KR100598805B1 - Method and system for controlling regenerative braking of four wheel drive electric vehicle - Google Patents

Abstract

When the brake of the four-wheel drive electric vehicle is operated, the regenerative braking of the front wheel motor is controlled based on the current shift stage and the current vehicle speed, thereby shifting the front wheel target regenerative power corresponding to the target regenerative power. Regardless of the desired value can be implemented.

Electric vehicle, 4-wheel drive, rear motor, regenerative braking, manual transmission

Description

TECHNICAL AND SYSTEM FOR CONTROLLING REGENERATIVE BRAKING OF FOUR WHEEL DRIVE ELECTRIC VEHICLE}

1 is a block diagram of a regenerative braking control system of a four-wheel drive electric vehicle according to an embodiment of the present invention.

2 is a block diagram of a regenerative braking control system for a four-wheel drive electric vehicle according to an exemplary embodiment of the present invention.

3 is a flowchart illustrating a regenerative braking control method for a four-wheel drive electric vehicle according to an exemplary embodiment of the present invention.

The present invention relates to an electric vehicle, and more particularly, to a braking control of an electric vehicle.

As is well known, an electric vehicle is a vehicle that can use electric energy stored in a battery as a power source. In order to improve the energy efficiency and mileage of the electric vehicle, the braking of the electric vehicle is performed by regenerative braking which recovers a part of the braking energy as electric energy. This is controlled.

Conventional electric vehicles are mainly equipped with automatic transmission or continuously variable transmission (CVT).

When the manual transmission is mounted on the electric vehicle, the driver directly manipulates the clutch, so that the driver feels the vehicle vehavior caused by the regenerative braking control. Therefore, in the case of an electric vehicle equipped with a manual transmission, regenerative braking must be precisely controlled.

Four-wheel drive powertrains that can apply both front and rear wheels have advantages in many respects. This advantage is still valid even when the electric vehicle powertrain is configured by four-wheel drive.

By the way, when the manual transmission is mounted on the four-wheel drive type power train, the shift stage is arbitrarily operated by the driver.

In this case, since only one deceleration is applied to the rear wheel, the same regenerative braking torque is applied to the rear wheel when the rear motor is driven with the same regenerative braking torque. By the way, in the case of the front wheel, the reduction ratio is applied differently for each gear stage, depending on the shift stage operating state of the driver. Therefore, even if the regenerative braking torque for driving the front wheel motor is the same, if the shift stage is different, the regenerative braking torque applied to the front wheel will be different.

In consideration of the fact that the same speed can be driven at various gear stages, if the regenerative braking torque applied to the front wheels is changed as the gear stage is changed, there is a risk of deteriorating the stability of the vehicle behavior.

Accordingly, an object of the present invention is to provide a regenerative braking control method and system for a four-wheel drive electric vehicle for implementing stable regenerative braking in consideration of a shift stage state of a transmission.

In order to achieve the above object, a regenerative braking control system for a four-wheel drive electric vehicle according to the present invention includes a front wheel and a rear wheel, and a four-wheel drive electric vehicle including a brake device for applying mechanical braking force to the front wheel and the rear wheel. Regenerative braking control system,

A front wheel motor for applying a driving force and a regenerative braking force to the front wheel;

A rear wheel motor for applying a driving force and a regenerative braking force to the rear wheel;

A transmission interposed between the front wheel motor and the front wheel;

A vehicle speed detector for detecting a vehicle speed of the four-wheel drive electric vehicle;

A shift stage detector for detecting a shift stage of the transmission;

A brake operation detector for detecting whether the brake device is operated and an amount of operation; And

And a controller configured to control regenerative braking of the front wheel motor and the rear wheel motor based on the signals detected from the detectors.

The controller,

It is characterized by carrying out the method of the invention described below.

