Control system for electric vehicle

Abstract

To provide a control system for an electric vehicle capable of adjusting the balance between NVH and fuel consumption of an internal combustion engine.SOLUTION: A control system for an electric vehicle includes: an internal combustion engine which is installed in the electric vehicle; a generator which is driven by the internal combustion engine; a motor capable of driving wheels of the electric vehicle; and a control device which controls the electric vehicle. The control device has the first control that prioritizes fuel consumption of the internal combustion engine and increases the rotation frequency, and the second control that increases the rotation frequency more gradually than the first control. The control device acquires the target fuel consumption being the target fuel consumption of the internal combustion engine, and the actual fuel consumption of the internal combustion engine when increasing the rotation frequency of the internal combustion engine during the series operation where the motor is driven with the power obtained by driving the generator by the internal combustion engine, and changes weighting between the first control and the second control according to the target fuel consumption and the actual fuel consumption.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, a control system for an electric vehicle in which wheels are driven by a motor is known (see, for example, Patent Document 1). Such an electric vehicle has a series mode in which a generator is driven by an internal combustion engine, and the motor is driven by electric power generated by the generator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-131151 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a control system for an electric vehicle to improve the NVH (NVH is an abbreviation for Noise, Vibration, Harshness) of an internal combustion engine when increasing the rotation speed of the internal combustion engine during series mode operation (series operation). However, controlling the internal combustion engine to improve the NVH results in a deterioration of the fuel efficiency of the internal combustion engine.

[0005] An object of the present disclosure is to provide a control system for an electric vehicle that is capable of adjusting the balance between NVH and fuel economy of an internal combustion engine. [Means for solving the problem]

[0006] The control system for an electric vehicle according to the present disclosure includes an internal combustion engine mounted on an electric vehicle, a generator driven by the internal combustion engine, a motor capable of driving wheels of the electric vehicle, and a control device that controls the electric vehicle, wherein the control device has a first control that increases the rotation speed by prioritizing fuel efficiency of the internal combustion engine, and a second control that increases the rotation speed more slowly than the first control, and when increasing the rotation speed of the internal combustion engine during series operation in which the internal combustion engine drives the motor with electric power obtained by driving a generator, the control device obtains a target fuel efficiency, which is a target fuel efficiency of the internal combustion engine, and an actual fuel efficiency, which is the actual fuel efficiency of the internal combustion engine, and changes the weighting of the first control and the second control depending on the target fuel efficiency and the actual fuel efficiency. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a control system for an electric vehicle that is capable of adjusting the balance between NVH and fuel economy of an internal combustion engine. [Brief description of the drawings]

[0008] [Figure 1] 1 is a system diagram of an electric vehicle according to one embodiment of the present disclosure. [Diagram 2] 4 is a diagram showing an increase rate of the rotation speed of an internal combustion engine under a first control according to an embodiment of the present disclosure. FIG. [Diagram 3] FIG. 4 is a diagram showing an increase rate of the rotation speed of the internal combustion engine under the second control according to the 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. [Diagram 5] 4 is a timing chart showing an example of control executed by a control device according to an embodiment of the present disclosure. [Figure 6] 5 is an example of a target fuel efficiency setting screen displayed on a display according to an embodiment of the present disclosure. [Figure 7] 13 is an example of a fuel efficiency achievement degree display screen displayed on a display according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] As shown in FIG. 1, the control system 3 of the electric vehicle C includes an internal combustion engine 1, a motor (FrM: an example of a rotating electric machine) 2, a generator (GEN) 4, a drive battery (BT) 6, a transaxle 8, an inverter 12 that controls the motor 2 and the generator 4, a touch panel display (an example of a setting means and a notification means) 14 that can be operated by a user of the electric vehicle C, an accelerator pedal 16 that is operated by a user of the electric vehicle C, a charger 18 that can be connected to an external power source, a vehicle control device (an example of a control device) 20, and an engine control device 22 that controls the internal combustion engine 1. In addition, the control system 3 of the electric vehicle C may include a power supply device 24 that can supply power to an external device such as a home appliance, and a charge button (not shown) that a user instructs to charge. In this embodiment, the electric vehicle C is a plug-in hybrid vehicle (PHEV) that includes external charging that can store power from an external power source in the drive battery 6 by the charger 18, or external power supply that can supply power from the drive battery 6 to an external device by the power supply device 24.

