JP7655089B2 - Control method for electric vehicle and control device for electric vehicle - Google Patents

Description

The present invention aims to provide a method for controlling an electric vehicle and a control device for an electric vehicle.

When a driver drives a vehicle, the driver can select a specific driving mode from among multiple driving modes, allowing the vehicle to run according to the selected driving mode. For example, Patent Document 1 discloses a technology in which a driver selects one of three driving modes and drives the vehicle in accordance with the selected mode.

JP 2014-129026 A

According to the technology disclosed in Patent Document 1, a dial-type switch or the like is used as a means for selecting a driving mode. However, since manual switch operation is required to select a driving mode, the driver must perform operations other than the conventional driving operations of the steering wheel and pedals.

According to one aspect of the present invention, in a control method for an electric vehicle that controls a motor as a drive source in accordance with an accelerator opening, a first operation region, a second operation region in which the accelerator opening is smaller than the first operation region, and a third operation region in which the accelerator opening is smaller than the second operation region are provided as regions corresponding to the magnitude of the accelerator opening. According to the control method for an electric vehicle, when the accelerator opening is included in the second operation region, a torque command value for the motor is changed in accordance with a driving pattern corresponding to the surrounding conditions of the electric vehicle, and when the accelerator opening is included in the first operation region and the third operation region, the motor is driven to generate a drive force corresponding to the accelerator opening.

According to one aspect of the driving assistance device of the present invention, it is possible to facilitate the driver's selection of a driving mode.

FIG. 1 is a block diagram showing the configuration of a vehicle according to this embodiment. FIG. 2 is a schematic diagram illustrating the accelerator opening. FIG. 3 is a flowchart showing the driving force control. FIG. 4 is a timing chart showing a case where the vehicle starts moving when the traffic light ahead changes to a start permission state. FIG. 5 is a timing chart for when the vehicle starts moving over a step in a paid parking lot. FIG. 6 is a flowchart showing a driving force control according to a modified example.

Next, an embodiment of the present invention will be described in detail with reference to the drawings. In the description, the same parts will be given the same reference numerals and duplicated description will be omitted. Note that in each embodiment, an example will be described in which a motor is the driving source and a hybrid vehicle is provided with an engine capable of generating power to be supplied to the motor, but this is not limited to this. The present invention may also be implemented in an electric vehicle that does not have an engine, an electric vehicle that has a fuel cell as a power generation source, etc.

Figure 1 is a schematic diagram of a vehicle 100 according to this embodiment. The vehicle 100 is a hybrid vehicle equipped with an engine 1 (internal combustion engine), a generator 2 (electric motor), a motor 3 (drive source), a battery 4, and wheels 7 (drive wheels). In the vehicle 100, the driving force of the vehicle 100 is obtained not from the engine 1, but from the motor 3 which is driven to rotate by receiving power from the battery 4. Such a vehicle 100 is called a series hybrid vehicle because the engine 1, battery 4, motor 3, and wheels 7 are connected in series (series connection). The motor 3 is also sometimes called a drive motor because it serves as the drive source of the vehicle.

The engine 1 is mechanically connected to the generator 2. The generator 2 is electrically connected to the battery 4 so that it can transmit and receive electricity. The generator 2 and the motor 3, and the motor 3 and the battery 4 are electrically connected so that they can transmit and receive electricity. The motor 3 is mechanically connected to the axle 6 via the gear 5, and the axle 6 is connected to the wheels 7.

The driving torque generated by the engine 1 is transmitted to the generator 2, and the generator 2 rotates using the engine 1 as a driving source to generate electricity. When the generated power of the generator 2 flows to the battery 4, the power is charged to the battery 4. When the generated power of the generator 2 flows to the motor 3, the power is used to drive the motor 3.

The motor 3 receives power from either the generator 2 or the battery 4, or both, and rotates using the power to generate drive torque. The drive torque of the motor 3 is transmitted to the wheels 7 via the gears 5 and the axles 6. The wheels 7 rotate due to the drive torque of the motor 3, causing the vehicle 100 to travel.

When the vehicle 100 decelerates or when the vehicle 100 descends a slope, the motor 3 operates as a generator and generates regenerative power. When the motor 3 generates regenerative power, a regenerative braking force is generated in the wheels 7 via the gear 5 and the axle 6. In addition, the regenerative power generated by the motor 3 flows to the battery 4, and the regenerative power charges the battery 4.

The battery 4 is a secondary battery that can be charged and discharged. The battery 4 can be charged with the power generated by the generator 2 and the power generated by the motor 3 that performs regenerative braking. On the other hand, the battery 4 discharges when supplying power to the motor 3.

