Electric Vehicles

Abstract

To provide an electric automobile using an electric motor as a power device for travel which enables enjoyment of driving sensation like a clutch pedal-less MT vehicle having a sequential shifter.SOLUTION: An electric automobile includes an accelerator pedal, a sequential shifter, and a control device. The control device changes a motor torque output by an electric motor in response to operation of the accelerator pedal and operation of the sequential shifter. Specifically, the control device changes a change rate of the motor torque during a predetermined shift time at least twice in response to operation of the sequential shifter, and makes shift time different according to a predetermined condition.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to an electric vehicle that uses an electric motor as a power unit for running. [Background technology]

[0002] The electric motor used as the power unit for driving an electric vehicle has torque characteristics that are significantly different from those of the internal combustion engines used as the power unit for driving a conventional vehicle. Due to the difference in torque characteristics of the power unit, a transmission is essential for a conventional vehicle, whereas an electric vehicle generally does not have a transmission. Of course, an electric vehicle does not have a manual transmission (MT) that allows the driver to manually change the gear ratio. For this reason, there is a significant difference in the driving sensation between driving a conventional vehicle with a MT (hereinafter referred to as a MT vehicle) and driving an electric vehicle.

[0003] On the other hand, the torque of an electric motor can be controlled relatively easily by controlling the applied voltage and the magnetic field. Therefore, with an electric motor, it is possible to obtain desired torque characteristics within the operating range of the electric motor by implementing appropriate control. Technologies that utilize this feature to control the torque of an electric vehicle and simulate the torque characteristics unique to MT vehicles have been proposed, for example, in Patent Documents 1 and 2. The electric vehicles disclosed in these patent documents are provided with a pseudo shifter and a pseudo clutch pedal so that the driving sensation can be obtained as with a MT vehicle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-118569 A [Patent Document 2] Patent Publication No. 2022-036845 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the operation of the clutch pedal is unique to manual transmission vehicles, providing an electric vehicle with a pseudo clutch pedal appeals to users who want to enjoy the driving experience of an automatic transmission vehicle. However, for today's drivers who are accustomed to driving vehicles with automatic transmissions, the operation of the clutch pedal can be troublesome and difficult in some cases. Also, if the only operation required was the operation of the shifter, it would be possible to change gears more quickly.

[0006] It is estimated that there are a certain number of users who want to enjoy the driving sensation of a manual transmission vehicle, but are not good at or do not need to operate a clutch pedal. Strictly speaking, it is estimated that the driving sensation desired by such users is the driving sensation of a clutch-pedalless manual transmission vehicle that does not have a clutch pedal. Many clutch-pedalless manual transmission vehicles use a sequential shifter. The driving sensation of a clutch-pedalless manual transmission vehicle, including the operating sensation of the sequential shifter, is different from the driving sensation of a normal manual transmission vehicle with a clutch pedal.

[0007] The electric vehicle disclosed in the above-mentioned patent document is designed to simulate the output characteristics of a normal MT vehicle equipped with a clutch pedal. Therefore, simply removing the pseudo clutch pedal from the electric vehicle disclosed in the above-mentioned patent document cannot satisfy users who desire a driving feel similar to that of a clutch pedal-less MT vehicle with a sequential shifter.

[0008] The present disclosure has been made in consideration of the above problems. One objective of the present disclosure is to enable an electric vehicle that uses an electric motor as a power unit for running to have a driving sensation similar to that of a clutch pedal-less MT vehicle having a sequential shifter. [Means for solving the problem]

[0009] The present disclosure provides an electric vehicle to achieve the above object. The electric vehicle of the present disclosure includes an accelerator pedal and a sequential shifter. The electric vehicle of the present disclosure also includes a control device that changes the motor torque output by the electric motor in response to the operation of the accelerator pedal and the operation of the sequential shifter. The control device is configured to change the rate of change of the motor torque at least twice during a predetermined shift time in response to the operation of the sequential shifter.

[0010] The sequential shifter may be, for example, a paddle-type shifter or a lever-type shifter. In other words, the sequential shifter may have a structure and an operational feel similar to that of a sequential shifter equipped in a clutch pedal-less MT vehicle. However, as described above, the operation of the sequential shifter acts on the motor torque of the electric motor, and is different in function from the sequential shifter equipped in a clutch pedal-less MT vehicle. In order to distinguish it from the sequential shifter equipped in a clutch pedal-less MT vehicle, the sequential shifter equipped in the electric vehicle of the present disclosure will be referred to as a pseudo-sequential shifter hereinafter.

[0011] According to the configuration of the electric vehicle of the present disclosure, the motor torque changes with output characteristics similar to the drive wheel torque of a clutch pedal-less MT vehicle when the sequential shifter is operated, by shifting the pseudo sequential shifter, allowing the driver to enjoy the driving sensation of a clutch pedal-less MT vehicle having a sequential shifter in the electric vehicle.

[0012] The control device varying the rate of change of the motor torque at least twice during the shift time may include the control device decreasing the motor torque to a minimum value and then increasing it again during the shift time. By temporarily decreasing the motor torque, a driving sensation is created when the clutch is temporarily released by the shift operation of the sequential shifter in a clutch pedal-less MT vehicle. In this case, the control device may set the minimum value to zero and maintain the motor torque at zero for a predetermined time during the shift time. Furthermore, the control device may overshoot the motor torque when the shift time has elapsed. The driving sensation obtained by the shift operation of the pseudo sequential shifter depends on the setting of the change characteristic of the motor torque during the shift time.

[0013] The illustrated change characteristic of the motor torque within the shift time may be applied to an upshift operation of a pseudo-sequential shifter, or may be applied to a downshift operation of a pseudo-sequential shifter.

