阅读说明：本技术 一种电电混合燃料电池汽车的能量分配控制方法 (Energy distribution control method for electric-electric hybrid fuel cell automobile ) 是由 王涛 吴星成 夏沙 谢奇光 于 2021-07-29 设计创作，主要内容包括：本发明公开了一种电电混合燃料电池汽车的能量分配控制方法。车辆行驶过程中,实时获取车辆行驶参数,根据行驶参数确定电机需求功率、燃料电池最大放电功率和锂电池最大放电功率,根据车辆状态、电机需求功率与燃料电池最大放电功率和锂电池最大放电功率之间的大小关系确定电机的工作模式,根据电机的工作模式对燃料电池和锂电池的输出功率进行实时分配。能够在保证燃料电池、锂电池安全运行前提下,避免燃料电池功率快速波动,并尽可能利用燃料电池作为动力系统的能源供给,使得燃料电池尽可能运行在其高效率输出区间。(The invention discloses an energy distribution control method of an electric-electric hybrid fuel cell automobile. In the vehicle running process, vehicle running parameters are obtained in real time, the required power of a motor, the maximum discharge power of a fuel cell and the maximum discharge power of a lithium battery are determined according to the running parameters, the working mode of the motor is determined according to the size relation among the vehicle state, the required power of the motor, the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, and the output power of the fuel cell and the output power of the lithium battery are distributed in real time according to the working mode of the motor. The method can avoid the rapid fluctuation of the power of the fuel cell on the premise of ensuring the safe operation of the fuel cell and the lithium battery, and utilize the fuel cell as the energy supply of a power system as much as possible, so that the fuel cell can operate in a high-efficiency output interval as much as possible.)

1. An energy distribution control method of an electric-electric hybrid fuel cell vehicle is characterized in that: in the vehicle running process, vehicle running parameters are obtained in real time, the required power of a motor, the maximum discharge power of a fuel cell and the maximum discharge power of a lithium battery are determined according to the running parameters, the working mode of the motor is determined according to the size relation among the vehicle state, the required power of the motor, the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, and the output power of the fuel cell and the output power of the lithium battery are distributed in real time according to the working mode of the motor.

2. The energy distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 1, characterized in that: the working mode of the motor is any one of an overload mode, a large-torque operation mode, a light-load operation mode and a feedback power mode.

3. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 2, characterized in that: and if the required power of the motor is greater than the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium cell, determining that the motor is in an overload mode, sending a load reduction command to a motor controller, and controlling the required power of the motor to be equal to the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium cell.

4. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 2, characterized in that: and if the required power of the motor is larger than the maximum discharge power of the fuel cell and smaller than or equal to the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, determining that the motor is in a high-torque operation mode, setting the current expected output power of the fuel cell as the maximum discharge power of the fuel cell, determining the current actual output power of the fuel cell based on the current expected output power of the fuel cell, and determining the current actual output power of the lithium battery according to the current actual output power of the fuel cell, the required power of the motor and the maximum discharge power of the lithium battery.

5. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 4, characterized in that: the process of determining the actual output power of the current lithium battery comprises the following steps:

setting the difference value between the required power of the motor and the actual output power of the current fuel cell as the expected output power of the current lithium battery, and if the expected output power of the current lithium battery is greater than the maximum discharge power of the lithium battery, determining the actual output power of the current lithium battery as the maximum discharge power of the lithium battery; and if the expected output power of the current lithium battery is less than or equal to the maximum discharge power of the lithium battery, determining the actual output power of the current lithium battery as the expected output power of the current lithium battery.

6. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 2, characterized in that: if the required power of the motor is less than or equal to the maximum discharge power of the fuel cell, determining that the motor is in a light-load operation mode, determining whether to charge the lithium cell according to the residual electric quantity of the lithium cell,

if the lithium battery is not charged, setting the current expected output power of the fuel cell as the required power of the motor, and determining the current actual output power of the fuel cell based on the current expected output power of the fuel cell, wherein the current actual output power of the lithium battery is zero;

if the lithium battery is charged, calculating the current expected charging power of the lithium battery, determining the current expected output power of the fuel battery according to the current expected charging power of the lithium battery, determining the current actual output power of the fuel battery based on the current expected output power of the fuel battery, wherein the current actual charging power of the lithium battery is the difference value between the current actual output power of the fuel battery and the required power of the motor.

7. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 6, characterized in that: when the lithium battery is charged, the process of determining the current expected output power of the fuel battery is as follows:

setting the current theoretical expected output power of the fuel cell as the sum of the current expected charging power of the lithium battery and the required power of the motor;

if the current theoretical expected output power of the fuel cell is smaller than the maximum discharge power of the fuel cell, determining the current theoretical expected output power of the fuel cell as the current theoretical expected output power of the fuel cell;

and if the current theoretical expected output power of the fuel cell is greater than or equal to the maximum discharge power of the fuel cell, determining the current expected output power of the fuel cell as the maximum discharge power of the fuel cell.

8. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 4 or 6, characterized in that: the process of determining the current actual output power of the fuel cell is as follows:

calculating a power difference value between the current desired output power of the fuel cell and the actual output power of the fuel cell in the previous period, determining the current actual output power of the fuel cell based on the power difference value by the following formula,

wherein, P_fcActual output power of the fuel cell

P_fc1-current actual fuel cell output power;

current desired output power of the fuel cell stack;

P_fc0-actual output power of the fuel cell in the previous cycle;

ΔP_fc-a limit value for the allowable fluctuation of the fuel cell output power per unit period.

9. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 2, characterized in that: and if the vehicle is in the fuel-electric mode, the gear of the whole vehicle is in the D gear, and the depth of the accelerator is 0, determining that the motor is in the power feedback mode, and determining whether to perform normal feedback according to the difference value between the maximum allowable charging power of the lithium battery and the actual output power of the fuel battery.

10. The power distribution control method of an electric-electric hybrid fuel cell vehicle according to claim 9, characterized in that: if the difference value is larger than or equal to the feedback power of the current motor, the motor carries out normal feedback and generates power to charge the lithium battery; and if the difference value is smaller than the current motor feedback power, the motor does not feed back energy.

Technical Field

The invention belongs to the technical field of automobiles, and particularly relates to an energy distribution control method of an electric-electric hybrid fuel cell automobile.

Background

The existing fuel cell automobile works in a constant power output mode, and the technology is insufficient:

1) the dynamic response of the fuel cell as a power supply of the electric automobile has a certain time lag. When the load fluctuates, the output of the fuel cell can be adjusted to adapt to the change of the load usually after a period of time, the real-time power requirement of the vehicle power is difficult to meet, meanwhile, the overcharge and the over-discharge of the lithium battery pack are easy to cause, and the service life of the lithium battery pack is shortened;

2) when the motor performs regenerative braking, the vehicle needs to have an energy storage device to absorb electric energy fed back by the motor so as to increase the vehicle energy and prolong the endurance time, but the fuel cell does not support bidirectional flow of energy, cannot absorb electric energy generated in the braking process of the motor, needs an auxiliary energy storage power supply device with larger energy density and power density to be complementary with the fuel cell and supplies power to a load together, and the two energy sources have the problem of complicated power distribution.

Disclosure of Invention

The present invention is directed to solve the above-mentioned drawbacks of the prior art, and to provide an energy distribution control method for an electric-electric hybrid fuel cell vehicle.

The technical scheme adopted by the invention is as follows: the energy distribution control method of the electric-electric hybrid fuel cell automobile comprises the steps of obtaining vehicle running parameters in real time (periodically) in the running process of the automobile, determining the required power of a motor, the maximum discharge power of a fuel cell and the maximum discharge power of a lithium battery according to the running parameters, determining the working mode of the motor according to the size relation among the vehicle state, the required power of the motor, the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, and distributing the output power of the fuel cell and the output power of the lithium battery in real time according to the working mode of the motor.

Further, the working mode of the motor is any one of an overload mode, a large-torque operation mode, a light-load operation mode and a feedback power mode.

Further, if the required power of the motor is larger than the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, the motor is determined to be in an overload mode, a load reduction command is sent to a motor controller, and the required power of the motor is controlled to be equal to the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery.

Further, if the required power of the motor is larger than the maximum discharge power of the fuel cell and smaller than or equal to the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, the motor is determined to be in a high-torque operation mode, the current expected output power of the fuel cell is set to be the maximum discharge power of the fuel cell, the current actual output power of the fuel cell is determined based on the current expected output power of the fuel cell, and the current actual output power of the lithium battery is determined according to the current actual output power of the fuel cell, the required power of the motor and the maximum discharge power of the lithium battery.

