Electric vehicle control device

Abstract

A control device for an electric vehicle that can smooth out changes in the output of the electric vehicle. [Solution] The vehicle comprises hybrid control for hybrid driving using power generated by an internal combustion engine and power from a drive battery, EV control for EV driving using power from the drive battery, and EV priority control for prioritizing EV driving over hybrid driving, wherein during EV priority control, the drive battery can output power up to a first battery upper limit output, and during hybrid control, the drive battery can output power up to a second battery upper limit output that is higher than the first battery upper limit output, and when the output required by the electric vehicle during EV priority control exceeds a predetermined value, switching control from the EV priority control to the hybrid control is executed, and the output of the drive battery is increased within a range above the first battery upper limit output and below the second battery upper limit output, while limiting the degree of change in the increase in drive battery output.

Description

[Technical Field]

[0001] The present disclosure relates to a control device for an electric vehicle. [Background technology]

[0002] Conventionally, there is known a control device for an electric vehicle that can switch between EV driving, in which the motor is driven only by power from a drive battery, and series hybrid driving (hereinafter referred to as hybrid driving), in which the motor is driven by power generated by an internal combustion engine (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-60622 Summary of the Invention [Problem to be solved by the invention]

[0004] Such electric vehicle control devices may have an EV priority mode that prioritizes EV driving. In EV priority mode, the control device makes it difficult for the internal combustion engine to start by limiting the drive battery's output to a predetermined upper limit, even when the user presses the accelerator. When the upper limit is reached, the control device switches to hybrid driving and starts the internal combustion engine. Starting the internal combustion engine uses power from the drive battery. Therefore, the upper limit of the drive battery's power during EV driving is lower than the upper limit of the drive battery's power during hybrid driving by the amount of power required to start the internal combustion engine. As a result, when switching from EV driving to hybrid driving, the upper limit of the power that can be output from the drive battery increases significantly.

[0005] In this way, when switching from EV driving to hybrid driving while in EV priority mode, the upper limit value changes significantly, resulting in a significant increase in the power that can be output from the drive battery. This can cause a sudden increase in motor torque, resulting in a sudden change in the output of the electric vehicle. A sudden change in the output of the electric vehicle can be undesirable depending on the state of the electric vehicle, such as causing the user to feel a strong acceleration.

[0006] An object of the present disclosure is to provide a control device for an electric vehicle that can smooth out changes in the output of the electric vehicle. [Means for solving the problem]

[0007] The control device for an electric vehicle according to the present disclosure is a control device for an electric vehicle having a motor that drives wheels of the vehicle, a drive battery that supplies power to the motor, and an internal combustion engine that can charge the drive battery, and includes hybrid control that performs hybrid driving by driving the motor using power generated by the internal combustion engine and power from the drive battery, EV control that performs EV driving by driving the motor using power from the drive battery while the internal combustion engine is stopped, EV priority control that prioritizes the EV driving over the hybrid driving, and EV control that performs EV driving from the EV driving. and switching control for switching from EV priority control to hybrid driving, wherein during the EV priority control, the drive battery can output power up to a first battery upper limit output, and during the hybrid control, the drive battery can output power up to a second battery upper limit output that is higher than the first battery upper limit output, and when the output required by the electric vehicle during the EV priority control becomes equal to or greater than a predetermined value, the switching control is executed, and during the switching control, the output of the drive battery is increased within a range equal to or greater than the first battery upper limit output and equal to or less than the second battery upper limit output, while limiting the rate of change in the increase in the drive battery output. [Effects of the Invention]