Regenerative braking control method for a four-wheel drive electric vehicle according to the present invention,

Regeneration of a four wheel drive electric vehicle having a front motor and a rear motor and including a manual transmission interposed between the front motor and the front drive wheel. As a regenerative braking control method,

A brake operation determining step of determining whether the brake of the four-wheel drive electric vehicle is operated;

A target regenerative power calculating step of calculating a target regenerative power of the four-wheel drive electric vehicle when the brake of the four-wheel drive electric vehicle is operated;

Calculating the target regenerative braking power of the front wheel motor and the target regenerative braking power of the rear wheel motor based on the target regenerative braking power;

Detecting a current shift stage;

A front wheel regenerative braking control step of controlling regenerative braking of the front wheel motor based on the current shift stage and the current vehicle speed; And

And a rear wheel regenerative braking control step of controlling regenerative braking of the rear wheel motor based on a target regenerative braking power of the rear wheel motor.

The target regenerative braking power calculation step,

A brake actuation amount detecting step of detecting a brake actuation amount; And

And a current vehicle speed detecting step of detecting a current vehicle speed of the four-wheel drive electric vehicle when the brake of the four-wheel drive electric vehicle is operated.

Preferably, the target regenerative braking power is calculated based on the brake actuation amount and the current vehicle speed.

The target regenerative braking power calculation step,

Calculating a maximum regenerative braking power based on the brake actuation amount and the current vehicle speed; And

Calculating an acceptable power of the battery;

Preferably, the target regenerative braking power is calculated using a value less than or equal to the acceptable power of the battery and the maximum regenerative braking power.

In the front and rear wheel target regenerative braking power calculating step, it is preferable to calculate the front wheel target regenerative braking power and the rear wheel target regenerative braking power to a value that satisfies the set ratio.

The front wheel regenerative braking control step,

A front wheel target regenerative braking torque calculating step of calculating a target regenerative braking torque of the front wheel motor based on the current shift stage and the current vehicle speed; And

And a front wheel regenerative braking starting step of starting the regenerative braking driving of the front wheel motor based on a target regenerative braking torque of the front wheel motor.

The front wheel target regenerative braking torque calculating step,

Calculating a current speed of a front wheel motor corresponding to the current speed change stage and the current vehicle speed;

And calculating front wheel regenerative braking torque based on the current shift stage, the current speed of the front wheel motor, and the front wheel target regenerative braking power.

The regenerative braking control method for a four-wheel drive electric vehicle according to the present invention may further include determining which one of the forward shift stages is the current shift stage.

The front wheel regenerative braking control step is preferably performed when the current shift stage is any one of the forward shift stages.

The rear wheel regenerative braking control step,

Calculating a target regenerative braking torque of the rear wheel motor based on the target regenerative braking power of the rear wheel motor; And

And a rear wheel regenerative braking starting step of starting regenerative braking driving of the rear wheel motor based on the calculated rear wheel regenerative braking torque.

The rear wheel regenerative braking start step may be performed after the front wheel regenerative braking start step.

A regenerative braking control method for a four-wheel drive electric vehicle according to the present invention includes: a brake operation amount determining step of determining whether the brake operation amount is within a set operating range;

And a current vehicle speed determining step of determining whether the current vehicle speed is within a set vehicle speed range.

In this case, the target regenerative braking power calculating step is preferably performed only when the brake operation amount is included in the set operating range and the current vehicle speed is included in the set vehicle speed range.

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

1 is a block diagram of a regenerative braking control system of a four wheel drive electric vehicle according to an embodiment of the present invention. 2 is a block diagram of a regenerative braking control system for a four-wheel drive electric vehicle according to an exemplary embodiment of the present invention.

1 and 2, the four-wheel drive electric vehicle 100 according to an embodiment of the present invention, the front wheel 102 and the rear wheel 104, and the front wheel 102 and rear wheel 104 Brake apparatus (180) for applying a mechanical braking force to the ().

