CN106541834A - A kind of method that regulation and control extended-range forerunner mixes electrical automobile braking torque - Google Patents

Abstract

The invention discloses a method for regulating and controlling the braking torque of a range-extended front-drive hybrid vehicle, which includes the regulation and control of the energy recovery braking torque after the vehicle enters the brake system braking and natural braking states. When the vehicle speed is greater than the threshold, the vehicle controller VCU multiplies the obtained wheel drive shaft torque by the current speed of the drive shaft to obtain the regenerative braking request power, and then calculates the regenerative braking request power and the maximum charging power P allowed by the high-voltage battery _Max is compared, and the smaller one is taken as the limited regenerative braking request power; the limited regenerative braking torque request value can be obtained by dividing the limited regenerative braking request power by the drive shaft speed. The method of the present invention is used to regulate the braking torque of the electric/generator of the front drive power source during the braking energy recovery process of the extended-range front-drive hybrid vehicle, so as to ensure the driving safety of the vehicle and improve the fuel economy of the whole vehicle, which has the advantages of Advantages of low cost, easy implementation and high reliability.

Description

A method for regulating the braking torque of an extended-range front-drive hybrid vehicle

technical field

The invention belongs to the technical field of hybrid electric vehicles, and relates to the braking energy recovery control technology of its power system. More specifically, the invention relates to a method for regulating and controlling the braking torque of a range-extended front-drive hybrid vehicle.

Background technique

The global energy crisis and environmental degradation have become important factors restricting development, and research on energy-efficient and green vehicles is one of the effective means to alleviate energy pressure and reduce environmental pollution. Since the range-extended hybrid electric vehicle is one of the most feasible new energy vehicle solutions at present, most domestic and foreign vehicle manufacturers have carried out corresponding research and development on the extended-range hybrid electric vehicle. Range-extended hybrid electric vehicles (PHEV) have the following typical features: (1) have the function of external charging, and can use charging piles and charging stations to charge to obtain electric energy; (2) have the function of pure electric driving; (3 ) has the function of recovering and reusing braking energy, and recovers the energy in the braking process of the vehicle to improve the energy utilization rate.

Compared with pure electric vehicles (EV), PHEV has multiple driving modes, including: pure electric mode, hybrid mode, charging mode, and regenerative braking mode. PHEV can effectively improve the problem of short mileage of pure electric vehicles; compared with hybrid electric vehicles (HEV) without external charging function, PHEV has more powerful pure electric driving functions, which can effectively improve the practicability of the whole vehicle , Reduce vehicle emissions. It can be seen that PHEV takes into account the advantages of pure electric vehicles (EV) and hybrid electric vehicles (HEV). The PHEV braking energy recovery function recovers and stores the energy during vehicle braking, and releases the recovered energy during vehicle driving, which is one of the important factors affecting the economical and practicality of the vehicle.

Contents of the invention

The invention provides a method for adjusting and controlling the braking torque of a range-extended front-drive hybrid vehicle, and the purpose is to improve the economic performance of the PHEV. In order to achieve the above object, the technical scheme that the present invention takes is:

The vehicle controller VCU judges whether the vehicle is running normally: the motor controller is detected through CAN communication, and the motor controller feeds back the running status of the motor/generator to the controller VCU. If the running status of the motor/generator is abnormal, braking will not be performed energy recovery;

If the current vehicle is in a normal driving state, the vehicle controller VCU detects whether the braking energy recovery system is normal through CAN communication: whether the AC/DC inverter module, the high-voltage battery, the battery controller and the motor controller are connected smoothly; If the connection status of the energy recovery system is abnormal, braking energy recovery will not be performed;

If the current braking energy recovery system is normal, the vehicle controller VCU judges whether the accelerator pedal is released, and if the accelerator pedal is not released, braking energy recovery will not be performed;

If the accelerator pedal is in the released state, it is judged whether the brake pedal is in the released state;

If the driver depresses the brake pedal, the vehicle braking system will apply the brakes;

If the driver does not step on the brake pedal, it will enter the natural braking state;

After entering the braking system of the vehicle or entering the natural braking state, the energy recovery braking torque is further regulated.

