Electric Vehicles

Abstract

To provide an electric vehicle that enables drivers to easily enjoy zero-start acceleration similar to the same of a manual transmission vehicle.SOLUTION: A control device of an electric vehicle uses an electric motor as a power source device for traveling. The control device incudes an accelerator pedal, a simulated clutch pedal, a memory, and a processor. The memory stores a clutch model defining a relation between a degree of depression of the simulated clutch pedal and a torque transmission gain. The processor determines motor torque output from the electric motor based on the degree of depression of the simulated clutch pedal and the torque transmission gain. The clutch model is adapted to allow the relation between the degree of depression of the simulated clutch pedal and the torque transmission gain to be variable.SELECTED DRAWING: Figure 12

Description

[Technical field]

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

[0002] Electric motors used as a power unit for driving electric vehicles (EVs) have torque characteristics that are significantly different from the internal combustion engines used as a power unit for driving conventional vehicles. Due to the difference in torque characteristics of the power units, CVs require a transmission, whereas EVs generally do not have a transmission. Of course, EVs do 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 EV.

[0003] On the other hand, the torque of an electric motor can be controlled relatively easily by controlling the applied voltage and magnetic field. Therefore, with an electric motor, it is possible to obtain the desired torque characteristics within the operating range of the electric motor by implementing appropriate control. Taking advantage of this feature, technologies have been proposed to control the torque of an EV and simulate the torque characteristics unique to MT vehicles.

[0004] Patent Document 1 discloses a technology for producing a pseudo-shift change in a vehicle that transmits torque to the wheels by a drive motor. In this vehicle, torque fluctuation control is performed in which the torque of the drive motor is reduced by a set fluctuation amount at a predetermined trigger defined by the vehicle speed, accelerator opening, accelerator opening speed, or brake depression amount, and then the torque is increased again in a predetermined time. This is said to suppress the discomfort felt by drivers who are accustomed to vehicles equipped with a stepped transmission. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-166386 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above technology, the timing of the torque variation control that simulates the shifting operation cannot be determined by the driver's own operation. In particular, for drivers who are accustomed to driving MT vehicles, the pseudo shifting operation that does not involve the driver's own manual shifting operation may give an uncomfortable driving sensation to drivers who are looking for the fun of operating a MT.

[0007] Considering these circumstances, the inventors of the present application are considering providing an EV with a pseudo shift device and a pseudo clutch pedal so that the driving sensation of a manual transmission vehicle can be obtained. Of course, this does not mean simply attaching these pseudo devices to an EV. The inventors of the present application are considering making it possible to control an electric motor so that torque characteristics similar to those of a manual transmission vehicle can be obtained by operating the pseudo shift device and the pseudo clutch pedal.

[0008] One of the joys of driving a manual transmission vehicle is zero-start acceleration. Zero-start acceleration is acceleration from a stopped state. To do this quickly and smoothly in a manual transmission vehicle, the driver must skillfully coordinate the operation of the accelerator pedal, shift device, and clutch pedal. In particular, the operation of the accelerator pedal and clutch pedal at the moment the vehicle starts moving is important in determining quick acceleration.

[0009] However, since today's drivers are accustomed to driving vehicles with automatic transmissions (ATs), it is not easy to perform zero-start acceleration operations skillfully in manual transmission vehicles. This is also a problem that can arise when reproducing the driving feel of a manual transmission vehicle in an EV. In particular, while an EV can generate large torque from a stopped state, a manual transmission vehicle has low torque at low speeds, and there is a big difference in the driving feel. Therefore, for drivers who are familiar with the driving feel of an EV, even if the torque characteristics of a manual transmission vehicle are realized in an EV and zero-start acceleration becomes possible, there is a possibility that they will not be able to perform the necessary operations skillfully.