[0011] The internal combustion engine 1 is connected to a generator 4 and drives the generator 4. Furthermore, in this embodiment, the internal combustion engine 1 is capable of driving wheels C1 via a transaxle 8. The internal combustion engine 1 in this embodiment is an in-line four-cylinder gasoline engine. The internal combustion engine 1 receives fuel from a fuel tank 26, and burns and consumes the fuel.

[0012] The motor 2 is connected to the wheels C1 via a transaxle 8 and an axle 10, and drives the wheels C1. The motor 2 in this embodiment is a three-phase AC motor having a plurality of coils and a plurality of permanent magnets. The generator 4 is connected to the internal combustion engine 1 and is capable of driving the internal combustion engine 1. The generator 4 performs motoring to drive the internal combustion engine 1 while the internal combustion engine 1 is being powered by electric power from the drive battery 6. On the other hand, the generator 4 is driven by the internal combustion engine 1 to generate electricity while the internal combustion engine 1 is in operation. Therefore, the generator 4 is a motor-generator capable of powering and generating electricity.

[0013] The driving battery 6 outputs electric power to the motor 2 and the generator 4, and also receives electric power generated by the motor 2 and the generator 4. Furthermore, the driving battery 6 receives external electric power via a charger 18.

[0014] The transaxle 8 has a plurality of gears and a clutch 8a. The internal combustion engine 1 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 internal combustion engine 1 and the axle 10, and when the clutch 8a is in a engaged state, the power of the internal combustion engine 1 is transmitted to the axle 10.

[0015] The inverter 12 converts the DC power supplied from the drive battery 6 into AC power, and adjusts the power supplied to the motor 2, thereby controlling the power running torque of the motor 2. When the motor 2 regenerates, the inverter 12 converts the AC power supplied from the motor 2 into DC power, and adjusts the power supplied to the drive battery 6, thereby controlling the regenerative torque of the motor 2.

[0016] The display 14 is disposed in a position visible to a user of the electric vehicle C, and is a device capable of notifying the user of information relating to the electric vehicle C. In this embodiment, the display 14 is a touch panel type liquid crystal or organic EL display disposed in the cabin of the electric vehicle C. The display 14 is electrically connected to the vehicle control device 20, acquires information relating to the electric vehicle C from the vehicle control device 20, generates a notification screen, and generates buttons that can be touched and operated by the user.

[0017] The vehicle control device 20 is electrically connected to the motor 2 via the inverter 12, and is a device that controls the motor 2. The motor 2 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 20 controls the electric vehicle C based on maps and programs stored in the memory.

[0018] The vehicle control device 20 of this embodiment is further electrically connected to an engine control device 22. The engine control device 22 is electrically connected to various devices included in the internal combustion engine 1, and controls the internal combustion engine 1. The control of the internal combustion engine 1 may be performed by the vehicle control device 20 in addition to the engine control device 22. The vehicle control device 20 may also be electrically connected to various other devices of the electric vehicle C and perform various controls.

[0019] The electric vehicle C of this embodiment has various modes such as an EV mode, a series mode, a parallel mode, and a charging mode. In the EV mode, the electric vehicle C drives the motor 2 with electric power from the driving battery 6. In the series mode, the electric vehicle C drives the generator 4 with the internal combustion engine 1, and drives the motor 2 with electric power generated by the generator 4. In the parallel mode, the electric vehicle C connects the clutch 8a and drives the axle 10 with the power of the internal combustion engine 1. In the charging mode, the electric vehicle C drives the generator 4 with the internal combustion engine 1, and stores the electric power generated by the generator 4 in the driving battery 6. In the electric vehicle C, the vehicle control device 20 switches between the various modes according to the depression state of the accelerator pedal 16 and the operation state of the charge button, and controls the motor 2 and the generator 4 via the inverter 12, and causes the engine control device 22 to control the internal combustion engine 1.

[0020] In such an electric vehicle C, when the accelerator pedal 16 is depressed in the series mode, an engine required output, which is an output required of the internal combustion engine 1, is calculated based on the depression amount of the accelerator pedal 16. The vehicle control device 20 increases the rotation speed of the internal combustion engine 1 so as to achieve the engine required output. In this way, the vehicle control device 20 increases the amount of power generated by the generator 4. When increasing the rotation speed of the internal combustion engine 1, the vehicle control device 20 has a first control that increases the rotation speed while prioritizing the fuel efficiency of the internal combustion engine 1, and a second control that increases the rotation speed more gently than the first control and improves the NVH of the internal combustion engine 1 more than the first control.

