阅读说明：本技术 一种氢能汽车的燃料电池制动能量回收系统 (fuel cell braking energy recovery system of hydrogen energy automobile ) 是由 程飞 陈华明 郝义国 于 2019-08-22 设计创作，主要内容包括：本发明提供了一种氢能汽车的燃料电池制动能量回收系统,包括：整车控制器VCU、电机控制器MCU、动力电池管理子系统BMS和燃料电池子系统FCU；BMS用于检测动力电池的剩余电量SOC和动力电池可充电功率；FCU用于控制燃料电池的输出功率,并控制燃料电池为动力电池充电功率；MCU用于获取电机的转速和电机最大回馈扭矩,并控制电机的扭矩；VCU通过获取油门踏板的开度信号作为能量回收的触发开关信号,通过获取制动踏板的开度信号作为能量回收功率大小的判断依据,通过获取BMS的SOC和可充电功率、MCU的电机转速和电机最大回馈扭矩以及燃料电池的工作状态,进行制动能量回收。本发明的有益效果是：提高了氢能燃料电池汽车的能量利用率。(The invention provides a fuel cell braking energy recovery system of a hydrogen energy automobile, which comprises: the system comprises a vehicle control unit VCU, a motor controller MCU, a power battery management subsystem BMS and a fuel battery subsystem FCU; the BMS is used for detecting the residual charge SOC of the power battery and the chargeable power of the power battery; the FCU is used for controlling the output power of the fuel cell and controlling the fuel cell to charge power for the power battery; the MCU is used for acquiring the rotating speed of the motor and the maximum feedback torque of the motor and controlling the torque of the motor; the VCU recovers the braking energy by acquiring the opening degree signal of the accelerator pedal as a trigger switch signal of energy recovery, acquiring the opening degree signal of the brake pedal as a judgment basis of the magnitude of energy recovery power, and acquiring the SOC and the chargeable power of the BMS, the motor rotating speed and the maximum feedback torque of the MCU and the working state of the fuel cell. The invention has the beneficial effects that: the energy utilization rate of the hydrogen energy fuel cell automobile is improved.)

1. a fuel cell braking energy recovery system of a hydrogen energy automobile comprises: the system comprises a vehicle control unit VCU, a motor controller MCU, a power battery management subsystem BMS and a fuel battery subsystem FCU;

The BMS, the FCU, the MCU and the VCU carry out data transmission through a CAN bus;

the BMS is used for detecting the residual charge SOC of the power battery and the chargeable power of the power battery;

The FCU is used for controlling the output power of the fuel cell and controlling the charging power of the fuel cell for charging the power battery;

The MCU is used for acquiring the rotating speed of the motor and the maximum feedback torque of the motor and controlling the torque of the motor;

The method is characterized in that:

The VCU recovers the braking energy by acquiring the opening degree signal of the accelerator pedal as a trigger switch signal of energy recovery, acquiring the opening degree signal of the brake pedal as a judgment basis of the magnitude of energy recovery power, and acquiring the SOC and the chargeable power of the BMS, the motor rotating speed and the maximum feedback torque of the MCU and the working state of the fuel cell.

2. the fuel cell braking energy recovery system of a hydrogen-powered vehicle as claimed in claim 1, wherein: the hydrogen energy automobile comprises three working modes:

The first mode is as follows: the power battery is used as a pure electric state of power source output;

and a second mode: the fuel cell and the power cell are used as a hybrid state of power source output;

and a third mode: the fuel cell is used as a pure fuel cell state of the power source output.

3. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as claimed in claim 2, wherein: the VCU acquires an opening signal of an accelerator pedal as a trigger switch signal of energy recovery, and comprises the following steps: when the hydrogen energy automobile is in a mode I, if the opening degree of an accelerator pedal is less than 3 percent and the brake pedal is not stepped for braking, the braking energy recovery system starts to work, the maximum braking negative torque limit value to be sent out by the motor controller for power generation is calculated according to the vehicle speed, the chargeable power of the power battery and the maximum feedback torque of the MCU motor under the condition that the opening degree of the accelerator pedal is less than 3 percent, a braking negative torque is generated by taking the maximum braking negative torque limit value as the maximum value, then the braking negative torque is sent to the motor for execution, the motor is reversely dragged, and finally energy recovery is carried out while braking is realized.

4. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as claimed in claim 2, wherein: when the hydrogen energy automobile is in a mode I, after the opening degree of an accelerator pedal is less than 3%, and a brake pedal is simultaneously stepped for braking, in order to realize a more reasonable and efficient energy recovery function, the opening degree signal of the brake pedal is included when the braking energy recovery system calculates braking negative torque.

5. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as claimed in claim 2, wherein: in the mode I, when the vehicle speed is reduced to 8Km/h, the braking energy recovery system stops working; at the moment, under the condition that a driver does not actively accelerate and brake, the vehicle enters a crawling mode according to the speed; the traveling speed in the creep mode is 8 Km/h.

6. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as claimed in claim 2, wherein: when the braking energy recovery system is in the second mode; if the hydrogen energy automobile runs in a low-power state and the power of the fuel cell is greater than the consumed power of the whole automobile, the power cell is in a charging state at the moment, part of the output power of the fuel cell is used for driving the hydrogen energy automobile to run by the motor, and part of the output power of the fuel cell is used for charging the power cell; under the working condition, the braking negative torque needs to be calculated according to the difference value between the chargeable power of the power battery and the power charged by the fuel battery and the maximum feedback torque of the MCU motor, and the calculated braking negative torque is taken as the maximum value to limit the braking negative torque generated by the power generation of the motor controller so as to prevent the braking negative torque from being overlarge and exceeding the chargeable power of the power battery and the maximum feedback torque of the MCU motor; and when the whole vehicle power consumption of the hydrogen energy vehicle is less than a preset value x, judging that the hydrogen energy vehicle is in a low-power state.

7. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as set forth in claim 6, wherein: when the hydrogen fuel cell works, the charging and discharging state of the power cell is judged by calculating the output power of the fuel cell and the power of the motor; if the power battery is in a discharging state, the braking energy recovery is carried out according to the first mode; if the power battery is in a charging state, the opening degree of an accelerator pedal is less than 3 percent and is used as a starting trigger signal of a braking energy recovery system, the maximum allowable braking energy recovery power is the power difference value between the chargeable power of the power battery and the input power of the fuel battery to the power battery, and then the smaller value is selected as the basis for calculating the braking negative torque of the motor according to the power difference value and the maximum feedback torque of the MCU motor; the calculated braking negative torque and the vehicle speed are subjected to logical operation to obtain the actual output negative torque which can be output by the motor, so that the actual output negative torque, the chargeable power, the maximum feedback torque of the motor and the real-time vehicle speed are dynamically associated, the real-time control of energy recovery is realized on the premise of ensuring the normal use of a power battery, and the maximized braking energy recovery is realized on the premise of ensuring the braking performance and the comfort of the whole vehicle; if the output power of the fuel cell is greater than or equal to the power of the motor, the power cell is in a charging state; otherwise, the power battery is in a discharging state; the maximum feedback torque of the MCU motor is detected by the motor controller.

8. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as set forth in claim 6, wherein: when the hydrogen energy automobile is in the second mode, if the speed of the automobile is reduced to 8Km/h, the system automatically exits the braking energy recovery mode; at this time, the vehicle enters the creeping mode at the vehicle speed without the driver actively accelerating and braking.

9. The fuel cell braking energy recovery system of a hydrogen-powered vehicle as claimed in claim 2, wherein: when the hydrogen energy automobile is in the third mode, the VCU forbids the function of recovering the braking energy, and the hydrogen fuel cell supplies all power consumption of the whole automobile without supporting energy recovery.

Technical Field

The invention relates to the field of new energy automobiles, in particular to a fuel cell braking energy recovery system of a hydrogen energy automobile.

background

In order to cope with international environmental problems and energy crisis, new energy vehicles have been vigorously developed. The driving range is a great restriction condition for the development of new energy automobiles, so how to improve the energy utilization rate is a very important topic.

in the current state of the art, there are many technical solutions for recovering braking energy; however, there is no mature and suitable solution for hydrogen fuel vehicles with hydrogen fuel cells and other auxiliary energy sources (power cells), and the imperfection of the energy recovery strategy affects the service life and usability of the auxiliary energy sources, and affects the braking performance and driving feeling.