[0008] This electric vehicle control device can limit the rate of change in drive battery output increase from the first battery upper limit output to the second battery upper limit output when switching from EV driving to hybrid driving during EV priority control. This allows the electric vehicle control device to limit a sudden increase in power output from the drive battery. As a result, this electric vehicle control device can smooth out changes in the electric vehicle's output. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a system diagram of a vehicle control system according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a system diagram of an engine according to one embodiment of the present disclosure. [Figure 3] 4 is a timing chart illustrating switching control according to an embodiment of the present disclosure. [Figure 4] 4 is a flowchart showing a control procedure executed by a control device according to an embodiment of the present disclosure. [Figure 5] 10 is a flowchart showing a control procedure of a restriction process according to an embodiment of the present disclosure. [Figure 6] 10 is a graph illustrating a target increased power output according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0011] 1 and 2, the electric vehicle C has an engine (an example of an internal combustion engine) 2, a motor (FrM) 3, a generator (GEN) 4, a drive battery (BT) 6, a transaxle 8, an inverter 12 that controls the motor 3 and the generator 4, an accelerator pedal 14 operated by a user of the electric vehicle C, an EV priority switch 16, a vehicle control device (an example of a control device) 18, an engine control device 20 that controls the engine 2, a drive battery control device (BMU) 22, and a following vehicle detection device 24. In addition, the electric vehicle C may have a charger 26 that can be connected to an external power source, an external power supply device 28 that can supply power to external devices, and a charge button (not shown) that the user uses to instruct charging. The electric vehicle C of this embodiment is a plug-in hybrid electric vehicle (PHEV) equipped with external charging that allows power from an external power source to be stored in the drive battery 6 by a charger 26, and external power feeding that allows power from the drive battery 6 to be supplied to external devices by an external power feeding device 28.

[0012] As shown in FIG. 1, the engine 2 is connected to a generator 4 and drives the generator 4. Furthermore, in this embodiment, the engine 2 is capable of driving wheels C1 via a transaxle 8. The engine 2 in this embodiment is an in-line four-cylinder gasoline engine. The engine 2 receives fuel from a fuel tank 30 and burns and consumes the fuel.

[0013] As shown in FIG. 2, the engine 2 has an exhaust purification device 40. The exhaust purification device 40 is a device that purifies the exhaust gas of the engine 2. The exhaust purification device 40 may include a catalyst 40a. The exhaust purification device 40 requires warming up. The exhaust purification device 40 detects the purification state of the exhaust gas using multiple sensors (e.g., oxygen sensors or air-fuel ratio sensors) 40b. The multiple sensors 42b are electrically connected to the engine control device 20. The engine control device 20 estimates and obtains the catalyst temperature TC, which is the temperature of the catalyst 40a, from the operating time of the engine 2, the water temperature, etc. Note that the engine control device 20 may obtain the catalyst temperature TC using a sensor that detects the temperature of the catalyst 40a.

[0014] As shown in FIG. 1 , the motor 3 is connected to the wheels C1 via a transaxle 8 and an axle 10 to drive the wheels C1. The motor 3 in this embodiment is a three-phase AC motor having multiple coils and multiple permanent magnets. The motor 3 is driven by the rotation of the axle 10 (wheels C1) to generate (regenerate) electricity. Therefore, the motor 3 is a motor-generator capable of power running and generating electricity. The generator 4 is connected to the engine 2 and is capable of driving the engine 2. The generator 4 performs motoring, driving the engine 2, while power running is performed using electric power from the drive battery 6. On the other hand, the generator 4 is driven by the engine 2 to generate electricity while the engine 2 is operating. Therefore, the generator 4 is a motor-generator capable of power running and generating electricity.

[0015] The drive battery 6 outputs electric power to the motor 3 and the generator 4, and also receives electric power generated by the motor 3 and the generator 4. Furthermore, the drive battery 6 receives external electric power via a charger 26. In this embodiment, the drive battery 6 is made up of multiple lithium-ion batteries.

[0016] The transaxle 8 has multiple gears and a clutch 8a. The engine 2 is connected to the generator 4 and the axle 10 via the transaxle 8. When the clutch 8a is in a disengaged state, the transaxle 8 cuts off the power transmission between the engine 2 and the axle 10, and when the clutch 8a is in a engaged state, the power of the engine 2 is transmitted to the axle 10.

[0017] The inverter 12 converts the DC power supplied from the drive battery 6 into AC power and adjusts the power supplied to the motor 3 to control the power running torque of the motor 3. When the motor 3 regenerates electricity, the inverter 12 converts the AC power supplied from the motor 3 into DC power and adjusts the power supplied to the drive battery 6 to control the regenerative torque of the motor 3.

[0018] The vehicle control device 18 is electrically connected to the motor 3 via the inverter 12 and controls the motor 3. The vehicle control device 18 is actually an ECU (Electronic Control Unit) configured by a microcomputer including a calculation device, a memory, an input / output buffer, etc. The vehicle control device 18 controls the electric vehicle C based on maps and programs stored in the memory.