The direction of power exchange between the generator 2, motor 3, and battery 4 can change based on the charging state of the battery 4, the driving state of the motor 3, etc., depending on the driving situation of the vehicle and the power supply and demand situation of the entire vehicle including auxiliary equipment installed in the vehicle (air conditioner, car stereo, navigation system, etc.). The direction of power exchange between the generator 2, motor 3, and battery 4 is determined by the control of the controller 10, which will be described later.

For example, when the motor 3 needs to generate driving force, power is supplied from the battery 4 to the motor 3. When the battery 4 cannot supply sufficient power to the motor 3, the engine 1 is driven to generate power in the generator 2, and the power generated by the generator 2 in addition to the power stored in the battery 4 is supplied to the motor 3.

When charging of the battery 4 is not complete, regenerative power generated by the motor 3 when the vehicle decelerates or descends a slope is supplied from the motor 3 to the battery 4. Furthermore, when charging of the battery 4 is not complete, the engine 1 may be driven to generate power in the generator 2, and the power generated in the generator 2 may be supplied to the battery 4.

When the state of charge (SOC) of the battery 4 is high (high SOC), the regenerative power generated by the motor 3 when the vehicle decelerates or descends a slope is supplied to the generator 2. In this case, the regenerative power supplied from the motor 3 to the generator 2 is forcibly discharged.

The vehicle 100 includes a controller 10 for overall control, a function switch 11, a select lever 12, a brake sensor 13, an accelerator position sensor 14 (APS), a camera 15, a GPS 16, a communication unit 17, and a gyro sensor 18. The controller 10 is electrically connected to each of the function switch 11, the select lever 12, the brake sensor 13, the accelerator position sensor 14, the camera 15, the GPS 16, the communication unit 17, and the gyro sensor 18.

The function switch 11 is a switch configured to be operable by the driver. When one of the multiple driving support functions is selected by operating the function switch 11, a signal indicating the selected driving support function is output to the controller 10. The driving support functions selectable by the function switch 11 include a vehicle following driving support function that automatically follows a vehicle ahead. When the vehicle following driving support function is executed, the speed of the vehicle 100 and the distance to the vehicle ahead are automatically adjusted, and the vehicle 100 follows the vehicle ahead. In the vehicle following driving support function, the accelerator, brakes, and steering may all be automatically controlled, and such a function can reduce the burden on the driver. In the vehicle following driving support function, for example, in addition to controlling the vehicle to maintain a constant distance from the vehicle ahead at a vehicle speed (30 to 100 km/h) set by the driver, steering control may be performed to drive in the center of the lane. In addition, when the vehicle following driving support function is being executed, a message to that effect is displayed on the display.

The select lever 12 is a lever used to select a driving range by the driver. Ranges selectable by the select lever 12 include, for example, a drive range (D), a brake range (B), a reverse range (R), a neutral range (N), and a parking range (P). The controller 10 receives a signal indicating the driving range selected by the select lever 12.

The brake sensor 13 is located near the brake pedal and detects the amount of brake pedal operation by the driver. When the brake sensor 13 detects the amount of brake pedal operation by the driver, it outputs a signal indicating the amount of operation to the controller 10 in order to generate a braking force according to the detected amount of operation.

The accelerator position sensor 14 is located near the accelerator pedal and detects the amount of accelerator pedal operation by the driver. When the accelerator position sensor 14 detects the accelerator opening degree Ac, which is the amount of accelerator pedal operation by the driver, it outputs a signal indicative of the detected accelerator opening degree Ac to the controller 10.

When the camera 15 captures an image of the area around the vehicle 100, it outputs the captured image or video data to the controller 10. When the GPS (Global Positioning System) 16 acquires location information of the vehicle 100, it outputs the acquired location information to the controller 10. The communication unit 17 is configured to be able to communicate with various devices including a server via a network, and acquires information about the conditions around the vehicle 100, such as traffic conditions and weather information. When the gyro sensor 18 detects the inclination and acceleration of the vehicle 100, it outputs the detected angle and acceleration to the controller 10.

The controller 10 is electrically connected to the engine 1, the generator 2, and the motor 3 via signal lines. The controller 10 calculates a torque command value Tc and transmits it to the motor 3 in order to cause the motor 3 to generate a driving torque corresponding to the accelerator opening Ac. Note that the motor 3 may be controlled by the rotation speed instead of the torque. Since the correlation between the rotation speed and the vehicle speed is determined by the configuration ratio of the gears 5, the vehicle speed can be directly controlled when the rotation speed is controlled.

At the same time, the controller 10 controls the engine 1, the generator 2, and the motor 3 according to the state of charge (SOC) of the battery 4. The controller 10 controls the drive states of the engine 1, the generator 2, and the motor 3, and also determines the states of other auxiliary machinery (not shown), thereby determining the flow of power between the generator 2, the motor 3, and the battery 4.

