Electric vehicle, control method, and control program

Abstract

To provide a technology capable of reducing a sense of incongruity when generating an artificial sound corresponding to a driving state of an electric vehicle even when a request torque independent of an operation amount of an accelerator operation device is generated to a driving system in the electric vehicle.SOLUTION: The electric vehicle includes one or more processors configured to generate an artificial sound associated with a required torque for a drive system of the electric vehicle and output the artificial sound from a speaker mounted on the electric vehicle. In the first mode, the one or more processors are configured to generate an artificial sound associated with a first required torque independent of an operation amount of an accelerator operating device of the electric vehicle.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to an electric vehicle having an electric motor as a drive source. [Background technology]

[0002] Patent Document 1 discloses a vehicle control device that generates, inside the cabin of a real vehicle equipped with an electric motor (rotating machine) as a drive source, the sound generated when a virtual vehicle equipped with a virtual engine as a drive source is driven. The control device disclosed in Patent Document 1 estimates the load on the virtual engine when the virtual engine is controlled based on driving operations including accelerator operation, and estimates the sound that will be generated when the virtual engine is controlled to achieve the estimated load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-036005 Summary of the Invention [Problem to be solved by the invention]

[0004] The sound experienced by the driver while the vehicle is running is one of the factors that contribute to the driver's enjoyment of driving the vehicle. On the other hand, in electric vehicles using an electric motor as a drive source, the driving noise of the electric motor is low, so the sound experienced by the driver while the electric vehicle is running is low. Therefore, as disclosed in Patent Document 1, a conventional approach has been to output an artificial sound from a speaker that changes depending on the amount of operation of the accelerator operating device of the electric vehicle. The amount of operation of the accelerator operating device is the torque required for the drivetrain of the electric vehicle. Therefore, by outputting an artificial sound that changes depending on the amount of operation of the accelerator operating device, the driver can enjoy a sound that matches the driving state of the electric vehicle.

[0005] However, electric vehicles may be driven in accordance with a required torque that is not dependent on the amount of operation of the accelerator operation device. For example, this occurs when a control function that instructs the required torque for the drivetrain is activated. In the past, in such cases, a discrepancy occurred between the driving state of the electric vehicle and the output artificial sound, causing a problem of discomfort to the driver.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and one objective of the present disclosure is to provide a technology that can reduce the sense of discomfort felt when generating an artificial sound according to the driving state of an electric vehicle, even when a required torque that is not dependent on the amount of operation of an accelerator operation device is generated. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to an electric vehicle having an electric motor as a drive source. The electric vehicle includes one or more processors that generate an artificial sound linked to a torque required for the driveline of the electric vehicle and output the artificial sound from a speaker mounted on the electric vehicle. In a first mode, the one or more processors are configured to generate the artificial sound linked to a first torque required that is independent of the amount of operation of an accelerator operating device of the electric vehicle. [Effects of the Invention]

[0008] According to the present disclosure, when a first required torque that is not dependent on the amount of operation of the accelerator operating device is generated, an artificial sound linked to the first required torque can be output from the speaker in the first mode. This makes it possible to output an artificial sound that is in line with the driving state of the electric vehicle even when a first required torque that is not dependent on the amount of operation of the accelerator operating device is generated. As a result, it is possible to reduce the sense of discomfort felt when generating an artificial sound that is in line with the driving state of the electric vehicle. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram schematically illustrating a configuration of an electric vehicle according to an embodiment. [Figure 2]FIG. 2 is a diagram illustrating a functional configuration of a control device related to drive control of an electric vehicle. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a vehicle model. [Figure 4] FIG. 10 is a block diagram showing a comparative example of the functional configuration of a control device related to sound control. [Figure 5] 5 is a time chart showing an example of sound control by a control device according to a comparative example. [Figure 6] 2 is a block diagram showing a functional configuration of a control device related to sound control according to the embodiment; FIG. [Figure 7] 7 is a flowchart showing a processing flow of a mode selection process executed by a sound generation parameter acquisition unit shown in FIG. 6. [Figure 8] 7 is a block diagram showing an example of output of sound generation parameters by the sound generation parameter acquisition unit shown in FIG. 6. FIG. [Figure 9] 4 is a time chart showing an example of sound control by the control device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each drawing, the same or corresponding components are designated by the same reference numerals, and the description thereof will be simplified or omitted.

[0011] 1. Electric vehicle drivetrain configuration 1 is a diagram that schematically shows the configuration of an electric vehicle 100 according to this embodiment. First, the configuration of the drive system of the electric vehicle 100 will be described with reference to FIG.

