阅读说明：本技术 多堆氢燃料电池系统功率管理方法 (Power management method for multi-stack hydrogen fuel cell system ) 是由 庄伟超 牛俊严 殷国栋 于 2021-07-30 设计创作，主要内容包括：本发明涉及一种多堆氢燃料电池系统功率管理方法,包括以下步骤：获取车辆速度、加速度和油门踏板实时信息；计算车辆实时功率需求P-(d)；获取多堆燃料电池系统和动力电池的实时状态信息；根据所述功率需求P-(d)和所述实时状态信息,通过滞后控制策略确定每一时刻的多堆氢燃料电池系统中燃料电池堆的开启数量,然后根据每个燃料电池堆的累计运行时间,依据工作时间均匀分布的原则确定开启哪些燃料电池堆,实现动力电池和多堆氢燃料电池系统的功率流分配。本发明的电池系统功率管理方法缩短了每个燃料电池堆的有效工作时间,减少了启停次数,延长了使用寿命；保证了各燃料电池堆的老化程度相近,便于维护。(The invention relates to a power management method of a multi-stack hydrogen fuel cell system, which comprises the following steps: acquiring vehicle speed, acceleration and accelerator pedal real-time information; calculating vehicle real-time power demand P d (ii) a Acquiring real-time state information of a multi-stack fuel cell system and a power cell; according to said power demand P d And the real-time state information determines the starting number of the fuel cell stacks in the multi-stack hydrogen fuel cell system at each moment through a hysteresis control strategy, and then determines which fuel cell stacks are started according to the accumulated running time of each fuel cell stack and the principle of uniform distribution of working timeThe fuel cell stack realizes the power flow distribution of the power cell and the multi-stack hydrogen fuel cell system. The power management method of the battery system shortens the effective working time of each fuel cell stack, reduces the starting and stopping times and prolongs the service life; the aging degree of each fuel cell stack is ensured to be similar, and the maintenance is convenient.)

1. A power management method for a multi-stack hydrogen fuel cell system, the multi-stack hydrogen fuel cell system and a power cell being matched to power an electric vehicle, the multi-stack hydrogen fuel cell system comprising a plurality of fuel cell stacks, the power management method comprising the steps of:

step 1): acquiring real-time information of vehicle speed, acceleration and accelerator pedal travel;

step 2): calculating the real-time power demand P of the vehicle according to the real-time information and the vehicle driving dynamics equation_d；

Step 3): acquiring real-time state information of the multi-stack hydrogen fuel cell system and the power cell, wherein the real-time state information comprises the accumulated running time of each fuel cell stack and the charge state of the power cell;

step 4): according to said power demand P_dAnd 3) determining the starting number N of the fuel cell stacks in the multi-stack hydrogen fuel cell system at each moment through the real-time state information obtained in the step 3) through a hysteresis control strategy_fRealizing the power flow distribution of the power battery and the multi-stack hydrogen fuel cell system;

step 5): the number N of the startup units obtained in the step 4) is used_fAnd determining which fuel cell stacks are started according to the principle of uniform distribution of working time by combining the accumulated running time of each fuel cell stack, and executing related actions through corresponding electronic control programs.

2. The power management method for a multi-stack hydrogen fuel cell system according to claim 1, wherein in the step 3), the maximum state of charge SOC of the power battery is set according to actual application scenarios_upperLowest state of charge SOC_lowMaximum state of charge SOC_maxAnd minimum state of charge SOC_minSatisfies SOC_min＜SOC_low＜SOC_upper＜SOC_max(ii) a Selecting a fuel cell stack in the multi-stack hydrogen fuel cell systemN and a fixed output power P per fuel cell stack_fc；

In the step 4), the hysteresis control strategy is as follows:

the starting number of the fuel cell stack at the moment of primarily selecting k +1 is N_d(k+1)，N_d(k +1) satisfies: n is a radical of_d(k+1)P_fc≤P_d(k+1)≤(N_d(k+1)+1)P_fcCondition (1) P_d(k +1) represents the power demand of the vehicle at time k +1, and the following logical decision is made:

if N is present_d(k +1) is more than or equal to N, then the starting number N of the fuel cell stack at the moment of k +1_f(k+1)＝n；

If N is present_d(k +1) < n, and the state of charge SOC (k) of the power battery at the moment k is less than or equal to SOC_lowThen N is_f(k+1)＝N_d(k+1)+1；

If N is present_d(k +1) < n, and the state of charge SOC (k) of the power battery at the moment k is more than or equal to SOC_upperThen N is_f(k+1)＝N_d(k+1)；

If N is present_d(k +1) < n, and SOC_low≤SOC(k)≤SOC_upperAnd the number N of the fuel cell stack started at the time k_f(k)≤N_d(k +1), then N_f(k+1)＝N_d(k+1)；

If N is present_d(k +1) < n, and SOC_low≤SOC(k)≤SOC_upperAnd the number N of the fuel cell stack started at the time k_f(k)＞N_d(k +1), then N_f(k+1)＝N_d(k+1)+1。

Technical Field

The invention relates to the technical field of power management of battery systems of electric vehicles, in particular to a power management method of a multi-stack hydrogen fuel battery system.