[0019] The vehicle control device 18 of this embodiment is further electrically connected to an engine control device 20. The engine control device 20 is electrically connected to various devices provided in the engine 2 and controls the engine 2. The control of the engine 2 may be performed by the vehicle control device 18 in addition to the engine control device 20. The vehicle control device 18 may also be electrically connected to various other devices of the electric vehicle C and perform various controls. Like the vehicle control device 18, the engine control device 20 is an ECU (Electronic Control Unit) configured by a microcomputer including a calculation device, a memory, an input / output buffer, etc.

[0020] The electric vehicle C of this embodiment has driving modes such as EV driving, series hybrid driving (an example of hybrid driving), and parallel hybrid driving. In EV driving, the electric vehicle C drives the motor 3 solely with power from the drive battery 6 while the engine 2 is stopped. In series hybrid driving, the electric vehicle C disengages the clutch 8a, drives the generator 4 with the engine 2, and uses the power generated by the generator 4 to drive the motor 3 and drive the wheels C1. In parallel hybrid driving, the electric vehicle C engages the clutch 8a, and uses the power of the engine 2 to drive the wheels C1 via the axle 10. In the electric vehicle C, the vehicle control device 18 switches between each driving mode depending on the depression state of the accelerator pedal 14, controls the motor 3 and the generator 4 via the inverter 12, and causes the engine control device 20 to control the engine 2.

[0021] The vehicle control device 18 includes EV control for executing EV driving, hybrid control for executing series hybrid driving, switching control for switching from EV driving to series hybrid driving, and EV priority control for prioritizing EV driving over series hybrid driving. For example, the vehicle control device 18 may execute the EV priority control when the user turns on the EV priority switch 16. The switching control may also execute control for switching from EV driving or series hybrid driving to parallel hybrid driving.

[0022] The drive battery control device 22 controls the output of the drive battery 6. In this embodiment, the drive battery control device 22 calculates a first battery upper limit output BL1 and a second battery upper limit output BL2. The first battery upper limit output BL1 is the upper limit of the power that the drive battery 6 can output per unit time during EV driving. The second battery upper limit output BL2 is the upper limit of the power that the drive battery 6 can output per unit time during hybrid driving. The first battery upper limit output BL1 is the maximum output of the drive battery 6 minus the output (power) required to start the engine 2, and the second battery upper limit output BL2 is the maximum output of the drive battery 6. After switching to hybrid driving, the engine 2 begins generating power, and the power that can be supplied to the motor 3 is the maximum output of the drive battery 6 plus the power generated by the engine 2. 3, in this embodiment, the first battery upper limit output BL1 is set to a lower value than the second battery upper limit output BL2 used after the engine 2 starts and the vehicle is switched to hybrid driving, in order to leave enough power to be used for the generator 4 to motor the engine 2 and start the engine 2. In other words, the second battery upper limit output BL2 is a higher output (power) than the first battery upper limit output BL1.

[0023] The drive battery control device 22 is actually an ECU (Electronic Control Unit) configured with a microcomputer including an arithmetic device, memory, input / output buffers, etc. The drive battery control device 22 includes a battery temperature detection device 22a that detects the temperature of the drive battery 6, and a state-of-charge detection device 22b that detects the state of charge (SOC) as the state of charge of the drive battery 6. The drive battery control device 22 calculates the first battery output upper limit BL1 and the second battery output upper limit BL2 using the battery temperature TB obtained from the battery temperature detection device 22a, the state of charge SOC obtained from the state-of-charge detection device 22b, and a program or map stored in memory.

[0024] The vehicle control device 18 acquires the first battery output upper limit BL1 and the second battery output upper limit BL2 from the drive battery control device 22. During EV priority control, the vehicle control device 18 can output power from the drive battery 6 up to the first battery output upper limit BL1. During hybrid control, the vehicle control device 18 can output power from the drive battery 6 up to the second battery output upper limit BL2.