[0010] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide an electric vehicle that allows the driver to easily enjoy zero start acceleration like that of a manual transmission vehicle. [Means for solving the problem]

[0011] The electric vehicle according to the present invention is an electric vehicle that uses an electric motor as a power unit for running, and includes an acceleration pedal, a pseudo clutch pedal, a pseudo shift device, a pseudo engine tachometer, and a control device that controls the motor torque output by the electric motor.

[0012] The control device includes a memory and a processor. The memory stores an MT vehicle model. The MT vehicle model is a model that simulates the torque characteristics of the drive wheel torque in a MT vehicle. The MT vehicle here refers to a vehicle that has an internal combustion engine whose torque is controlled by the operation of a gas pedal, and a manual transmission whose gear stages are changed by the operation of a clutch pedal and a shift device.

[0013] The processor executes the following first to sixth processes. The first process is a process of accepting the operation amount of the acceleration pedal as an input of the operation amount of the gas pedal for the MT vehicle model. The second process is a process of accepting the operation amount of the pseudo clutch pedal as an input of the operation amount of the clutch pedal for the MT vehicle model. The third process is a process of accepting the shift position of the pseudo shift device as an input of the shift position of the shift device for the MT vehicle model. The fourth process is a process of calculating the driving wheel torque determined by the operation amount of the acceleration pedal, the operation amount of the pseudo clutch pedal, and the shift position of the pseudo shift device, using the MT vehicle model. The fifth process is a process of calculating the motor torque for applying the driving wheel torque to the driving wheels of the host vehicle. And the sixth process is a process of displaying the rotation speed of the internal combustion engine calculated using the MT vehicle model on a pseudo engine rotation speed meter.

[0014] When a zero start acceleration operation is detected while the electric vehicle is stopped, the processor executes at least one of the following seventh and eighth processes. The zero start acceleration operation is an operation of engaging the pseudo clutch pedal while increasing the rotation speed of the internal combustion engine displayed on the pseudo engine speed meter, i.e., the rotation speed of the virtual internal combustion engine calculated by the MT vehicle model, to approximately a predetermined rotation speed. The seventh process is a process of increasing the torque of the electric motor to a value greater than that during normal starting. The eighth process is a process of increasing the torque transmission gain determined by the amount of operation of the pseudo clutch pedal to a value greater than that during normal starting.

[0015] According to the above configuration, the driver can drive the electric vehicle as if it were a MT vehicle having an internal combustion engine and a manual transmission. When zero start acceleration is desired, the torque of the electric motor is made larger than that during normal start. Alternatively, or in addition, the torque transmission gain determined by the amount of operation of the pseudo clutch pedal is made larger than that during normal start. This allows sufficient driving force to be obtained at start, and the driver can easily enjoy zero start acceleration like a MT vehicle. Effect of the Invention

[0016] As described above, according to the present invention, it is possible to provide an electric vehicle that allows the driver to easily enjoy zero start acceleration like that of a manual transmission vehicle. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing a schematic configuration of a power system of an electric vehicle according to an embodiment of the present invention; [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 diagram showing an example of a motor torque command map provided in the control device shown in FIG. 3. [Diagram 5] 4 is a block diagram showing an example of a MT vehicle model provided in the control device shown in FIG. 3. [Figure 6] FIG. 6 is a diagram showing an example of an engine model constituting the MT vehicle model shown in FIG. 5. [Figure 7] 6 is a diagram showing an example of a clutch model constituting the MT vehicle model shown in FIG. 5. [Figure 8] 6 is a diagram showing an example of an MT model constituting the MT vehicle model shown in FIG. 5. [Figure 9] 11 is a diagram showing a comparison between the torque characteristics of the electric motor realized in the MT driving mode and the torque characteristics of the electric motor realized in the EV driving mode. FIG. [Figure 10] 4 is a flowchart showing a procedure of zero start acceleration control. [Figure 11] FIG. 11 is a diagram showing a first method of torque boost for zero start acceleration. [Figure 12] FIG. 11 is a diagram showing a second method of torque boost for zero start acceleration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, when the number, quantity, amount, range, etc. of each element is mentioned in the following embodiments, the present invention is not limited to the mentioned number unless otherwise specified or clearly specified in principle. Furthermore, the structures, etc. described in the following embodiments are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle. In each drawing, the same or corresponding parts are given the same reference numerals, and the duplicated description will be appropriately simplified or omitted.