[0012] The electric vehicle 100 is equipped with two electric motors (M) 4F, 4R at the front and rear as drive sources. The electric motors 4F, 4R are, for example, three-phase AC motors. Inverters (INV) 3F, 3R are attached to the front electric motor 4F and the rear electric motor 4R, respectively. The front electric motor 4F is provided to drive the front wheels 6F and is connected to the front drive shaft 5F via a reduction gear and a differential mechanism. The rear electric motor 4R is provided to drive the rear wheels 6R and is connected to the rear drive shaft 5R via a reduction gear and a differential mechanism. The front electric motor 4F and the front inverter 3F, and the rear electric motor 4R and the rear inverter 3R may each be integrally configured as an e-axle.

[0013] The front inverter 3F and the rear inverter 3R are each connected to a battery (BATT) 2. In other words, the electric vehicle 100 is a battery electric vehicle (BEV) that runs on electric energy stored in the battery 2. The inverters 3F, 3R are, for example, voltage-type inverters, and control the torque of the electric motors 4F, 4R by PWM control.

[0014] 2. Electric vehicle control system configuration Next, the configuration of the control system of the electric vehicle 100 will be described with reference to FIG.

[0015] The electric vehicle 100 is equipped with a vehicle speed sensor 11. At least one of wheel speed sensors (not shown) provided on each of the left and right front wheels 6F and the left and right rear wheels 6R is used as the vehicle speed sensor 11.

[0016] The electric vehicle 100 also includes an accelerator operation amount detection sensor 12. The accelerator operation amount detection sensor 12 is provided in an accelerator operation device 22. The accelerator operation device 22 is a device that is operated to drive the electric vehicle 100. Typically, the accelerator operation device 22 is an accelerator pedal. Alternatively, the accelerator operation device 22 may be a lever-type operation device or a dial-type operation device that is operated by hand. The accelerator operation amount detection sensor 12 outputs a signal that indicates the operation amount of the accelerator operation device 22. Typically, the accelerator operation amount detection sensor 12 is an accelerator pedal stroke sensor that outputs a signal that indicates the accelerator opening degree of the accelerator pedal.

[0017] The electric vehicle 100 also includes a brake operation amount detection sensor 13. The brake operation amount detection sensor 13 is provided in a brake operation device 23. The brake operation device 23 is a device that is operated to brake the electric vehicle 100. Typically, the brake operation device 23 is a brake pedal. Alternatively, the brake operation device 23 may be a lever-type operation device or a dial-type operation device that is operated by hand. The brake operation amount detection sensor 13 outputs a signal that indicates the operation amount of the brake operation device 23. Typically, the brake operation amount detection sensor 13 is a brake pedal stroke sensor that outputs a signal that indicates the brake opening degree of the brake pedal.

[0018] The accelerator operation device 22 and the brake operation device 23 are driving operation members used to drive the electric vehicle 100. In addition to these driving operation members, the electric vehicle 100 is equipped with pseudo gearshift operation members that imitate the gearshift members used to change gears in a manually shiftable engine vehicle (a vehicle powered by an internal combustion engine). The pseudo gearshift operation members include a pseudo shifter 24 and a pseudo clutch pedal 25.

[0019] The pseudo shifter 24 is, for example, a pseudo H-type shifter that imitates an H-type shifter. The pseudo H-type shifter has a structure that resembles a shift stick provided on a console and is configured to be able to move between shift positions along an H-shaped gate. Alternatively, the pseudo shifter 24 may be a pseudo sequential shifter that imitates a sequential shifter. The pseudo shifter 24 is provided with a shift position sensor 14. The shift position sensor 14 outputs a signal that indicates the shift position selected by the pseudo shifter 24. For example, the shift positions that can be selected by the pseudo shifter 24 include neutral, 1st, 2nd, 3rd, 4th, 5th, and 6th.

[0020] The pseudo clutch pedal 25 has a structure similar to that of a clutch pedal provided in a conventional manual transmission engine vehicle. For example, the pseudo clutch pedal 25 is equipped with a reaction force mechanism that generates a reaction force when the driver presses the pedal. The position when no pressure is applied to the pseudo clutch pedal 25 is the start end position of the pseudo clutch pedal 25, and the position when the pseudo clutch pedal is pressed all the way down is the end position of the pseudo clutch pedal 25. The driver can operate the pseudo clutch pedal 25 from the start end position to the end end position against the reaction force from the reaction force mechanism. The pseudo clutch pedal 25 is equipped with a clutch pedal stroke sensor 15. The clutch pedal stroke sensor 15 outputs a signal indicating the amount of depression of the pseudo clutch pedal 25.