The controller 10 can be realized, for example, by a general-purpose microcomputer equipped with a CPU (central processing unit), memory, and an input/output unit. A computer program (control program) for causing the microcomputer to function as the controller 10 is installed in the microcomputer and executed. In this way, the general-purpose microcomputer functions as the controller 10.

In this embodiment, an example is shown in which the controller 10 is realized by software, but it is also possible to configure the controller 10 by preparing dedicated hardware for executing each of the information processes described below. In addition, multiple units included in the controller 10 may be configured by individual hardware. Furthermore, the controller 10 may also be used as an electronic control unit (ECU) used for other control related to the vehicle.

Next, a method for controlling the motor 3 during normal driving when the adaptive cruise control function is not being executed will be described with reference to Figures 2 and 3. Here, Figure 2 is an explanatory diagram of the level of accelerator opening degree Ac. Figure 3 is a flowchart showing the control of the motor 3 according to the accelerator opening degree Ac.

Figure 2 is an explanatory diagram of the amount of depression of the accelerator pedal. As shown in this figure, the accelerator opening Ac, which is determined according to the amount of depression of the accelerator pedal, is acquired by the accelerator position sensor 14 and is included in one of the operation regions 21 to 23 indicated by three levels. The controller 10 then switches the calculation method of the torque command value Tc depending on the operation region 21 to 23 in which the accelerator opening Ac falls.

When the accelerator pedal is not depressed, the accelerator opening degree Ac is 0, and the greater the accelerator pedal depression amount, the greater the accelerator opening degree Ac. In addition, a first operation area 21, a second operation area 22, and a third operation area 23 are provided in order of increasing accelerator opening degree Ac (depressed), and each operation area is adjacent to each other. Note that the third operation area 23 includes the case where the accelerator opening degree Ac is 0.

For example, when the driver depresses the accelerator pedal to start the vehicle 100, the operation region including the accelerator opening Ac transitions in the order of the third operation region 23, the second operation region 22, and the first operation region 21. In this transition, while the accelerator opening Ac is in the third operation region 23, the controller 10 generates a torque command value Tc corresponding to the accelerator opening Ac. Then, when the accelerator opening Ac falls within the second operation region 22, the controller 10 sets the torque command value Tc so as to perform the optimal driving force control described below regardless of the accelerator opening Ac. Then, when the accelerator opening Ac falls within the first operation region 21, the controller 10 again sets the torque command value Tc corresponding to the accelerator opening Ac.

The optimal driving force control is executed (ON) when the accelerator opening Ac is within the second operation region 22, and is not executed (OFF) when it is within the first operation region 21 and the third operation region 23. In other words, the optimal driving force control is selectively turned on/off depending on the accelerator opening Ac. Therefore, the second operation region 22 can be understood as the switch-on region of the optimal driving force control, and the first operation region 21 and the third operation region 23 as the switch-off region of the optimal driving force control.

When the accelerator opening degree Ac is within the second operation range 22, the controller 10 calculates the torque command value Tc for the motor 3 so as to achieve an optimal vehicle speed change according to the surrounding condition information of the vehicle 100, such as road and traffic conditions.

As an example of optimal driving force control, when the vehicle 100 turns left at an intersection after the traffic light ahead has changed to indicate OK to proceed (green), the torque command value Tc is changed so as to realize a change in vehicle speed so that the vehicle proceeds at a predetermined speed while turning left. For example, a general-purpose navigation system is used to determine the driving scene based on the position information acquired by the GPS 16. In addition to the selector lever 12, an on-board camera and a radar may be used as an auxiliary in determining the driving scene. Then, the vehicle speed is set according to the driving scene, and the torque command value for the motor 3 is set so that the vehicle speed becomes the set vehicle speed. Specifically, when starting at an intersection, the torque command value Tc is set so that the vehicle speed is about 20 km/h. As a result, the driver only needs to operate the accelerator pedal so that the accelerator opening Ac is included in the second operation region 22, so that the driver can concentrate on steering. As another example of optimal driving force control, when parking in a coin parking lot with a lock plate and setting off the vehicle 100 after paying, the vehicle 100 needs to move forward or backward over a step caused by the stored lock plate. In such a case, the controller 10 generates a torque command value Tc that does not cause shaking inside the vehicle 100. Specifically, when climbing over a folded lock plate in a coin parking lot or the like, the torque command value Tc is set so that the vehicle speed is about 5 to 7 km/h. As a result, discomfort caused by the vertical acceleration of the vehicle 100 can be suppressed.