[0019] 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.

[0020] 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).

[0021] The electric vehicle 10 includes a battery 14 and an inverter 16. The battery 14 stores electric energy for driving the electric motor 2. The inverter 16 converts DC power input from the battery 14 into power for driving the electric motor 2. The power conversion by the inverter 16 is performed under PWM (Pulse Wave Modulation) control by a control device 50. The inverter 16 is connected to the control device 50 via an in-vehicle network.

[0022] The electric vehicle 10 is equipped with an accelerator pedal (acceleration pedal) 22 for inputting an acceleration request and a brake pedal 24 for inputting a braking request, as operation request input devices for the driver to input an operation request to the electric vehicle 10. The accelerator pedal 22 is provided with an accelerator position sensor 32 for detecting an accelerator opening Pap [%] 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.

[0023] The electric vehicle 10 further includes a pseudo shift lever (pseudo shift device) 26 and a pseudo clutch pedal 28 as motion input devices. The shift lever (shift device) and clutch pedal are devices for operating a manual transmission (MT), but the electric vehicle 10 naturally does not include an MT. The pseudo shift lever 26 and pseudo clutch pedal 28 are merely dummies that are different from an actual shift lever and clutch pedal.

[0024] The pseudo shift lever 26 has a structure simulating a shift lever equipped in a manual transmission vehicle. The arrangement and operation feel of the pseudo shift lever 26 are the same as those of an actual manual transmission vehicle. The pseudo shift lever 26 has positions corresponding to each gear stage, for example, 1st gear, 2nd gear, 3rd gear, 4th gear, 5th gear, 6th gear, and neutral. The pseudo shift lever 26 is provided with a shift position sensor 36 that detects the gear stage by determining which position the pseudo shift lever 26 is in. The shift position sensor 36 is connected to the control device 50 by an in-vehicle network.

[0025] The pseudo clutch pedal 28 has a structure simulating a clutch pedal equipped in a manual transmission vehicle. The arrangement and operation feel of the pseudo clutch pedal 28 are the same as those of an actual manual transmission vehicle. When the driver wishes to change the gear setting using the pseudo shift lever 26, he or she depresses the pseudo clutch pedal 28, and when the gear setting change is complete, the driver stops depressing the pseudo clutch pedal 28 and returns the pseudo clutch pedal 28 to its original position. The pseudo clutch pedal 28 is provided with a clutch position sensor 38 for detecting the depression amount Pc [%] of the pseudo clutch pedal 28. The clutch position sensor 38 is connected to the control device 50 by an in-vehicle network.

[0026] 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 simulates 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. In the case of a liquid crystal 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.

[0027] The electric vehicle 10 includes a mode selection switch 42. The mode selection switch 42 is a switch for selecting a driving mode of the electric vehicle 10. The driving modes of the electric vehicle 10 include an MT mode and an EV mode. The mode selection switch 42 is configured to be able to arbitrarily select either the MT mode or the EV mode. Although details will be described later, in the MT mode, the electric motor 2 is controlled in a control mode (first mode) for driving the electric vehicle 10 like a MT vehicle. In the EV mode, the electric motor 2 is controlled in a normal control mode (second mode) for general electric vehicles. The mode selection switch 42 is connected to the control device 50 by an in-vehicle network.