Background

The traditional single-pile fuel cell power generation system has the defects of poor durability, high cost and poor reliability, and the popularization and the use of the current fuel cell power generation system are seriously restricted. Currently, multi-stack fuel cell systems are the first choice to address this problem. Multi-stack fuel cell systems increase the complexity of control while improving fuel cell durability and reliability. In view of the above, researchers at home and abroad have conducted a lot of theoretical and experimental discussion, and how to better distribute the power flow between a plurality of fuel cell stacks and a power battery and prolong the service life of the fuel cell becomes a technical problem to be solved.

Disclosure of Invention

In view of the defects of the prior art, the invention provides a power management method of a multi-stack hydrogen fuel cell system, aiming at balancing the power flow between a fuel cell stack and a power cell and prolonging the service life of the fuel cell.

The technical scheme adopted by the invention is as follows:

a power management method for a multi-stack hydrogen fuel cell system and a power cell that cooperate to power an electric vehicle, the multi-stack hydrogen fuel cell system including a plurality of fuel cell stacks, the power management method comprising the steps of:

step 1): acquiring real-time information of vehicle speed, acceleration and accelerator pedal travel;

step 2): calculating the real-time power demand P of the vehicle according to the real-time information and the vehicle driving dynamics equation_d；

Step 3): acquiring real-time state information of the multi-stack hydrogen fuel cell system and the power cell, wherein the real-time state information comprises the accumulated running time of each fuel cell stack and the charge state of the power cell;

step 4): according to said power demand P_dAnd 3) determining the starting number N of the fuel cell stacks in the multi-stack hydrogen fuel cell system at each moment through the real-time state information obtained in the step 3) through a hysteresis control strategy_fRealizing the power flow distribution of the power battery and the multi-stack hydrogen fuel cell system;

step 5): the starting number N obtained according to the step 4)_fAnd determining the fuel cell stacks to be started according to the principle that the working time is uniformly distributed, and executing related actions through corresponding electric control programs.

The further technical scheme is as follows:

in the step 3), the highest charging state SOC of the power battery is set according to the actual application scene_upperLowest state of charge SOC_lowMaximum state of charge SOC_maxAnd minimum state of charge SOC_minSatisfies SOC_min＜SOC_low＜SOC_upper＜SOC_max(ii) a Selecting a total number n of fuel cell stacks in the multi-stack hydrogen fuel cell system and a fixed output power P of each fuel cell stack_fc；

In the step 4), the hysteresis control strategy is as follows:

the starting number of the fuel cell at the moment of initially selecting k +1 is N_d(k+1)，N_d(k +1) satisfies: n is a radical of_d(k+1)P_fc≤P_d(k+1)≤(N_d(k+1)+1)P_fcCondition (1) P_d(k +1) represents the power demand of the vehicle at time k +1, and the following logical decision is made:

if N is present_d(k +1) is more than or equal to N, then the starting number N of the fuel cell stack at the moment of k +1_f(k+1)＝n；

If N is present_d(k +1) < n, and the state of charge SOC (k) of the power battery at the moment k is less than or equal to SOC_lowThen N is_f(k+1)＝N_d(k+1)+1；

If N is present_d(k +1) < n, and the state of charge SOC (k) of the power battery at the moment k is more than or equal to SOC_upperThen N is_f(k+1)＝N_d(k+1)；

If N is present_d(k +1) < n, and SOC_low≤SOC(k)≤SOC_upperAnd the number N of the fuel cell stack started at the time k_f(k)≤N_d(k +1), then N_f(k+1)＝N_d(k+1)；

If N is present_d(k +1) < n, and SOC_low≤SOC(k)≤SOC_upperAnd the number N of the fuel cell stack started at the time k_f(k)＞N_d(k +1), then N_f(k+1)＝N_d(k+1)+1。

The invention has the following beneficial effects:

the method of the invention has simple and effective power distribution strategy and is convenient for real-time detection and application. By determining the proper starting number of the fuel cell stack, the power is reasonably distributed, the durability of the cell is obviously improved, and the reliability of a fuel cell system is obviously improved. The invention controls the on-off of the fuel cell stacks, so that the effective running time and the aging degree of each fuel cell stack are close, and the maintenance is convenient.