Although FIG. 1 illustrates a specific type of electric vehicle, that is, a four wheel drive hybrid electric vehicle (hereinafter, referred to as “4WD-HEV”), the protection scope of the present invention is limited thereto. It should not be. That is, the present invention can be applied to pure electric vehicles as well as hybrid electric vehicles. In addition, it can be applied regardless of parallel type and series type hybrid electric vehicles.

The regenerative braking control system according to an embodiment of the present invention for controlling the regenerative braking of the 4WD-HEV 100 includes a front wheel motor for applying a driving force and a regenerative braking force to the front wheel 102. front motor 112; A rear motor 114 for applying a driving force and a regenerative braking force to the rear wheel 104; A manual transmission (140) interposed between the front wheel motor (112) and the front wheel (102); A vehicle speed detector (210) for detecting a vehicle speed of the 4WD-HEV (100); A brake operation detector 220 for detecting whether the brake device 180 is operated and an amount of operation; A front wheel speed detector 132 for detecting wheel speed of the front wheel 102; A rear wheel speed detector 134 for detecting a wheel speed of the rear wheel 104; A shift stage detector 230 for detecting a shift-speed of the manual transmission 140; And a controller 150 that controls regenerative braking of the front wheel motor 112 and the rear wheel motor 114 based on signals detected from the detectors 210, 220, 230, 132, and 134.

The brake operation detector 220 may be, for example, a distance sensor connected to the brake pedal 175 to detect an operating distance of the brake pedal 175. It can be used as a braking hydraulic pressure sensor that detects.

The front wheel speed detector 132 and the rear wheel speed detector 134 may be implemented as, for example, a toothed ring and a magnetic sensor.

The shift stage detector 230 may be a sensor for detecting a position of a shift lever (not shown) for shift operation of the manual transmission 140.

The controller 150 may be implemented as one or more microprocessors operated by a set program, and the set program may execute a series of instructions for performing each step included in the regenerative braking control method according to the embodiment of the present invention described below. It can be included.

More specifically, the brake device 180 may include a front wheel brake device 122 and a brake pedal 175 for applying hydraulic braking force to the front wheel 102 according to the operation of the brake pedal 175. The rear wheel brake device 124 for applying the hydraulic braking force to the rear wheel 104 according to the operation of the wheel), and the hydraulic braking force by the operation of the brake pedal 175 is applied to the front wheel brake device 122 and the rear wheel brake device. Hydraulic Module (HM) 170 for supplying 124.

More specifically, the controller 150 may include a front wheel motor controller (MCU_F) 152 for controlling the front wheel motor 112, a rear wheel motor controller (MCU_R) 154 for controlling the rear wheel motor 114, and a battery. Battery control system (Battery Management Syste BMS) 153 for controlling (160), the engine control unit (Engine Control Unit; ECU) 156 for controlling the engine 144 of the 4WD-HEV (100), hydraulic braking force A brake control unit (BCU) 157 for controlling the control unit, and a hybrid control unit (HCU) 158 for implementing total control of the hybrid vehicle. Each of these controllers 152, 153, 154, 156, 157, 158 communicates with each other by CAN communication with each other.

Hereinafter, the regenerative braking control method for a four-wheel drive electric vehicle according to an embodiment of the present invention will be described in detail.

3 is a flowchart illustrating a regenerative braking control method for a four-wheel drive electric vehicle according to an exemplary embodiment of the present invention.

First, the controller 150 determines whether the brake of the 4WD-HEV 100 is operated (S305).

When the brake is operated in the determination step (S305), the controller 150 detects the brake operation amount (BPS) (S310), the operating range (B _L ~ B _H ) is set to the brake operation amount (BPS) It is determined whether it is included in (S315). The set operating range B _L to B _H may be set to, for example, an allowable reference value that may be generated from the brake actuation detector 220.

When the brake operation amount BPS is not included in the set operating ranges B _L to B _H , the controller 150 returns without regenerative braking driving of the front wheel motor 112 and the rear wheel motor 114. .