[0028] The control device 50 is typically an ECU (Electronic Control Unit) 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 (Random Access Memory) for temporarily recording data, and a ROM (Read Only Memory) for storing control programs executable by the processor 56 and various data related to the control programs. The processor 56 reads and executes the control 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. Signals are input to the control device 50 from at least the wheel speed sensor 30, the accelerator position sensor 32, the brake position sensor 34, the shift position sensor 36, the clutch position sensor 38, the rotation speed sensor 40, and the 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] Furthermore, signals are output from the control device 50 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 zero start acceleration request determination unit 500 and a function as a control signal calculation unit 520. In detail, a program stored in a memory 54 (see FIG. 1) is executed by a processor 56 (see FIG. 1), so that the processor 56 functions as at least the zero start acceleration request determination unit 500 and the control signal calculation unit 520. The control signal calculation is a function of calculating control signals for actuators and devices. The control signals include at least a signal for PWM control of the inverter 16 and a signal for displaying information on the pseudo engine speed meter 44. These 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, control signal calculation unit 520 includes an MT vehicle model 530, a required motor torque calculation unit 540, a motor torque command map 550, and a changeover switch 560. Signals from the wheel speed sensor 30, the accelerator position sensor 32, the shift position sensor 36, the clutch position sensor 38, the rotational speed sensor 40, and the mode selection switch 42 are input to control signal calculation unit 520. Control signal calculation unit 520 processes the signals from these sensors and calculates the motor torque to be output by electric motor 2.

[0034] There are two ways of calculating the motor torque by control signal calculation unit 520: calculation using MT vehicle model 530 and required motor torque calculation unit 540, and calculation using motor torque command map 550. The former is used to calculate the motor torque when electric vehicle 10 is run in MT mode. The latter is used to calculate the motor torque when electric vehicle 10 is run in EV mode. Which motor torque is used is determined by changeover switch 560. Changeover switch 560 is operated by a signal input from mode selection switch 42.

[0035] 2-2. Calculation of motor torque in MT mode The drive wheel torque in a MT vehicle is determined by the operation of the gas pedal that controls the fuel supply to the engine, the operation of the shift lever (shift device) that switches the gear stages of the MT, and the operation of the clutch pedal that operates the clutch between the engine and the MT. If the electric vehicle 10 is equipped with an engine, a clutch, and a MT, the MT vehicle model 530 is a model that calculates the drive wheel torque obtained by the operation of the accelerator pedal 22, the pseudo clutch pedal 28, and the pseudo shift lever 26. Hereinafter, the engine, clutch, and MT virtually realized by the MT vehicle model 530 in the MT mode will be referred to as the virtual engine, virtual clutch, and virtual MT.

[0036] A signal from accelerator position sensor 32 is input to MT vehicle model 530 as the operation amount of the gas pedal of the virtual engine. A signal from shift position sensor 36 is input as the shift position of the shift device of the virtual MT. Furthermore, a signal from clutch position sensor 38 is input as the operation amount of the clutch pedal of the virtual clutch. A signal from wheel speed sensor 30 is also input to MT vehicle model 530 as a signal indicating the load state of the vehicle. MT vehicle model 530 is a model that simulates the torque characteristics of the driving wheel torque in a MT vehicle. MT vehicle model 530 is created so that the operation of accelerator pedal 22, pseudo shift lever 26, and pseudo clutch pedal 28 by the driver is reflected in the value of the driving wheel torque. Details of MT vehicle model 530 will be described later.

[0037] Required motor torque calculation unit 540 converts the drive torque calculated by MT vehicle model 530 into required motor torque. The required motor torque is the motor torque required to achieve the drive torque calculated by MT vehicle model 530. The reduction ratio from the output shaft 3 of electric motor 2 to drive wheels 8 is used to convert the drive torque into required motor torque. In addition, a signal is input to required motor torque calculation unit 540 from zero start acceleration request determination unit 500. The contents of the determination by zero start acceleration request determination unit 500 and the processing of required motor torque calculation unit 540 that receives the determination result will be described later.