Disclosure of Invention

in order to solve the problems, the invention provides a fuel cell braking energy recovery system of a hydrogen energy automobile; a fuel cell braking energy recovery system of a hydrogen energy automobile comprises: the system comprises a vehicle control unit VCU, a motor controller MCU, a power battery management subsystem BMS and a fuel battery subsystem FCU;

the BMS, the FCU, the MCU and the VCU carry out data transmission through a CAN bus;

The BMS is used for detecting the residual charge SOC of the power battery and the chargeable power of the power battery;

the FCU is used for controlling the output power of the fuel cell and controlling the charging power of the fuel cell for charging the power battery;

the MCU is used for acquiring the rotating speed of the motor and the maximum feedback torque of the motor and controlling the torque of the motor;

the method is characterized in that:

The VCU recovers the braking energy by acquiring the opening degree signal of the accelerator pedal as a trigger switch signal of energy recovery, acquiring the opening degree signal of the brake pedal as a judgment basis of the magnitude of energy recovery power, and acquiring the SOC and the chargeable power of the BMS, the motor rotating speed and the maximum feedback torque of the MCU and the working state of the fuel cell.

further, the hydrogen energy automobile comprises three working modes:

The first mode is as follows: the power battery is used as a pure electric state of power source output;

And a second mode: the fuel cell and the power cell are used as a hybrid state of power source output;

And a third mode: the fuel cell is used as a pure fuel cell state of the power source output.

Further, the VCU acquiring the opening signal of the accelerator pedal as the trigger switch signal for energy recovery includes: when the hydrogen energy automobile is in a mode I, if the opening degree of an accelerator pedal is less than 3 percent and the brake pedal is not stepped for braking, the braking energy recovery system starts to work, calculates the maximum braking negative torque limit value required to be sent by the power generation of a motor controller according to the vehicle speed, the chargeable power of a power battery and the maximum feedback torque of an MCU motor under the condition that the opening degree of the accelerator pedal is less than 3 percent, generates a braking negative torque according to the maximum braking negative torque limit value serving as the maximum value, then sends the braking negative torque to the motor for execution, carries out motor back-dragging, and finally realizes energy recovery while braking.

Further, when the hydrogen energy automobile is in the first mode, after the opening of the accelerator pedal is less than 3%, and the brake pedal is simultaneously stepped for braking, in order to realize a more reasonable and efficient energy recovery function, the braking energy recovery system also includes an opening signal of the brake pedal when calculating the braking negative torque.

Further, in the mode one, when the vehicle speed is reduced to 8Km/h, the braking energy recovery system stops working; at the moment, under the condition that a driver does not actively accelerate and brake, the vehicle enters a crawling mode according to the speed; the traveling speed in the creep mode is 8 Km/h.

further, when the braking energy recovery system is in the second mode; if the hydrogen energy automobile runs in a low-power state and the power of the fuel cell is greater than the consumed power of the whole automobile, the power cell is in a charging state at the moment, part of the output power of the fuel cell is used for driving the hydrogen energy automobile to run by the motor, and part of the output power of the fuel cell is used for charging the power cell; under the working condition, the braking negative torque needs to be calculated according to the difference value between the chargeable power of the power battery and the power charged by the fuel battery and the maximum feedback torque of the MCU motor, and the calculated braking negative torque is taken as the maximum value to limit the braking negative torque generated by the power generation of the motor controller so as to prevent the braking negative torque from being overlarge and exceeding the chargeable power of the power battery and the maximum feedback torque of the MCU motor; and when the whole vehicle power consumption of the hydrogen energy vehicle is less than a preset value x, judging that the hydrogen energy vehicle is in a low-power state.

Further, when the hydrogen fuel cell works, the charging and discharging state of the power cell is judged by calculating the output power of the fuel cell and the power of the motor; if the power battery is in a discharging state, the braking energy recovery is carried out according to the first mode; if the power battery is in a charging state, the opening degree of an accelerator pedal is less than 3 percent and is used as a starting trigger signal of a braking energy recovery system, the maximum allowable braking energy recovery power is the power difference value between the chargeable power of the power battery and the input power of the fuel battery to the power battery, and then the smaller value is selected as the basis for calculating the braking negative torque of the motor according to the power difference value and the maximum feedback torque of the MCU motor; the calculated braking negative torque and the vehicle speed are subjected to logical operation to obtain the actual output negative torque which can be output by the motor, so that the actual output negative torque, the chargeable power, the maximum feedback torque of the motor and the real-time vehicle speed are dynamically associated, the real-time control of energy recovery is realized on the premise of ensuring the normal use of a power battery, and the maximized braking energy recovery is realized on the premise of ensuring the braking performance and the comfort of the whole vehicle; if the output power of the fuel cell is greater than or equal to the power of the motor, the power cell is in a charging state; otherwise, the power battery is in a discharging state; the maximum feedback torque of the MCU motor is detected by the motor controller.

Further, when the hydrogen energy automobile is in the second mode, if the speed of the automobile is reduced to 8Km/h, the system automatically exits the braking energy recovery mode; at this time, the vehicle enters the creeping mode at the vehicle speed without the driver actively accelerating and braking.

further, when the hydrogen energy automobile is in the third mode, the VCU prohibits the braking energy recovery function, and at this time, the hydrogen fuel cell supplies all power consumption of the whole automobile, and the energy recovery is not supported.