[0021] 2 and 3 are iso-fuel consumption maps of the internal combustion engine 1. The solid line Tmax in FIG. 2 and FIG. 3 indicates the maximum torque at each revolution speed of the internal combustion engine 1. The spiral solid line is a line connecting lines that provide the same fuel consumption at each engine revolution speed and each torque. In the iso-fuel consumption map, the closer to the center of the vortex, the better the fuel consumption. The solid line FEb is the best fuel consumption line (an example of best fuel consumption) when the revolution speed of the internal combustion engine 1 is increased by series operation from the revolution speed and torque of the internal combustion engine 1 at point A to the revolution speed and torque of the internal combustion engine 1 at point B.

[0022] Next, a difference between the first control and the second control when the output required of the internal combustion engine 1 changes from point A to point B in FIG. 2 and FIG. 3 will be described.

[0023] In the first control, the vehicle control device 20 controls the internal combustion engine 1 so that the torque and rotation speed are set to the best fuel efficiency of the internal combustion engine 1. In this embodiment, in the first control, the vehicle control device 20 increases the rotation speed and torque of the internal combustion engine 1 along the solid line FEb. More specifically, the vehicle control device 20 stores a first rotation change rate (one example of a first increase rate) d1 of the best fuel efficiency line. By using this first rotation change rate d1, the vehicle control device 20 increases the rotation speed of the internal combustion engine 1 to the engine required output (point B) while passing through the best fuel efficiency line, as shown in FIG. 2. In this way, in the first control, the rotation speed of the internal combustion engine 1 increases while passing through the fuel-efficient rotation speed and torque, so that the fuel efficiency of the internal combustion engine 1 is good. However, since fuel efficiency is prioritized, there is a risk that the NVH will be worse than in the second control. Specifically, the output of the internal combustion engine 1 is determined by the product of the torque and the rotation speed, but the output of the best fuel efficiency line is lower than the output at point B (engine required output). Therefore, when the vehicle control device 20 operates the internal combustion engine 1 only by the first control, the output of the internal combustion engine 1 becomes insufficient with respect to the engine required output while the rotation speed of the internal combustion engine 1 is increasing. In order to reduce the state in which the output of the internal combustion engine 1 is insufficient with respect to the engine required output, it is preferable that the vehicle control device 20 quickly increases the output of the internal combustion engine 1 along the best fuel efficiency line in the first control. For this reason, it is preferable to set the first rotation change rate d1 to a rate higher than a second rotation change rate d2 described later. As a result, the vehicle control device 20 increases the rotation speed of the internal combustion engine 1 more quickly than in the second control. As a result, the first control is more likely to deteriorate NVH than the second control.

[0024] As shown in FIG. 3, in the second control, the vehicle control device 20 controls the internal combustion engine 1 while gradually increasing the rotation speed of the internal combustion engine 1. In this embodiment, as shown by the dashed line in FIG. 3, the torque of the internal combustion engine 1 is once increased to point C where the engine required output (the same output as point B) is achieved while maintaining the rotation speed, and then the rotation speed is gradually increased while decreasing the torque to point B on the best fuel consumption line while keeping the output constant. The dashed line from point C to point B in FIG. 3 indicates a line where the product of the torque and rotation speed of the internal combustion engine 1 is the same output as point B. The vehicle control device 20 increases the rotation speed while decreasing the torque along this dashed line. At this time, the vehicle control device 20 increases the rotation speed by a second rotation change rate (an example of a second increase rate) d2, which is a rotation change rate that is gentler than the first rotation change rate d1. The second rotation change rate d2 is a value that is set in advance by experiments or the like so that the increase in the rotation speed of the internal combustion engine 1 is NVH to an extent that does not cause discomfort to the user of the electric vehicle C. The vehicle control device 20 stores this preset second rotation change rate d2. The vehicle control device 20 uses this second rotation change rate d2 to increase the rotation speed of the internal combustion engine 1 to point B while achieving the required engine output. In this way, in the second control, the rotation speed of the internal combustion engine 1 increases while prioritizing NVH. However, since the torque and rotation speed at which fuel efficiency is poor are passed, the fuel efficiency is worse than that of the first control.