[0038] 2-3. Calculation of motor torque in EV mode 4 is a diagram showing an example of a motor torque command map 550 used for calculating the motor torque in the EV mode. The motor torque command map 550 is a map that determines the motor torque using the accelerator opening, Pap, and the rotational speed of the electric motor 2 as parameters. The signal of the accelerator position sensor 32 and the signal of the rotational speed sensor 40 are input to each parameter of the motor torque command map 550. The motor torque command map 550 outputs the motor torque corresponding to these signals.

[0039] 2-4.Motor torque switching The motor torque calculated using motor torque command map 550 is denoted as Tev, and the motor torque calculated using MT vehicle model 530 and required motor torque calculation unit 540 is denoted as Tmt. The motor torque selected by changeover switch 560 from the two motor torques Tev, Tmt is given to electric motor 2 as a motor torque command value.

[0040] In the EV mode, even if the driver operates the pseudo shift lever 26 or the pseudo clutch pedal 28, the operation is not reflected in the driving of the electric vehicle 10. In other words, in the EV mode, the operation of the pseudo shift lever 26 and the operation of the pseudo clutch pedal 28 are invalidated. However, even while the motor torque Tev is being output as the motor torque command value, the calculation of the motor torque Tmt using the MT vehicle model 530 continues. Conversely, even while the motor torque Tmt is being output as the motor torque command value, the calculation of the motor torque Tev continues. In other words, both the motor torque Tev and the motor torque Tmt are continuously input to the changeover switch 560.

[0041] By switching the input by the changeover switch 560, the motor torque command value is switched from the motor torque Tev to the motor torque Tmt, or from the motor torque Tmt to the motor torque Tev. At this time, if there is a difference between the two motor torques, a torque step occurs with the switching. For this reason, for a while after the switching, a gradual change process is performed on the motor torque command value so that a sudden change in torque does not occur. For example, in switching from the EV mode to the MT mode, the motor torque command value is not immediately switched from the motor torque Tev to the motor torque Tmt, but is changed toward the motor torque Tmt at a predetermined change rate. A similar process is performed in switching from the MT mode to the EV mode.

[0042] The changeover switch 560 operates according to the driving mode selected by the mode selection switch 42. When the EV mode is selected by the mode selection switch 42, the changeover switch 560 connects to the motor torque command map 550 and outputs the motor torque Tev input from the motor torque command map 550 as a motor torque command value. When the MT mode is selected by the mode selection switch 42, the changeover switch 560 switches the connection destination to the required motor torque calculation unit 540. Then, the changeover switch 560 outputs the motor torque Tmt input from the required motor torque calculation unit 540 as a motor torque command value. Such input switching is performed in conjunction with the selection of the driving mode by the mode selection switch 42.

[0043] 2-5.MT vehicle model 2-5-1. Overview Next, MT vehicle model 530 will be described. Fig. 5 is a block diagram showing an example of MT vehicle model 530. MT vehicle model 530 is composed of engine model 531, clutch model 532, MT model 533, and axle / driving wheel model 534. Engine model 531 models a virtual engine. Clutch model 532 models a virtual clutch. MT model 533 models a virtual MT. Axle / driving wheel model 534 models a virtual torque transmission system from the axle to the driving wheels. Each model may be represented by a calculation formula or a map.

[0044] Calculation results are input and output between each model. Furthermore, accelerator opening Pap detected by accelerator position sensor 32 is input to engine model 531. Clutch depression amount Pc detected by clutch position sensor 38 is input to clutch model 532. Shift position Sp detected by a shift position sensor is input to MT model 533. Furthermore, in MT vehicle model 530, vehicle speed Vw (or wheel speed) detected by wheel speed sensor 30 is used in multiple models. In MT vehicle model 530, driving wheel torque Tw and virtual engine rotation speed Ne are calculated based on these input signals.

[0045] 2-5-2.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 slip of the clutch mechanism.