[0025] During EV priority control, the vehicle control device 18 executes switching control when the output Q required by the electric vehicle C is equal to or greater than a predetermined value Qt. When switching control is executed, the vehicle control device 18 calculates a target increased output power BU. The target increased output power BU is a value indicating the target degree of increase (degree of change) in output (electric power) when increasing the output of the drive battery 6 within a range equal to or greater than the first battery output upper limit BL1 and equal to or less than the second battery output upper limit BL2. During switching control, the vehicle control device 18 controls the drive battery 6 so that the output from the drive battery 6 becomes the target increased output power BU. Furthermore, the vehicle control device 18 executes a limiting process that limits the degree of change in the target increased output power BU. Details will be described later. Note that these controls may be executed by the drive battery control device 22, for example.

[0026] The following vehicle detection device 24 can detect the approach of a vehicle following the electric vehicle C. The following vehicle detection device 24 may detect the approach of the following vehicle by using the time TR it takes for the following vehicle to approach within a predetermined distance, for example, from the distance and speed difference between the vehicle following the electric vehicle C and the electric vehicle C. Alternatively, the following vehicle detection device 24 may detect the distance between the vehicle following the electric vehicle C and the electric vehicle C, and detect whether the distance between the following vehicle and the electric vehicle C is within a predetermined distance.

[0027] Next, a control procedure executed by the vehicle control device 18 will be described using the flowchart of Fig. 4. The vehicle control device 18 starts the control procedure when an ignition switch (not shown) is turned on.

[0028] In step S1, the vehicle control device 18 determines whether or not the vehicle is running in EV mode. The vehicle control device 18 may determine that the vehicle is running in EV mode if EV control is being executed. If the vehicle control device 18 determines that the vehicle is running in EV mode (YES in step S1), the process proceeds to step S2.

[0029] In step S2, the vehicle control device 18 acquires the first battery upper limit output BL1. After acquiring the first battery upper limit output BL1, the vehicle control device 18 proceeds to step S3.

[0030] In step S3, the vehicle control device 18 determines whether the vehicle is in the EV priority mode. For example, the vehicle control device 18 may determine that the vehicle is in the EV priority mode if the EV priority switch is on. If the vehicle control device 18 determines that the vehicle is in the EV priority mode (YES in step S3), the process proceeds to step S4.

[0031] In step S4, the vehicle control device 18 generates output from the drive battery 6 up to the first battery output upper limit BL1, and proceeds to step S5. In step S5, the vehicle control device 18 determines whether the output Q required by the electric vehicle C (hereinafter referred to as required output Q) is a predetermined value Qt. The required output Q is an output calculated by the vehicle control device 18 in accordance with the accelerator opening Th of the accelerator pedal 14. If the vehicle control device 18 determines that the required output is equal to or greater than the predetermined value Qt (YES in step S5), it executes switching control and proceeds to step S6. If the vehicle control device 18 determines that the required output is less than the predetermined value Qt (NO in step S5), it repeats steps S4 and S5 until the required output becomes equal to or greater than the predetermined value Qt.

[0032] In step S6, the vehicle control device 18 switches from EV control to hybrid control and starts the engine 2. After starting the engine 2, the vehicle control device 18 proceeds to the process of step S7.

[0033] In step S7, the vehicle control device 18 calculates the target increased output BU. After calculating the target increased output BU, the vehicle control device 18 executes a limiting process to limit the degree of change in the target increased output BU depending on the state of the electric vehicle C. After executing the limiting process, the vehicle control device 18 returns.

[0034] As shown in the upper graph of FIG. 3, when EV control is in EV priority mode, the vehicle control device 18 starts the engine 2 to generate electricity when the required output Q exceeds a predetermined value Qt. The solid line in the lower graph of FIG. 3 shows changes in the required drive output QR. The required drive output QR is the power per unit time required for the motor 3 to output the required output Q. As shown by the solid line from time t1 to time t2 in the lower graph of FIG. 3, the vehicle control device 18 outputs power from the drive battery 6 up to the first battery output upper limit BL1 (see step S4). The output from the drive battery 6 remains constant at the first battery output upper limit BL1 between time t1 and time t2. In other words, in EV priority mode, allowing the drive battery 6 to output power up to the first battery output upper limit BL1 makes it difficult for the engine 2 to start, and prioritizes running the electric vehicle C using the output from the drive battery 6 when the engine 2 is stopped. For this reason, for example, as shown from time t1 to time t2, there is a period during which the output of the drive battery 6 is fixed at the output value of the first battery output upper limit BL1. The vehicle control device 18 starts the engine 2 between time t1 and time t2. That is, from time t1 to time t2 until the start of the engine 2 is completed, there is a period during which the output of the electric vehicle C is constant even though the user is depressing the accelerator pedal 14.

