JP2022073408A - Electric vehicle control device - Google Patents

Abstract

To provide an electric vehicle capable of securing drivability while curbing degradation of fuel economy.SOLUTION: When an opening of an accelerator pedal is 0% with no operation made to request an electric vehicle to accelerate, that is no operation to step on the accelerator pedal, regenerative operation of a drive motor is performed and regenerative braking force is applied to a driving system with the driving motor functioning as resistance. In this instance, when the opening of the accelerator pedal becomes 0% in a speed range where a speed of an electric vehicle 1 is a vehicle speed V4 or higher, target deceleration of the electric vehicle 1 is set at a constant value D3 until the speed thereof is reduced to less than the vehicle speed V4.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device for an electric vehicle such as a hybrid vehicle (HV).

For example, a series hybrid vehicle is equipped with a power generation motor that generates electricity from the power of an engine, a drive motor that generates power for driving, and a drive battery that stores the power used to drive the drive motor. .. Therefore, the series hybrid vehicle can adopt a one-pedal system that can control acceleration, deceleration, and stopping from deceleration by operating only the accelerator pedal.

In the one-pedal system, when the accelerator pedal is depressed, the drive motor generates power according to the operation amount (accelerator opening) of the accelerator pedal by the power running operation of the drive motor. When the accelerator pedal is not depressed and the accelerator opening is 0%, the drive motor becomes a resistance of the drive system due to the regenerative operation of the drive motor, and the braking force due to the resistance acts on the drive system. The electric power generated by the regenerative operation of the drive motor is stored in the drive battery.

Japanese Unexamined Patent Publication No. 2017-47820

FIG. 3A is a diagram showing an example of the relationship between the vehicle speed when the accelerator opening is 0% and the regenerative power (generated power) obtained by the regenerative operation of the drive motor, and FIG. 3B is a diagram. It is a figure which shows an example of the relationship between the vehicle speed and the deceleration of a hybrid vehicle when the accelerator opening degree is 0%.

When the accelerator opening degree is 0%, the larger the deceleration of the hybrid vehicle, the more the regenerative power obtained by the regenerative operation of the drive motor, and the better the fuel efficiency of the hybrid vehicle. On the other hand, since there is a limit on the charging power (charging power) of the drive battery, an upper limit of regenerative power (upper limit of regenerative power) is set, and accordingly, a limit is set on the deceleration of the hybrid vehicle.

If the maximum deceleration according to the vehicle speed (deceleration at the time of ideal regeneration) is set within the limit, the maximum regenerative power can be obtained without the regenerative power exceeding the charging power. However, when the vehicle speed continuously decelerates from the high speed range at an accelerator opening of 0%, the fluctuation range of the deceleration until the hybrid vehicle stops becomes large, and the drivability deteriorates. In order to set the deceleration so that the fluctuation range is within the allowable fluctuation range in which drivability can be ensured, it is necessary to reduce the maximum deceleration as shown by the broken line in FIG. 3 (b). When the maximum deceleration is lowered, as shown by the broken line in FIG. 3A, the regenerative power in the low speed range of the vehicle speed decreases from the ideal regenerative power for fuel consumption (ideal regenerative power) shown by the solid line. Fuel economy deteriorates.

An object of the present invention is to provide a control device for an electric vehicle capable of ensuring drivability while avoiding deterioration of fuel efficiency.

In order to achieve the above object, the control device for an electric vehicle according to the present invention includes a drive motor that generates power transmitted to the drive system by power running operation and generates power by the power of the drive system by regenerative operation, and a drive motor. An electric vehicle equipped with a drive battery that stores the power used for power driving, and regenerative braking force is applied to the drive system by the regenerative operation of the drive motor when the operation that requires acceleration of the electric vehicle is not performed. A setting means for setting the deceleration of the electric vehicle to be less than or equal to a predetermined maximum deceleration according to the vehicle speed when the operation requesting the acceleration of the electric vehicle is not performed, and the maximum deceleration. An adjustment means for adjusting the deceleration set by the setting means at a predetermined vehicle speed or higher so that the fluctuation range of the deceleration set by the setting means is within the allowable fluctuation range based on the speed, and the result of the adjustment, When the regenerative power obtained by the regenerative operation of the drive motor exceeds the charging power that the drive battery can accept, the waste power means for forcibly consuming the power is included.