[0021] Although the pseudo-clutch pedal 25 is a pedal-type operating device operated by foot, a lever-type operating device or a dial-type operating device operated by hand may also be provided as the pseudo-clutch operating device. The pseudo-clutch operating device can be configured in a variety of ways as long as the driver can operate it from the start position to the end position against a reaction force and can provide the same feel as a clutch pedal provided in a conventional manual transmission engine vehicle with a foot or hand.

[0022] The electric vehicle 100 also includes a human-machine interface (HMI) 20. The HMI 20 presents various types of information to the user through visual and audio displays and accepts various types of input from the user. The HMI 20 is composed of a display (e.g., a multi-information display, a meter display), switches, a microphone, a touchpad, a touchscreen, and the like. For example, the HMI 20 displays various types of information on a display and accepts input from the user regarding the displayed content by operating a switch. For example, the HMI 20 displays various types of information on a touchscreen and accepts input from the user regarding the displayed content by touching the touchscreen.

[0023] The electric vehicle 100 also includes one or more speakers 21. The speakers 21 are, for example, in-vehicle speakers that output sound into the cabin of the electric vehicle 100. As another example, the speakers 21 may be exterior speakers that output sound outside the electric vehicle 100. The electric vehicle 100 may include both in-vehicle speakers and exterior speakers as the speakers 21. The speakers 21 may be configured as part of the HMI 20.

[0024] The electric vehicle 100 is equipped with a control device 101. Various sensors and devices to be controlled that are mounted on the electric vehicle 100 are connected to the control device 101 via an on-board network such as a control area network (CAN). Various sensors (for example, a rotational speed sensor that outputs a signal indicating the motor rotation speed of the electric motors 4F, 4R) other than a vehicle speed sensor 11, an accelerator operation amount detection sensor 12, a brake operation amount detection sensor 13, a shift position sensor 14, and a clutch pedal stroke sensor 15 may also be mounted on the electric vehicle 100 and connected to the control device 101 via the on-board network.

[0025] The control device 101 generates control signals for various controls of the electric vehicle 100 based on signals acquired from each sensor. The control device 101 is typically an electronic control unit (ECU). The control device 101 may be a combination of multiple ECUs. The control device 101 includes one or more processors 102 (hereinafter simply referred to as processors 102) and one or more storage devices 103 (hereinafter simply referred to as storage devices 103).

[0026] The processor 102 executes various processes. The processor 102 may be configured, for example, as a general-purpose processor, a special-purpose processor, a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), an integrated circuit, a conventional circuit, or a combination of one or more of these. The processor 102 may also be referred to as circuitry or processing circuitry. Circuitry is hardware programmed to realize the functions of the control device 101, or hardware that executes the functions of the control device 101.

[0027] The storage device 103 stores various types of information required for the processor 102 to execute processing. The storage device 103 is configured with a recording medium such as a random access memory (RAM), a read only memory (ROM), a solid state drive (SSD), or a hard disk drive (HDD). The storage device 103 stores a computer program 104 executable by the processor 102 and various data 105. The computer program 104 is configured with a plurality of instruction codes that describe the processing to be executed by the processor 102. The computer program 104 is recorded on a computer-readable recording medium. The functions of the control device 101 are realized by cooperation between the processor 102, which executes the computer program 104, and the storage device 103.

[0028] 3. Electric vehicle drive control The control device 101 controls the electric motors 4F, 4R to control the drive of the electric vehicle 100. FIG. 2 is a block diagram showing the functional configuration of the control device 101 related to the drive control of the electric vehicle 100. The control device 101 includes functional blocks: a required torque calculation unit 110, a required torque acquisition unit 120, a required torque arbitration unit 130, and a motor control unit 140. These functional blocks are realized by the cooperation of a processor 102 and a storage device 103. Information required to execute processing is stored in the storage device 103 as data 105.

[0029] The required torque calculation unit 110 calculates the required torque CT for the drive system of the electric vehicle 100 in response to the operation of the accelerator operation device 22, the pseudo shifter 24, and the pseudo clutch pedal 25. The required torque calculation unit 110 receives signals from the vehicle speed sensor 11, the accelerator operation amount detection sensor 12, the shift position sensor 14, and the clutch pedal stroke sensor 15.

[0030] In this embodiment, the control device 101 controls the electric vehicle 100 to simulate the driving characteristics of a virtual vehicle, which is a manually variable-speed engine vehicle. For this purpose, the required torque calculation unit 110 calculates the required torque CT using a vehicle model ML1 that models the virtual vehicle to be simulated.