[0035] On the other hand, as shown at time t2, when the engine 2 starts, the electric power required to start the engine 2 is no longer needed, and the required drive output QR increases to the second battery output upper limit BL2. As a result, the output from the drive battery 6 increases instantaneously, as indicated by the target increased output BU shown by the solid line in the graph at the bottom of FIG. 3. This gives the user the feeling that the electric vehicle C has instantaneously accelerated in response to the degree to which the accelerator pedal 14 is depressed. This behavior of the electric vehicle C may cause the user to feel uncomfortable, depending on the driving state of the electric vehicle C. To alleviate this feeling of discomfort, the vehicle control device 18 executes a limitation process. Note that, as shown after time t2, when the engine 2 generates electricity, the generated electricity can also be used, and the required drive output QR increases. More details about the limitation process will be described later.

[0036] As shown in Fig. 4, if the vehicle control device 18 determines in step S3 that the EV priority mode is not selected (step S3 NO), the vehicle control device 18 proceeds to step S8. In step S8, the vehicle control device 18 sets a margin Mg for the first battery upper limit output BL1. The vehicle control device 18 sets a setting such that switching control is executed when the required drive output QR becomes the power obtained by subtracting the margin Mg from the first battery upper limit output BL1. After executing the process of step S8, the vehicle control device 18 proceeds to step S9.

[0037] In step S9, if the vehicle control device 18 determines that the required output Q is equal to or greater than the value obtained by subtracting the margin Mg from the first battery upper limit output BL1 (YES in step S9), the process proceeds to step S10. If the vehicle control device 18 determines that the required output Q is less than the value obtained by subtracting the margin Mg from the first battery upper limit output BL1 (NO in step S9), the vehicle control device 18 repeats steps S8 and S9 until the required output Q is equal to or greater than the value obtained by subtracting the margin Mg from the first battery upper limit output BL1.

[0038] In step S10, the vehicle control device 18 executes switching control to start the engine 2. After starting the engine, the vehicle control device 18 proceeds to step S11. In step S11, the vehicle control device 18 switches the upper limit of power that can be output by the driving battery 6 to the second battery output upper limit BL2. After switching to the second battery output upper limit BL2, the vehicle control device 18 returns.

[0039] As shown in the lower graph of FIG. 3, when the vehicle is in EV driving mode (i.e., normal mode) and not in EV priority mode, the vehicle control device 18 starts the engine 2 with a margin Mg of power above the first battery upper limit output BL1. Therefore, the drive battery 6 can output power up to the second battery upper limit output BL2 without being fixed at the first battery upper limit output BL1. That is, as shown by the dashed-dotted line in the lower graph of FIG. 3, the vehicle control device 18 starts the engine 2 at time t1 and increases the output from the drive battery 6 at a substantially constant rate from time t1 to time t2 without causing any step in the output. As a result, the user does not experience the discomfort that occurs in EV priority mode. Meanwhile, the engine 2 starts more frequently in normal mode EV control.

[0040] If the vehicle control device 18 determines that the vehicle is not running in EV mode (NO in step S1), the process proceeds to step S12. In step S12, the vehicle control device 18 has already executed hybrid control. While executing hybrid control, the vehicle control device 18 proceeds to step S13. In step S13, the vehicle control device 18 acquires the second battery upper limit output BL2 and returns.

[0041] Next, the control procedure of the restriction process executed by the vehicle control device 18 will be described with reference to the flowchart of FIG.