[0014] When the accelerator pedal operation amount is constant, the control device may generate a difference in motor torque according to the shift direction of the sequential shifter before and after the shift time has elapsed. If the pseudo-sequential shifter is operated as an upshift operation, the control device may reduce the motor torque before and after the shift time has elapsed. Also, if the pseudo-sequential shifter is operated as a downshift operation, the control device may increase the motor torque before and after the shift time has elapsed.

[0015] The change characteristic of the motor torque within the shift time may be changeable. For example, if the electric vehicle of the present disclosure includes a drive mode selection switch, the control device may change the change characteristic of the motor torque within the shift time according to the drive mode selected by the drive mode selection switch. With this configuration, the driver can arbitrarily obtain a driving sensation that suits his / her mood or a driving sensation that suits the driving situation by appropriately selecting the drive mode.

[0016] The driving sensation that the driver gets depends on visual information. Therefore, by visually expressing the behavior unique to the clutch pedal-less MT vehicle, it is expected that a more realistic driving sensation will be given to the driver. The electric vehicle of the present disclosure may be equipped with a pseudo engine speed meter as a device for visually expressing the behavior unique to the clutch pedal-less MT vehicle. The pseudo engine speed meter displays the virtual engine speed of the clutch pedal-less MT vehicle simulated by the electric vehicle of the present disclosure. As one example, when the pseudo sequential shifter is upshifted, the pseudo engine speed meter may display the virtual engine speed that monotonically decreases during the shift time in response to the upshift operation. As another example, when the pseudo sequential shifter is downshifted, the pseudo engine speed meter may display the virtual engine speed that increases at a predetermined timing within the shift time in response to the downshift operation.

[0017] The calculation of the motor torque by the control device may be performed using a clutch pedal-less MT vehicle model that simulates the output characteristics of the drive wheel torque in a clutch pedal-less MT vehicle. The clutch pedal-less MT vehicle model and a method of calculating the motor torque using the same will be described in the embodiments of the present disclosure below. Effect of the Invention

[0018] As described above, according to the electric vehicle of the present disclosure, the driver can enjoy a driving sensation similar to that of a clutch pedal-less MT vehicle having a sequential shifter. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an electric vehicle according to an embodiment of the present disclosure. [Diagram 2] 2 is a block diagram showing a configuration of a control system for the electric vehicle shown in FIG. 1. [Diagram 3] 2 is a block diagram showing the functions of a control device for the electric vehicle shown in FIG. 1. [Figure 4] 4 is a block diagram showing an example of a clutch pedal-less MT vehicle model provided in the control device shown in FIG. 3. [Diagram 5] FIG. 5 is a diagram showing an example of an engine model constituting the clutch pedal-less MT vehicle model shown in FIG. 4. [Figure 6] 5 is a diagram showing an example of a clutch model constituting the clutch pedal-less MT vehicle model shown in FIG. 4. [Figure 7] FIG. 5 is a diagram showing an example of a sequential transmission model constituting the clutch pedal-less MT vehicle model shown in FIG. 4. [Figure 8] FIG. 11 is a diagram showing a comparison of the torque characteristics of an electric motor achieved by motor control using a clutch pedal-less MT vehicle model with the torque characteristics of an electric motor achieved by normal motor control in an electric vehicle. [Figure 9] FIG. 11 is a diagram showing an example of a calculation of a motor torque using a clutch pedal-less MT vehicle model performed in response to an upshift operation. [Figure 10] FIG. 11 is a diagram showing another example of calculation of motor torque using a clutch pedal-less MT vehicle model performed in response to an upshift operation. [Figure 11] FIG. 11 is a diagram showing an example of a calculation of a motor torque using a clutch pedal-less MT vehicle model performed in response to a downshift operation. [Figure 12] FIG. 11 is a diagram showing another example of calculation of motor torque using a clutch pedal-less MT vehicle model performed in response to a downshift operation. [Figure 13] FIG. 10 is a diagram illustrating a modified example of the configuration of an electric vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1. Electric vehicle configuration FIG. 1 is a diagram showing a schematic configuration of a power system of an electric vehicle 10 according to this embodiment. As shown in FIG. 1, the electric vehicle 10 is equipped with an electric motor 2 as a power source. The electric motor 2 is, for example, a brushless DC motor or a three-phase AC synchronous motor. The electric motor 2 is provided with a rotation speed sensor 40 for detecting the rotation speed thereof. An output shaft 3 of the electric motor 2 is connected to one end of a propeller shaft 5 via a gear mechanism 4. The other end of the propeller shaft 5 is connected to a drive shaft 7 at the front of the vehicle via a differential gear 6.

[0021] The electric vehicle 10 has driving wheels 8 which are front wheels and driven wheels 12 which are rear wheels. The driving wheels 8 are provided on both ends of a drive shaft 7. Each wheel 8, 12 is provided with a wheel speed sensor 30. In FIG. 1, only the wheel speed sensor 30 of the right rear wheel is illustrated as a representative. The wheel speed sensor 30 is also used as a vehicle speed sensor for detecting the vehicle speed of the electric vehicle 10. The wheel speed sensor 30 is connected to a control device 50 (described later) by an in-vehicle network such as a controller area network (CAN).

[0022] The electric vehicle 10 includes a battery 14 and an inverter 16. The battery 14 stores electric energy for driving the electric motor 2. In other words, the electric vehicle 10 is a battery electric vehicle (BEV) that runs on the electric energy stored in the battery 14. The inverter 16 converts DC power input from the battery 14 into drive power for the electric motor 2. The power conversion by the inverter 16 is performed by PWM control by a control device 50. The inverter 16 is connected to the control device 50 by an on-board network.