When the brake operating amount BPS is included in the set operating range B _L to B _H , the controller 150 detects the current vehicle speed V of the 4WD-HEV 100 (S320). In operation S325, it is determined whether the current vehicle speed V is included in the set vehicle speed range V _L to V _H.

If the vehicle is traveling at very low or very high speeds, regenerative braking risks impairing the stability of the vehicle. Therefore, the set vehicle speed range (V _L ~ V _H ) is set to a range that ensures the stability of the vehicle behavior of the four-wheel drive electric vehicle when the regenerative braking is implemented by the regenerative braking method / apparatus according to the technical idea of the present invention. . The vehicle speed range (V _L ~ V _H ) may vary depending on the specifications of the vehicle, but those skilled in the art will be able to set it clearly according to the design criteria. For example, in the embodiment of the present invention, the vehicle speed range (V _L ~ V _H ) is determined in the range of 0 ~ 95km / h.

When the current vehicle speed V is not included in the set vehicle speed range V _L to V _H , the controller 150 returns without regenerative braking driving of the front wheel motor 112 and the rear wheel motor 114.

When the current vehicle speed V is included in the set vehicle speed range V _L to V _H , the controller 150 may perform maximum regenerative braking based on the brake operation amount BPS and the current vehicle speed V. FIG. A maximum regenerative braking power P _{REG_MAX} is calculated (S330).

In general, the braking power that can be applied to the vehicle is limited by the grounding force of the vehicle, and the limit of the grounding force of the vehicle is dependent on the vehicle speed. The braking power of the electric vehicle includes a mechanical braking power and a regenerative braking power, which is determined by the brake actuation amount (BPS). Therefore, when the driver operates the brake at a specific vehicle speed V at a specific brake operation amount BPS, the maximum regenerative braking power P _{REG_MAX} that can be realized is determined by the brake operation amount BPS and the vehicle speed V. It can be calculated on a basis. Such calculations can be apparent to those skilled in the art based on the foregoing description.

Next, the controller 150 calculates the acceptable power P _{IN_BAT} of the battery 160 (S335).

That is, the regenerative braking is to charge the battery 160, there is a limit to the power that the battery 160 can be charged. The acceptable power P _{IN_BAT} of the battery 160 refers to a limit of the charging speed of the battery 160, and can be calculated by those skilled in the art in consideration of the characteristics of the battery 160.

Next, the controller 150 calculates a target regenerative braking power P _{REG_TARGET} based on the brake operation amount BPS and the current vehicle speed V (S340). In this case, the controller 150 calculates the target regenerative braking power P _{REG_TARGET} with a value less than or equal to the acceptable power P _{IN_BAT} of the battery and the maximum regenerative braking power P _{REG_MAX} . Is calculated as the smaller of these (min {P _{REG_MAX} , P _{IN_BAT} }).

Next, the controller 150 calculates the target regenerative braking power P _{REG_F} of the front wheel motor and the target regenerative braking power P _{REG_R of the} rear wheel motor based on the target regenerative braking power P _{REG_TARGET} (S345). That is, the whole be implemented target regenerative braking power (P _{REG_TARGET)} of calculating the front wheel motor target regeneration to 112 is in charge of the braking power (P _{REG_R)} and the rear wheel motor 114, a target regenerative braking power (P _{REG_R)} to charge It is.

At this time, the controller 150 calculates the ratio between the front wheel target regenerative braking power P _{REG_F} and the rear wheel target regenerative braking power P _{REG_R} so as to be satisfied. The set ratio may be obvious to those skilled in the art in consideration of the specifications of the 4WD-HEV 100 so that stable vehicle behavior may be achieved during braking.

Next, the controller 150 calculates the target regenerative braking torque T _{REG_R} of the rear wheel motor 114 based on the target regenerative braking power P _{REG_R} of the rear motor 114 (S350). _Calculating the target regenerative braking torque T _{REG_R} of the rear wheel motor 114 from the target regenerative braking power P _{REG_R} of the rear wheel 114 can be calculated by a person skilled in the art in consideration of the reduction ratio applied to the rear wheel. .