When entering the natural braking state and adjusting the braking torque: the vehicle controller VCU judges whether the vehicle speed is ≤ V ₁ , and if the vehicle speed is ≤ V ₁ , set the braking energy recovery torque to 0; if the vehicle speed > V ₁ , then set The real-time vehicle speed look-up table shows that the wheel drive shaft torque T ₁ (equal to the regenerative braking request torque); V ₁ is the vehicle speed for exiting regenerative braking set by the system according to different models and road conditions, and there is no fixed value here. In braking torque regulation, the vehicle controller VCU multiplies the regenerative braking request torque T ₁ obtained in the natural braking state by the current speed n ₁ of the drive shaft to obtain the regenerative braking request power P ₁ to prevent P ₁ When the high-voltage battery is damaged due to excessive charging, P1 needs to be limited. _The method is: compare P1 with the maximum charging power P _max allowed by the high-voltage battery, and take the smaller _one as the limited regenerative braking request power P That is, P=min(P ₁ , P _max ); the limited regenerative braking torque request value T is obtained by dividing the limited regenerative braking request power P by the drive shaft rotational speed n ₁ .

When the vehicle brake system performs braking and adjusts the braking torque: the vehicle controller VCU judges whether the ABS anti-lock braking system is normal. If the dead system is normal, the vehicle controller judges whether the vehicle speed is ≤V ₂ , if the vehicle speed is ≤V ₂ , the braking energy recovery torque is set to 0 _; Drive shaft torque T ₂ (equal to regenerative braking request torque); V ₂ is the vehicle speed for exiting regenerative braking set by the system according to different models and road conditions, and there is no fixed value here. _In the aforementioned braking torque regulation, the vehicle controller VCU multiplies the regenerative braking request torque T2 obtained during the braking of the vehicle braking system by the current driving shaft speed _n2 to obtain the regenerative braking request power _P2 , To prevent damage to the high-voltage battery when P ₂ is overcharged, P ₂ needs to be limited. The method is: compare P ₂ with P _max , and take the smaller one as the limited regenerative braking request power P', that is, P '=min(P ₂ , P _max ); divide the limited regenerative braking request power P' by the driving shaft speed n ₂ to obtain the limited regenerative braking torque request value T'.

Beneficial effects of the present invention:

(1) According to different braking modes, vehicle driving conditions and other factors, different vehicle speeds V ₁ and V ₂ are set, the braking strategy is reasonable, and the braking energy recovery of the whole vehicle is optimized.

(2) By controlling the regenerative braking request power of the whole vehicle, it is ensured that only the energy recovery power is always at a safe value, so that the vehicle-mounted high-voltage battery (6) can have a longer service life.

(3) The control strategy process of braking energy recovery is simple and clear, less prone to errors, and safe driving is guaranteed.

Description of drawings

Figure 1 Structural diagram of the range-extended front-drive hybrid vehicle system;

Figure 2 Braking energy recovery control flow chart;

Fig. 3 flow chart of natural braking regulation and braking torque;

Fig. 4 is a flow chart of braking torque regulation by the vehicle braking system;

Marked in the figure: 1—wheel; 2—drive axle; 3—generator; 4—engine and ECU; 5—AC/DC inverter module; 6—high voltage battery; 7—battery controller; 8—vehicle control 9—accelerator pedal; 10—brake pedal; 11—ABS; 12—motor controller; 13—electric/generator; 14—transmission.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings, so as to help those skilled in the art to fully, accurately and deeply understand the inventive concepts and technical solutions of the present invention. The technical scheme that the present invention takes is:

As shown in Figure 1, an extended-range front-drive hybrid vehicle system is provided with: wheels 1, transaxle 2, generator 3, engine and ECU 4, AC/DC inverter module 5, high-voltage battery 6, and battery controller 7 , Vehicle controller VCU8, accelerator pedal 9, brake pedal 10, ABS11, motor controller 12, motor/generator 13, transmission 14.

Wheel 1, drive axle 2, motor/generator 13 and transmission 14 are mechanically connected, and the output torque of motor/generator 13 is adjusted to an appropriate torque according to different driving needs through the transmission 14, and then transmitted to drive axle 2 and the wheels 1. Driving the vehicle.

The driver controls the driving and braking of the vehicle by stepping on the accelerator pedal 9 and the brake pedal 10, and the opening and closing signals of the accelerator pedal 9 and the brake pedal 10 are transmitted to the vehicle controller VCU8 through signal transmission, and the vehicle controller VCU8 can The driver's driving intention is judged by the opening and closing degree signal.

The battery controller 7 controls the high-voltage battery 6 through signal connection, and transmits the charge storage status of the high-voltage battery 6 to the vehicle controller VCU8 through CAN communication, and the vehicle controller 8 monitors the charge content of the high-voltage battery 6 in real time.