[0023] The electric vehicle 10 is equipped with an accelerator pedal 22 for inputting an acceleration request and a brake pedal 24 for inputting a braking request, as operation request input devices through which the driver inputs operation requests to the electric vehicle 10. The accelerator pedal 22 is provided with an accelerator position sensor 32 for detecting the accelerator opening degree, which is the amount of operation of the accelerator pedal 22. In addition, the brake pedal 24 is provided with a brake position sensor 34 for detecting the amount of brake depression, which is the amount of operation of the brake pedal 24. The accelerator position sensor 32 and the brake position sensor 34 are connected to the control device 50 by an in-vehicle network.

[0024] The electric vehicle 10 further includes a pseudo paddle shifter 26 as an action input device. A paddle shifter, i.e., a paddle-type sequential shifter, is a device for operating a sequential manual transmission (SMT), but the electric vehicle 10 naturally does not include an SMT. The pseudo paddle shifter 26 is merely a dummy that is different from an actual paddle shifter. In general, an MT vehicle that includes a paddle shifter is a clutch-pedal-less MT vehicle that does not include a clutch pedal. Therefore, although the electric vehicle 10 includes the pseudo paddle shifter 26, it does not include a pseudo clutch pedal that resembles a clutch pedal.

[0025] The pseudo paddle shifter 26 has a structure similar to a paddle shifter equipped in a clutch pedal-less MT vehicle. The pseudo paddle shifter 26 is attached to the steering wheel. The pseudo paddle shifter 26 includes an upshift switch 26u and a downshift switch 26d. The upshift switch 26u is provided on the right side of the steering wheel, and the downshift switch 26d is provided on the left side of the steering wheel. The upshift switch 26u and the downshift switch 26d can be operated independently. The upshift switch 26u issues a signal when pulled toward the driver, and the downshift switch 26d also issues a signal when pulled toward the driver. Hereinafter, the operation of pulling the upshift switch 26u toward the driver is referred to as an upshift operation, and the signal issued by the upshift switch 26u due to the upshift operation is referred to as an upshift signal. In addition, the operation of pulling the downshift switch 26d toward the driver is referred to as a downshift operation, and the signal issued by the downshift switch 26d due to the downshift operation is referred to as a downshift signal. The upshift switch 26u and the downshift switch 26d are connected to the control device 50 via an in-vehicle network.

[0026] The electric vehicle 10 includes a drive mode selection switch 42. The drive mode selection switch 42 is a switch for selecting a drive mode of the electric vehicle 10. In the example shown in FIG. 1, three drive modes, A mode, B mode, and C mode, can be selected by the drive mode selection switch 42. Each type of drive mode provides a different driving sensation to the driver. Examples of the drive mode include a sports mode, a comfort mode, a racing mode, and a normal mode. The drive mode is associated with at least the output characteristics of the electric motor 2. The drive mode selection switch 42 is connected to the control device 50 by an in-vehicle network.

[0027] The electric vehicle 10 is equipped with a pseudo engine tachometer 44. An engine tachometer is a device that displays the rotation speed of an internal combustion engine (engine) to the driver, but the electric vehicle 10 is naturally not equipped with an engine. The pseudo engine tachometer 44 is merely a dummy that is different from an actual engine tachometer. The pseudo engine tachometer 44 has a structure that resembles an engine tachometer equipped in a conventional vehicle. The pseudo engine tachometer 44 may be of a mechanical type or a liquid crystal display type. Alternatively, it may be of a projection display type using a head-up display. In the case of a liquid crystal display type or a projection display type, the rev limit may be set arbitrarily. The pseudo engine tachometer 44 is connected to the control device 50 by an in-vehicle network.

[0028] The control device 50 is typically an electronic control unit (ECU) mounted on the electric vehicle 10. The control device 50 may be a combination of multiple ECUs. The control device 50 includes an interface 52, a memory 54, and a processor 56. An in-vehicle network is connected to the interface 52. The memory 54 includes a RAM for temporarily recording data, and a ROM for storing programs executable by the processor 56 and various data related to the programs. The programs are made up of multiple instructions. The processor 56 reads and executes the programs and data from the memory 54, and generates control signals based on signals acquired from each sensor.

[0029] 2 is a block diagram showing the configuration of a control system for the electric vehicle 10 according to this embodiment. The control device 50 receives input of signals from at least the wheel speed sensor 30, the accelerator position sensor 32, the brake position sensor 34, the upshift switch 26u, the downshift switch 26d, the rotation speed sensor 40, and the drive mode selection switch 42. An in-vehicle network is used for communication between these sensors and the control device 50. Although not shown in the figure, various other sensors are also mounted on the electric vehicle 10 and connected to the control device 50 by the in-vehicle network.

[0030] The control device 50 also outputs signals to at least the inverter 16 and the pseudo engine revolution speed meter 44. An in-vehicle network is used for communication between these devices and the control device 50. Although not shown in the figure, various other actuators and displays are also mounted on the electric vehicle 10 and connected to the control device 50 by the in-vehicle network.

[0031] The control device 50 has a function as a control signal calculation unit 520. In detail, the processor 56 executes a program stored in the memory 54, so that the processor 56 functions at least as the control signal calculation unit 520. The control signal calculation is a function of calculating a control signal for an actuator or device. The control signal includes at least a signal for PWM control of the inverter 16 and a signal for displaying information on the pseudo engine speed meter 44. The functions of the control device 50 will be described below.

[0032] 2. Functions of the control device 2-1.Motor torque calculation function 3 is a block diagram showing functions of the control device 50 according to this embodiment, in particular functions related to calculation of a motor torque command value for the electric motor 2. The control device 50 calculates the motor torque command value using the functions shown in this block diagram, and generates a control signal for PWM controlling the inverter 16 based on the motor torque command value.

[0033] 3, the control signal calculation unit 520 includes a clutch pedal-less MT vehicle model 530 and a required motor torque calculation unit 540. Signals from at least the wheel speed sensor 30, the accelerator position sensor 32, the upshift switch 26u, the downshift switch 26d, and the drive mode selection switch 42 are input to the control signal calculation unit 520. The control signal calculation unit 520 processes the signals from these sensors and switches, and calculates the motor torque to be output by the electric motor 2.

