric motor 10 that generates regenerative braking force, and the horizontal axis represents the motor rotation speed. There are three drive modes, from drive mode 1 to drive mode 3, and the strength of the regenerative braking force is pre-set for each drive mode. When the right paddle of the paddle shifter 23, i.e. the paddle that weakens the regenerative braking force, is pulled, the BEV-ECU 30 switches to a drive mode with one level weaker regenerative braking force, and when the left paddle, i.e. the paddle that strengthens the regenerative braking force, is pulled, it switches to a drive mode with one level stronger regenerative braking force.

[0036] Each drive mode may be given a situation-appropriate name to help the driver make a selection. For example, the drive modes could be named Eco mode, Normal mode, and Sport mode, in order from weakest to strongest regenerative braking force. By defining the regenerative characteristics for each drive mode in this way, drivers can more easily select the strength of regenerative braking force that suits their preferences and the situation.

[0037] Furthermore, in this case, when the control mode is switched from manual mode to automatic mode, the BEV-ECU30 may set the drive mode to the previously selected mode. For example, suppose the driver selects sport mode while driving in automatic mode. Then, after switching the control mode from automatic mode to manual mode, and then switching back from manual mode to automatic mode, the BEV-ECU30 sets the drive mode to sport mode, which the driver selected previously. In this way, the drive mode setting can be carried over to the driver's preference without the driver having to perform any selection operation themselves. [Explanation of Symbols]

[0038] 10 Electric motor, 11 Meter, 12 Buzzer, 13 Speaker, 20 Shift range selector, 21 Control mode switch, 22 Accelerator pedal, 23 Paddle shifter, 24 Multimedia system, 30 BEV-ECU, 31 SBW-ECU, 32 MM-ECU, 33 MG-ECU, 34 Meter-ECU, 35 ASC-ECU, 100 Electric vehicle, 310 Control mode switching unit, 320 Automatic mode parameter calculation unit, 330 Manual mode parameter calculation unit, 331 Virtual engine, 332 Virtual transmission

Claims

1. An electric vehicle that uses an electric motor as a power source for driving, A control device for controlling the electric vehicle, Shifta and, Equipped with, The control device is In response to the driver's input, the system switches between an automatic mode, which operates as a normal electric vehicle, and a manual mode, which accepts virtual gear changes via the shifter and simulates driving a manual transmission vehicle. In the manual mode, the regenerative braking force of the electric motor is switched according to the virtual gear shift operation. An electric vehicle characterized by the following features.

2. An electric vehicle according to claim 1, The regenerative characteristics of the electric motor in the manual mode are different from those in the automatic mode. An electric vehicle characterized by the following features.

3. An electric vehicle according to claim 1 or 2, The aforementioned automatic mode includes a plurality of drive modes with different strengths of regenerative braking force. An electric vehicle characterized by the following features.

4. An electric vehicle according to claim 3, When the control mode is switched from manual mode to automatic mode, the control device sets the drive mode to the previously set drive mode. An electric vehicle characterized by the following features.

5. An electric vehicle according to claim 3, The control device switches the drive mode in response to the operation of the shifter. An electric vehicle characterized by the following features.

6. An electric vehicle according to claim 1 or 2, The aforementioned shifter is a paddle shifter consisting of a pair of paddles, The control device is In the manual mode, the virtual shift position is shifted up in response to the operation of one paddle of the paddle shifter, and the virtual shift position is shifted down in response to the operation of the other paddle of the paddle shifter. In the automatic mode, the regenerative braking force is weakened in response to the operation of one paddle, and strengthened in response to the operation of the other paddle. An electric vehicle characterized by the following features.

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