Next, the controller 150 detects a current shift stage SP of the manual transmission 140 (S355), and the current shift stage is any one of forward speeds. It is determined whether or not (S360).

When the current shift stage is not included in the forward shift stage, that is, when the current shift stage is the neutral stage (N) or the reverse stage (R), the controller 150 of the front wheel motor 112 and the rear wheel motor 114 Return without regenerative braking.

When the current shift stage is any one of forward speeds, the controller 150 displays the current of the front wheel motor 112 corresponding to the current shift stage SP and the current vehicle speed V. FIG. The speed ω is calculated (S365).

That is, even when the 4WD-HEV 100 travels at the same speed V, when the speed of the transmission 140 is different, the reduction ratio is changed so that the rotation speed of the front wheel motor 112 is changed. Therefore, in step S365, the current speed ω of the front wheel motor 112 is calculated as a value corresponding to the current shift stage SP.

Next, the controller 150, the current gear position (SP), the front wheels the current speed (ω) and the front wheel target regenerative braking power based on the front wheel regenerative braking torque (T _{REG_F)} to the (P _{REG_F)} of the motor (112) To calculate (S370). _Calculating the target regenerative braking torque T _{REG_F} of the front wheel motor 112 from the target regenerative braking power P _{REG_F} of the front wheel motor 112 is apparent to those skilled in the art in view of the reduction ratio by the current shift stage SP. Can be calculated.

Next, the controller 150 starts the regenerative braking drive of the front wheel motor 112 based on the target regenerative braking torque T _{REG_F} of the front wheel motor 112 (S375).

The controller 150 which has started the regenerative braking drive of the front wheel motor 112 starts the regenerative braking drive of the rear wheel motor 114 based on the target regenerative braking power T _{REG_R} of the rear wheel motor 114 ( S380).

As such, the regenerative braking drive of the rear wheel motor 114 is started after the regenerative braking drive of the front wheel motor 112 is started, and thus the long-term reliability of the 4WD-HEV 100 may be improved by the regenerative braking.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and easily changed and equalized by those skilled in the art from the embodiments of the present invention. It includes all changes to the extent deemed acceptable.

According to an embodiment of the present invention, since the regenerative braking torque of the front wheel motor is implemented according to each shift stage of the four-wheel drive electric vehicle, the braking force distribution acting on the front wheel and the rear wheel as a result can be maintained at an ideal distribution. Therefore, the vehicle behavior of the four-wheel drive electric vehicle during braking is improved.

Claims (14)