[0034] The clutch pedal-less MT vehicle model 530 is a model that calculates the drive wheel torque that should be obtained by the operation of the accelerator pedal 22 and the pseudo paddle shifter 26 when the electric vehicle 10 is assumed to be a clutch pedal-less MT vehicle. The clutch pedal-less MT vehicle is equipped with an engine, an SMT, and a clutch that connects the engine and the SMT, but is an MT vehicle that does not have a clutch pedal because the clutch is operated automatically. The drive wheel torque in the clutch pedal-less MT vehicle is determined by the operation of the gas pedal that controls the fuel supply to the engine and the operation of the paddle shifter that switches the gear stages of the SMT. The engine may be a spark ignition engine or a diesel engine. Hereinafter, the engine, clutch, and SMT virtually realized by the clutch pedal-less MT vehicle model 530 are referred to as a virtual engine, a virtual clutch, and a virtual SMT, respectively.

[0035] The clutch pedal-less MT vehicle model 530 receives as input the accelerator opening Pap detected by the accelerator position sensor 32 as the operation amount of the gas pedal of the virtual engine. In addition, the clutch pedal-less MT vehicle model 530 receives as inputs the operation of the paddle shifters that determine the gear stage of the virtual SMT, an upshift signal Su transmitted from the upshift switch 26u and a downshift signal Sd transmitted from the downshift switch 26d. In addition, the clutch pedal-less MT vehicle model 530 also receives as input the vehicle speed Vw (or wheel speed) detected by the wheel speed sensor 30 as a signal indicating the load state of the vehicle.

[0036] A mode selection signal is input to the clutch pedal-less MT vehicle model 530 from the drive mode selection switch 42. The clutch pedal-less MT vehicle model 530 includes a plurality of models simulating clutch pedal-less MT vehicles with different output characteristics. Each model is associated with a drive mode selected by the drive mode selection switch 42. In the example shown in FIG. 3, the clutch pedal-less MT vehicle model 530 includes an A-mode model corresponding to the A mode, a B-mode model corresponding to the B mode, and a C-mode model corresponding to the C mode. One model is selected from these models according to the drive mode selected by the drive mode selection switch 42, and the selected model is used to calculate the drive wheel torque Tw.

[0037] The required motor torque calculation unit 540 converts the driving wheel torque Tw calculated by the clutch pedal-less MT vehicle model 530 into a required motor torque Tm. The required motor torque Tm is the motor torque required to realize the driving wheel torque Tw calculated by the clutch pedal-less MT vehicle model 530. The reduction ratio from the output shaft 3 of the electric motor 2 to the driving wheels 8 is used to convert the driving wheel torque Tw into the required motor torque Tm.

[0038] 2-2. Clutch pedal-less MT vehicle model 2-2-1. Overview Next, the clutch pedal-less MT vehicle model 530 will be described. FIG. 4 is a block diagram showing an example of the clutch pedal-less MT vehicle model 530. The clutch pedal-less MT vehicle model 530 is composed of an engine model 531, a clutch model 532, an SMT model 533, an axle / driving wheel model 534, and a PCU model 535. In the engine model 531, a virtual engine is modeled. The virtual engine of this embodiment is a spark ignition engine whose torque is controlled by the throttle opening. In the clutch model 532, a virtual clutch is modeled. In the SMT model 533, a virtual SMT is modeled. In the axle / driving wheel model 534, a virtual torque transmission system from the axle to the driving wheel is modeled. And in the PCU model 535, some functions of a virtual plant control unit (PCU) that performs integrated control of the virtual engine, the virtual clutch, and the virtual SMT are modeled. Each model may be expressed, for example, by a calculation formula or a map.

[0039] Calculation results are input and output between each model. The accelerator opening Pap, upshift signal Su, and downshift signal Sd input to the clutch pedal-less MT vehicle model 530 are used in the PCU model 535. The vehicle speed Vw (or wheel speed) is used in multiple models. The clutch pedal-less MT vehicle model 530 calculates the drive wheel torque Tw and the virtual engine rotation speed Ne based on these input signals.

[0040] 2-2-2.PCU model The PCU model 535 calculates a virtual throttle opening of the virtual engine, a virtual clutch opening of the virtual clutch, and a virtual gear stage of the virtual SMT. The PCU model 535 is composed of a throttle opening model that calculates a virtual throttle opening, a clutch opening model that calculates a virtual clutch opening, and a gear stage model that calculates a virtual gear stage.

[0041] The throttle opening model receives the accelerator opening Pap, the upshift signal Su, and the downshift signal Sd as inputs and outputs a virtual throttle opening TA. In the throttle opening model, the virtual throttle opening TA is related to the accelerator opening Pap, and the virtual throttle opening TA is increased as the accelerator opening Pap increases. However, when the upshift signal Su or the downshift signal Sd is input, the virtual throttle opening TA is temporarily reduced regardless of the accelerator opening Pap. This means that the virtual throttle is temporarily closed when the pseudo paddle shifter 26 is shifted. The virtual throttle opening TA output from the throttle opening model is input to the engine model 531.

[0042] The clutch opening model outputs a virtual clutch opening CP upon receiving the upshift signal Su and the downshift signal Sd. The virtual clutch opening CP is basically set to 0%. That is, the basic state of the virtual clutch is an engaged state. When the upshift signal Su is input and when the downshift signal Sd is input, the virtual clutch opening CP is temporarily set to 0%. This means that when the pseudo paddle shifter 26 is shifted, the virtual clutch is temporarily released. The vehicle speed Vw and the virtual engine rotation speed are used to calculate the virtual clutch opening CP when the virtual clutch is engaged. The clutch opening model calculates the virtual clutch opening CP based on the rotation speed difference so that the rotation speed of the input shaft of the virtual SMT calculated from the vehicle speed Vw and the virtual engine rotation speed are smoothly matched. The virtual clutch opening CP output from the clutch opening model is input to the clutch model 532.