[0042] 6, in this embodiment, the vehicle control device 18 sets five levels of change rate restrictions: a first level L1 that does not set a limit on the rate of change of the target increased output power BU; a second level L2 (an example of a first change degree) that sets a small limit on the rate of change; a third level L3 that sets a medium limit on the rate of change; a fourth level L4 that sets a limit on the rate of change to the same level as in normal mode; and a fifth level L5 that sets a large limit on the rate of change. The vehicle control device 18 stores the target increased output power BUs of the first level L1 to the fifth level L5 in a memory, and selects and switches one of the target increased output power BUs of the first level L1 to the fifth level L5 depending on the state of the electric vehicle C. That is, the vehicle control device 18 relaxes or strengthens the limit on the rate of change of the target increased output power BU depending on multiple conditions related to the state of the electric vehicle C, using the limit of the fourth level L4 as a reference.

[0043] In step S101, the vehicle control device 18 relaxes the restriction when the following vehicle detection device 24 detects the approach of a following vehicle. In this embodiment, if it is determined that the approach time TR of the following vehicle is equal to or shorter than the predetermined time TRt (YES in step S101), the process proceeds to step S102. Note that the following vehicle detection device 24 may also determine that the approach time TR of the following vehicle is equal to or shorter than the predetermined time TRt when the distance to the following vehicle C is within a predetermined distance. In step S102, the vehicle control device 18 selects the increased output power of the first level L1 and ends the restriction process. That is, the vehicle control device 18 does not impose a restriction on the target increased output power BU. In this case, the power output by the driving battery 6 is instantly switched from the first battery output upper limit BL1 to the second battery output upper limit BL2. When a following vehicle is approaching, the user of the electric vehicle C often desires to accelerate the electric vehicle C quickly. For this reason, the vehicle control device 18 selects the target increased output power BU of the first level L1, which enables quick acceleration. Furthermore, if a following vehicle is approaching, there is a possibility that the risk of collision is imminent for the electric vehicle C. Therefore, whether or not a following vehicle is approaching has the greatest impact on the safety of the electric vehicle C. For this reason, the vehicle control device 18 first executes step S101 in the restriction processing.

[0044] If the vehicle control device 18 determines that the approach time TR of the following vehicle exceeds the predetermined time TRt (NO in step S101), the process proceeds to step S103. In step S103, the vehicle control device 18 determines whether the battery temperature TB of the drive battery 6 is equal to or higher than the predetermined battery temperature TBt. If the vehicle control device 18 determines that the battery temperature TB of the drive battery 6 is equal to or higher than the predetermined battery temperature TBt (YES in step S103), the process proceeds to step S104. In step S104, the vehicle control device 18 strengthens the restriction by selecting the fifth level L5 of increased output power and ends the restriction process. That is, the vehicle control device 18 strengthens the restriction on the rate of change of the target increased output power BU. If the battery temperature TB is high, it is necessary to reduce the burden on the drive battery 6. For this reason, the vehicle control device 18 selects the fifth level L5 of target increased output power BU, which has the smallest rate of change and imposes the least burden on the drive battery 6. Furthermore, an abnormality in the drive battery 6 has a significant impact on the running of the electric vehicle C and has a significant impact on the safety of the electric vehicle C. Therefore, the vehicle control device 18 executes step S103 second in the restriction process.

[0045] If the vehicle control device 18 determines that the battery temperature TB of the drive battery 6 is below the predetermined battery temperature TBt (NO in step S103), the process proceeds to step S105. In step S105, the vehicle control device 18 determines whether the catalyst temperature TC is equal to or lower than the predetermined catalyst temperature TCt. If the vehicle control device 18 determines that the catalyst temperature TC is equal to or lower than the predetermined catalyst temperature TCt (YES in step S105), the process proceeds to step S106. In step S106, the vehicle control device 18 relaxes the restriction by selecting the second level L2 of increased output and ends the restriction process. If the catalyst temperature TC is equal to or lower than the predetermined catalyst temperature TCt, the exhaust gas is not sufficiently purified, so exhaust gas emissions must be suppressed. As a result, the engine 2 cannot generate sufficient output and the amount of power generation is low. As a result, the power performance of the electric vehicle C is inferior to that after warm-up is complete. Therefore, in order to ensure power performance, the vehicle control device 18 relaxes the restriction on the rate of change of the target increased output BU, creating a state in which it is easier to output the power of the drive battery 6. Furthermore, the power performance of the electric vehicle C has a large impact on safety. For this reason, the vehicle control device 18 executes step S105 thirdly in the restriction processing.