[0031] As shown in FIG. 3 , the vehicle model ML1 includes an engine model ML11, a clutch model ML12, and a transmission model ML13. The engine model ML11 models a virtual engine of the virtual vehicle. The clutch model ML12 models a virtual clutch of the virtual vehicle. The transmission model ML13 models a virtual transmission of the virtual vehicle. The vehicle model ML1 can also be referred to as a plant model of a virtual powertrain of the virtual vehicle. The vehicle model ML1 is generated in advance and stored in the storage device 103 as data 105. In particular, multiple vehicle models ML1 corresponding to multiple types of virtual vehicles may be stored in the storage device 103. The required torque calculation unit 110 may then read out a vehicle model ML1 to be used from the multiple vehicle models ML1. The control device 101 may receive a selection input from a user via the HMI 20, selecting one of the multiple types of virtual vehicles. In this case, the required torque calculation unit 110 may be configured to read out the vehicle model ML1 corresponding to the selected virtual vehicle.

[0032] The engine model ML11 calculates a virtual engine speed Ne and a virtual engine torque Te. The virtual engine speed Ne is calculated from the output shaft speed and gear ratio Gr of the virtual transmission. The output shaft speed of the virtual transmission is calculated from the vehicle speed and the reduction ratio determined by the mechanical structure from the virtual transmission to the drive wheels. Alternatively, the output shaft speed of the virtual transmission may be calculated from the motor speeds of the electric motors 4F and 4R. The engine model ML11 defines a relationship between the virtual engine speed Ne and the virtual engine torque Te for each operation amount (e.g., accelerator opening) of the accelerator operation device 22. In other words, the virtual engine torque Te is calculated from the operation amount of the accelerator operation device 22 and the virtual engine speed Ne. When the virtual engine and virtual transmission are in a power disconnected state (e.g., when the shift position is changed using the pseudo shifter 24), the engine model ML11 calculates the virtual engine speed Ne from the current virtual engine torque Te and specification information of the virtual engine.

[0033] The clutch model ML12 calculates a torque transmission gain. The torque transmission gain is a gain for calculating the degree of torque transmission of the virtual clutch according to the clutch opening. In the clutch model ML12, the torque transmission gain is given with respect to the clutch opening. The torque transmission gain is converted into the clutch torque capacity of the virtual clutch (virtual clutch torque capacity). Then, based on a comparison between the virtual clutch torque capacity and the virtual engine torque calculated by the engine model ML11, the virtual clutch torque input from the virtual clutch to the virtual transmission is calculated.

[0034] The transmission model ML13 calculates the gear ratio Gr. The gear ratio Gr is set for each shift position. In the example shown in FIG. 3, the maximum gear ratio is set for 1st, and the gear ratios Gr decrease in the order of 2nd, 3rd, 4th, 5th, and 6th. The shift position is determined by a signal from the shift position sensor 14. The transmission model ML13 further calculates the output torque of the virtual transmission using the gear ratio Gr and the virtual clutch torque.

[0035] The output torque of the virtual transmission is the required torque CT calculated by the required torque calculation unit 110. In this way, the required torque calculation unit 110 calculates the required torque CT using the vehicle model ML1. As described above, the required torque CT depends on the amount of operation of the accelerator operation device 22.

[0036] The electric vehicle 100 has various control functions that instruct the required torque for the drivetrain. For example, the electric vehicle 100 has a control function related to driving assistance control. Examples of driving assistance control include an Advanced Emergency Braking System (AEBS), a Lane Keeping Assist System (LKAS), and an Adaptive Cruise Control (ACC). The electric vehicle 100 also has a control function related to component protection. Examples of component protection include suppressing excessive temperature increases in the battery 2 and the electric motors 4F and 4R, and preventing excessive current from flowing through the electric motors 4F and 4R. When these control functions are activated, the required torque is instructed according to the purpose of the control. Typically, the required torque is instructed to be limited to a certain value or less. For example, when the AEBS is activated, the required torque is instructed so that the electric vehicle 100 decelerates. The required torque instructed by the activation of the control functions can be said to be a required torque that does not depend on the amount of operation of the accelerator operation device 22.

[0037] The required torque obtaining unit 120 obtains the required torque AT that does not depend on the amount of operation of the accelerator operation device 22. In the following description, the required torque AT obtained by the required torque obtaining unit 120 is referred to as the "first required torque AT." Furthermore, the required torque CT calculated by the required torque calculation unit 110 is referred to as the "second required torque CT."

[0038] The required torque arbitration unit 130 arbitrates between the first required torque AT and the second required torque CT, and outputs the required torque Tp after arbitration (hereinafter referred to as the "final required torque Tp"). As described above, the first required torque AT is generated when the control function is activated. Proper operation of the control function is important from the perspective of the safety of the electric vehicle 100, etc. Therefore, the required torque arbitration unit 130 arbitrates between the first required torque AT and the second required torque CT so as to give priority to the first required torque AT. In other words, when the first required torque AT is generated (when the control function is activated), the required torque arbitration unit 130 outputs the first required torque AT as the final required torque Tp. On the other hand, when the first required torque AT is not generated (when the control function is not activated), the required torque arbitration unit 130 outputs the second required torque CT as the final required torque Tp. When the first required torque AT is generated (when the operation of the control function starts), the required torque arbitration unit 130 may perform a gradual change process to gradually change the final required torque Tp from the second required torque CT to the first required torque AT. Similarly, when the generation of the first required torque AT ends (when the operation of the control function ends), the required torque arbitration unit 130 may perform a gradual change process to gradually change the final required torque Tp from the first required torque AT to the second required torque CT.

