JP7438619B2 - Regeneration control device - Google Patents

Description

The present invention relates to a regeneration control device mounted on a vehicle such as an electric vehicle (EV) or a hybrid vehicle (HV).

2. Description of the Related Art Vehicles such as hybrid vehicles (HV) and electric vehicles (EV) are equipped with a motor as a drive source for driving. The power of the motor is transmitted to a differential gear, and from the differential gear to left and right drive wheels. When the vehicle is decelerating, the power input to the rotating shaft of the motor is converted into electric power by regenerative control of the motor. At this time, the motor acts as a resistance in the drive system, and this resistance acts as a regenerative braking force to brake the vehicle (regenerative braking). The electric power generated by the motor is stored in a battery and used for subsequent driving of the motor. Therefore, by actively performing regeneration control, fuel efficiency or electricity consumption of the vehicle is improved.

On the other hand, vehicles are equipped with hydraulic braking devices. In a braking system installed in an electric vehicle or hybrid vehicle, when the brake pedal is stepped on, for example, an electric hydraulic pump is driven, and hydraulic pressure is supplied to the brake actuator, which then sends hydraulic pressure to the brake cylinders installed on each wheel. Hydraulic pressure is distributed and the brake pad is pressed against a brake rotor that rotates integrally with the wheel, thereby applying frictional braking force to the wheel (hydraulic brake).

The regenerative brake and the hydraulic brake are used together through regenerative cooperative control. In regenerative cooperative control, a target braking force is set according to the vehicle speed, the amount of brake pedal depression, etc., and this target braking force is distributed between regenerative braking force (regenerative braking amount) and friction braking force (hydraulic braking amount). . Then, the motor, electric hydraulic pump, etc. are controlled so that the regenerative braking force and the frictional braking force are respectively obtained.

Further, some vehicles are equipped with a vehicle stability control device (vehicle attitude control device) that stabilizes vehicle behavior during cornering. In the control by the vehicle stability control system, a target yaw rate is determined from vehicle speed, steering angle, etc., and a target yawing moment is set from the deviation between the target yaw rate and the actual yaw rate. Then, the braking force necessary to obtain the target yawing moment is applied to each of the front, rear, left and right wheels. Thereby, it is possible to improve the turning performance of the vehicle and stabilize the vehicle behavior in the turning limit region.

Japanese Patent Application Publication No. 10-181389

However, in conventional vehicles, if control by the vehicle stability control device intervenes during regeneration control of the motor, the regeneration control is interrupted. Due to the interruption of regenerative control, the regenerative braking force sharply decreases to 0, and this decrease in the regenerative braking force appears as a change (shock) in the acceleration of the vehicle. As a result, the noise vibration (NV) characteristics of the vehicle deteriorate.

An object of the present invention is to provide a regeneration control device that can reduce changes in acceleration due to fluctuations in regenerative braking force when control by a vehicle stability control device intervenes during regeneration control.

In order to achieve the above object, a regeneration control device according to one aspect of the present invention includes a motor that applies power for traveling to the drive system through power running and a regenerative braking force to the drive system through regenerative operation. , a regeneration control device that is installed in a vehicle together with a hydraulic braking device that applies frictional braking force by hydraulic pressure to the drive system, and a hydraulic braking control device that controls the hydraulic braking device, and controls the regenerative operation of the motor. During the control of motor regenerative operation, control intervention for stabilizing vehicle behavior by the hydraulic braking control device is estimated from predetermined parameters, and if the control intervention is estimated, the control is performed before the intervention. Controls regenerative operation of the motor to reduce regenerative braking force.

According to this configuration, when control intervention for stabilizing the behavior of the vehicle is estimated during control of the regenerative operation of the motor, the regenerative braking force due to the regenerative operation of the motor is reduced in preparation for the intervention. . Therefore, when the control for stabilizing the behavior of the vehicle is actually intervened and the regenerative driving control is interrupted, the amount of decrease in the regenerative braking force (the amount of decrease to 0) can be suppressed to a small value. As a result, changes in vehicle acceleration due to a decrease in regenerative braking force are reduced, and the noise vibration characteristics and stability of the vehicle are improved.