[0046] As described above, the vehicle control device 18 checks whether the battery temperature TB is equal to or higher than the predetermined battery temperature TBt, giving priority to checking whether the catalyst temperature TC is equal to or lower than the predetermined catalyst temperature TCt. That is, when the battery temperature TB is equal to or higher than the predetermined battery temperature TBt, the vehicle control device 18 tightens the restriction by giving priority to the case where the catalyst temperature TC is equal to or lower than the predetermined catalyst temperature TCt. In this way, the vehicle control device 18 checks by giving priority to the condition that has the greatest impact on the safety of the electric vehicle C.

[0047] If the vehicle control device 18 determines that the catalyst temperature TC is greater than the predetermined catalyst temperature TCt (NO in step S105), the process proceeds to step S107. In step S107, the vehicle control device 18 determines whether the state of charge (SOC) is equal to or less than a predetermined state of charge (SOCt) (an example of a predetermined state of charge). If the vehicle control device 18 determines that the state of charge (SOC) is equal to or less than the predetermined state of charge (SOCt) (YES in step S107), the process proceeds to step S108. In step S108, the vehicle control device 18 strengthens the restriction by selecting the fifth level L5 of increased output and ends the restriction process. If the state of charge (SOC) is equal to or less than the predetermined state of charge (SOCt), if the degree of change in the target increased output power BU is large, the power of the drive battery 6 may decrease rapidly, which may result in a rapid drop in the state of charge (SOC). As a result, the output of the electric vehicle C may decrease rapidly as the state of charge (SOC) decreases. For this reason, the vehicle control device 18 strengthens the restriction on the rate of change in the target increased output power BU. Furthermore, the decrease in the state of charge SOC has a smaller impact on safety than step S105. Therefore, the vehicle control device 18 executes step S108 fourth in the restriction process.

[0048] If the vehicle control device 18 determines that the state of charge SOC is greater than the predetermined state of charge SOCt (NO in step S107), the process proceeds to step S109. In step S109, the vehicle control device 18 determines whether the accelerator opening Th is greater than or equal to the predetermined opening Tht. If the vehicle control device 18 determines that the accelerator opening Th is greater than or equal to the predetermined opening Tht (YES in step S109), the process proceeds to step S110. In step S110, the vehicle control device 18 relaxes the restriction by selecting the target increased output BU of the third level L3, and ends the restriction process. If the accelerator opening Th is greater than or equal to the predetermined opening Tht, the electric vehicle C is in an accelerating state, and the user is unlikely to feel a step in the output. Therefore, the vehicle control device 18 relaxes the restriction slightly to ensure the power performance of the electric vehicle C.

[0049] If the vehicle control device 18 determines that the accelerator opening degree Th is less than the predetermined opening degree Tht (NO in step S109), the process proceeds to step S111. In step S111, the vehicle control device 18 determines whether the speed V of the electric vehicle C is equal to or greater than a predetermined speed Vt. If the vehicle control device 18 determines that the speed V of the electric vehicle C is equal to or greater than the predetermined speed Vt (YES in step S111), the process proceeds to step S112. In step S112, the vehicle control device 18 relaxes the restriction by selecting the target increased power output BU of the second level L2, and ends the restriction process. If the speed V of the electric vehicle C is equal to or greater than the predetermined speed Vt, the electric vehicle C is traveling at high speed, and the user is unlikely to feel a step in the output. Therefore, the vehicle control device 18 relaxes the restriction to ensure the power performance of the electric vehicle C.

[0050] If the speed V of the electric vehicle C is less than the predetermined speed Vt (NO in step S111), the vehicle control device 18 proceeds to step S113. In step S113, the vehicle control device 18 selects the target increased output power BU of the fourth level L4 in the normal state, and ends the limitation process.

[0051] In this way, the vehicle control device 18 relaxes or tightens the restrictions in accordance with a plurality of conditions, and the more safety-related the conditions, the higher the priority of the conditions to be checked.

[0052] As explained above, when switching from EV driving to hybrid driving during EV priority control, the vehicle control device 18 can limit the rate of change in the increase in drive battery 6 output from the first battery output upper limit BL1 to the second battery output upper limit BL2. This allows the vehicle control device 18 to limit a sudden increase in the power output from the drive battery 6. This allows the output of the electric vehicle C to change smoothly.