Drawings

FIG. 1 is a flow chart of a method of an embodiment of the present invention.

Fig. 2 is a schematic flow chart of a hysteresis control strategy according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a switch control principle according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of an electric vehicle power supply system according to an embodiment of the present invention.

In the figure: 1. a fuel cell stack; 2. a hydrogen supply module; 3. an air supply module; 4. a multi-stack hydrogen fuel cell subsystem; 5. a power battery pack; 6. a DC/AC converter; 7. an electric motor.

Detailed Description

The following describes embodiments of the present invention with reference to the drawings.

The power management method of the multi-stack hydrogen fuel cell system is applied to a power supply system of an electric automobile: the system comprises a multi-pile hydrogen fuel cell system and a power battery which are matched to supply power for the electric automobile. The multi-stack fuel cell system is formed by connecting a plurality of fuel cell stacks, and the connection mode of the plurality of fuel cell stacks comprises series connection, parallel connection or series-parallel connection; the power battery can adopt a lithium titanate battery; the method for estimating the state of charge (SOC) of the power battery can adopt an open-circuit voltage method. As shown in fig. 4, in the multi-stack hydrogen fuel cell system of the present application, n fuel cell stacks 1 (fuel cell stack 1, fuel cell stack 2 … …, fuel cell stack n in the figure) are connected to form a multi-stack hydrogen fuel cell subsystem 4, which is connected in parallel with a power battery pack 5, then connected in series with a DC/AC converter 6, and then connected in series with a motor 7 to supply power to an electric vehicle. Each fuel cell stack is connected with a hydrogen supply module 2 and an air supply module 3 to form a hydrogen fuel cell.

The power management method of the multi-stack hydrogen fuel cell system of the present application can refer to fig. 1, and includes the following procedures:

in the first step, a speed sensor, an acceleration sensor and an accelerator pedal position sensor are respectively used for obtaining real-time information of vehicle speed, acceleration and accelerator pedal travel.

Secondly, calculating the real-time power demand P of the vehicle according to the real-time information obtained in the first step and the vehicle running dynamics equation_d。

And step three, acquiring real-time state information of a multi-pile hydrogen fuel cell system and a power cell: the accumulated running time of each fuel cell stack can be recorded by a timer, and the state of charge (SOC) of the power cell can be monitored in real time by an open-circuit voltage method;

according to the practical application scene, determining the total number n of the fuel cell stacks and the fixed output power P of each fuel cell stack_fcSetting the maximum state of charge SOC of the power battery_upperLowest state of charge SOC_lowMaximum state of charge SOC_maxAnd minimum state of charge SOC_minAnd satisfy SOC_min＜SOC_low＜SOC_upper＜SOC_max。

Fourth step, at power demand P_dAnd on the basis of monitoring the obtained state of charge information of the power battery in real time, determining the starting number of the fuel battery stacks at each moment, namely the optimal starting number, by a hysteresis control strategy, and realizing the power flow distribution of the power battery and the multi-stack hydrogen fuel battery system. As shown in fig. 2, the specific process is as follows:

firstly, initially selecting the starting number N of the fuel cell stack at the moment of k +1_d(k +1), wherein "on" means that the fuel cell stack is in operationAnd the line state, the on-off operation of the fuel cell stack is executed by a corresponding electronic control system. In the initial selection, make N_d(k +1) satisfies N_d(k+1)P_fc≤P_d(k+1)≤(N_d(k+1)+1)P_fcIn which P is_d(k +1) represents the power demand of the vehicle at time k + 1. The starting number of the initially selected fuel cells at the moment k +1 meets the power requirement of the vehicle at the moment, and the power requirement of the vehicle at the moment is not less than that after one more fuel cell is started than the initially selected starting number.

Then, the following judgment is made:

if N is present_d(K +1) is more than or equal to N, then the starting number N of the fuel cell stack at the moment of K +1_f(k+1)＝n；

If N is present_d(K +1) < n, and when the state of charge SOC (K) of the power battery is less than or equal to SOC (K)_low(the power battery is in an extremely low state of charge, has no power supply capacity and has the capacity of recovering power), the actual startup number N of the fuel cell stack at the moment K +1_f(k +1) should be equal to the number of initial selections N_d(k +1) plus 1, i.e. N_f(k+1)＝N_d(k +1) + 1; at the moment, a part of the power provided by the fuel cell is used for meeting the power requirement P of the electric automobile at the moment k +1_d(k +1), the other part is used for charging the power battery, wherein the fuel cell system provides power P_f(k+1)＝(N_d(k+1)+1)P_fcThe power battery receiving power is P_b(k+1)＝P_f(k+1)-P_d(k+1)；