The vehicle controller VCU8 controls the engine and ECU4 through CAN communication, and the engine and ECU4 drive the generator 3 to generate AC through mechanical connection, and the AC is converted into DC through the AC-DC inverter module 5 through power transmission and stored in the high-voltage battery 6; The AC power generated by the motor/generator 13 in the kinetic energy recovery system is converted into DC power and stored in the high-voltage battery 6 through the AC-DC inverter module 5 through power transmission.

The vehicle controller VCU8 controls the AC/DC inverter module 5 through the CAN communication connection, and then controls the recovery and storage of electric energy.

Figure 2 is a flow chart of braking energy recovery control, the control process is as follows:

Brake energy recuperation consists of two phases:

Natural braking: also known as coasting braking, means that the driver releases the accelerator pedal 9 during driving, and the motor/generator 13 applies a certain braking force to the vehicle, so that the vehicle has a certain braking deceleration.

Braking of the vehicle braking system: refers to the fact that the driver releases the accelerator pedal 9 and steps on the brake pedal 10 to request braking force when the driver has a braking intention during driving.

First, the vehicle controller VCU8 detects the motor controller 12 through CAN communication, and the motor controller 12 feeds back the operating status of the motor/generator 13 to the controller VCU8, thereby judging whether the vehicle is running normally. If the motor/generator 13 If the running state is abnormal, no braking energy recovery will be performed;

If the current vehicle is in a normal driving state, the vehicle controller VCU8 detects whether the braking energy recovery system is normal through CAN communication: whether the AC/DC inverter module 5, the high-voltage battery 6, the battery controller 7 and the motor controller 12 are connected smoothly , if the connection state of the braking energy recovery system is not normal, the braking energy recovery will not be performed;

If the current braking energy recovery system is normal, the vehicle controller VCU8 judges whether the accelerator pedal is released, and if the accelerator pedal is not released, braking energy recovery will not be performed;

If the accelerator pedal is in the released state, it is judged whether the brake pedal is in the released state;

If the driver does not step on the brake pedal, it will enter the natural braking state;

If the driver depresses the brake pedal, the vehicle braking system will apply the brakes;

After entering the braking system of the vehicle or entering the natural braking state, the energy recovery braking torque is further regulated.

Fig. 3 is a flow chart of natural braking regulating braking torque:

When entering the natural braking state and adjusting the braking torque: the vehicle controller VCU8 judges whether the vehicle speed is ≤ V ₁ , if the vehicle speed is ≤ V ₁ , set the braking energy recovery torque to 0; if the vehicle speed is > V ₁ , then set The real-time vehicle speed look-up table shows that the wheel drive shaft torque T ₁ (equal to the regenerative braking request torque); V ₁ is the vehicle speed for exiting regenerative braking set according to different models and road conditions. In braking torque regulation, the vehicle controller VCU8 multiplies the regenerative braking request torque T ₁ obtained in the natural braking state by the current speed n ₁ of the drive shaft to obtain the regenerative braking request power P ₁ to prevent P ₁ When the high-voltage battery 6 is damaged due to overcharging, it is necessary to limit P1. _The method is: compare P1 with the maximum charging power P _max allowed by the high-voltage battery ₆ , and take the smaller one as the regenerative braking request after the limit Power P, that is, P=min(P ₁ , P _max ); divide the limited regenerative braking request power P by the driving shaft speed n ₁ to obtain the limited regenerative braking torque request value T.

Fig. 4 is a flow chart of the vehicle braking system for braking regulation and braking torque:

When the vehicle brake system performs braking and adjusts the braking torque: the vehicle controller VCU8 judges whether the ABS anti-lock braking system is normal. If the system is normal, the vehicle controller 8 judges whether the vehicle speed is ≤ V ₂ , and if the vehicle speed ≤ V ₂ , sets the braking energy recovery torque to 0 _; Drive shaft torque T ₂ (equal to regenerative braking request torque); V ₂ is the vehicle speed for exiting regenerative braking set by the system according to different models and road conditions, and there is no fixed value here. In the aforementioned braking torque regulation, the vehicle controller _VCU8 multiplies the regenerative braking request torque T2 obtained in the braking of the vehicle braking system by the current driving shaft speed _n2 to obtain the regenerative braking request power _P2 , To prevent damage to the high-voltage battery 6 when P ₂ is overcharged, P ₂ needs to be limited. The method is: compare P ₂ with P _max , and take the smaller one as the limited regenerative braking request power P', That is, P'=min(P ₂ , P _max ); divide the limited regenerative braking request power P' by the driving shaft speed n ₂ to obtain the limited regenerative braking torque request value T'.