[0025] Thus, the first control and the second control each have advantages and disadvantages. Therefore, the vehicle control device 20 can change the weighting of the first control and the second control. In this embodiment, the vehicle control device 20 changes the weighting of the first control and the second control by changing the change rate coefficient K by which the first rotation change rate d1 and the second rotation change rate d2 are multiplied. In this embodiment, the vehicle control device 20 has a fuel efficiency mode in which the user can set a target fuel efficiency, and when the user selects the fuel efficiency mode, the weighting can be changed. When the user does not select the fuel efficiency mode, the vehicle control device 20 controls the internal combustion engine 1 by the second control.

[0026] Next, a control procedure executed by the vehicle control device 20 will be described with reference to the flowchart of Fig. 4. In this embodiment, the vehicle control device 20 starts the control procedure when the fuel economy mode is selected.

[0027] In step S1, the vehicle control device 20 displays a target fuel efficiency setting screen on the display 14. As shown in FIG. 6, the target fuel efficiency setting screen may display, for example, the size of the target fuel efficiency Ft as a bar, and may display the upper and lower limits of the target fuel efficiency Ft superimposed on the bar-shaped target fuel efficiency Ft. Furthermore, the vehicle control device 20 may display buttons 30 that allow the user to increase or decrease the target fuel efficiency Ft. In any case, the target fuel efficiency setting screen may be any screen that allows the user to set the target fuel efficiency Ft. When the user sets the target fuel efficiency Ft, the vehicle control device 20 stores the target fuel efficiency Ft. After storing the target fuel efficiency Ft, the vehicle control device 20 proceeds to step S2.

[0028] In step S2, the vehicle control device 20 determines whether the target fuel efficiency Ft is within a standard range. In this embodiment, whether the target fuel efficiency Ft is within the standard range is determined based on whether the target fuel efficiency Ft set by the user is between an upper limit value and a lower limit value. The upper limit value is, for example, the best fuel efficiency value that the electric vehicle C can achieve. The lower limit value is, for example, the worst fuel efficiency value of the electric vehicle C. When the vehicle control device 20 determines that the target fuel efficiency Ft is within the standard range (step S2 YES), the process proceeds to step S3.

[0029] In step S3, the vehicle control device 20 starts measuring fuel efficiency. The vehicle control device 20 acquires the actual fuel efficiency, which is the actual fuel consumption amount of the internal combustion engine 1, by detecting the remaining amount of fuel in the fuel tank 26, etc. After starting the measurement of fuel efficiency, the vehicle control device 20 advances the process to step S4.

[0030] In step S4, the vehicle control device 20 determines an initial value K0 of the change rate coefficient K, which is a value between 1 and 0. After determining the initial value K0 of the change rate coefficient K, the vehicle control device 20 advances the process to step S5.

[0031] In step S5, the vehicle control device 20 determines the rotation change rate α. In this embodiment, the initial value α0 of the rotation change rate α is calculated by multiplying the first rotation change rate d1 by the initial value K0 of the change rate coefficient K, multiplying the second rotation change rate d2 by a value obtained by subtracting the initial value K0 from 1, and then summing these products. That is, the vehicle control device 20 calculates the initial value α0 of the rotation change rate α by the following formula (1). α0=d1×K0+d2×(1-K0)...Equation (1) After determining the initial value α0 of the rotation change rate α, the vehicle control device 20 advances the process to step S6.

[0032] In step S6, the vehicle control device 20 judges whether the electric vehicle C has traveled for a predetermined period. In this embodiment, the vehicle control device 20 judges whether the electric vehicle C has traveled a predetermined distance ODt. Specifically, the vehicle control device 20 counts the travel distance OD of the electric vehicle C from the start of fuel efficiency measurement (step S3), and sets a flag to proceed to processing in step S7 and thereafter each time the travel distance OD reaches the predetermined distance ODt. The predetermined distance ODt may be any value as long as the value of the target fuel efficiency Ft and the value of the actual fuel efficiency can be compared. In addition, the vehicle control device 20 may count the time from the start of fuel efficiency measurement (step S3) instead of the predetermined distance ODt, and set a flag to proceed to processing in step S7 and thereafter every predetermined time T. When the vehicle control device 20 judges that the electric vehicle C has traveled for a predetermined period (step S6 YES), the vehicle control device 20 advances the processing to step S7.

[0033] In step S7, the vehicle control device 20 acquires the target fuel efficiency Ft and the actual fuel efficiency, and compares the target fuel efficiency Ft with the actual fuel efficiency. After comparing the target fuel efficiency Ft with the actual fuel efficiency, the vehicle control device 20 advances the process to step S8.