According to this configuration, when the operation requesting acceleration of the electric vehicle is not performed, the regenerative operation of the drive motor is performed, and the regenerative braking force due to the drive motor acting as a resistance is applied to the drive system. At this time, the deceleration of the electric vehicle is set to be equal to or less than a predetermined maximum deceleration, and the deceleration is adjusted so that the fluctuation range of the deceleration is within the allowable fluctuation range based on the maximum deceleration. As a result, the fluctuation range of the deceleration can be kept within the allowable fluctuation range without reducing the maximum deceleration, and drivability can be ensured while avoiding deterioration of fuel efficiency.

However, as a result of such deceleration adjustment, the regenerative power obtained by the regenerative operation of the drive motor may exceed the charge power that can be accepted by the drive battery. In this case, control is performed to forcibly consume electric power. As a result, it is possible to consume a portion exceeding the charging power in the regenerative power, and the remaining regenerative power can be stored in the drive battery.

For example, when the electric vehicle is equipped with an engine and a power generation motor that generates power by the power of the engine, the control for forcibly consuming the power may be a control in which the engine is motorized by the power generation motor.

Further, the control for forcibly consuming electric power may be a control for operating an electric compressor of an air conditioner or a control for operating an electric water pump for circulating cooling water.

The adjusting means adjusts the deceleration of the electric vehicle to a constant value at a predetermined vehicle speed or higher, and the control device targets the regenerative torque generated by the regenerative operation of the drive motor so that the deceleration after adjustment by the adjusting means can be obtained. The configuration may further include a regenerative control means for setting a value and controlling the regenerative operation of the drive motor based on the target value.

With this configuration, the deceleration can be easily adjusted and the load on the control device can be reduced. Further, since the deceleration is adjusted at a predetermined vehicle speed or higher, as a result of the adjustment, when the regenerative power obtained by the regenerative operation of the drive motor exceeds the charge power that the drive battery can accept, the power is forcibly consumed. Even if the control is performed, it is possible to suppress the discomfort caused by the control from being given to the user. For example, when the control for forcibly consuming electric power is the control for motoring the engine by a power generation motor, the motoring is not performed at a vehicle speed lower than a predetermined vehicle speed, so that it is possible to suppress the user from feeling uncomfortable due to the start of the engine. .. Further, at a predetermined vehicle speed or higher, even if motoring is performed, the engine sound is masked by the running sound, so that it is possible to suppress the discomfort (noise) caused by the engine sound to the user.

According to the present invention, drivability can be ensured while avoiding deterioration of fuel efficiency.

It is a block diagram which shows the structure of the electric vehicle which concerns on one Embodiment of this invention. It is a figure for demonstrating the setting of deceleration of an electric vehicle, and (a) shows an example of the relationship between the vehicle speed when the accelerator opening is 0%, and the regenerative power obtained by the regenerative operation of a drive motor. , (B) show an example of the relationship between the vehicle speed and the vehicle deceleration when the accelerator opening is 0%. (A) is a diagram showing an example of the relationship between the vehicle speed when the accelerator opening is 0% and the regenerative power obtained by the regenerative operation of the drive motor, and (b) is a diagram showing an example of the relationship between the accelerator opening being 0% and the accelerator opening being 0%. It is a figure which shows an example of the relationship between the vehicle speed and the vehicle deceleration at a certain time.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Electric vehicle>
FIG. 1 is a block diagram showing a configuration of an electric vehicle 1 according to an embodiment of the present invention.

The electric vehicle 1 is equipped with a series-type hybrid system 2. The hybrid system 2 includes an engine (ENG) 11, a power generation motor (MG1) 12, a drive motor (MG2) 13, a drive battery 14, and a PCU (Power Control Unit) 15.

The engine 11 is, for example, a gasoline engine or a diesel engine. The crankshaft 21 of the engine 11 is provided with an engine output gear 22 so as to rotate integrally with the crankshaft 21.

The power generation motor 12 comprises, for example, a permanent magnet synchronous motor. The rotary shaft 23 of the power generation motor 12 is provided with a power generation motor gear 24 so as to rotate integrally. The power generation motor gear 24 meshes with the engine output gear 22. The power generation motor 12 is used as a starter motor for cranking the engine 11 when the engine 11 is stopped. After starting the engine 11, the power generation motor 12 functions as a generator that converts the power of the engine 11 into electric power.

The drive motor 13 is composed of, for example, a permanent magnet synchronous motor larger than the power generation motor 12. The rotation shaft of the drive motor 13 is connected to the drive system 25 of the electric vehicle 1. The drive system 25 includes a differential gear, and the power of the drive motor 13 is transmitted to the differential gear, and is distributed and transmitted from the differential gear to the drive wheels 26 including the left and right front wheels or the rear wheels. As a result, the left and right drive wheels 26 rotate, and the electric vehicle 1 moves forward or backward.