The series of detailed descriptions listed above are only specific descriptions for the feasible implementation of the present invention, as long as various insubstantial improvements are adopted from the method concept and technical solutions of the present invention, or without improvement Directly applying the conception and technical solutions of the present invention to other occasions falls within the protection scope of the present invention.

Claims (7)

1. A method for regulating and controlling the braking torque of a range-extended front-drive hybrid vehicle, characterized in that, Step 1: First, the vehicle controller VCU (8) judges whether the vehicle is running normally: the motor controller (12) is detected through CAN communication, and the motor controller (12) feeds back the operating status of the motor/generator (13) to the control VCU (8), if the motor/generator (13) is in an abnormal operating state, braking energy recovery will not be performed; Step 2: If the current vehicle is in a normal driving state, the vehicle controller VCU (8) detects whether the braking energy recovery system is normal through CAN communication: AC/DC inverter module (5), high-voltage battery (6), battery control Whether the connection between the device (7) and the motor controller (12) is smooth, if the connection status of the braking energy recovery system is not normal, the braking energy recovery will not be performed; Step 3: If the current braking energy recovery system is normal, the vehicle controller VCU (8) judges whether the accelerator pedal is released. If the accelerator pedal is not released, braking energy recovery is not performed; Step 4: If the accelerator pedal is in the released state, then judge whether the brake pedal is in the released state; Step 5: If the driver depresses the brake pedal, the vehicle braking system performs braking; Step 6: If the driver does not step on the brake pedal, enter the natural braking state; Step 7: After entering the braking system of the vehicle or entering the natural braking state, the energy recovery braking torque is adjusted. 2. A method for adjusting and controlling the braking torque of an extended-range front-drive hybrid vehicle according to claim 1, characterized in that, after entering the natural braking state in the step 7, the method for regulating and controlling the energy recovery braking torque as follows: The vehicle controller VCU (8) judges whether the vehicle speed is less than or equal to V ₁ , and if the vehicle speed ≤ V ₁ , sets the braking energy recovery torque to 0 _; Shaft torque T ₁ ; in braking torque regulation, the vehicle controller VCU (8) multiplies the wheel drive shaft torque T ₁ obtained in the natural braking state with the current speed n ₁ of the drive shaft to obtain the regenerative braking request Power P ₁ , then compare P ₁ with the maximum charging power P _max allowed by the high-voltage battery (6), and take the smaller one as the limited regenerative braking request power P, that is, P=min(P ₁ , P _max ) ; Divide the limited regenerative braking request power P by the driving shaft speed n ₁ to obtain the limited regenerative braking torque request value T. 3. A method for adjusting and controlling the braking torque of an extended-range front-drive hybrid vehicle according to claim 1, characterized in that, the method for regulating the energy recovery braking torque after entering the braking system of the vehicle in the step 7 as follows: The vehicle controller VCU (8) judges whether the ABS anti-lock braking system is normal. If the ABS warning light on the cab display is on, indicating that the ABS is abnormal, the process ends automatically; if the ABS anti-lock braking system is normal, the vehicle controller (8) Determine whether the vehicle speed is less than or equal to V ₂ , if the vehicle speed ≤ V ₂ , set the braking energy recovery torque to _{0 ;} In the dynamic torque regulation, the vehicle controller VCU (8) multiplies the wheel drive shaft torque T ₂ obtained during the braking of the vehicle braking system by the current drive shaft speed n ₂ to obtain the regenerative braking request power P ₂ , and then P ₂ Compare with P _max , take the smaller one as the limited regenerative braking request power P', that is, P'=min(P ₂ , P _max ); divide the limited regenerative braking request power P' by the drive shaft speed n ₂ , the limited regenerative braking torque request value T' is obtained. 4. A method for regulating the braking torque of a range-extended front-drive hybrid vehicle according to claim ₂ , wherein the magnitude of the wheel drive shaft torque T1 is equal to the regenerative braking request torque. 5. A method for adjusting and controlling the braking torque of an extended-range front-drive hybrid vehicle according to claim ₂ , wherein the value of V is determined according to the vehicle speed of exiting regenerative braking set by different vehicle types and road conditions . 6. A method for regulating the braking torque of an extended-range front-drive hybrid vehicle according to claim 3, wherein the magnitude of the wheel drive shaft torque T ₂ is equal to the regenerative braking request torque. 7. A method for adjusting and controlling the braking torque of a range-extended front-drive hybrid vehicle according to claim ₃ , wherein the value of V2 is determined according to the vehicle speed of exiting regenerative braking set according to different vehicle types and road conditions .