On the other hand, in the first operation region 21 and the third operation region 23, the optimal driving force control is not executed. In the first operation region 21, the torque command value Tc is set according to the accelerator opening Ac operated by the driver. When the accelerator opening Ac is included in the third operation region 23 and the accelerator opening Ac transitions from zero to the third operation region 23, the vehicle 100 starts, so the torque command value Tc is set according to the accelerator opening Ac operated by the driver. On the other hand, when the accelerator opening Ac is included in the third operation region 23 and the accelerator opening Ac transitions from the second operation region 22 to the third operation region 23, a negative torque command value Tc is generated so that the vehicle 100 stops. In this case, the negative torque command value Tc is set so that the absolute value becomes larger as the vehicle speed increases, and the absolute value becomes smaller as the vehicle speed decreases.

In this way, the driver can execute (ON) optimal driving force control by controlling the accelerator pedal so that the accelerator opening Ac falls within the range of the second operation region 22. As a result, the driver does not need to operate the accelerator precisely, reducing fatigue, and optimal driving according to the surrounding conditions of the vehicle 100 is possible regardless of the driver's skill.

In addition, the optimal driving force control can be switched on and off using a method that is easy for the driver to operate, such as the accelerator pedal, rather than using a manual switch, so there is no hassle with manual switch operation. Furthermore, because the second operation area 22 that performs optimal driving force control and the first operation area 21 that performs driving force control according to the accelerator opening Ac are continuous, the driver can feel as if he or she is driving according to his or her own will. In this way, it is possible to switch the optimal driving force control on and off in a relatively simple manner and in line with the driver's intentions.

Figure 3 is a flowchart showing the driving force control of this embodiment. Note that the control shown in the flowchart is performed when the vehicle 100 starts moving, and in the initial state, the vehicle speed is zero and the accelerator opening Ac is zero.

In step S1, the controller 10 acquires detection signals from the function switch 11, the select lever 12, the brake sensor 13, and the accelerator position sensor 14. Furthermore, the controller 10 acquires sensor values acquired by the gyro sensor 18, images captured by the camera 15, location information detected by the GPS 16, and traffic and weather information acquired via the communication unit 17. Note that acquisition of sensor detection values, etc. is not limited to step S1 and may be performed at any timing.

In step S2, the controller 10 determines whether the accelerator opening Ac is included in the third operation region 23. If the accelerator opening Ac is not included in the third operation region 23 (S2: No), the controller 10 next performs the process of step S4. If the accelerator opening Ac is included in the third operation region 23 (S2: Yes), the controller 10 next performs the process of step S3.

In step S3, the controller 10 performs driving force control according to the accelerator opening Ac. When the accelerator opening Ac changes from zero to the third operation range 23, the vehicle 100 is about to start, and it is determined that the driver is trying to obtain a larger driving force. Therefore, the controller 10 calculates a torque command value Tc according to the accelerator opening Ac. After completing the process of step S3, the controller 10 returns to the process of step S1 and acquires the sensor detection value again.

In step S4, the controller 10 determines the driving scene of the vehicle 100 based on the vehicle speed, current position, surrounding condition information (including traffic lights and weather conditions), and the inclination of the vehicle 100 acquired in step S1 (these may be collectively referred to as the surrounding conditions of the vehicle 100). For example, driving scenes include a case where the signal on the traffic light ahead changes from stop (red) to proceed (green) before the traffic light, or a case where the vehicle climbs over a folded lock plate while stopped in a coin parking lot and starts moving.

In step S5, the controller 10 reads out a vehicle speed map corresponding to the driving scene determined in step S4 from among the vehicle speed maps stored in accordance with the driving scene. The vehicle speed map shows the relationship between the elapsed time after starting and the vehicle speed. The controller 10 changes the torque command value Tc of the motor 3 so that the vehicle speed changes over time according to the vehicle speed map, thereby enabling optimal drive force control according to the driving scene.

In step S6, the controller 10 determines whether the accelerator opening Ac is within the second operation region 22. If the accelerator opening Ac is not within the second operation region 22 (S6: No), it is determined that the accelerator opening Ac has again entered a state within the third operation region 23 during the starting process, or has even entered a state within the first operation region 21, and the process returns to step S3. If the accelerator opening Ac is within the second operation region 22 (S6: Yes), the controller 10 determines that it is necessary to execute optimal driving force control, and then performs the process of step S7.

In step S7, the controller 10 calculates the torque command value Tc for the motor 3 based on the rotation speed input from the motor 3 so that the vehicle speed is as shown in the vehicle speed map selected in step S5. Since the vehicle speed map shows the vehicle speed that changes over time, it is possible to obtain the optimal driving force according to the driving conditions.

In step S8, the controller 10 again determines whether the accelerator opening Ac is within the second operation region 22. If the accelerator opening Ac is within the second operation region 22 (S8: Yes), the controller 10 determines that it is necessary to continue optimal driving force control, and then returns to step S1 to perform the sensor value acquisition process. On the other hand, if it is determined that the accelerator opening Ac is not within the second operation region 22, that is, is within the first operation region 21 or the third operation region 23 (S8: No), then the process of step S9 is performed.