[0034] In step S8, the vehicle control device 20 determines whether the actual fuel efficiency is equal to or greater than the target fuel efficiency Ft. If the vehicle control device 20 determines that the actual fuel efficiency is equal to or greater than the target fuel efficiency Ft (YES in step S8), the process proceeds to step S9.

[0035] In step S9, the vehicle control device 20 subtracts a predetermined value Kt from the initial value K0 of the change rate coefficient K. The predetermined value Kt may be set to a value that increases as the difference between the target fuel efficiency Ft and the actual fuel efficiency increases. However, the predetermined value Kt may have an upper limit. If the predetermined value Kt is set to a particularly large value, the slope of the rotation speed of the internal combustion engine changes abruptly, and the NVH of the internal combustion engine improves abruptly. This may cause the user to feel uncomfortable. By setting an upper limit to the predetermined value Kt, it is possible to prevent the user from feeling uncomfortable. When the actual fuel efficiency is equal to or greater than the target fuel efficiency Ft, it is preferable for the vehicle control device 20 to prioritize NVH over improving fuel efficiency. Therefore, the vehicle control device 20 lowers the value of the change rate coefficient K, reduces the weighting of the first control that prioritizes fuel efficiency, and increases the weighting of the second control that prioritizes NVH. After subtracting the predetermined value Kt from the initial value K0 of the change rate coefficient K, the vehicle control device 20 proceeds to step S10.

[0036] In step S10, the vehicle control device 20 calculates the rotation change rate α by a change rate coefficient K1 obtained by subtracting a predetermined value Kt from an initial value K0, and determines the rotation change rate α1. In this embodiment, the vehicle control device 20 calculates the rotation change rate α1 by the following formula (2). α1=d1×K1+d2×(1-K1)...Equation (2) In this way, the vehicle control device 20 changes the rotation change rate α from the initial value α0 to the rotation change rate α1, and proceeds to step S11.

[0037] In step S11, the vehicle control device 20 notifies the user of the degree of achievement of the target fuel efficiency Ft. In addition, when the rotation change rate α is changed, the vehicle control device 20 notifies the user of that fact. As shown in FIG. 7, the degree of achievement of the target fuel efficiency Ft may be, for example, shown by a bar graph indicating the actual fuel efficiency, a solid line indicating the target fuel efficiency Ft, and a distance between the bar graph and the solid line of the target fuel efficiency Ft indicating the degree of achievement of the target fuel efficiency Ft. In FIG. 7, the actual fuel efficiency is equal to or greater than the target fuel efficiency Ft, and the bar graph indicates a state in which the actual fuel efficiency exceeds the solid line of the target fuel efficiency Ft. In this embodiment, the vehicle control device 20 generates these pieces of information and displays them on the display 14. In addition, the fact that the rotation change rate α has changed may be displayed by text information, symbols, or a combination of these. After executing the process of step S11, the vehicle control device 20 proceeds to the process of step S12.

[0038] In step S12, the vehicle control device 20 determines whether the fuel economy mode has ended. In this embodiment, when the user cancels the selection of the fuel economy mode, the vehicle control device 20 determines that the fuel economy mode has ended. When the vehicle control device 20 determines that the fuel economy mode has ended (step S12 YES), the process ends.

[0039] In step S2, when the vehicle control device 20 determines that the target fuel efficiency Ft is outside the reference range (step S2 NO), the vehicle control device 20 proceeds to the process of step S13. In step S13, the vehicle control device 20 sets the target fuel efficiency Ft to a value that is closest to the fuel efficiency selected by the user from the values ​​within the reference range. Specifically, when the user selects a fuel efficiency higher than the upper limit of the target fuel efficiency Ft, the vehicle control device 20 sets the fuel efficiency of the upper limit value as the target fuel efficiency. Conversely, when the user selects a fuel efficiency higher than the lower limit value of the target fuel efficiency Ft, the vehicle control device 20 sets the fuel efficiency of the lower limit value as the target fuel efficiency. When the vehicle control device 20 sets the target fuel efficiency Ft to be within the reference range, the process proceeds to step S3.

[0040] In step S6, when the vehicle control device 20 determines that the electric vehicle C has not been running for the predetermined period (NO in step S6), the vehicle control device 20 repeats the process of step S6. That is, the vehicle control device 20 waits for the process until the electric vehicle C has been running for the predetermined period.