After estimating control intervention for stabilizing the behavior of the vehicle, the regenerative braking device may reduce the regenerative braking force in stages as the timing of the intervention approaches.

With this configuration, it is possible to suppress sudden changes in regenerative braking force before intervention of control for stabilizing the behavior of the vehicle.

The present invention can also be regarded as an invention related to a control device including a hydraulic brake control device and a regeneration control device. That is, a control device according to another aspect of the present invention includes a motor that applies power for traveling to the drive system through power running, a motor that applies regenerative braking force to the drive system through regenerative operation, and a friction braking force using hydraulic pressure. A control device used in a vehicle equipped with a hydraulic braking device that controls the hydraulic braking device and a regenerative braking force being applied to the drive system. When the hydraulic braking control device estimates control intervention to stabilize vehicle behavior from predetermined parameters, a regeneration control device is installed that controls the regenerative operation of the motor to reduce the regenerative braking force before the intervention. include.

The hydraulic braking control device may control the hydraulic braking device so that, in response to the reduction of the regenerative braking force by the regeneration control device, the frictional braking force corresponding to the reduction is increased.

With this configuration, it is possible to suppress insufficient braking force due to reduction in regenerative braking force. Moreover, since much of the necessary braking force can be borne by the frictional braking force before the control for stabilizing the behavior of the vehicle is started, the control can be started smoothly.

According to the present invention, it is possible to reduce changes in vehicle acceleration due to a decrease in regenerative braking force when control by a vehicle stability control device intervenes during regeneration control, and it is possible to improve noise vibration characteristics and stability of the vehicle. .

FIG. 1 is a block diagram showing the configuration of main parts of a vehicle in which a regeneration control device according to an embodiment of the present invention is incorporated into a control system. 2 is a flowchart (part 1) showing the flow of regeneration reduction processing. 12 is a flowchart (part 2) showing the flow of regeneration reduction processing.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<Configuration of main parts of vehicle>
FIG. 1 is a block diagram showing the configuration of essential parts of a vehicle 1 in which a regeneration control device according to an embodiment of the present invention is incorporated into a control system.

The vehicle 1 is an electric vehicle (EV) equipped with a motor 2 as a drive source for driving. The motor 2 is, for example, a permanent magnet synchronous motor (PMSM) using a permanent magnet in a rotor.

During power running of the motor 2, DC power output from a battery (not shown) mounted on the vehicle 1 is converted into AC power by an inverter, and the AC power is supplied to the motor 2. As a result, the motor 2 generates power, and the power is transmitted to the left and right drive wheels via a differential gear or the like.

On the other hand, during regenerative operation of the motor 2, the motor 2 converts power from the drive wheels into AC power. At this time, the motor 2 acts as a resistance in the drive system, and regenerative braking force due to the resistance acts on the drive wheels. That is, the motor 2 functions as a regenerative brake. AC power generated by the motor 2 is converted into DC power by an inverter, and the battery is charged.

The vehicle 1 is equipped with a hydraulic brake 3. In the hydraulic brake 3, when the brake pedal is operated by the user (driver of the vehicle 1), the electric hydraulic pump is driven, hydraulic pressure is supplied to the brake actuator, and the brake actuator applies pressure to each wheel (drive wheel, driven wheel). Hydraulic pressure is distributed to the provided brake cylinders, and the brake pads are pressed against the brake rotor that rotates integrally with the wheels, thereby applying frictional braking force to the wheels.

The vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units) to control various parts. Each ECU includes a microcomputer (microcontroller). The plurality of ECUs are connected to enable bidirectional communication using a CAN (Controller Area Network) communication protocol. Further, various sensors necessary for control are connected to each ECU.

The plurality of ECUs include a brake ECU 4 and a motor control ECU 5. An outside temperature sensor 11, a wheel speed sensor 12, a vehicle speed sensor 13, a steering angle sensor 14, and a yaw rate sensor 15 are connected to the brake ECU 4.