[0043] The gear stage model outputs a virtual gear stage GP upon receiving an upshift signal Su and a downshift signal Sd. The number of gear stages of the virtual SMT is N (N is a natural number equal to or greater than 2). The virtual gear stage GP is raised by one stage each time an upshift signal Su is input. However, when the virtual gear stage GP is at the Nth stage, the virtual gear stage GP is maintained at the Nth stage even when an upshift signal Su is input. Also, the virtual gear stage GP is lowered by one stage each time a downshift signal Sd is input. However, when the virtual gear stage GP is at the first stage, the virtual gear stage GP is maintained at the first stage even when a downshift signal Sd is input. The virtual gear stage GP output from the gear stage model is input to the SMT model 533.

[0044] 2-2-3.Engine model The engine model 531 calculates a virtual engine rotation speed Ne and a virtual engine output torque Teout. The engine model 531 is composed of a model for calculating the virtual engine rotation speed Ne and a model for calculating the virtual engine output torque Teout. For example, a model expressed by the following equation (1) is used to calculate the virtual engine rotation speed Ne. In the following equation (1), the virtual engine rotation speed Ne is calculated from the rotation speed Nw of the wheels 8, the overall reduction ratio R, and the slip ratio Rslip of the virtual clutch.

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[0045] In equation (1), the rotation speed Nw of the wheels 8 is detected by the wheel speed sensor 30. The overall reduction ratio R is calculated from the gear ratio (speed ratio) r calculated by an SMT model 533 (described later) and the reduction ratio defined by an axle / driving wheel model 534. The slip ratio Rslip is calculated by a clutch model 532 (described later). The virtual engine rotation speed Ne is displayed on a pseudo engine rotation speed meter 44.

[0046] However, formula (1) is a formula for calculating the virtual engine rotation speed Ne in a state in which the virtual engine and the virtual SMT are connected by the virtual clutch. When the virtual clutch is disengaged, the virtual engine torque Te generated by the virtual engine can be considered to be used to increase the virtual engine rotation speed Ne. The virtual engine torque Te is a torque obtained by adding the torque due to the moment of inertia to the virtual engine output torque Teout. When the virtual clutch is disengaged, the virtual engine output torque Teout is zero. Therefore, when the virtual clutch is disengaged, the engine model 531 calculates the virtual engine rotation speed Ne by the following formula (2) using the virtual engine torque Te and the moment of inertia J of the virtual engine. A map using the virtual throttle opening TA as a parameter is used to calculate the virtual engine torque Te.

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[0047] During idling of a clutch pedal-less MT vehicle, idle speed control is performed to maintain the engine speed at a constant speed. Therefore, when the virtual clutch is disengaged, the vehicle speed is 0, and the virtual throttle opening TA is 0%, the engine model 531 calculates the virtual engine speed Ne as a predetermined idling speed (e.g., 1000 rpm). When the driver depresses the accelerator pedal 22 while the vehicle is stopped to rev the engine, the idling speed is used as the initial value of the virtual engine speed Ne calculated by equation (2).

[0048] The engine model 531 calculates a virtual engine output torque Teout from the virtual engine rotation speed Ne and the virtual throttle opening TA. For example, a map as shown in FIG. 5 is used to calculate the virtual engine output torque Teout. This map specifies the relationship between the virtual throttle opening TA in a steady state, the virtual engine rotation speed Ne, and the virtual engine output torque Teout. In this map, the virtual engine output torque Teout for the virtual engine rotation speed Ne is given for each virtual throttle opening TA. The torque characteristics shown in FIG. 5 can be set to characteristics assuming a naturally aspirated engine, or can be set to characteristics assuming a supercharged engine. In addition, the torque characteristics shown in FIG. 5 can be set to characteristics assuming a diesel engine by replacing the virtual throttle opening TA with a virtual fuel injection amount. The virtual engine output torque Teout calculated by the engine model 531 is input to the clutch model 532.

[0049] 2-2-4. Clutch model The clutch model 532 calculates a torque transmission gain k. The torque transmission gain k is a gain for calculating the degree of torque transmission of the virtual clutch according to the virtual clutch opening CP. The clutch model 532 has, for example, a map as shown in FIG. 6. In this map, the torque transmission gain k is given for the virtual clutch opening CP. In FIG. 6, the torque transmission gain k is given so that the virtual clutch opening CP is 1 when the virtual clutch opening CP is in the range from CP0 to CP1, monotonically decreases at a constant gradient to 0 when the virtual clutch opening CP is in the range from CP1 to CP2, and is 0 when the virtual clutch opening CP is in the range from CP2 to CP3. Here, CP0 corresponds to a clutch opening of 0%, and CP3 corresponds to a clutch opening of 100%. The ranges from CP0 to CP1 and from CP2 to CP3 are dead zones in which the torque transmission gain k does not change depending on the virtual clutch opening CP.

[0050] The clutch model 532 calculates the clutch output torque Tcout using the torque transmission gain k. The clutch output torque Tcout is a torque output from the virtual clutch. The clutch model 532 calculates the clutch output torque Tcout from the virtual engine output torque Teout and the torque transmission gain k, for example, by the following equation (3). The clutch output torque Tcout calculated by the clutch model 532 is input to the SMT model 533.

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[0051] Further, the clutch model 532 calculates a slip ratio Rslip. The slip ratio Rslip is used to calculate a virtual engine rotation speed Ne in the engine model 531. To calculate the slip ratio Rslip, a map in which the slip ratio Rslip is given with respect to the clutch pedal depression amount Pc can be used, similar to the torque transmission gain k. Instead of such a map, the slip ratio Rslip may be calculated from the torque transmission gain k by the following equation (4) which expresses the relationship between the slip ratio Rslip and the torque transmission gain.