[0039] The motor control unit 140 acquires the final required torque Tp output from the required torque arbitration unit 130. The motor control unit 140 controls the electric motors 4F, 4R via the inverters 3F, 3R so that the electric vehicle 100 is driven at the acquired final required torque Tp. As a result, when the final required torque Tp is the second required torque CT, driving of the electric vehicle 100 that simulates the driving characteristics of the virtual vehicle represented by the vehicle model ML1 is realized. Furthermore, when the final required torque Tp is the first required torque AT, drive control of the electric vehicle 100 is realized using the control function.

[0040] 4. Sound Control The control device 101 performs sound control to control the sound output from the speaker 21. In particular, in the sound control, the control device 101 generates an artificial sound linked to the torque required for the drivetrain of the electric vehicle 100 and outputs the generated artificial sound from the speaker 21. The artificial sound is, for example, a "pseudo engine sound" that simulates the engine sound of a virtual engine of a virtual vehicle. However, in this embodiment, the artificial sound output from the speaker 21 by sound control is not limited to the pseudo engine sound. For example, the artificial sound may be a pseudo drive sound that simulates the drive sound of a moving object other than an automobile (e.g., a train, an airplane, etc.). As another example, the artificial sound may be music.

[0041] 4.1 Comparative Example Fig. 4 is a block diagram showing a comparative example of the functional configuration of the control device 101 related to sound control compared to this embodiment. In the comparative example shown in Fig. 4, the control device 101 includes, as functional blocks, a required torque calculation unit 110, an artificial sound generation unit 210, and a sound output control unit 220. These functional blocks are realized by cooperation between the processor 102 and the storage device 103.

[0042] The artificial sound generation unit 210 (artificial sound simulator) is a simulator that generates an artificial sound. In the comparative example shown in FIG. 4, the artificial sound generation unit 210 acquires sound generation parameters SP that determine the characteristics (e.g., sound pressure, frequency, etc.) of the artificial sound from the required torque calculation unit 110. When the artificial sound is a pseudo-engine sound, the sound generation parameters SP are typically a virtual engine torque Te and a virtual engine speed Ne. The virtual engine torque Te and the virtual engine speed Ne are calculated in the engine model ML11. The sound generation parameters SP can be configured appropriately depending on the artificial sound to be generated. For example, the sound generation parameter SP may be a second required torque CT calculated by the required torque calculation unit 110.

[0043] The artificial sound generation unit 210 uses the acquired sound generation parameters SP and sound source to generate an artificial sound according to the sound generation parameters SP. For example, consider a case where the artificial sound is a pseudo-engine sound, and the virtual engine rotation speed Ne and the virtual engine torque Te are the sound generation parameters SP. In this case, the artificial sound generation unit 210 generates a pseudo-engine sound by increasing or decreasing the sound pressure in proportion to the virtual engine torque Te and increasing or decreasing the frequency in proportion to the virtual engine rotation speed Ne. The sound source is stored in the storage device 103 as data 105, and in particular, multiple sound sources may be stored in the storage device 103. The artificial sound generation unit 210 may then read out a sound source to be used from the multiple sound sources. For example, the artificial sound generation unit 210 may be configured to read out a sound source corresponding to the vehicle model ML1 used in the required torque calculation unit 110. The artificial sound generation unit 210 outputs artificial sound data ES indicating the generated artificial sound.

[0044] The sound output control unit 220 acquires the artificial sound data ES generated by the artificial sound generation unit 210. The sound output control unit 220 outputs the artificial sound from the speaker 21 based on the artificial sound data ES.

[0045] In this way, in the comparative example, an artificial sound linked to the torque required for the drivetrain of the electric vehicle 100 is generated and output from the speaker 21. In particular, in the comparative example, an artificial sound linked to the second required torque CT calculated by the required torque calculation unit 110 is generated and output from the speaker 21. The second required torque CT is a required torque that depends on the amount of operation of the accelerator operation device 22. By outputting an artificial sound linked to the torque required for the drivetrain of the electric vehicle 100 from the speaker 21, the driver can enjoy a sound that is in line with the driving state of the electric vehicle 100.