The outside air temperature sensor 11 outputs a detection signal according to the air temperature outside the vehicle (outside air temperature).

The wheel speed sensor 12 is provided for each wheel and outputs a detection signal (a pulse signal synchronized with the rotation of the wheel) according to the rotational speed of the wheel.

The vehicle speed sensor 13 outputs a detection signal according to the traveling speed (vehicle speed) of the vehicle 1.

The steering angle sensor 14 outputs a detection signal corresponding to the steering angle of the steering mechanism of the vehicle 1 with respect to the midpoint of the steering angle. The steering angle may be a steering angle (rotation operation angle) of a steering wheel operated by a driver from a neutral position, or a turning angle of a steering wheel from a neutral position by a steering mechanism.

The yaw rate sensor 15 outputs a detection signal corresponding to a yaw rate that is a rotational angular velocity around a vertical axis passing through the center of gravity of the vehicle 1.

In the vehicle 1, when the driver performs a brake operation (accelerator pedal return operation, brake pedal depression operation), regenerative cooperative control is executed if regenerative operation of the motor 2 is possible. In the regenerative cooperative control, the brake ECU 4 sets a target braking force according to the vehicle speed, the amount of depression of the brake pedal, etc., and the target braking force is distributed to the regenerative braking force (regeneration amount) and the friction braking force. Then, the motor 2 is controlled by the brake ECU 4 so that the target frictional braking force is obtained. Further, the brake ECU 4 issues an instruction to the motor control ECU 5 to obtain a target regenerative braking force, and the motor control ECU 5 controls the regenerative operation of the motor 2 in accordance with the instruction.

Further, the brake ECU 4 may perform vehicle stability control to stabilize vehicle behavior when the vehicle 1 is turning. In vehicle stability control, a target yaw rate is determined from vehicle speed, steering angle, etc., and a target yawing moment is set from the deviation between the target yaw rate and the actual yaw rate. Then, the electric hydraulic pump and the brake actuator are controlled so that the braking force necessary to obtain the target yawing moment is applied to each of the front, rear, left, and right wheels. This vehicle stability control can improve the turning performance of the vehicle 1 and stabilize the behavior in the turning limit region.

<Regeneration reduction processing>
2A and 2B are flowcharts showing the flow of regeneration reduction processing.

When vehicle stability control intervenes during regenerative cooperative control, the regenerative cooperative control is interrupted and the regenerative operation of the motor 2 is interrupted. In order to suppress the occurrence of a shock due to a decrease in the amount of regeneration (regenerative braking force) due to interruption of the regenerative operation of the motor 2, the brake ECU 4 executes a regeneration reduction process during the regenerative operation of the motor 2.

In the regeneration reduction process, an actual outside temperature T, which is an actual value of the outside air temperature, is determined from the detection signal of the outside air temperature sensor 11 (step S11).

Then, it is determined whether the actually measured outside temperature T is less than a predetermined threshold T0 (step S12). If the actual outside temperature T is less than the threshold T0 (YES in step S12), an outside temperature caution coefficient Tk0 of less than 1 is set (step S13). On the other hand, if the actual outside temperature T is equal to or higher than the threshold T0 (NO in step S12), it is determined whether the actual outside temperature T is less than a threshold T1, which is larger than the threshold T0 (step S14). If the actual outside temperature T is less than the threshold T1 (YES in step S14), an outside temperature caution coefficient Tk1 that is less than 1 and larger than the outside temperature caution coefficient Tk0 is set (step S15). If the actual outside temperature T is equal to or higher than the threshold T1 (NO in step S14), an outside temperature caution coefficient Tk2 that is even larger than the outside temperature caution coefficient Tk1 is set (step S16). The outside temperature caution coefficient Tk2 may be 1. As a result, the lower the actually measured outside temperature T, the smaller the outside temperature caution coefficient Tk0<Tk1<Tk2 is set.

Further, the rotational speed (wheel speed) of each wheel is determined from the detection signal of each wheel speed sensor 12, and the friction coefficient (road surface μ) of the road surface on which the vehicle 1 is located is estimated from the rotational speed of each wheel. (Step S17).