In step S9, the controller 10 determines whether the accelerator opening Ac is included in the third operation region 23. If the accelerator opening Ac is not included in the third operation region 23 (S9: No), the controller 10 determines that the accelerator opening Ac is included in the first operation region 21, and then performs the process of step S12. On the other hand, if the accelerator opening Ac is included in the third operation region 23 (S9: Yes), the controller 10 then performs the process of step S10.

In step S10, the controller 10 performs optimal deceleration control according to the accelerator opening Ac. When the accelerator opening Ac changes from the second operation range 22 to the third operation range 23, it is determined that the driver is reducing the driving force. Therefore, the controller 10 calculates a smaller torque command value Tc so that the vehicle 100 decelerates. In optimal deceleration control, the controller 10 decelerates the vehicle 100 by generating a negative torque whose absolute value increases as the vehicle speed increases. This allows the vehicle 100 to decelerate from a state in which a driving force according to the optimal vehicle speed map is obtained to a stopped state. By performing such optimal deceleration control, deceleration can be performed without depressing the brake pedal, reducing the frequency of depressing the brake pedal and reducing the operational burden on the driver.

In step S11, the controller 10 determines whether the accelerator opening Ac has increased and is included in the second operation region 22. If the accelerator opening Ac is not included in the second operation region 22 (S11: No), the controller 10 determines that the accelerator opening Ac continues to be included in the third operation region 23, and then returns to step S10 to perform processing. On the other hand, if the accelerator opening Ac is included in the second operation region 22 (S11: Yes), the controller 10 returns to step S1 to perform processing again to perform optimal driving force control according to the driving scene.

On the other hand, in step S12, since the accelerator opening Ac is included in the first operation region 21, the controller 10 performs driving force control according to the accelerator opening Ac. When the accelerator opening Ac changes from the second operation region 22 to the first operation region 21, it is determined that the driver is attempting to obtain a larger driving force. Therefore, the controller 10 calculates a torque command value Tc according to the accelerator opening Ac so as to obtain a driving force exceeding the optimal driving force control.

In step S13, the controller 10 determines whether the accelerator opening Ac has decreased and is now in the second operation region 22. If the accelerator opening Ac is in the second operation region 22 (S13: Yes), the controller 10 returns to the process of step S1 to perform the sensor value acquisition process in order to perform optimal driving force control. If the accelerator opening Ac is not in the second operation region 22 (S13: No), the controller 10 next performs the process of step S14 to further determine whether the accelerator opening Ac is in the first operation region 21 or the third operation region 23.

In step S14, the controller 10 determines whether the accelerator opening Ac is within the third operation region 23. If the accelerator opening Ac is within the third operation region 23 (S14: Yes), the controller 10 next performs the process of step S10 to perform optimal deceleration control. On the other hand, if the accelerator opening Ac is not within the third operation region 23 (S14: No), it can be determined that the accelerator opening Ac is within the first operation region 21, and therefore the controller 10 next performs the process of step S12.

In this way, when the accelerator opening Ac is within the second operation region 22, optimal driving force control is performed (S7), and when the accelerator opening Ac is within the first operation region 21, which is larger than the second operation region 22, driving force control according to the accelerator opening Ac is performed (S12). When the accelerator opening Ac is within the third operation region 23, which is smaller than the second operation region 22, and the accelerator opening Ac increases from zero (S2: Yes), a driving force according to the accelerator opening Ac is generated (S3), and the vehicle 100 starts moving. On the other hand, when the accelerator opening Ac is within the third operation region 23 and the accelerator opening Ac decreases from the second operation region 22 (S2: Yes), optimal deceleration control is performed (S10).

In this way, when the accelerator opening Ac is within the second operation region 22, optimal driving force control is performed, making it possible to generate an optimal driving force according to the surrounding conditions. On the other hand, when the accelerator opening Ac is within the third operation region 23, which is larger than the second operation region 22 and is within the region (switch-off region) in which optimal driving force control is not performed, a driving force according to the accelerator opening Ac is generated, allowing the driver to obtain a driving force according to his or her own operation and reducing discomfort. On the other hand, when the accelerator opening Ac decreases and changes from the second operation region 22 to the first operation region 21, optimal deceleration control is performed to generate a negative torque according to the vehicle speed, allowing the vehicle to decelerate appropriately.

Next, the optimum driving force control according to the running state will be described with reference to FIG. 4 and FIG.
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Figure 4 is a timing chart for when the traffic light ahead turns green and the vehicle starts moving. In this diagram, the horizontal axis indicates time, and the vertical axis indicates the state of the vehicle 100. The vehicle state indicated vertically includes the state of the accelerator pedal operated by the driver, the accelerator opening Ac, the switch state of the optimal driving force control, the actual vehicle speed, and the vehicle acceleration.