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[0052] 2-2-5.SMT model The SMT model 533 calculates the gear ratio (speed ratio) r. The gear ratio r is determined by the virtual gear stage GP in the virtual SMT. The SMT model 533 has a map as shown in FIG. 7, for example. In this map, the gear ratio r is given for the virtual gear stage GP. As shown in FIG. 7, the gear ratio r becomes smaller as the virtual gear stage GP becomes larger.

[0053] The SMT model 533 calculates the transmission output torque Tgout using the gear ratio r. The transmission output torque Tgout is a torque output from the virtual SMT. The MT model 533 calculates the transmission output torque Tgout from the clutch output torque Tcout and the gear ratio r, for example, by the following equation (5). The transmission output torque Tgout calculated by the MT model 533 is input to the axle / driving wheel model 534.

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[0054] 2-2-5. Axle and driving wheel model The axle and driving wheel model 534 calculates the driving wheel torque Tw using a predetermined reduction gear ratio rr. The reduction gear ratio rr is a fixed value determined by the mechanical structure from the virtual SMT to the driving wheels 8. The value obtained by multiplying the reduction gear ratio rr by the gear ratio r is the above-mentioned overall reduction gear ratio R. The axle and driving wheel model 534 calculates the driving wheel torque Tw from the transmission output torque Tgout and the reduction gear ratio rr, for example, by the following equation (6). The driving wheel torque Tw calculated by the axle and driving wheel model 534 is output to the required motor torque calculation unit 540.

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[0055] 2-3. Torque characteristics of electric motor realized in clutch pedal-less MT vehicle model The required motor torque calculation unit 540 converts the drive wheel torque Tw calculated by the clutch pedal-less MT vehicle model 530 into a motor torque. FIG. 8 is a diagram showing the torque characteristics of the electric motor 2 realized by motor control using the clutch pedal-less MT vehicle model 530 in comparison with the torque characteristics of the electric motor 2 realized by normal motor control for an electric vehicle (EV). According to the motor control using the clutch pedal-less MT vehicle model 530, as shown in FIG. 8, it is possible to realize torque characteristics (solid line in the figure) that simulate the torque characteristics of a clutch pedal-less MT vehicle in accordance with the virtual gear stage set by the pseudo paddle shifter 26. Note that in FIG. 8, the number of gear stages of the virtual SMT is set to six.

[0056] 3. Example of motor torque control in response to shift operation 3-1. Example of motor torque control in response to upshift operation Fig. 9 is a diagram showing an example of a calculation of motor torque using the clutch pedal-less MT vehicle model 530 performed in response to an upshift operation of the pseudo paddle shifter 26. In the example shown in Fig. 9, an upshift operation is performed while keeping the accelerator opening constant when the electric vehicle 10 is accelerating.

[0057] An upshift signal is input from the upshift switch 26u by an upshift operation of the pseudo paddle shifter 26. In response to the upshift signal, the PCU model 535 of the clutch pedal-less MT vehicle model 530 decreases the virtual throttle opening at a predetermined speed, and simultaneously increases the virtual clutch opening at a predetermined speed. At approximately the same time that the virtual throttle opening becomes 0% and the virtual throttle is completely closed, the virtual clutch opening becomes 100%, and the virtual clutch is completely released.

[0058] At the timing when the virtual throttle is completely closed and the virtual clutch is completely released, the PCU model 535 increases the virtual gear stage of the virtual SMT by one stage. Then, at the timing when a predetermined time has elapsed since the virtual gear stage was increased by one stage, the PCU model 535 increases the virtual throttle opening at a predetermined speed and simultaneously decreases the virtual clutch opening at a predetermined speed. At the timing when the virtual throttle opening returns to the original opening before the upshift operation, the virtual clutch opening becomes 0% and the virtual clutch is fully engaged. This completes the upshift of the virtual SMT. In this specification, the time when the upshift operation of the pseudo paddle shifter 26 is detected is defined as the start of the upshift, and the time when the virtual clutch is fully engaged is defined as the completion of the upshift. In this specification, the time from the start of the upshift to the completion of the upshift (time t shown in FIG. 9) is defined as the shift time of the upshift.

[0059] During the shift time, the virtual clutch is released and the virtual throttle is closed, so that the virtual engine rotates by inertia. As a result, the virtual engine speed decreases monotonically during the shift time. Then, the virtual clutch is re-engaged and the virtual throttle is re-opened, so that the virtual engine speed starts to increase again. Since the driving sensation that the driver gets depends on visual information, the virtual engine speed that changes in response to the upshift operation is displayed on the pseudo engine speed meter 44, so that the driver is given a realistic driving sensation.

[0060] The bottom row of FIG. 9 shows the change in motor torque achieved by changing the virtual throttle opening, virtual clutch opening, and virtual gear position in response to an upshift operation. In the example shown in FIG. 9, the motor torque decreases as the virtual clutch is released, and decreases to zero when the virtual clutch is completely released. Then, while the virtual clutch is released, the motor torque is maintained at zero. When the virtual clutch starts to be engaged, the motor torque increases as the virtual clutch is engaged. However, the motor torque at the time when the virtual clutch is completely engaged and the upshift is completed is lower than the motor torque at the time when the upshift starts. In other words, in the control of the motor torque in response to the upshift operation, the motor torque is reduced before and after the shift time has elapsed. By controlling the motor torque in this manner, the driver can enjoy a driving sensation in the electric vehicle 10 similar to that when the driver performs an upshift operation using a paddle shifter in a clutch pedal-less MT vehicle.