The drive battery 14 is an assembled battery in which a plurality of secondary batteries (for example, a lithium ion battery) are combined. The drive battery 14 outputs, for example, a DC power of about 200 to 350 V (volts).

The PCU 15 is a unit for controlling the drive of the power generation motor 12 and the drive motor 13, and includes a first inverter (MG1 INV) 31, a second inverter (MG2 INV) 32, and a boost converter (Bst CONV) 33. ..

When the electric vehicle 1 is accelerating, the drive motor 13 is driven by power running, and the drive motor 13 generates power for power running. At this time, the DC power output from the drive battery 14 is boosted as necessary by the boost converter 33, and the DC power output from the boost converter 33 is converted into AC power by the second inverter 32, and the AC power is converted to AC power. Is supplied to the drive motor 13. This consumes the power of the drive battery 14.

Further, when the engine 11 is started, the DC power output from the drive battery 14 is boosted by the boost converter 33, the boosted DC power is converted into AC power by the first inverter 31, and the AC power is converted into AC power by the power generation motor 12. Is supplied to. As a result, the power generation motor 12 is power-running, and the engine 11 is motorized by the power generation motor 12. When the spark plug of the engine 11 is sparked while the rotation speed of the crankshaft 21 of the engine 11 has increased to the rotation speed required for starting by motoring, the engine 11 is started.

When the power generation motor 12 is operated to generate power while the engine 11 is operating, the power generation motor 12 generates AC power. The AC power generated by the power generation motor 12 is converted into DC power by the first inverter 31. Then, the DC power output from the first inverter 31 is converted into AC power by the second inverter 32, and the AC power is supplied to the drive motor 13. When it is not necessary to supply electric power to the drive motor 13, the DC power output from the first inverter 31 is stepped down by the boost converter 33, and the DC power after stepping down is supplied to the drive battery 14. , The drive battery 14 is charged.

In the electric vehicle 1, a one-pedal system is adopted, and the accelerator pedal is not depressed not only when decelerating due to the operation of the service brake (foot brake), and the amount of operation by the driver with respect to the maximum amount of operation of the accelerator pedal is The drive motor 13 is regeneratively operated even when the accelerator opening degree, which is a ratio, is 0%. By the regenerative operation of the drive motor 13, the power transmitted from the drive wheels 5 to the drive motor 13 is converted into AC power. At this time, the drive motor 13 becomes the resistance of the drive system 25, and the resistance acts as a braking force (regenerative braking force) for braking the electric vehicle 1. The AC power generated by the drive motor 13 is converted into DC power by the second inverter 32. Then, the DC power output from the second inverter 32 is stepped down by the boost converter 33, and the DC power after the step-down is supplied to the drive battery 14, so that the drive battery 14 is charged.

Further, the electric vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU includes a microcomputer (microcontroller unit) 42, and the microcomputer 42 has, for example, a non-volatile memory such as a CPU and a flash memory and a volatile memory such as a DRAM (Dynamic Random Access Memory). .. The plurality of ECUs are connected so as to be capable of bidirectional communication by a CAN (Controller Area Network) communication protocol. FIG. 1 shows one ECU 41 among a plurality of ECUs.

Various sensors required for control are connected to the ECU 41. As an example of the sensor, an accelerator sensor 43 that outputs a detection signal according to the operation amount of the accelerator pedal is connected to the ECU 41. The accelerator opening degree is calculated from the detection signal of the accelerator sensor 43 in the ECU 41.

<Deceleration setting>
FIG. 2 is a diagram for explaining the setting of deceleration of the electric vehicle 1, and FIG. 2A is a diagram showing the vehicle speed when the accelerator opening is 0% and the regenerative power obtained by the regenerative operation of the drive motor 13. An example of the relationship with the generated power) is shown, and (b) shows an example of the relationship between the vehicle speed when the accelerator opening is 0% and the deceleration of the electric vehicle 1 (vehicle deceleration).

When the accelerator opening is 0%, the ECU 41 sets the deceleration (target) of the electric vehicle 1, and the target value of the regenerative torque generated by the drive motor 13 is set so that the deceleration can be obtained. .. Then, the regenerative operation of the drive motor 13 is controlled by the ECU 41 so that the regenerative torque generated by the drive motor 13 matches the target value.