From time t0 to t1, the vehicle 100 is stopped, and the vehicle speed and vehicle acceleration are both zero. Then, at time t1, the traffic light ahead of the vehicle 100 changes from a stop (red) signal to a go (green) signal, and the vehicle 100 accelerates from time t1 to t2. This causes the vehicle speed to increase from zero to a predetermined magnitude.

When the vehicle speed reaches a constant value at time t2, the vehicle 100 cruises while maintaining a constant vehicle speed from time t2 to t3. After that, when the driver depresses the accelerator pedal at time t3, the vehicle 100 accelerates again from time t3 to t4, and the vehicle speed increases.

At time t4, the vehicle speed increases to a predetermined level, and when the driver operates the accelerator pedal opening Ac, the vehicle 100 cruises while maintaining a constant vehicle speed from time t4 to t5. After that, when the driver reduces the accelerator pedal opening Ac at time t5, for example by removing his/her foot from the accelerator pedal, the vehicle 100 decelerates from time t5 to t6 and finally comes to a stop.

The following describes the driving control by the controller 10 in such a driving state.

First, from time t0 to t1, as shown in the accelerator state, the accelerator pedal is not operated, and the vehicle speed and vehicle acceleration are zero. Because the accelerator opening Ac is zero, the optimal driving force control is switched off. Note that the switch state of the optimal driving force control in the figure is indicated by hatching in the switch-on region of the optimal driving force control.

Between times t1 and t2, the accelerator pedal is depressed through the third operation range 23 and into the second operation range 22, as shown in the accelerator state. In this case, the accelerator opening Ac is included in the third operation range 23 between times t1 and t1a, and is included in the second operation range 22 between times t1a and t2. Therefore, the vehicle speed increases between times t1 and t1a, and the vehicle acceleration becomes positive. Then, between times t1a and t2, the vehicle speed continues to increase due to optimal driving force control. Note that when the vehicle speed reaches a predetermined speed just before time t2, the vehicle acceleration becomes zero and acceleration ends.

Between times t2 and t3, the accelerator opening Ac changes but remains within the second operation range 22. Therefore, optimal driving force control is performed, and the vehicle speed and vehicle acceleration do not change according to the accelerator opening Ac, and the vehicle continues to travel at a predetermined cruising speed.

Between times t3 and t4, when the accelerator pedal is depressed from the second operation range 22 to the first operation range 21, the accelerator opening Ac is included in the first operation range 21. In such a case, control is switched to one based on the accelerator opening Ac, the vehicle acceleration becomes a positive value, and the vehicle speed increases to a predetermined speed.

Between times t4 and t5, the accelerator opening Ac changes but remains within the second operation range 22. Therefore, the vehicle speed and vehicle acceleration do not change according to the accelerator opening Ac, and a predetermined cruising speed is maintained by optimal driving force control.

Between times t5 and t6, when the accelerator pedal operation ends as shown in the accelerator state, the accelerator opening Ac is included in the third operation region 23. In such a case, optimal deceleration control is performed, the vehicle acceleration becomes a negative value, and the vehicle speed decreases. Then, the vehicle 100 decelerates and finally stops.

In this way, optimal driving force control is performed at times t1a to t3 and times t4 to t5 because the accelerator opening Ac is within the second operation range 22. As a result, the vehicle acceleration does not change in response to changes in the accelerator opening Ac, and the optimal vehicle speed according to the driving situation is realized, eliminating the need for delicate operation of the accelerator pedal by the driver and reducing the operational burden.

Between times t1 and t1a, the accelerator opening Ac increases from zero and enters the third operation region 23, so driver control is performed in which a torque command value Tc corresponding to the accelerator opening Ac is set, and starting control is performed. Between times t3 and t4, the accelerator opening Ac increases and enters the third operation region 23, so driver control is performed in which a torque command value Tc corresponding to the accelerator opening Ac is set, and the vehicle 100 starts traveling. In this way, the second operation region 22, which performs optimal driving force control, and the first operation region 21 and third operation region 23, which perform driving force control according to the accelerator opening Ac, are continuous, so the driver is less likely to feel uncomfortable when driving.

In addition, from time t5 to t6, the accelerator opening Ac decreases and falls within the third operation region 23, so optimal deceleration control is performed. When the accelerator opening Ac is changing small in this way, the higher the vehicle speed, the larger the absolute value of the negative torque generated, making it possible to perform deceleration control without causing discomfort to the driver.

In the time chart shown in FIG. 4, the vehicle speed and vehicle acceleration determined by the driving force generated by the motor 3 are explained, but the steering operation is not explained. However, for example, the steering operation may be performed when turning right or left at an intersection. As described above, regarding the vehicle speed, the driver only needs to operate the accelerator pedal so that the accelerator opening Ac is included in the second operation range 22, so the driver can concentrate on steering.