[0061] After the upshift is completed, the motor torque is calculated according to the virtual gear position and the virtual throttle opening. However, immediately after the shift time has elapsed, the motor torque may be made to overshoot the value determined by the virtual gear position and the virtual throttle opening, as shown by the dashed line in Figure 9, taking into account the inertia caused by the rotation of the virtual engine. Alternatively, conversely, the motor torque may be made to undershoot the value determined by the virtual gear position and the virtual throttle opening.

[0062] 10A and 10B are diagrams showing another example of the calculation of motor torque using the clutch pedal-less MT vehicle model 530 performed in response to an upshift operation of the pseudo paddle shifter 26.

[0063] In the example shown in Fig. 10A, the motor torque is reduced to a minimum value during the shift time and then increased again, and the motor torque is reduced before and after the shift time has elapsed. The minimum value is zero. The example shown in Fig. 10A has in common with the example shown in Fig. 9 in terms of temporarily reducing the motor torque. By temporarily reducing the motor torque, a driving sensation is created when an upshift operation of a paddle shifter is performed in a clutch pedal-less MT vehicle.

[0064] In the example shown in FIG. 10B, the motor torque is reduced at a constant rate of change from the start of the upshift to the end of the upshift, and the motor torque is reduced before and after the shift time has elapsed. In the example shown in FIG. 10B, unlike the examples shown in FIG. 9 and FIG. 10A, the motor torque is not caused to have a minimum value during the shift time. However, the rate of change of the motor torque is changed at the start of the upshift and the end of the upshift. In other words, the example shown in FIG. 10A is common to the examples shown in FIG. 9 and FIG. 10A in that the rate of change of the motor torque is changed at least twice during the shift time. Note that in each of the examples shown in FIG. 9, FIG. 10A, and FIG. 10B, the rate of change of the motor torque may be changed after a predetermined delay time has elapsed since the upshift operation was detected.

[0065] According to the clutch pedal-less MT vehicle model 530, the model used for calculating the motor torque can be switched according to the drive mode selected by the drive mode selection switch 42. For example, the motor torque change characteristic shown in FIG. 9 may be the change characteristic obtained in the A mode, the motor torque change characteristic shown in FIG. 10A may be the change characteristic obtained in the B mode, and the motor torque change characteristic shown in FIG. 10B may be the change characteristic obtained in the C mode. Also, for example, the waveform of the motor torque change characteristic may be common between drive modes, and the shift time of the upshift may be different for each drive mode. If the motor torque change characteristic differs, the driving sensation experienced by the driver will also differ. By appropriately selecting a drive mode with the drive mode selection switch 42, the driver can freely obtain a driving sensation that suits his / her mood or a driving sensation that suits the driving situation.

[0066] 3-2. Example of motor torque control in response to downshift operation Fig. 11 is a diagram showing an example of a calculation of motor torque using the clutch pedal-less MT vehicle model 530 performed in response to a downshift operation of the pseudo paddle shifter 26. In the example shown in Fig. 11, a downshift operation is performed while keeping the accelerator opening constant when the electric vehicle 10 is decelerating.

[0067] A downshift signal is input from the downshift switch 26d by a downshift operation of the pseudo paddle shifter 26. In response to the input of the downshift signal, the PCU model 535 of the clutch pedal-less MT vehicle model 530 decreases the virtual throttle opening at a predetermined speed, and at the same time increases the virtual clutch opening at a predetermined speed. At approximately the same timing when the virtual throttle opening becomes 0% and the virtual throttle is completely closed, the virtual clutch opening becomes 100% and the virtual clutch is completely released.

[0068] At the timing when the virtual throttle is completely closed and the virtual clutch is completely released, the PCU model 535 reduces the virtual gear of the virtual SMT by one step. Then, at the timing when a predetermined time has elapsed since the virtual gear was reduced by one step, the PCU model 535 temporarily opens the virtual throttle. After that, the PCU model 535 continues to increase the virtual throttle opening at a predetermined speed and simultaneously reduces the virtual clutch opening at a predetermined speed. At the timing when the virtual throttle opening returns to the original opening before the downshift operation, the virtual clutch opening becomes 0% and the virtual clutch is fully engaged. This completes the downshift of the virtual SMT. In this specification, the time when the downshift operation of the pseudo paddle shifter 26 is detected is defined as the start of the downshift, and the time when the virtual clutch is fully engaged is defined as the completion of the downshift. In this specification, the time from the start of the downshift to the completion of the downshift (time t shown in FIG. 11) is defined as the shift time of the downshift.

[0069] The operation of temporarily opening the virtual throttle while the virtual clutch is released is performed to increase the virtual engine rotation speed and make the virtual engine rotation speed coincide with the rotation speed of the input shaft of the virtual SMT, which is determined from the vehicle speed. The engagement of the virtual clutch is started when the difference between the rotation speed of the input shaft of the virtual SMT and the virtual engine rotation speed falls within a predetermined threshold. When a downshift operation is performed, the virtual engine rotation speed increases before the virtual clutch is engaged and the motor torque increases. Such a change in the virtual engine rotation speed is displayed on the pseudo engine rotation speed meter 44, so that the driver can obtain a driving sensation during downshifting from visual information.

[0070] The bottom row of FIG. 11 shows the change in motor torque achieved by changing the virtual throttle opening, virtual clutch opening, and virtual gear position in response to a downshift operation as described above. In the example shown in FIG. 11, the motor torque decreases as the virtual clutch is released, and decreases to zero when the virtual clutch is completely released. Then, while the virtual clutch is released, the motor torque is maintained at zero. When the virtual clutch starts to be engaged, the motor torque increases as the virtual clutch is engaged. However, the motor torque at the time when the virtual clutch is completely engaged and the downshift is completed is higher than the motor torque at the time when the downshift starts. In other words, in the control of the motor torque in response to the downshift operation, the motor torque is increased before and after the shift time has elapsed. By controlling the motor torque in this manner, the driver can enjoy a driving sensation in the electric vehicle 10 similar to that when the driver performs a downshift operation using a paddle shifter in a clutch pedal-less MT vehicle.