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[0046] In equation (1), the rotation speed Nw of the wheels 8 is calculated from the wheel speed detected by the wheel speed sensor 30. The overall reduction ratio R is calculated from the gear ratio (speed change ratio) r calculated by an MT model 533 (described later) and the reduction ratio defined by an axle / driving wheel model 534. The slip ratio slip 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 when the MT mode is selected.

[0047] During idling of a manual transmission vehicle, an idle speed control (ISC control) is performed to maintain the engine speed at a constant speed. Therefore, when the vehicle speed is 0 and the accelerator opening Pap is 0%, the engine model 531 calculates the virtual engine speed Ne as a predetermined idling speed (for example, 1000 rpm).

[0048] The engine model 531 calculates the virtual engine output torque Teout from the virtual engine rotation speed Ne and the accelerator opening Pap. For example, a two-dimensional map as shown in FIG. 6 is used to calculate the virtual engine output torque Teout. In this two-dimensional map, the virtual engine output torque Teout for the virtual engine rotation speed Ne is given for each accelerator opening Pap. The torque characteristics shown in FIG. 6 can be set to characteristics assuming a gasoline engine or to characteristics assuming a diesel engine. Also, they can be set to characteristics assuming a naturally aspirated engine or to characteristics assuming a supercharged engine. A switch for switching the virtual engine in the MT mode may be provided so that the driver can switch to a preferred setting. The virtual engine output torque Teout calculated by the engine model 531 is output to the clutch model 532.

[0049] 2-5-3.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 depression amount of the pseudo clutch pedal 28. The clutch model 532 has a map as shown in FIG. 7, for example. In this map, the torque transmission gain k is given with respect to the clutch pedal depression amount Pc. In FIG. 7, the torque transmission gain k is given so that the clutch pedal depression amount Pc is 1 when the clutch pedal depression amount Pc is in the range of Pc0 to Pc1, the clutch pedal depression amount Pc monotonically decreases at a constant gradient to 0 when the clutch pedal depression amount Pc is in the range of Pc1 to Pc2, and the clutch pedal depression amount Pc is 0 when the clutch pedal depression amount Pc is in the range of Pc2 to Pc3. Here, Pc0 corresponds to the clutch pedal depression amount Pc of 0%, Pc1 corresponds to the play limit when the clutch pedal is depressed, Pc3 corresponds to the clutch pedal depression amount Pc of 100%, and Pc2 corresponds to the play limit just before Pc3.

[0050] 7 is an example, and there is no limitation on the change curve of the torque transmission gain k with respect to an increase in the clutch pedal depression amount Pc, so long as it is a broadly-defined monotonous decrease toward 0. For example, the change in the torque transmission gain k from Pc1 to Pc2 may be a monotonous decrease curve that is convex upward, or a monotonous decrease that is convex downward.

[0051] 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 (2). The clutch output torque Tcout calculated by the clutch model 532 is output to the MT model 533.

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[0052] 2-5-4.MT model The MT model 533 calculates a gear ratio (gear ratio) r. The gear ratio r is determined by the shift position Sp of the pseudo shift lever 26 in the virtual MT. There is a one-to-one relationship between the shift position Sp of the pseudo shift lever 26 and the gear stage of the virtual MT. The MT model 533 has, for example, a map as shown in FIG. 8. In this map, the gear ratio r is given for each gear stage. As shown in FIG. 8, the gear ratio r becomes smaller as the gear stage becomes larger.

[0053] The MT 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 transmission. 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 (3). The transmission output torque Tgout calculated by the MT model 533 is output to the axle / driving wheel model 534.

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[0054] 2-5-5. Axle and driving wheel model The axle / 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 MT to the driving wheels 8. The axle / 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 (4). The driving wheel torque Tw calculated by the axle / driving wheel model 534 is output to the required motor torque calculation unit 540.