[0053] <Other embodiments> Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0054] In the above embodiment, an example has been described in which the rate of change of the target increased output power BU is limited to five levels, but the present disclosure is not limited thereto. For example, the vehicle control device 18 may store a plurality of target increased output power BUs each having a limited amount of change in the target increased output power BU. Furthermore, the vehicle control device 18 may store a coefficient according to the state of the electric vehicle C, and may, for example, multiply a predetermined target increased output power BU by the coefficient to relax or tighten the limit on the rate of change.

[0055] In the above embodiment, the approach of a following vehicle, battery temperature TB, catalyst temperature TC, state of charge SOC, accelerator opening Th, and speed V are used as examples of the multiple conditions, but the present disclosure is not limited to these. The vehicle control device 18 may relax or tighten restrictions depending on other conditions. Furthermore, the vehicle control device 18 may check other conditions with a higher priority, especially those related to safety. [Explanation of symbols]

[0056] 2: Engine (internal combustion engine), 3: Motor, 4: Generator, 6: Drive battery 14: Accelerator pedal, 16: EV priority switch 18: Vehicle control device, 20: Engine control device 22: Drive battery control device, 22a: Battery temperature detection device, 22b: Charge state detection device 24: Following vehicle detection device 40: exhaust purification device, 40a: catalyst, 42b: sensor BL1: First battery upper limit output, BL2: Second battery upper limit output, BU: Target increased output TB:Battery temperature C: Electric vehicle, C1: Wheel Q: output, Qt: predetermined value SOC: Charging rate, SOCt: Predetermined charging rate TB: Battery temperature, TBt: Predetermined battery temperature TC: Catalyst temperature, TCt: Predetermined catalyst temperature TR: Approach time, TRt: Predetermined time Th: accelerator opening, Tht: predetermined opening V: velocity, Vt: defined velocity

Claims

1. A control device for an electric vehicle having a motor that drives wheels of the vehicle, a drive battery that supplies power to the motor, and an internal combustion engine that can charge the drive battery, hybrid control that performs hybrid traveling by driving the motor using electric power generated by the internal combustion engine and electric power from the drive battery; EV control for performing EV driving by driving the motor using electric power from the drive battery while the internal combustion engine is stopped; EV priority control that prioritizes the EV driving over the hybrid driving; Switching control for switching from the EV driving to the hybrid driving; Equipped with During the EV priority control, the power of the drive battery can be output up to a first battery upper limit output, During the hybrid control, the electric power of the drive battery can be output up to a second battery upper limit output that is higher than the first battery upper limit output, When the output required by the electric vehicle becomes equal to or greater than a predetermined value during the EV priority control, the switching control is executed, and during the switching control, the output of the drive battery is increased within a range equal to or greater than the first battery upper limit output and equal to or less than the second battery upper limit output, while limiting the rate of change in the increase in the drive battery output. Control device for electric vehicles.

2. the electric vehicle has a following vehicle detection device capable of detecting the approach of a following vehicle of the electric vehicle, the control device relaxes the restriction when the following vehicle detection device detects the approach of the following vehicle. The control device for an electric vehicle according to claim 1.

3. the electric vehicle acquires a catalyst temperature that is a temperature of a catalyst that purifies exhaust gas from the internal combustion engine; The control device relaxes the restriction when the acquired catalyst temperature is equal to or lower than a predetermined catalyst temperature. The control device for an electric vehicle according to claim 1.

4. the electric vehicle has a battery temperature detection device that detects the temperature of the drive battery, When the battery temperature detected by the battery temperature detection device is equal to or higher than a predetermined battery temperature, the control device prioritizes strengthening the restriction on the catalyst over when the catalyst temperature is equal to or lower than the predetermined catalyst temperature. The control device for an electric vehicle according to claim 3.

5. the electric vehicle has a state-of-charge detection device that detects a state of charge of the drive battery, The control device strengthens the restriction when the state of charge is lower than a predetermined state of charge. The control device for an electric vehicle according to claim 1.

6. The control device relaxes or strengthens the restriction in accordance with a plurality of conditions; The conditions related to safety are given priority. The control device for an electric vehicle according to any one of claims 1 to 5.

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