Figure 5 shows a timing chart for when you start moving over a step created by a folded lock plate after paying the parking fee in a coin parking lot.

Between times t0 and t1, the vehicle 100 is stopped, and the vehicle speed and vehicle acceleration are both zero. Then, at time t1, the motor 3 generates torque, and the vehicle 100 starts moving forward or backward, attempting to climb up the step formed by the folded lock plate. Then, at time t2, as the vehicle 100 approaches the completion of climbing up the step, the vehicle acceleration is controlled to decrease.

After that, from time t2 to t3, the vehicle travels over the step by inertial running at a predetermined speed. When the driver takes his/her foot off the accelerator pedal at time t3, when the vehicle starts to descend the step, optimal deceleration control is performed and negative torque is generated, thereby suppressing acceleration when the vehicle 100 descends the step. In this way, the generation of longitudinal acceleration of the vehicle 100 when descending the step can be suppressed.

The following describes the driving control by the controller 10 in such a driving state.

First, from time t0 to t1, the accelerator pedal is not operated as shown in the accelerator state. Therefore, the accelerator opening Ac is zero, and the optimal driving force control is switched off.

Next, from time t1 to t2, the accelerator pedal is depressed through the third operation range 23 to the second operation range 22, as shown in the accelerator state. In this case, the accelerator opening Ac is within the third operation range 23 from time t1 to t1a, and within the second operation range 22 from time t1a to t2. Therefore, a torque according to the accelerator opening Ac is generated until time t1a, and from time t1a onwards, the torque increases due to optimal driving force control. As a result, the vehicle acceleration increases as if climbing up a step, and the vehicle speed increases. Then, when a predetermined vehicle speed is reached just before time t2 when climbing up the step is completed, torque generation stops and the vehicle acceleration decreases.

At time t2, the accelerator opening Ac is within the second operation region 22. In this case, the controller 10 does not generate torque through optimal driving force control, so the vehicle acceleration is zero. However, from time t1 to t2, the vehicle 100 can continue traveling due to inertia even if no torque is being generated in the motor 3. This completes climbing up the step.

At time t3, the driver stops operating the accelerator pedal. The accelerator opening Ac decreases and falls within the third operation region 23, so optimal deceleration control is performed. As a result, negative torque is generated, and negative vehicle acceleration occurs when the vehicle 100 descends from the step. As a result, acceleration when descending from the step is suppressed, and the vehicle finally stops at time t4.

In this way, optimal driving force control is performed from time t1a to t3 because the accelerator opening Ac is within the second operation range 22. As a result, the vehicle acceleration (torque) changes according to the driving pattern of climbing up the step, not according to changes in the accelerator opening Ac. Furthermore, from time t3 to t4, the accelerator opening Ac is within the third operation range 23, so the vehicle can be stopped by optimal deceleration control without the driver's operation. In this way, even in driving situations such as climbing up a step, the driver does not need to delicately operate the accelerator pedal for both acceleration and deceleration, reducing the operational burden.

In this embodiment, the following effects can be obtained:

According to the control method for the vehicle 100 of this embodiment, when the accelerator opening Ac is within the second operation region 22, the motor 3 is driven using a driving pattern according to the surrounding conditions of the vehicle 100, regardless of the accelerator opening Ac (S7). On the other hand, when the accelerator opening Ac is within the first operation region 21 and the third operation region 23, the motor 3 is driven so as to generate a driving force according to the accelerator opening Ac (S3, S12).

In this way, the driver can perform optimal driving force control according to the driving pattern without finely operating the accelerator pedal, thereby reducing the operational burden on the driver. In addition, the driver can select the optimal driving force control mode simply by operating the accelerator pedal so that the accelerator opening Ac is included in the second operation range 22, regardless of driving technique, making it easier for the driver to select the driving mode.

Also, by providing the first operation area 21 to the third operation area 23 consecutively, it is possible to seamlessly realize acceleration that is in line with the driver's driving intention. Furthermore, because optimal driving force control can be performed using the accelerator pedal, the hassle of manual switch operation can be reduced. Also, when the accelerator opening Ac transitions from a state in which it is included in the second operation area 22 to a state in which it is included in the first operation area 21, the timing of acceleration that exceeds the optimal driving force control is determined by the driver's intention, so that an assist function that is in line with the driver's driving intention can be realized even without an advanced driving assist function.

According to the control method for an electric vehicle of this embodiment, the driving pattern used to drive the motor 3 when the accelerator opening Ac is within the second operation range 22 is determined according to the position information of the vehicle 100 and surrounding condition information such as traffic lights and road surfaces. In this way, intersections and parking lots are determined using the position information, and the optimal driving pattern is determined using surrounding condition information such as traffic conditions and traffic lights, making it possible to perform optimal drive force control according to the surrounding conditions of the vehicle.