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[0055] 2-6.Torque characteristics of electric motors realized in MT mode Required motor torque calculation unit 540 converts driving wheel torque Tw calculated by MT vehicle model 530 into motor torque. Fig. 9 is a diagram showing a comparison between the torque characteristics of electric motor 2 realized in MT driving mode and the torque characteristics of electric motor 2 realized in EV driving mode. In the case of MT mode, as shown in Fig. 9, it is possible to realize torque characteristics (solid line in the figure) that mimic the torque characteristics of a MT vehicle in accordance with the gear stage set by pseudo shift lever 26.

[0056] 2-6. Zero start acceleration requirement judgment 2-6-1. Overview Next, the zero start acceleration request determination by the zero start acceleration request determination unit 500 will be described. The zero start acceleration is acceleration from a stopped state. In an AT vehicle or a normal EV, quick acceleration can be achieved by depressing the accelerator pedal. If a greater acceleration is desired, the driver can depress the accelerator pedal while depressing the brake pedal, and release the brake pedal while applying torque to the drive wheels. However, in the case of an MT vehicle, a more complicated operation is required. In an MT vehicle, an operation of depressing the accelerator pedal while disengaging the clutch pedal, and engaging the clutch pedal while increasing the engine rotation speed to near the maximum torque, that is, a zero start acceleration operation, is required. The zero start acceleration operation is also required for zero start acceleration when the electric vehicle 10 is driven in MT mode.

[0057] When a zero start acceleration operation is performed in MT mode, the zero start acceleration request determination unit 500 determines that the driver is requesting zero start acceleration. The zero start acceleration operation by the driver can be detected from the virtual engine rotation speed Ne when the vehicle is stopped and the depression amount Pc of the pseudo clutch pedal. When a zero start acceleration request is detected, the zero start acceleration request determination unit 500 outputs a torque increase instruction signal to the required motor torque calculation unit 540. Upon receiving the torque increase instruction signal, the required motor torque calculation unit 540 increases the motor torque at the time of starting to be greater than the motor torque at the time of normal starting in MT mode.

[0058] 2-6-2. Procedure for determining zero start acceleration requirement FIG. 10 is a flowchart showing the procedure of the zero start acceleration control including the zero start acceleration request determination. In step S101, it is determined whether the current driving mode is the MT mode. If the current driving mode is the EV mode, the subsequent processing is skipped. Note that in the EV mode, acceleration by the large torque unique to the EV mode is possible.

[0059] If the current driving mode is the MT mode, in step S102, it is determined whether the vehicle is stopped. If the vehicle speed detected by the wheel speed sensor 30 is zero, it is determined that the vehicle is stopped. If the vehicle speed is not zero, the zero start acceleration is not achieved, and the subsequent processing is skipped.

[0060] When the vehicle is stopped, in step S103, it is determined whether the virtual engine rotation speed Ne is equal to or higher than a predetermined rotation speed Nes. The predetermined rotation speed Nes is a rotation speed at which the virtual engine output torque Teout falls within a predetermined range including the maximum torque. When the virtual engine rotation speed Ne is lower than the predetermined rotation speed Nes, it is unclear whether the driver intends to accelerate from zero start, so the subsequent processing is skipped.

[0061] When the virtual engine speed Ne becomes equal to or higher than a predetermined speed Nes, in step S104, it is determined whether the pseudo clutch pedal depression amount Pc has been returned to a predetermined value Pcs or less. The predetermined value Pcs is the depression amount when the virtual clutch is engaged. If the clutch pedal depression amount Pc is greater than the predetermined value Pcs, it is unclear whether the driver intends to accelerate from zero start, so the subsequent processing is skipped.

[0062] When the depression amount Pc of the pseudo clutch pedal becomes equal to or less than a predetermined value Pcs, torque is increased for zero start acceleration in step S105. This makes it possible to obtain sufficient driving force at the time of starting, and the driver can easily enjoy zero start acceleration like that of a manual transmission vehicle.