[0046] However, as explained in Section 3, when the control function of the electric vehicle 100 is activated, the electric vehicle 100 drives in accordance with the first required torque AT, which is different from the second required torque CT. The first required torque AT is a required torque that does not depend on the amount of operation of the accelerator operating device 22. For this reason, in the comparative example, when the control function of the electric vehicle 100 is activated (when the first required torque AT is generated), a discrepancy occurs between the driving state of the electric vehicle 100 and the artificial sound that is output, which may cause the driver to feel uncomfortable.

[0047] FIG. 5 is a time chart showing an example of sound control by the control device 101 according to the comparative example. The example shown in FIG. 5 illustrates a case where the driver maintains a constant amount of operation (accelerator opening) of the accelerator operating device 22. Therefore, the second required torque CT is constant. Furthermore, in the example shown in FIG. 5, the sound generation parameter SP is the virtual engine torque Te and the virtual engine speed Ne. In the example shown in FIG. 5, the operation of the control function starts at time t1 and ends at time t2. Therefore, the final required torque Tp is the first required torque AT from time t1 to time t2. In other words, the electric vehicle 100 is driven in accordance with the first required torque AT from time t1 to time t2. Meanwhile, in the comparative example, an artificial sound linked to the second required torque CT is generated from time t1 to time t2. In the example shown in FIG. 5, it can be seen that the virtual engine torque Te and the virtual engine speed Ne, which are the sound generation parameters SP, do not change from time t1 to time t2. As a result, a discrepancy occurs between the driving state of the electric vehicle 100 and the artificial sound that is output between time t1 and time t2.

[0048] As described above, in the comparative example, there is a risk that a discrepancy will occur between the driving state of the electric vehicle 100 and the output artificial sound, causing the driver to feel uncomfortable. Therefore, this embodiment proposes a control device 101 that is capable of outputting artificial sound that does not cause the driver to feel uncomfortable even when the first required torque AT is generated. The sound control by the control device 101 according to this embodiment will be described below.

[0049] 4.2 Functional Configuration Fig. 6 is a block diagram showing the functional configuration of the control device 101 related to sound control according to this embodiment. The functional configuration shown in Fig. 6 further includes a required torque acquisition unit 120 and a sound generation parameter acquisition unit 200 as functional blocks compared to the comparative example shown in Fig. 4. These functional blocks are realized by cooperation between the processor 102 and the storage device 103.

[0050] 6, the artificial sound generation unit 210 is configured to acquire sound generation parameters SP from the sound generation parameter acquisition unit 200. The sound generation parameter acquisition unit 200 generates and outputs the sound generation parameters SP through communication with the required torque calculation unit 110 and the required torque acquisition unit 120. The sound generation parameter acquisition unit 200 has two modes for the sound generation parameters SP to be output: a "first mode" and a "second mode."

[0051] In the first mode, the sound generation parameter acquisition unit 200 outputs a sound generation parameter SP that causes the artificial sound generation unit 210 to generate an artificial sound that is linked to the first required torque AT acquired by the required torque acquisition unit 120. On the other hand, in the second mode, the sound generation parameter acquisition unit 200 outputs a sound generation parameter SP that causes the artificial sound generation unit 210 to generate an artificial sound that is linked to the second required torque CT calculated by the required torque calculation unit 110. An example of the sound generation parameter SP that is generated in each of the first mode and the second mode will be described later.

[0052] The sound generation parameter acquisition unit 200 selects one of the first mode and the second mode by executing a mode selection process P10. Figure 7 is a flowchart showing the processing flow of the mode selection process P10. The processing flow shown in Figure 7 is repeatedly executed at a predetermined processing cycle.

[0053] In the mode selection process P10, the sound generation parameter acquisition unit 200 first determines whether or not the first required torque AT is being generated through communication with the required torque acquisition unit 120 (step S100). If the first required torque AT is being generated (step S100; Yes), the sound generation parameter acquisition unit 200 selects the first mode (step S110). On the other hand, if the first required torque AT is not being generated (step S100; No), the sound generation parameter acquisition unit 200 selects the second mode (step S120).

[0054] Referring again to Figure 6, the artificial sound generation unit 210 uses the sound generation parameters SP and a sound source acquired from the sound generation parameter acquisition unit 200 to generate an artificial sound corresponding to the sound generation parameters SP. In particular, when the first mode is selected in the sound generation parameter acquisition unit 200, the artificial sound generation unit 210 generates an artificial sound linked to the first required torque AT. Therefore, at this time, the artificial sound linked to the first required torque AT is output from the speaker 21. On the other hand, when the second mode is selected in the sound generation parameter acquisition unit 200, the artificial sound generation unit 210 generates an artificial sound linked to the second required torque CT. Therefore, at this time, the artificial sound linked to the second required torque CT is output from the speaker 21.