According to the control method for an electric vehicle of this embodiment, when the accelerator opening Ac decreases and changes from the second operation range 22 to the third operation range 23, the faster the speed of the vehicle 100 is, the greater the braking force generated to perform deceleration control, allowing for a smoother stop. In this way, even when decelerating the vehicle 100, it is possible to appropriately stop the vehicle by operating only the accelerator pedal.

(Modification)
In this modified example, a case will be described in which the function switch 11 is used to select the execution of a vehicle following driving function for automatically following a vehicle ahead.

Figure 6 is a part of a flowchart showing the driving force control in this modified example. This figure focuses on the differences from the flowchart shown in Figure 3. In detail, in this modified example, a determination process of step S21 is provided between steps S9 and S10, and the process of step S22 is performed in addition to step S10 depending on the determination result of step S21.

When the accelerator opening Ac decreases and changes from the second operation region 22 to the first operation region 21 (S9: Yes), in step S21, the controller 10 determines whether the vehicle following driving function is on. When the vehicle following driving function is not on (S21: No), the controller 10 then performs the optimal deceleration control of step S10 as in the above embodiment. On the other hand, when the vehicle following driving function is on (S22: Yes), the controller 10 then performs the process of step S22. In step S22, the controller 10 executes vehicle following driving.

By performing the control shown in this modified example, when the accelerator opening Ac decreases and the operation area transitions from the second operation area 22 to the first operation area 21, driving to follow the vehicle ahead can be performed instead of deceleration control. When the driving function to follow the vehicle ahead is on, it is preferable to follow the vehicle ahead according to the set function rather than performing optimal deceleration control. Therefore, when the accelerator opening Ac comes to be included in the third operation area 23, the burden on the driver can be reduced by switching to the driving function to follow the vehicle ahead.

The present invention naturally includes various embodiments not described here. Therefore, the technical scope of the present invention is determined only by the invention-specific matters related to the scope of the claims that are appropriate from the above description.

Each of the functions described in the above embodiments may be implemented by one or more processing circuits. Processing circuits include programmed processing devices, such as processors that include electrical circuitry. Processing devices also include devices such as application specific integrated circuits (ASICs) or conventional circuit components arranged to perform the functions described in the embodiments.

1 engine, 2 generator, 3 motor, 4 battery, 5 gear, 6 axle, 7 wheels, 10 controller, 11 mode switch, 14 accelerator position sensor, 21 first operation area, 22 second operation area, 23 third operation area, 100 vehicle

Claims (5)

A method for controlling an electric vehicle that controls a motor as a drive source in accordance with an accelerator opening, comprising:
As regions according to the magnitude of the accelerator opening, a first operation region, a second operation region in which the accelerator opening is smaller than the first operation region, and a third operation region in which the accelerator opening is smaller than the second operation region are provided,
When the accelerator opening degree is included in the second operation range, a torque command value for the motor is changed in accordance with a driving pattern according to a surrounding situation of the electric vehicle.
A method for controlling an electric vehicle, comprising: when the accelerator opening degree is included in the first operation range and the third operation range, driving the motor so as to generate a driving force corresponding to the accelerator opening degree. A method for controlling an electric vehicle according to claim 1,
The driving pattern is determined according to position information of the electric vehicle and surrounding condition information.
A method for controlling an electric vehicle. A method for controlling an electric vehicle according to claim 1 or 2, comprising:
When the accelerator opening degree decreases from the second operation range to the third operation range, the motor is controlled so as to generate a larger braking force as the speed of the electric vehicle increases.
A method for controlling an electric vehicle. A method for controlling an electric vehicle according to claim 3, comprising:
The electric vehicle is configured to selectively execute a forward vehicle following driving assistance function for following another vehicle ahead,
When the accelerator opening degree changes from the second operation range to the first operation range,
A method for controlling an electric vehicle, the method including: executing the driving support function for following the preceding vehicle when the driving support function for following the preceding vehicle is selected. A control device for an electric vehicle including a controller that controls a motor as a drive source in response to an accelerator opening,
As regions according to the magnitude of the accelerator opening, a first operation region, a second operation region in which the accelerator opening is smaller than the first operation region, and a third operation region in which the accelerator opening is smaller than the second operation region are provided,
The controller:
When the accelerator opening degree is included in the second operation range, a torque command value for the motor is changed in accordance with a driving pattern according to a surrounding situation of the electric vehicle.
A control device for an electric vehicle that drives the motor to generate a driving force corresponding to the accelerator opening when the accelerator opening is within the first operation range and the third operation range.

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