Then, it is determined whether the estimated road surface friction coefficient (estimated road surface μ) is less than a predetermined threshold value F0 (step S18). If the estimated road surface μ is less than the threshold value F0 (YES in step S18), a road surface μ caution coefficient Rk0 of less than 1 is set (step S19). On the other hand, if the estimated road surface μ is greater than or equal to the threshold F0 (NO in step S18), it is determined whether the estimated road surface μ is less than a threshold F1, which is larger than the threshold F0 (step S20). If the estimated road surface μ is less than the threshold value F1 (YES in step S20), a road surface μ caution coefficient Rk1 that is less than 1 and larger than the road surface μ caution coefficient Rk0 is set (step S21). If the estimated road surface μ is greater than or equal to the threshold value F1 (NO in step S20), a road surface μ caution coefficient Rk2 that is even larger than the road surface μ caution coefficient Rk1 is set (step S22). The road surface μ caution coefficient Rk1 may be 1. As a result, the road surface μ caution coefficient Rk0<Rk1<Rk2 is set, which increases as the estimated road surface μ decreases.

Furthermore, the actual vehicle speed V, which is the actual vehicle speed of the vehicle 1, is determined from the detection signal of the vehicle speed sensor 13 (step S23).

Then, it is determined whether the actual vehicle speed V is greater than a predetermined threshold value Vs and the estimated road surface μ is less than a predetermined threshold value F (step S24). When the actual vehicle speed V is greater than the threshold value Vs and the estimated road surface μ is less than the threshold value F (YES in step S24), a vehicle speed caution coefficient Vk0 of less than 1 is set (step S25). If the actual vehicle speed V is greater than or equal to the threshold Vs, or if the estimated road surface μ is greater than or equal to the threshold F (NO in step S24), the actual vehicle speed V is greater than the threshold Vs1, which is smaller than the threshold Vs, and the estimated road surface μ is greater than or equal to the threshold Vs1. It is determined whether or not it is less than a threshold value F (step S26). When the actual vehicle speed V is greater than the threshold value Vs1 and the estimated road surface μ is less than the threshold value F (YES in step S26), a vehicle speed caution coefficient Vk1 that is less than 1 and greater than the vehicle speed caution coefficient Vk0 is set (step S27). If the actual vehicle speed V is greater than or equal to the threshold value Vs1, or if the estimated road surface μ is greater than or equal to the threshold value F (NO in step S26), a vehicle speed caution coefficient Vk2 that is even larger than the vehicle speed caution coefficient Vk1 is set (step S28). . The vehicle speed caution coefficient Vk2 may be 1. As a result, the larger the actual vehicle speed V is, the larger the vehicle speed caution coefficient Vk0<Vk1<Vk2 is set.

Furthermore, the actual steering angle Θ, which is the actual steering angle, is determined from the detection signal of the steering angle sensor 14 (step S29). Thereafter, calculation is performed to estimate the yaw rate from the actual steering angle Θ (step S30). On the other hand, the actual yaw rate Yj, which is the actual yaw rate, is determined from the yaw rate sensor 15 (step S31).

Then, the actual yaw rate Yj is compared with the estimated yaw rate Yo estimated by calculation, and it is determined whether the vehicle 1 is slipping (skidding sideways) (step S32). That is, it is determined whether the estimated yaw rate Yo is greater than the actual yaw rate Yj. If the estimated yaw rate Yo is larger than the actual yaw rate Yj (YES in step S32), it can be considered that the vehicle 1 may be slipping. In this case, a relatively small yaw rate caution coefficient Yk0 that is less than 1 is set (step S33). Conversely, if the estimated yaw rate Yo is less than or equal to the actual yaw rate Yj (NO in step S32), it can be considered that the vehicle 1 is not slipping. In this case, a relatively large yaw rate caution coefficient Yk1 is set (step S34). The yaw rate caution coefficient Yk1 may be 1.