Further, the process of determining the actual output power of the current lithium battery is as follows:

setting the difference value between the required power of the motor and the actual output power of the current fuel cell as the expected output power of the current lithium battery, and if the expected output power of the current lithium battery is greater than the maximum discharge power of the lithium battery, determining the actual output power of the current lithium battery as the maximum discharge power of the lithium battery; and if the expected output power of the current lithium battery is less than or equal to the maximum discharge power of the lithium battery, determining the actual output power of the current lithium battery as the expected output power of the current lithium battery.

Further, if the power required by the motor is less than or equal to the maximum discharge power of the fuel cell, determining that the motor is in a light-load operation mode, determining whether to charge the lithium battery according to the residual electric quantity of the lithium battery,

if the lithium battery is not charged, setting the current expected output power of the fuel cell as the required power of the motor, and determining the current actual output power of the fuel cell based on the current expected output power of the fuel cell, wherein the current actual output power of the lithium battery is zero;

if the lithium battery is charged, calculating the current expected charging power of the lithium battery, determining the current expected output power of the fuel battery according to the current expected charging power of the lithium battery, determining the current actual output power of the fuel battery based on the current expected output power of the fuel battery, wherein the current actual charging power of the lithium battery is the difference value between the current actual output power of the fuel battery and the required power of the motor.

Further, when charging the lithium battery, the process of determining the current expected output power of the fuel cell is as follows:

setting the current theoretical expected output power of the fuel cell as the sum of the current expected charging power of the lithium battery and the required power of the motor;

if the current theoretical expected output power of the fuel cell is smaller than the maximum discharge power of the fuel cell, determining the current theoretical expected output power of the fuel cell as the current theoretical expected output power of the fuel cell;

and if the current theoretical expected output power of the fuel cell is greater than or equal to the maximum discharge power of the fuel cell, determining the current expected output power of the fuel cell as the maximum discharge power of the fuel cell.

Further, the process of determining the current actual output power of the fuel cell is:

calculating a power difference value between the current desired output power of the fuel cell and the actual output power of the fuel cell in the previous period, determining the current actual output power of the fuel cell based on the power difference value by the following formula,

wherein, P_fcActual output power of the fuel cell

P_fc1-current actual fuel cell output power;

-current desired output power of the fuel cell stack;

P_fc0-actual output power of the fuel cell in the previous cycle;

ΔP_fc-a limit value for the allowable fluctuation of the fuel cell output power per unit period.

Further, if the vehicle is in the fuel-electric mode, the gear of the whole vehicle is in the D gear, and the depth of the accelerator is 0, the motor is determined to be in the power feedback mode, and whether normal feedback is performed is determined according to the difference value between the maximum allowable charging power of the lithium battery and the actual output power of the fuel battery.

Furthermore, if the difference value is larger than or equal to the feedback power of the current motor, the motor carries out normal feedback to generate power to charge the lithium battery; and if the difference value is smaller than the current motor feedback power, the motor does not feed back energy.

The invention has the beneficial effects that:

the invention determines the working mode of the motor according to the power required by the motor and the maximum discharge power of the fuel cell and the lithium cell, determines the distribution of different output powers of the fuel cell and the lithium cell according to different working modes of the motor, limits the output power of the fuel cell during the distribution, can avoid the large fluctuation of the output power of the fuel cell on the premise of ensuring the safe operation of the fuel cell and the lithium cell, enhances the performance and the service life of the fuel cell, and utilizes the fuel cell as the energy supply of a power system as much as possible to ensure that the fuel cell operates in a high-efficiency output interval as much as possible; the safe operation of the lithium battery is guaranteed, namely the output of the fuel battery is preferentially utilized to meet the power requirement of the load, and the lithium battery pack only plays a role in peak clipping and valley filling on the load under the condition that the lithium battery pack is not over charged or is started under the condition that the safety of the fuel battery is guaranteed.

Drawings

FIG. 1 is a schematic diagram of a control system of the present invention.

FIG. 2 is a control flow chart of the present invention.

Fig. 3 is a schematic diagram of a lithium battery charging threshold according to the present invention.

Fig. 4 is a motor power feedback flow chart according to the present invention.