Regeneration of a four wheel drive electric vehicle having a front motor and a rear motor and including a manual transmission interposed between the front motor and the front drive wheel. As a regenerative braking control method, A brake operation determining step of determining whether the brake of the four-wheel drive electric vehicle is operated; A target regenerative power calculating step of calculating a target regenerative power of the four-wheel drive electric vehicle when the brake of the four-wheel drive electric vehicle is operated; Calculating the target regenerative braking power of the front wheel motor and the target regenerative braking power of the rear wheel motor based on the target regenerative braking power; Detecting a current shift stage; A front wheel regenerative braking control step of controlling regenerative braking of the front wheel motor based on the current shift stage and the current vehicle speed; And And a rear wheel regenerative braking control step of controlling regenerative braking of the rear wheel motor based on a target regenerative braking power of the rear wheel motor. The front wheel regenerative braking control step, A front wheel target regenerative braking torque calculating step of calculating a target regenerative braking torque of the front wheel motor based on the current shift stage and the current vehicle speed; And And a front wheel regenerative braking starting step of starting regenerative braking driving of the front wheel motor based on a target regenerative braking torque of the front wheel motor. The rear wheel regenerative braking control step, Calculating a target regenerative braking torque of the rear wheel motor based on the target regenerative braking power of the rear wheel motor; And And a rear wheel regenerative braking starting step of starting regenerative braking driving of the rear wheel motor based on the calculated rear wheel regenerative braking torque. The rear wheel regenerative braking start step is performed after the front wheel regenerative braking start step. In claim 1, The target regenerative braking power calculation step, A brake actuation amount detecting step of detecting a brake actuation amount; And And a current vehicle speed detecting step of detecting a current vehicle speed of the four-wheel drive electric vehicle when the brake of the four-wheel drive electric vehicle is operated. And regulating the target regenerative braking power on the basis of the brake operation amount and the current vehicle speed. In claim 1, The target regenerative braking power calculation step, Calculating a maximum regenerative braking power based on the brake actuation amount and the current vehicle speed; And Calculating an acceptable power of the battery; And regulating the target regenerative braking power to a value less than or equal to the acceptable power of the battery and the maximum regenerative braking power. In claim 2, The target regenerative braking power calculation step, Calculating a maximum regenerative braking power based on the brake actuation amount and the current vehicle speed; And Calculating an acceptable power of the battery; And regulating the target regenerative braking power to a value less than or equal to the acceptable power of the battery and the maximum regenerative braking power. In claim 1, The front and rear wheel target regenerative braking power calculating step, the regenerative braking control method of the four-wheel drive electric vehicle characterized in that for calculating the front wheel target regenerative braking power and the rear wheel target regenerative braking power to a value that satisfies the set ratio. In claim 1, The target regenerative braking power calculation step, A brake actuation amount detecting step of detecting a brake actuation amount; A current vehicle speed detection step of detecting a current vehicle speed of the four-wheel drive electric vehicle when the brake of the four-wheel drive electric vehicle is operated; Calculating a maximum regenerative braking power based on the brake actuation amount and the current vehicle speed; And Calculating an acceptable power of the battery; And regulating the target regenerative braking power to a value less than or equal to the acceptable power of the battery and the maximum regenerative braking power, based on the brake actuation amount and the current vehicle speed. delete In claim 1, The front wheel target regenerative braking torque calculating step, Calculating a current speed of a front wheel motor corresponding to the current speed change stage and the current vehicle speed; And calculating front wheel regenerative braking torque based on the current shift stage, the current speed of the front wheel motor, and the front wheel target regenerative braking power. In claim 1, Determining which one of the forward shift stages is the current shift stage; The regenerative braking control method of the front wheel regenerative braking is performed when the current shift stage is any one of the forward shift stages. In claim 1, The rear wheel regenerative braking control step, Calculating a target regenerative braking torque of the rear wheel motor based on the target regenerative braking power of the rear wheel motor; And Regenerative braking control method for a four-wheel drive electric vehicle comprising a; starting the regenerative braking of the rear wheel motor based on the calculated rear wheel regenerative braking torque. delete delete In claim 1, A brake actuation amount determining step of determining whether the brake actuation amount is within a set operating range; A current vehicle speed determination step of determining whether the current vehicle speed is within a set vehicle speed range; The regenerative braking power calculating step of the target regenerative braking power is performed only when the brake operation amount is included in the set operating range and the current vehicle speed is included in the set vehicle speed range. A regenerative braking control system for a four-wheel drive electric vehicle having a front wheel and a rear wheel and a brake device for applying mechanical braking force to the front wheel and the rear wheel, A front wheel motor for applying a driving force and a regenerative braking force to the front wheel; A rear wheel motor for applying a driving force and a regenerative braking force to the rear wheel; A transmission interposed between the front wheel motor and the front wheel; A vehicle speed detector for detecting a vehicle speed of the four-wheel drive electric vehicle; A shift stage detector for detecting a shift stage of the transmission; A brake operation detector for detecting whether the brake device is operated and an amount of operation; And And a controller configured to control regenerative braking of the front wheel motor and the rear wheel motor based on the signals detected from the detectors. The controller, A regenerative braking control system for a four-wheel drive electric vehicle, comprising performing the method of any one of claims 1 to 6, 8 to 10, or 14.

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