As shown in FIG. 2A, since there is a limit to the charging power (charging power) of the drive battery 14, an upper limit of regenerative power (upper limit of regenerative power) is set, and the electric vehicle 1 is accompanied by this. There is a limit on deceleration. If the maximum deceleration according to the vehicle speed (deceleration at the time of ideal regeneration) is set within the limit, the maximum regenerative power can be obtained without the regenerative power exceeding the charging power.

As shown in FIG. 2B, in the high speed range where the vehicle speed is V1 or higher, the deceleration at the time of ideal regeneration becomes a constant value D1 regardless of the vehicle speed. When the deceleration target of the electric vehicle 1 is set to a constant value D1 in the high speed range where the vehicle speed is V1 or higher, the actual deceleration of the electric vehicle 1 increases as the vehicle speed increases due to the influence of air resistance and the like. It will be a small value. In the medium speed range where the vehicle speed is V2 or higher and less than V1, the ideal regeneration as the vehicle speed decreases so that the line showing the relationship between the vehicle speed and the deceleration of the electric vehicle 1 becomes a curve that curves downward. The deceleration of time increases from the value D1 to the value D2. In the low speed range where the vehicle speed is less than the vehicle speed V2, the deceleration at the time of ideal regeneration becomes a constant value D2. When the vehicle speed drops to the vehicle speed V3 or less due to deceleration, the electric vehicle 1 tends to stop. Therefore, even if the deceleration target is set to a certain value D2, the actual deceleration of the electric vehicle 1 increases as the vehicle speed decreases. It decreases toward 0.

However, when the deceleration target of the electric vehicle 1 is set to the deceleration at the time of ideal regeneration, the accelerator opening becomes 0% in the vehicle speed range where the vehicle speed of the electric vehicle 1 exceeds the vehicle speed V4, and the accelerator opening becomes 0% as it is. When the electric vehicle 1 continues to decelerate continuously, the fluctuation range of the deceleration in the period until the electric vehicle 1 stops exceeds the allowable fluctuation range in which drivability can be ensured, and the drivability deteriorates. ..

In other words, in the vehicle speed range where the vehicle speed of the electric vehicle 1 is the vehicle speed V4 or higher, the deceleration at the time of ideal regeneration is the value obtained by subtracting the allowable fluctuation range that can secure drivability from the value D2 of the maximum deceleration at the time of ideal regeneration. Since it becomes a certain value D3 or more, when the electric vehicle 1 continuously decelerates from a vehicle speed range exceeding the vehicle speed V4 at an accelerator opening of 0%, the fluctuation range of the deceleration in the period until the electric vehicle 1 stops is large. The permissible fluctuation range is exceeded, and drivability deteriorates.

Therefore, when the vehicle speed of the electric vehicle 1 becomes 0% in the vehicle speed range of the vehicle speed V4 or higher, the vehicle speed drops to less than V4 as shown by the two-dot chain line in FIG. 2 (b). Until then, the deceleration target of the electric vehicle 1 is set to a constant value D3. In other words, in the vehicle speed range of the vehicle speed V4 or higher in which the deceleration at the time of ideal regeneration is a value of the value D3 or higher, the deceleration target of the electric vehicle 1 is set to a constant value D3.

When the deceleration target of the electric vehicle 1 is set to a constant value D3 in the vehicle speed range of the vehicle speed V4 or higher, it is obtained by the regenerative operation of the drive motor 13 as shown by the two-dot chain line in FIG. 2 (a). The regenerative power may exceed the charging power that the drive battery 14 can accept. In this case, in order to forcibly consume electric power, for example, a target of engine speed is set according to regenerative power and vehicle speed, and the power generation motor 12 is supplied so that the engine speed matches the target. The supply of drive power is controlled, and the motoring of the engine 11 by the power generation motor 12 is executed (motoring control). As a result, a portion exceeding the charging power in the regenerative power is consumed, and the rest of the regenerative power is accepted by the drive battery 14.

If the brake pedal is depressed during deceleration of the electric vehicle 1 and the service brake is activated, the deceleration target of the electric vehicle 1 is maintained as it is, and when the service brake is released, the vehicle speed is adjusted. Deceleration is set.