[0055] As described above, according to this embodiment, the sound generation parameter acquisition unit 200 has a first mode for causing the artificial sound generation unit 210 to generate an artificial sound linked to the first required torque AT. As a result, when the first required torque AT is generated, the first mode allows the speaker 21 to output an artificial sound linked to the first required torque AT. In this way, the control device 101 according to this embodiment can output an artificial sound that is in line with the driving state of the electric vehicle even when the first required torque AT is generated. As a result, the sense of discomfort felt by the driver can be reduced. Furthermore, the control method according to this embodiment is realized by the processing executed by the control device 101 in this way. Furthermore, the control program according to this embodiment is realized by the computer program 104 that causes the control device 101 to execute the processing in this way.

[0056] 4.3 Examples of sound generation parameters FIG. 8 is a block diagram showing an example of output of sound generation parameters SP by the sound generation parameter acquisition unit 200. The example shown in FIG. 8 illustrates a case where the artificial sound is a pseudo engine sound. In the example shown in FIG. 8, the sound generation parameter acquisition unit 200 first executes process P20 based on the first required torque AT and the gear ratio Gr. The first required torque AT is acquired from the required torque acquisition unit 120. The gear ratio Gr is calculated in the transmission model ML13 and acquired from the required torque calculation unit 110. In process P20, an engine torque BTe of the virtual engine, in which the output torque of the virtual transmission is the first required torque AT, is back-calculated. That is, BTe = AT / Gr. Hereinafter, the engine torque BTe of the virtual engine back-calculated in process P20 will be referred to as the "first virtual engine torque BTe," and the virtual engine torque Te calculated in the engine model ML11 will be referred to as the "second virtual engine torque Te." The first virtual engine torque BTe is related to the first required torque AT, and the second virtual engine torque Te is related to the second required torque CT.

[0057] In the example shown in FIG. 8, the sound generation parameter acquisition unit 200 then executes process P30 to select one of the first virtual engine torque BTe and the second virtual engine torque Te. If the first mode is selected, the sound generation parameter acquisition unit 200 selects the first virtual engine torque BTe in process P30. On the other hand, if the second mode is selected, the sound generation parameter acquisition unit 200 selects the second virtual engine torque Te in process P30. The sound generation parameter acquisition unit 200 outputs the virtual engine rotation speed Ne and the virtual engine torque STe selected in process P30 (hereinafter referred to as the "final virtual engine torque STe") as the sound generation parameter SP.

[0058] When the first mode is selected, the final virtual engine torque STe is the first virtual engine torque BTe related to the first required torque AT. Therefore, the sound generation parameter SP related to the first mode causes the artificial sound generation unit 210 to generate a pseudo engine sound that is linked to the first required torque AT. Specifically, a pseudo engine sound whose sound pressure changes in accordance with the first required torque AT is generated. On the other hand, when the second mode is selected, the final virtual engine torque STe is the second virtual engine torque Te related to the second required torque CT. Therefore, the sound generation parameter SP related to the second mode causes the artificial sound generation unit 210 to generate a pseudo engine sound that is linked to the second required torque CT. Specifically, a pseudo engine sound whose sound pressure changes in accordance with the second required torque CT is generated.

[0059] As a modification, in the example shown in FIG. 8 , the required torque acquisition unit 120 may be replaced with the required torque arbitration unit 130. In this case, the sound generation parameter acquisition unit 200 executes the process P20 based on the final required torque Tp and the gear ratio Gr acquired from the required torque arbitration unit 130. That is, BTe = Tp ÷ Gr. When the first required torque AT is generated, the final required torque Tp becomes the first required torque AT. Therefore, even in this case, when the first mode is selected, the final virtual engine torque STe becomes equal to the first virtual engine torque BTe. Furthermore, when the required torque arbitration unit 130 is performing a gradual change process, this gradual change process can be taken into consideration. For example, when switching from the first mode to the second mode (when the operation of the control function ends), the final required torque Tp gradually changes from the first required torque AT to the second required torque CT. Furthermore, when switching from the second mode to the first mode (when the control function starts to operate), the final required torque Tp gradually changes from the second required torque CT to the first required torque AT.