The technical scheme provided by the invention has the beneficial effects that: the technical scheme provided by the invention improves the energy utilization rate of the hydrogen energy fuel cell automobile and designs a braking energy recovery strategy which accords with a specific hydrogen energy fuel cell automobile framework.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic diagram of a braking energy recovery system of a fuel cell of a hydrogen-powered vehicle according to an embodiment of the present invention;

fig. 2 is a structural diagram of a braking energy recovery system of a fuel cell of a hydrogen energy automobile according to an embodiment of the invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

the embodiment of the invention provides a fuel cell braking energy recovery system of a hydrogen energy automobile.

referring to fig. 1, fig. 1 is a schematic diagram of a braking energy recovery system of a fuel cell of a hydrogen vehicle according to an embodiment of the present invention; the method comprises the following steps: the system comprises a vehicle control unit VCU, a motor controller MCU, a power battery management subsystem BMS and a fuel battery subsystem FCU;

the BMS, the FCU, the MCU and the VCU carry out data transmission through a CAN bus;

The BMS is used for detecting the residual charge SOC of the power battery and the chargeable power of the power battery;

the FCU is used for controlling the output power of the fuel cell and controlling the charging power of the fuel cell for charging the power battery;

The MCU is used for acquiring the rotating speed of the motor and the maximum feedback torque of the motor and controlling the torque of the motor;

the VCU recovers the braking energy by acquiring the opening degree signal of the accelerator pedal as a trigger switch signal of energy recovery, acquiring the opening degree signal of the brake pedal as a judgment basis of the magnitude of energy recovery power, and acquiring the SOC and the chargeable power of the BMS, the motor rotating speed and the maximum feedback torque of the MCU and the working state of the fuel cell.

The hydrogen energy automobile comprises three working modes:

the first mode is as follows: the power battery is used as a pure electric state of power source output;

And a second mode: the fuel cell and the power cell are used as a hybrid state of power source output;

and a third mode: the fuel cell is used as a pure fuel cell state of the power source output.

the VCU acquires an opening signal of an accelerator pedal as a trigger switch signal of energy recovery, and comprises the following steps: when the hydrogen energy automobile is in a mode I, if the opening degree of an accelerator pedal is less than 3 percent and the brake pedal is not stepped for braking, the braking energy recovery system starts to work, calculates the maximum braking negative torque limit value required to be sent by the power generation of a motor controller according to the vehicle speed, the chargeable power of a power battery and the maximum feedback torque of an MCU motor under the condition that the opening degree of the accelerator pedal is less than 3 percent, generates a braking negative torque according to the maximum braking negative torque limit value serving as the maximum value, then sends the braking negative torque to the motor for execution, carries out motor back-dragging, and finally realizes energy recovery while braking.

The maximum braking negative torque limit value is calculated according to the following principle:

in the above formula, p is the chargeable power of the power battery and is provided to the VCU by the BMS; z is the motor speed and is provided to the VCU by the MCU; y is the maximum recovery negative torque limit value to be solved, and the braking negative torque required to be generated by the motor controller when the energy recovery system works cannot exceed the maximum recovery negative torque limit value.

The vehicle speed v is calculated as follows:

In the above equation, i is the speed reducer ratio and r is the wheel radius of the vehicle, and in the embodiment of the present invention, i is 7.82 and r is 0.29 m.

In the first mode, after the opening of the accelerator pedal is less than 3%, the brake pedal is simultaneously stepped for braking, and in order to realize a more reasonable and efficient energy recovery function, the braking energy recovery system also includes an opening signal of the brake pedal when calculating braking negative torque; the braking negative torque at this time is calculated according to the following steps: the vehicle speed when the opening degree of an accelerator pedal is less than 3%, the opening degree of a brake pedal, the maximum feedback torque of a motor and the chargeable power of a power battery; in the braking energy recovery process, the braking negative torque correspondingly changes along with the change of the vehicle speed, the braking opening, the maximum feedback torque of the motor and the chargeable power of the power battery, so that the maximization of energy recovery at each moment is ensured, and meanwhile, a driver can feel obvious braking force and comfortableness in the braking process; the method specifically comprises the following steps:

firstly, a first negative torque required by energy recovery of the power battery at the moment is obtained according to the chargeable power of the power battery and the vehicle speed at the moment, the first negative torque and the maximum feedback torque of the motor are compared, the smaller value of the first negative torque and the maximum feedback torque of the motor is obtained, and then a second negative torque is generated according to the opening degree of a brake pedal; comparing the smaller value with the second negative torque, and taking the minimum value of the two as the braking negative torque; and finally, the braking negative torque is sent to the motor to be executed, the motor is reversely dragged, and energy recovery is carried out while braking is realized. In the embodiment of the invention, the magnitude of the second negative torque is in direct proportion to the magnitude of the opening degree of the brake pedal, and the proportionality coefficient is set according to the actual driving requirement.