After that, the outside temperature caution coefficient Tki, road surface μ caution coefficient Rki, vehicle speed caution coefficient Vki, and yaw rate caution coefficient Yki (i = 0, 1, 2) set in the above processing are converted to the target regeneration amount set by the regeneration cooperative control. (target regenerative braking force), the target regeneration amount is reduced to a lower target regeneration amount (step S35).

<Effect>
As described above, while controlling the regenerative operation of the motor 2, the target regeneration amount is reduced according to the measured outside temperature T, the estimated road surface μ, the actual vehicle speed V, and the magnitude relationship between the estimated yaw rate Yo and the actual yaw rate Yj. . That is, when the measured outside temperature T is low, it can be estimated that the coefficient of friction of the road surface on which the vehicle 1 is located is low, and the vehicle 1 is likely to skid. Of course, when the estimated road surface μ is low, the vehicle 1 is likely to skid. Furthermore, when the actual vehicle speed V is high, the vehicle 1 exhibits understeer behavior and tends to skid. If the estimated yaw rate Yo is larger than the actual yaw rate Yj, it can be estimated that the vehicle 1 is actually skidding. In a situation where the vehicle 1 is likely to skid or is actually skidding, it is presumed that vehicle stability control to stabilize the vehicle behavior will subsequently intervene.

Therefore, in preparation for the intervention of vehicle stability control, the target regeneration amount by the regenerative operation of the motor 2 is reduced. Therefore, when the vehicle stability control is actually intervened and the regenerative operation of the motor 2 is interrupted, the decrease in the amount of regeneration (the amount of decrease to 0) can be suppressed to a small level. As a result, changes in the acceleration of the vehicle 1 due to a decrease in the amount of regeneration are reduced, and the noise vibration characteristics and stability of the vehicle 1 are improved.

Note that since the regeneration cooperative control is in progress, when the target regeneration amount is reduced, the frictional braking force increases by the amount of the reduction. Therefore, even if the target regeneration amount is reduced, insufficient braking force can be suppressed. Moreover, since much of the necessary braking force can be assumed by the friction braking force before the start of vehicle stability control, vehicle stability control can be started smoothly.

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

For example, in the regeneration reduction process, the target regeneration amount may be reduced in stages. That is, after a situation in which intervention of vehicle stability control is estimated to occur during regeneration cooperative control occurs, the target regeneration amount may be reduced in stages as the timing of the intervention approaches. This makes it possible to suppress sudden changes in regenerative braking force before intervention of vehicle stability control. As a result, even if the timing between the reduction in the target regeneration amount and the increase in the frictional braking force is slightly different, changes in acceleration due to changes in the braking force acting on the vehicle 1 can be suppressed, and the noise vibration characteristics and stability of the vehicle 1 can be suppressed. Further improvements can be made.

Further, in the above-described embodiment, the vehicle 1 is an electric vehicle, but the vehicle 1 may be a hybrid vehicle (HV) equipped with the motor 2 as a drive source for driving.

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

1: Vehicle 2: Motor 3: Hydraulic brake (hydraulic braking device)
4: Brake ECU (regeneration control device, hydraulic braking control device)
5: Motor control ECU (regeneration control device)

Claims (2)

a motor that applies power for traveling to the drive system through power running and regenerative braking force to the drive system through regenerative operation;
a hydraulic braking device that applies frictional braking force using hydraulic pressure to the drive system;
A regeneration control device that is mounted on a vehicle together with a hydraulic brake control device that controls the hydraulic brake device and controls regenerative operation of the motor,
While controlling the regenerative operation of the motor, estimating intervention of vehicle stability control by the hydraulic brake control device to stabilize the behavior of the vehicle when the vehicle is turning, based on predetermined parameters;
When intervention of the vehicle stability control is estimated, controlling regenerative operation of the motor to reduce the regenerative braking force before the intervention;
A regeneration control device that interrupts the regenerative operation of the motor when the vehicle stability control actually intervenes during the control of the regenerative operation of the motor. The regeneration control device according to claim 1, wherein after estimating the control intervention for stabilizing the behavior of the vehicle, the regenerative braking force is reduced in stages as the timing of the intervention approaches.

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