<Action effect>
As described above, when the operation for requesting acceleration of the electric vehicle 1, that is, the operation of depressing the accelerator pedal is not performed and the accelerator opening is 0%, the regenerative operation of the drive motor 13 is performed to drive the motor. A regenerative braking force due to the motor 13 acting as a resistance is applied to the drive system 25. At this time, the deceleration of the electric vehicle 1 is set at the maximum deceleration D2 or less, and the deceleration is adjusted so that the fluctuation range of the deceleration is within the allowable fluctuation range based on the maximum deceleration D2. .. That is, when the accelerator opening becomes 0% in the vehicle speed range where the vehicle speed of the electric vehicle 1 is the vehicle speed V4 or higher, the deceleration target of the electric vehicle 1 is constant until the vehicle speed drops to less than V4. It is set to the value D3. As a result, the fluctuation range of the deceleration can be kept below the allowable fluctuation range without reducing the maximum deceleration D2, and drivability can be ensured while avoiding deterioration of fuel efficiency.

Further, when the deceleration target of the electric vehicle 1 is set to a constant value D3 and the regenerative power obtained by the regenerative operation of the drive motor 13 exceeds the charging power acceptable to the drive battery 14. Motoring control is performed and power is forcibly consumed. As a result, it is possible to consume a portion exceeding the charging power in the regenerative power, and the drive battery 14 can be charged with the remaining regenerative power.

Since the deceleration target of the electric vehicle 1 is set to a constant value D3 in the vehicle speed range where the vehicle speed is V4 or higher, it is possible to suppress discomfort to the user even if the motoring control is performed. can. That is, in the vehicle speed range where the vehicle speed is less than the vehicle speed V4, motoring is not performed, so that it is possible to suppress giving the user a sense of discomfort due to the start of the engine 11. Further, in the vehicle speed range of vehicle speed V4 or higher, even if the engine 11 is motorized, the engine sound (the sound generated from the engine 11 by the motoring) is masked by the running sound, so that the engine noise causes discomfort (noise). ) Can be suppressed from being given to the user.

<Modification example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other embodiments.

For example, in the above-described embodiment, the motoring control is taken up as the control for forcibly consuming electric power, but the control for forcibly consuming electric power may be the control for operating the electric compressor of the air conditioner. Alternatively, the control may be such that the electric water pump that circulates the cooling water is operated.

The permissible fluctuation range that can ensure drivability may be variably set according to the slope of the road surface on which the electric vehicle 1 is traveling. For example, when the road surface is uphill, the permissible fluctuation range may be set smaller than when the road surface is flat, and when the road surface is downhill, the permissible fluctuation range may be set larger than when the road surface is flat. ..

Further, in the above-described embodiment, the electric vehicle 1 adopting the one-pedal system is taken up and the control when the accelerator opening degree is 0% has been described. However, in the present invention, when the accelerator opening degree is 0%. Not limited to this, it can be widely applied to the control when the regenerative operation of the drive motor 13 is being performed.

The present invention is applicable not only to the electric vehicle 1 equipped with the hybrid system 2, but also to an electric vehicle (EV: Electric Vehicle) not equipped with an engine as long as it is an electric vehicle equipped with a motor as a driving source for traveling. You can also do it.

In addition, various design changes can be made to the above-mentioned configuration within the scope of the matters described in the claims.

1: Electric vehicle 13: Drive motor 14: Drive battery 25: Drive system 41: ECU (control device)
42: Microcomputer (setting means, adjusting means, waste power means, regenerative control means)

Claims (2)

It is equipped with a drive motor that generates power transmitted to the drive system by power running operation and generates power by the power of the drive system by regenerative operation, and a drive battery that stores the power used for power running operation of the drive motor. A control device used for an electric vehicle in which a regenerative braking force is applied to the drive system by the regenerative operation of the drive motor when the operation requesting acceleration of the electric vehicle is not performed.
A setting means for setting the deceleration of the electric vehicle to be less than or equal to a predetermined maximum deceleration according to the vehicle speed when the operation requesting acceleration of the electric vehicle is not performed.
An adjusting means for adjusting the deceleration set by the setting means at a predetermined vehicle speed or higher so that the fluctuation range of the deceleration set by the setting means is within the allowable fluctuation range based on the maximum deceleration.
As a result of the adjustment, when the regenerative power obtained by the regenerative operation of the drive motor exceeds the charge power that the drive battery can accept, the control includes a waste power means for forcibly consuming the power. Device. The adjusting means adjusts the deceleration of the electric vehicle to a constant value at the predetermined vehicle speed or higher.
A target value of the regenerative torque generated by the regenerative operation of the drive motor is set so that the deceleration after adjustment by the adjusting means is obtained, and the regenerative operation of the drive motor is controlled based on the target value. The control device according to claim 1, further comprising a control means.

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