In the mode I, when the vehicle speed is reduced to 8Km/h, the braking energy recovery system stops working; at the moment, under the condition that a driver does not actively accelerate and brake, the vehicle enters a crawling mode according to the speed; the traveling speed in the creep mode is 8 Km/h.

when the braking energy recovery system is in the second mode; if the hydrogen energy automobile runs in a low-power state and the output power of the fuel cell is greater than the consumed power of the whole automobile, the power battery is in a charging state at the moment, part of the output power of the fuel cell drives the hydrogen energy automobile to run by the motor, and part of the output power of the fuel cell charges the power battery; under the working condition, the braking negative torque needs to be calculated according to the difference value between the chargeable power of the power battery and the power charged by the fuel battery and the maximum feedback torque of the MCU motor, and the calculated braking negative torque is taken as the maximum value to limit the braking negative torque generated by the power generation of the motor controller so as to prevent the braking negative torque from being overlarge and exceeding the chargeable power of the power battery and the maximum feedback torque of the MCU motor; when the whole vehicle power consumption of the hydrogen energy vehicle is less than a preset value x, judging that the hydrogen energy vehicle is in a low-power state; examples are as follows:

when the braking energy recovery system is in the second mode, if the hydrogen energy automobile runs in a low-power state, the output power of the fuel cell is 40kW and is greater than the consumed power of the whole automobile, the power cell is in a charging state, if the charging power of the fuel cell to the power cell is 10kW and the chargeable power of the power cell is 15kW, the charging power generated by the braking negative torque needs to be less than or equal to 15-10 kW and 5kW, and the braking negative torque to be generated by the motor controller is limited by taking the braking negative torque calculated according to 5kW as the maximum value.

When the hydrogen fuel cell works, the charging and discharging state of the power cell is judged by calculating the output power of the fuel cell and the power of the motor; if the power battery is in a discharging state, the braking energy recovery is carried out according to the first mode; if the power battery is in a charging state, the opening degree of an accelerator pedal is less than 3 percent and is used as a starting trigger signal of a braking energy recovery system, the maximum allowable braking energy recovery power is the power difference value between the chargeable power of the power battery and the input power of the fuel battery to the power battery, and then the smaller value is selected as the basis for calculating the braking negative torque of the motor according to the power difference value and the maximum feedback torque of the MCU motor; the calculated braking negative torque and the vehicle speed are subjected to logical operation to obtain the actual output negative torque which can be output by the motor, so that the actual output negative torque, the chargeable power, the maximum feedback torque of the motor and the real-time vehicle speed are dynamically associated, the real-time control of energy recovery is realized on the premise of ensuring the normal use of a power battery, and the maximized braking energy recovery is realized on the premise of ensuring the braking performance and the comfort of the whole vehicle; if the output power of the fuel cell is greater than or equal to the power of the motor, the power cell is in a charging state; otherwise, the power battery is in a discharging state; the maximum feedback torque of the MCU motor is detected by the motor controller.

when the hydrogen energy automobile is in the second mode, if the speed of the automobile is reduced to 8Km/h, the system automatically exits the braking energy recovery mode; at this time, the vehicle enters the creeping mode at the vehicle speed without the driver actively accelerating and braking.

When the hydrogen energy automobile is in the third mode, the VCU forbids the function of recovering the braking energy, and the hydrogen fuel cell supplies all power consumption of the whole automobile without supporting energy recovery.

Referring to fig. 2, fig. 2 is a structural diagram of a braking energy recovery system of a fuel cell of a hydrogen energy vehicle according to an embodiment of the present invention; the vehicle control unit VCU is integrated with a braking energy recovery management subsystem and a charging and discharging control subsystem, and is respectively used for controlling the energy recovery state of the fuel cell braking energy recovery system of the hydrogen energy vehicle and controlling the output power of the fuel cell and the charging power of the power cell.

the invention has the beneficial effects that: the technical scheme provided by the invention improves the energy utilization rate of the hydrogen energy fuel cell automobile and designs a braking energy recovery strategy which accords with a specific hydrogen energy fuel cell automobile framework.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.