[0063] In step S106, it is determined whether the vehicle has started moving. If the vehicle has not started moving, the subsequent processing is skipped.

[0064] When the vehicle starts moving, in step S107, it is determined whether or not slippage is occurring in the drive wheels 8. Slippage can be detected from the speed difference occurring between the wheel speed of the drive wheels 8 and the wheel speed of the driven wheels 12. If slippage is not occurring, the next process is skipped.

[0065] If slippage occurs in the drive wheels 8, the process of step S108 is executed. In step S108, torque-down control is executed to reduce the motor torque. For the torque-down control, TRC (Traction Control), which is a function for ensuring traction on slippery or rough road surfaces, is used. This suppresses slippage of the drive wheels 8, enabling a stable start.

[0066] 2-6-3. How to increase torque for zero start acceleration FIG. 11 is a diagram showing a first method of torque increase for zero start acceleration. In the first method, the torque of the electric motor 2 is increased compared to that during normal starting. Specifically, in the MT mode, a torque curve is determined for each gear stage, and the motor torque is determined along the torque curve. As can be seen from the torque curve at 1st gear, the motor torque obtained during 1st gear starting in normal MT mode is not large. Therefore, when a torque increase instruction signal is input from the zero start acceleration request determination unit 500 to the request motor torque calculation unit 540, the request motor torque calculation unit 540 releases the current limit and increases the motor torque to the maximum torque. This allows the electric motor 2 to output a large torque equivalent to that in the EV mode, so that even a driver who is accustomed to an EV can enjoy zero start acceleration without any discomfort.

[0067] FIG. 12 is a diagram showing a second method of torque-up for zero start acceleration. In the second method, a torque-up command signal is input from zero start acceleration request determination unit 500 to MT vehicle model 530. When a torque-up command signal is input to MT vehicle model 530, torque transmission gain k in clutch model 532 is made larger than that during normal starting. Specifically, when the depression amount Pc of the pseudo clutch pedal is returned to a predetermined value Pcs or less and the virtual clutch is engaged, torque transmission gain k is made larger than normal. As a result, the torque of electric motor 2 during starting is increased, so that the driver can enjoy zero start acceleration without feeling uncomfortable, similar to the first method.

[0068] 3.Other 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 provided with an in-wheel motor. For the MT vehicle model in these cases, a model of an all-wheel drive vehicle with MT can be used.

[0069] 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 MT vehicle model. [Explanation of symbols]

[0070] 2 Electric motor 8 Drive wheels 10. Electric Vehicles 16 Inverter 26 Pseudo shift lever (pseudo shift device) 28 Pseudo clutch pedal 30 Wheel speed sensor 40 Rotational Speed ​​Sensor 42 Mode selection switch 44 Pseudo engine tachometer 50 Control device 500 Zero start acceleration request judgment unit 520 Control signal calculation unit 530 MT vehicle model 540 Required motor torque calculation unit 550 Motor torque command map 560 Changeover Switch

Claims

1. An electric vehicle that uses an electric motor as a driving power unit, Accelerator pedal and A fake clutch pedal, a memory that stores a clutch model that defines a relationship between the depression amount of the pseudo clutch pedal and a torque transmission gain; a processor that determines a motor torque to be output by the electric motor based on the depression amount of the accelerator pedal and the torque transmission gain, The clutch model is configured to vary the relationship between the depression amount of the pseudo clutch pedal and the torque transmission gain. An electric vehicle characterized by

2. 2. The electric vehicle according to claim 1, The clutch model is configured to change the relationship between the depression amount of the pseudo clutch pedal and the torque transmission gain under a predetermined condition from the relationship during normal starting. An electric vehicle characterized by

3. 3. The electric vehicle according to claim 2, The clutch model is configured to make the torque transmission gain larger when a zero start acceleration request is detected than during normal start. An electric vehicle characterized by

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