[0060] FIG. 9 is a time chart showing an example of sound control by the control device 101 according to this embodiment, based on the configuration of the sound generation parameter acquisition unit 200 shown in FIG. 8 . The example shown in FIG. 8 , similar to the case shown in FIG. 5 , illustrates a case in which the driver maintains a constant operation amount (accelerator opening) of the accelerator operation device 22. Furthermore, in the example shown in FIG. 8 , operation of the control function starts at time t1 and ends at time t2. Therefore, similar to the case shown in FIG. 5 , the final required torque Tp is equal to the first required torque AT between time t1 and time t2. At this time, as shown in FIG. 9 , according to this embodiment, an artificial sound linked to the first required torque AT is generated between time t1 and time t2. In the example shown in FIG. 9 , it can be seen that the final virtual engine torque STe, which is the sound generation parameter SP, is equal to the first virtual engine torque BTe linked to the first required torque AT between time t1 and time t2. As a result, in the example shown in FIG. 9 , an artificial sound in accordance with the driving state of the electric vehicle 100 is output even between time t1 and time t2. As described above, according to this embodiment, even when the first required torque is generated, it is possible to output an artificial sound that is in line with the driving state of the electric vehicle.

[0061] 5. Other In this embodiment, the drive system of the electric vehicle 100 may have other configurations. For example, the electric vehicle 100 may be a two-wheel drive vehicle that includes only one electric motor and one inverter, and the electric motor drives either the front wheels or the rear wheels. Alternatively, the electric vehicle 100 may be a four-wheel drive vehicle that includes only one electric motor and one inverter, and drives both the front and rear wheels by distributing the output of the electric motor to the front and rear wheels using a transfer case.

[0062] Furthermore, in this embodiment, the pseudo shifter 24 and the pseudo clutch pedal 25 are not essential components. The technical features of this embodiment can also be applied to an electric vehicle 100 that does not have the pseudo shifter 24 or the pseudo clutch pedal 25. In this case, the virtual vehicle simulated in the drive control of the electric vehicle 100 may be an automatic transmission engine vehicle.

[0063] In this embodiment, the electric vehicle 100 may also have a control mode in which it operates with the driving characteristics of a normal EV. [Explanation of symbols]

[0064] 100 electric vehicles 101 Control device 102 processors 21 Speaker 22 Accelerator operating device

Claims

1. An electric vehicle having an electric motor as a drive source, one or more processors that generate an artificial sound linked to a torque required for a driveline of the electric vehicle and output the artificial sound from a speaker mounted on the electric vehicle; In a first mode, the one or more processors are configured to generate the artificial sound linked to a first required torque that is independent of an operation amount of an accelerator operation device of the electric vehicle. Electric car.

2. 10. The electric vehicle according to claim 1, The first required torque includes the required torque required by operation of driving assistance control of the electric vehicle. Electric car.

3. 10. The electric vehicle according to claim 1, In a second mode, the one or more processors are configured to generate the artificial sound linked to a second required torque that depends on the operation amount of the accelerator operation device. Electric car.

4. 4. The electric vehicle according to claim 3, the one or more processors: When the first required torque is generated, the first mode is selected; When the first required torque is not generated, the second mode is selected. It was configured as Electric car.

5. 5. The electric vehicle according to claim 4, the one or more processors: When switching from the first mode to the second mode, the required torque is gradually changed from the first required torque to the second required torque; When switching from the second mode to the first mode, the required torque is gradually changed from the second required torque to the first required torque. It was configured as Electric car.

6. 6. The electric vehicle according to claim 1, The artificial sound is a pseudo engine sound that simulates the engine sound of a virtual engine. Electric car.

7. 7. The electric vehicle according to claim 6, In the first mode, the one or more processors: reversely calculating an engine torque of the virtual engine from the first required torque; The pseudo engine sound that changes in response to the back-calculated engine torque is generated. It was configured as Electric car.

8. 8. The electric vehicle according to claim 7, The one or more processors further A second required torque dependent on the operation amount of the accelerator operation device is calculated so as to simulate the driving characteristics of a virtual vehicle equipped with the virtual engine. It was configured as Electric car.

9. 9. The electric vehicle according to claim 8, A pseudo shifter, A pseudo clutch operating device; Furthermore, the one or more processors: The second required torque is changed in accordance with the operation of the pseudo shifter and the operation of the pseudo clutch operating device. It was configured as Electric car.

10. A control method for controlling an electric vehicle having an electric motor as a drive source, comprising: generating an artificial sound linked to a torque demanded for a drivetrain of the electric vehicle; The artificial sound is output from a speaker mounted on the electric vehicle. This includes: In the first mode, the artificial sound is generated in accordance with a first required torque that is not dependent on an operation amount of an accelerator operation device of the electric vehicle. Control method.

11. A control program for controlling an electric vehicle having an electric motor as a drive source, The method is configured to cause a computer to execute a process of generating an artificial sound linked to a torque required for a drivetrain of the electric vehicle and outputting the artificial sound from a speaker mounted on the electric vehicle, In a first mode, the computer is configured to execute a process of generating the artificial sound linked to a first required torque that is independent of an operation amount of an accelerator operation device of the electric vehicle. Control program.

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