Detailed Description

The following further describes embodiments of the present invention with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present invention, but the present invention is not limited thereto. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Aiming at the defects that the charging and discharging current of a power lithium battery is strictly limited and the overcharge and overdischarge are strictly forbidden in the existing time lag of the output power of a fuel battery and the power distribution of the power lithium battery, an energy management control system disclosed by the invention adaptively distributes the power of the fuel battery and the power of the lithium battery by controlling the voltage of a bus as shown in figure 1. The energy management control system comprises 3 functional modules: the energy distribution algorithm is based on the motor power demand P_dAnd the working state of the hybrid power supply, and distributing the output power of the fuel cell and the lithium cell to obtain P_fcAnd P_dThe fuel cell operating point calculation module is based on P_fcAnd a voltage-current characteristic curve of the fuel cell, and calculating a target voltage U of the expected operating point_refGiven as a reference for the load voltage; actual output power P of lithium battery_bFollowing P_dAnd P_fcThe difference value of (a) is adaptively changed; the power conversion unit is used for executing an energy flow control strategy and regulating the bus voltage to a desired voltage.

As shown in fig. 2, the energy distribution management process of the present invention is as follows:

setting a limit value delta P of allowable fluctuation of output power of the fuel cell in a unit period_fcTaking + Δ P when loaded_fcTaking-delta P when load is reduced_fc。

Secondly, setting the charging and discharging SOC (residual electric quantity) upper line and lower limit of the lithium battery, and setting the maximum charging and discharging multiplying power.

Reading the real-time SOC value of the lithium battery and the accelerating torque T required by the driver_eThe SOC value of the power battery can be calculated by an ampere-hour method, the SOC value is reflected by the opening degree of an accelerator pedal, and the motor speed n fed back by a motor controller is combined according to a formula: p_d＝T_eN/9550 calculates the driver's motor power demand.

And fourthly, determining the working mode of the motor according to the required power of the motor, the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery and the size relation among the vehicle state, the required power of the motor, the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery, and distributing the output power of the fuel cell and the output power of the lithium battery in real time according to the working mode of the motor. The working mode of the motor is any one of an overload mode, a large-torque operation mode, a light-load operation mode and a feedback power mode.

a. Overload mode: and (3) judging that the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery is less than the required power of the motor, namely judging that the motor is overloaded, sending a load reduction command to a motor controller, and controlling the required power of the motor to be equal to the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery.

b. High torque operating mode: namely, the required power of the motor is larger than the maximum discharge power of the fuel cell and is less than or equal to the sum of the maximum discharge power of the fuel cell and the maximum discharge power of the lithium battery. In order to meet the load demand as quickly as possible, the current (cycle) expected output power P of the fuel cell needs to be set^* _fc1Assigned a value of P_fcmaxTo avoid large output power fluctuation of the fuel cell, P must be determined^* _fc1P relative to the previous control period_fc0The amount of fluctuation and the increment Δ P of_fc(upper limit of allowable fluctuation of output power of fuel cell per unit control period), and the actual output power P of fuel cell is corrected based on the upper limit_fc：

Wherein, P_fcActual output power of the fuel cell

P_fc1-current actual fuel cell output power;

-current desired output power of the fuel cell stack;

P_fc0-last cycle fuelActual output power of the battery;

ΔP_fc-a limit value for the allowable fluctuation of the fuel cell output power per unit period.

The meaning of each parameter in fig. 2 is as follows:

P_d-the motor demand power.

P_fcmax-maximum discharge power of the fuel cell.

+ΔP_fc-a limit increment of the allowable fluctuation of the fuel cell output power per unit period.

-ΔP_fc-a limit reduction of the allowable fluctuation of the fuel cell output power per unit period.

P′_fc1Under the working condition that the lithium battery and the motor are used as loads, the theoretical expected output power of the current fuel cell is obtained.

P_bmax-maximum discharge power of the lithium battery.

P_b-the actual output power of the lithium battery.

P_b1-the current actual output power of the lithium battery.

-current desired output power of the lithium battery.

The correction method ensures the actual output power P of the fuel cell_fcResponding slowly with load demand, and then utilizing fully distributed P_fc1Calculating the expected output power P of the lithium battery as a constraint condition^* _b1＝P_d-P_fc1And judging P of the lithium battery at the moment_bmaxWhether the expected value can be met or not and the actual output power P of lithium battery distribution_b＝P_b1＝min[P^* _b1,P_bmax]At P_bGet P_bmaxThe time indicates that the power actually distributed to the lithium battery pack is larger than the maximum power which can be provided by the lithium battery pack, and a load reduction protection command needs to be sent, so that the power distribution of the two energy sources in the large-torque operation mode is completed, and the actual output power P of the fuel cell is used_fcAnd the actual output power of the lithium batteryP_bAnd with P_fc+P_bThe sum is sent to the motor controller as the actual power setpoint.

c. Light load operation mode: p_d≤P_fcmaxAnd judging whether the fuel cell needs to charge the lithium battery pack except for supplying power to the load or not according to the current SOC value of the lithium battery. The charging threshold of the SOC for light load charging is designed according to the following parameters, as shown in fig. 3, and the threshold can ensure that the lithium battery pack has a certain margin to be charged or discharged.