[0071] After the downshift is completed, the motor torque is calculated according to the virtual gear position and the virtual throttle opening. However, immediately after the shift time has elapsed, taking into account the inertia caused by the rotation of the virtual engine, the motor torque may be made to overshoot the value determined by the virtual gear position and the virtual throttle opening, as shown by the dashed line in Figure 11. Alternatively, conversely, the motor torque may be made to undershoot the value determined by the virtual gear position and the virtual throttle opening.

[0072] 12A and 12B are diagrams showing another example of the calculation of motor torque using the clutch pedal-less MT vehicle model 530 performed in response to a downshift operation of the pseudo paddle shifter 26.

[0073] In the example shown in Fig. 12A, the motor torque is reduced to a minimum value during the shift time and then increased again, and the motor torque is increased before and after the shift time has elapsed. The minimum value is zero. The example shown in Fig. 12A has in common with the example shown in Fig. 11 with regard to the temporary reduction in motor torque. By temporarily reducing the motor torque, a driving sensation is created when a paddle shifter downshift operation is performed in a clutch pedal-less MT vehicle.

[0074] In the example shown in FIG. 12B, the motor torque is reduced at a constant rate of change from the start of the downshift to the end of the downshift, and the motor torque is increased before and after the shift time has elapsed. In the example shown in FIG. 12B, unlike the examples shown in FIG. 11 and FIG. 12A, the motor torque is not caused to have a minimum value during the shift time. However, the rate of change of the motor torque is changed at the start of the downshift and the end of the downshift. In other words, the example shown in FIG. 12A is common to the examples shown in FIG. 11 and FIG. 12A in that the rate of change of the motor torque is changed at least twice during the shift time. Note that in each of the examples shown in FIG. 11, FIG. 12A, and FIG. 12B, the rate of change of the motor torque may be changed after a predetermined delay time has elapsed since the downshift operation was detected.

[0075] The motor torque change characteristics shown in Figures 11, 12A, and 12B can be associated with drive modes selectable by drive mode selection switch 42. For example, the motor torque change characteristics shown in Figure 11 may be the change characteristics obtained in mode A, the motor torque change characteristics shown in Figure 12A may be the change characteristics obtained in mode B, and the motor torque change characteristics shown in Figure 12B may be the change characteristics obtained in mode C. Also, for example, the waveform of the motor torque change characteristics may be common between drive modes, and the downshift shift time may be different for each drive mode.

[0076] 4.Other 13 is a diagram showing a schematic diagram of a modified configuration of the electric vehicle 10 according to the embodiment described above. In this modified configuration, a lever-type pseudo shifter 28 is provided as a pseudo sequential shifter. The lever-type pseudo shifter 28 is configured to output an upshift signal when the shift lever 28a is tilted forward, and to output a downshift signal when the shift lever 28a is tilted backward. The lever-type pseudo shifter 28 is connected to the control device 50 via an in-vehicle network.

[0077] The electric vehicle 10 according to the above embodiment is a FF vehicle in which one electric motor 2 drives the front wheels. However, the present invention is also applicable to electric vehicles in which two electric motors are arranged at the front and rear to drive the front and rear wheels, respectively. The present invention is also applicable to electric vehicles in which each wheel is equipped with an in-wheel motor. For the clutch pedal-less MT vehicle model in these cases, a model of an all-wheel drive vehicle with SMT can be used.

[0078] The electric vehicle 10 according to the above embodiment does not include a transmission. However, the present invention can also be applied to an electric vehicle that includes a stepped or continuously variable automatic transmission. In this case, a powertrain consisting of an electric motor and an automatic transmission can be controlled to output the motor torque calculated by the clutch pedal-less MT vehicle model.

[0079] The motor torque control technology of the present disclosure is not limited to battery electric vehicles, but can be widely applied to any electric vehicle that uses an electric motor as a driving power unit. For example, the motor torque control technology of the present disclosure can be applied to hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) that have a mode in which the vehicle runs only on the driving force of an electric motor. The motor torque control technology of the present disclosure can also be applied to fuel cell electric vehicles (FCEVs) that supply electric energy generated by a fuel cell to an electric motor. [Explanation of symbols]

[0080] 2 electric motor, 8 drive wheel, 10 electric vehicle, 16 inverter, 26 pseudo paddle shifter (pseudo sequential shifter), 28 lever-type pseudo shifter (pseudo sequential shifter), 42 drive mode selection switch, 44 pseudo engine tachometer, 50 control device, 520 control signal calculation unit, 530 clutch pedal-less MT vehicle model, 540 required motor torque calculation unit

Claims

1. An electric vehicle that uses an electric motor as a driving power unit, Accelerator pedal and Sequential shifter and a control device that changes a motor torque output by the electric motor in response to an operation of the accelerator pedal and an operation of the sequential shifter, The control device includes: varying the rate of change of the motor torque at least twice during a given shift time in response to operation of the sequential shifter; The shift time is varied according to a predetermined condition, The waveform of the change characteristic of the motor torque during the shift time is constant regardless of the conditions. An electric vehicle characterized by

2. An electric vehicle that uses an electric motor as a power unit for driving, Accelerator pedal and Sequential shifter and a control device that changes a motor torque output by the electric motor in response to an operation of the accelerator pedal and an operation of the sequential shifter; A drive mode selection switch; The control device includes: varying the rate of change of the motor torque at least twice during a given shift time in response to operation of the sequential shifter; The shift time is varied according to a predetermined condition, The condition is the drive mode selected by the drive mode selection switch. An electric vehicle characterized by

3. 3. The electric vehicle according to claim 1, The shift time is the time from when the operation of the sequential shifter is detected to when the virtual engine rotation speed based on the wheel speed or the motor rotation speed ends decreasing and starts increasing again. An electric vehicle characterized by

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