[0041] In step S8, when the vehicle control device 20 determines that the actual fuel consumption is less than the target fuel consumption Ft (step S8 NO), the vehicle control device 20 proceeds to the process of step S14. In step S14, the vehicle control device 20 adds a predetermined value Kt to the initial value K0 of the change rate coefficient K. In this case, an upper limit value may be set for the predetermined value Kt. If the predetermined value Kt is set to a particularly large value, the slope of the rotation speed of the internal combustion engine may change abruptly, and the NVH of the internal combustion engine may suddenly deteriorate. This may cause a sense of discomfort to the user. If the actual fuel consumption is less than the target fuel consumption Ft, it is preferable for the vehicle control device 20 to prioritize improvement of fuel consumption over improvement of NVH. Therefore, the vehicle control device 20 increases the value of the change rate coefficient K, increases the weighting of the first control prioritizing fuel consumption, and decreases the weighting of the second control prioritizing NVH. After adding the predetermined value Kt to the initial value K0 of the change rate coefficient K, the vehicle control device 20 proceeds to the process of step S10.

[0042] In step S10, the vehicle control device 20 calculates the rotation change rate α by the change rate coefficient K2 obtained by adding a predetermined value Kt to the initial value K0, and determines the rotation change rate α2. In this embodiment, the vehicle control device 20 calculates the rotation change rate α1 by the following formula (3). α2=d1×K2+d2×(1-K2)...Equation (3) In this way, the vehicle control device 20 changes the rotation change rate α from the initial value α0 to the rotation change rate α2, and proceeds to step S11.

[0043] In step S12, when the vehicle control device 20 determines that the fuel efficiency mode has not ended (NO in step S12), the vehicle control device 20 proceeds to step S6 and repeats the processes from step S6 to step S12 and step S14. In this manner, the vehicle control device 20 changes the weighting of the first control and the second control while updating the change rate coefficient K.

[0044] Next, an example of the above control will be described with reference to the timing chart of FIG.

[0045] At time t0, the vehicle control device 20 starts fuel consumption measurement (see step S3). As shown from time t0 to time t1, the vehicle control device 20 sets the change rate coefficient K to an initial value K0 (0.5 in this embodiment), sets the rotation change rate α to an initial value α0, and increases the rotation speed of the internal combustion engine 1 (see steps S4 and S5). When the rotation change rate α is the initial value α0, the first control and the second control are equally weighted. Therefore, the rotation speed of the internal combustion engine 1 increases with the rotation change rate α that is intermediate between the first rotation change rate d1 and the second rotation change rate d2.

[0046] When the electric vehicle C travels for a predetermined period from time t0 to time t1 (travels a predetermined distance ODt in this embodiment), the vehicle control device 20 sets a flag at time t1 (see step S6 YES). In this embodiment, at time t1, the vehicle control device 20 determines that the actual fuel efficiency is equal to or greater than the target fuel efficiency Ft (see step S8 YES). In this case, the vehicle control device 20 calculates the rotation change rate α1 using the change rate coefficient K1 obtained by subtracting a predetermined value Kt (0.3 in this embodiment) from the initial value K0 (see steps S9 and S10). The vehicle control device 20 increases the rotation speed of the internal combustion engine 1 using the rotation change rate α1. Compared to the initial value α0, the rotation change rate α1 has a larger weighting of the second control and a smaller weighting of the first control. For this reason, the influence of the second rotation change rate d2 becomes larger, and the rotation speed of the internal combustion engine 1 increases more slowly than the increase in the rotation speed of the internal combustion engine 1 due to the initial value α0 of the rotation change rate α. As a result, NVH is improved when the rotation change rate α is α1 compared to when the rotation change rate α is the initial value α0.

[0047] When the electric vehicle C runs for a predetermined period from time t1 to time t2, the vehicle control device 20 sets a flag at time t2 (see YES in step S6). In this embodiment, at time t2, the vehicle control device 20 determines that the actual fuel consumption is less than the target fuel consumption Ft (see NO in step S8). In this case, the vehicle control device 20 calculates the rotation change rate α2 using the change rate coefficient K2 obtained by adding a predetermined value Kt (0.3 in this embodiment) to the initial value K0 (see steps S14 and S10). The vehicle control device 20 increases the rotation speed of the internal combustion engine 1 using the rotation change rate α2. Compared to the initial value α0, the rotation change rate α2 has a larger weighting of the first control and a smaller weighting of the second control. For this reason, the influence of the first rotation change rate d1 becomes larger, and the rotation speed of the internal combustion engine 1 increases higher than the increase in the rotation speed of the internal combustion engine 1 due to the initial value α0 of the rotation change rate α. As a result, fuel economy is improved when the rate of change in rotation α is α2 compared to when the rate of change in rotation α is the initial value α0.