When the SOC is less than or equal to 60 percent, the output power coefficient eta of the whole vehicle allowable fuel system_A0Switching from 0 to 1. After the fuel electric system is started to work, the whole vehicle carries out grading limitation on the power value of the fuel electric system according to the SOC value of the power battery. When the SOC is more than or equal to 90 percent, the output power coefficient eta of the whole vehicle allowable fuel system_A1When the power consumption is not less than 0kw, the fuel system is in an idle state, namely the output power of the fuel cell system only meets the self power consumption requirement; when the SOC is more than or equal to 85% and less than 90%, the output coefficient eta of the whole vehicle allowed fuel electric system_A20.5; when the SOC is more than or equal to 80% and less than 85%, the output power coefficient eta of the whole vehicle allowed combustion system_A3Linear smoothing from 0.5 to 0.7; when the SOC is more than or equal to 70% and less than 80%, the output power coefficient eta of the whole vehicle allowed combustion power system_A40.7; when the SOC is more than or equal to 65% and less than 70%, the output power coefficient eta of the whole vehicle allowed combustion system_A5Linear smoothing from 0.7 to 1; when the SOC is less than 65%, the output power coefficient eta of the whole vehicle allowable fuel system_A6＝1。

When the SOC is larger than the 90% threshold value, the charging is not needed under light load, and only the expected value P of the output power of the fuel cell is needed^* _fc1Is set to P_dAnd correcting the actual output power P of the current fuel cell according to the correction mode in the high-torque operation mode_fc1. It is apparent that the lithium ion battery pack is enabled to supplement the gap in load demand power only when the fuel cell output power exceeds a single step adjustment. When the SOC is less than 60% threshold value, the fuel cell charges the lithium battery pack on the premise of meeting the load power, and therefore the expected charging power P of the current lithium battery is calculated^* _b1. Setting the current theoretical expected output power of the fuel cell as the current expected charging power of the lithium battery and the motor demandThe sum of the powers; if the current theoretical expected output power of the fuel cell is smaller than the maximum discharge power of the fuel cell, determining the current theoretical expected output power of the fuel cell as the current theoretical expected output power of the fuel cell; and if the current theoretical expected output power of the fuel cell is greater than or equal to the maximum discharge power of the fuel cell, determining the current expected output power of the fuel cell as the maximum discharge power of the fuel cell. After the expected output power of the current fuel cell is determined, the actual output power P of the current fuel cell is corrected according to the correction mode in the high-torque operation mode_fc1。

And selecting constant-current quick charging for charging in the light load mode, and enabling the battery capacity to reach a desired value at a proper speed. In the mode, the lithium battery pack and the motor are both loads of the fuel cell, and P is judged_dAnd P^* _b1And if the sum is within the range allowed by the output of the fuel cell, reducing the charging current to ensure that the charging power and the load power are equal to the maximum discharging power of the fuel cell.

d. The motor power feedback mode is as follows: the output power of the fuel cell is distributed according to the SOC and the maximum allowable charging power (real-time maximum charging power) of the battery. As shown in fig. 4, when the voltage on the whole vehicle is high and the system has no fault, the whole vehicle controller determines that the whole vehicle is in the fuel-electric mode (in the working state of the fuel cell engine), the gear of the whole vehicle is in the D gear, and the accelerator depth is 0; calculating a maximum allowable charging power P of a battery of a BMS (Battery management System)_{Charge allowance}And the output power P of the fuel-electric system_{Gas and electricity}A difference value, the difference value being a positive value; if the difference value of the current motor feedback power and the current motor feedback power is larger than or equal to the current motor feedback power, charging the lithium battery according to the normal feedback of the motor; if the difference between the current motor feedback power and the current motor feedback power is less than the current motor feedback power, the motor does not feed back the power. The current motor feedback power is obtained by the driving motor controller through calculation according to the motor rotating speed and the torque and is sent to the whole vehicle controller through the CAN bus.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Those not described in detail in this specification are within the skill of the art.