[0048] When the electric vehicle C runs for a predetermined period from time t2 to time t3, the vehicle control device 20 sets a flag at time t3 (see YES in step S6). In this embodiment, the vehicle control device 20 determines that the actual fuel consumption is less than the target fuel consumption Ft at time t3, but the deviation is smaller than that between time t2 and time t3. In this case, the vehicle control device 20 calculates the rotation change rate α3 using a change rate coefficient K3 obtained by adding a predetermined value Kt (0.2 in this embodiment) to the initial value K0. The vehicle control device 20 increases the rotation speed of the internal combustion engine 1 using the rotation change rate α3. The rotation change rate α3 is weighted more heavily on the first control and less heavily on the second control than the initial value α0. On the other hand, the rotation change rate α3 is weighted less heavily on the first control and more heavily on the second control than the rotation change rate α2. Therefore, the increase in the rotation speed of the internal combustion engine 1 becomes more gradual than when the rotation change rate α2 is used. As a result, NVH is improved when the rotation change rate is α3 compared to when the rotation change rate is α2.

[0049] As described above, according to the present disclosure, it is possible to provide a control system 3 for an electric vehicle that is capable of adjusting the balance between NVH and fuel economy of an internal combustion engine.

[0050] <Other embodiments> Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention. In particular, the multiple modifications described in this specification can be arbitrarily combined as necessary.

[0051] (a) In the above embodiment, an example has been described in which the initial value K0 of the change rate coefficient K is set to 0.5, but the present disclosure is not limited to this. For example, the initial value K0 may be set to a value higher than 0.5 when priority is given to fuel economy. On the other hand, for example, the initial value K0 may be set to a value lower than 0.5 when priority is given to NVH.

[0052] (b) In the above embodiment, the electric vehicle C is described as a plug-in hybrid vehicle having series operation, but the present disclosure is not limited to this. The electric vehicle C may be, for example, a hybrid vehicle. [Explanation of symbols]

[0053] 1: Internal combustion engine, 2: Motor, 3: Control system, 4: Generator C: Electric vehicle, C1: Wheel FEb: Best fuel economy line (an example of best fuel economy) Ft: target fuel efficiency, K: change rate coefficient ODt: Predetermined distance (an example of a predetermined period) T: A specified time (an example of a specified period) d1: First rotation rate (an example of the first rate of increase) d2: Second rotation rate (an example of the second rate of increase)

Claims

1. An internal combustion engine mounted in an electric vehicle; a generator driven by the internal combustion engine; A motor capable of driving wheels of the electric vehicle; A control device for controlling the electric vehicle; Equipped with the control device has a first control for increasing a rotation speed of the internal combustion engine with a priority on fuel efficiency, and a second control for increasing the rotation speed more slowly than the first control, The control device acquires a target fuel efficiency, which is a fuel efficiency target of the internal combustion engine, and an actual fuel efficiency, which is an actual fuel efficiency of the internal combustion engine, during a series operation in which the internal combustion engine drives the motor with electric power obtained by driving the generator, and changes a weighting of the first control and the second control in accordance with the target fuel efficiency and the actual fuel efficiency when increasing the rotation speed of the internal combustion engine. Electric vehicle control system.

2. When the target fuel efficiency is higher than the actual fuel efficiency, the control device weights the first control higher than the second control. The control system for an electric vehicle according to claim 1 .

3. The control device increases the rotation speed at a first increase rate that passes through an optimal fuel efficiency of the internal combustion engine in the first control, In the second control, the rotation speed is increased at a second increase rate which is smaller than the first increase rate, A weighting of the first control and the second control is changed by multiplying the first rate of increase and the second rate of increase by a coefficient. The control system for an electric vehicle according to claim 1 .

4. The control device changes the weighting every predetermined period. The control system for an electric vehicle according to claim 1 .

5. A setting means for setting the target fuel efficiency; a notification means for notifying a user of the electric vehicle of an achievement degree of the actual fuel efficiency with respect to the target fuel efficiency; Further comprising: The control system for an electric vehicle according to any one of claims 1 to 4.

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