If N is present_d(K +1) < n, and the state of charge SOC (K) of the power battery is more than or equal to SOC at the moment K_upper(the power battery is in an extremely high charge state, has the capability of providing power and has no capability of recovering power), the actual startup number N of the fuel cell stack at the moment K +1_f(k +1) should be equal to the number of initial selections N_d(k +1), i.e. N_f(k+1)＝N_d(k +1) when the power battery is discharged, and the power battery and the fuel cell system together provide the power demand P of the electric vehicle at the k +1 moment_d(k +1) wherein the fuel cell system supplies power of P_f(k+1)＝N_d(k+1)P_fcThe power battery provides power P_b(k+1)＝P_d(k+1)-P_f(k+1)；

If N is present_d(k +1) < n, when SOC_low＜SOC(k)＜SOC_upper(the power battery has reasonable charge state, and has the capability of providing power and the capability of recovering power), and the actual startup number N of the fuel cell stack at the moment K_f(k) The number N of the initial selection start-up of the fuel cell stack at the moment less than or equal to K +1_d(k +1), i.e. N_f(k)≤N_d(k +1) at this time in order to satisfy the power demand P of the electric vehicle_d(K +1) and minimizing the startup times of the fuel cell stack, wherein the actual startup number N of the fuel cell stack at the moment of K +1_f(k +1) should be equal to the number of initial boot N_d(k +1), i.e. N_f(k+1)＝N_d(k +1), at the moment, the power battery discharges, and provides the power P required by the electric automobile together with the fuel cell system_d(k +1) wherein the power to be supplied by the fuel cell system is P_f(k+1)＝N_d(k+1)P_fcThe power needed to be provided by the power battery is P_b(k+1)＝P_d(k+1)-P_f(k+1)；

If N is present_d(k +1) < n, when SOC_low≤SOC(k)≤SOC_upper(the power battery has reasonable charge state, both the power supply capacity and the power recovery capacity), and the starting number N of the fuel cell stack at the moment K_f(k) Initial selection starting-up number N of fuel cell stacks at moment greater than K +1_d(k +1), i.e. N_f(k)＞N_d(k +1) at this time in order to satisfy the power demand P of the electric vehicle_d(K +1) and minimizing the shutdown times of the fuel cell stack, the actual startup number N of the fuel cell stack at the moment of K +1_f(k +1) should be equal to the number of initial boot N_d(k +1) +1, i.e. N_f(k+1)＝N_d(k +1) +1, at which time the power cell will be charged and the fuel cell system provides power P_f(k+1)＝(N_d(k+1)+1)P_fcThe power battery receiving power is P_b(k+1)＝P_f(k+1)-P_d(k+1)。

The above flow represents the hysteresis control strategy employed by the present application to achieve the goal of extending stack life: when power batterySOC at SOC_lowAnd SOC_upperWhen the power battery has the power supply capacity and the power recovery capacity, the actual starting number N of the fuel cell stack at the moment K +1 is enabled_fNumber of fuel cell stack start-up N at time (K +1) and K_f(k) As equal as possible, thereby reducing the number of times the fuel cell stack is turned on and off.

Fifthly, obtaining the number N of the fuel cell stacks which should be started at the moment K +1 according to the hysteresis control strategy_fAfter (k +1), it is also necessary to determine which N of the N fuel cell stacks should be turned on_fAnd (K +1), namely selecting the fuel cell stacks needing to be started up (or shut down) at the K +1 moment according to the accumulated running time of each fuel cell stack and the principle of uniform distribution of the running time, and executing related actions through corresponding electric control systems. As shown in fig. 3, the specific process is as follows:

the number N of fuel cell stacks needing to be started up at the moment of K +1_fNumber N of fuel cell stacks actually started at (k +1) and k times_f(k) Similarly, only N which is started at k moment is kept_f(k) The fuel cell stacks are still started; the number N of fuel cell stacks needing to be started up at the moment of K +1_f(k +1) number N of fuel cell stacks actually started up at the moment that k is less than k_f(k) Then only from N_f(k) Shutting down N in a fuel cell stack that has been started up_f(k)-N_f(k +1) fuel cell stacks having a long accumulated operating time; the number N of fuel cell stacks needing to be started up at the moment of K +1_fThe number N of fuel cell stacks which are actually started up when (k +1) is larger than k_f(k) Then only from N-N_f(k) Turning on N in a shutdown fuel cell stack_f(k+1)-N_f(k) A fuel cell stack with a shorter integrated operating time is sufficient.

The judgment of the running time, the control of opening and closing and the execution are conventional methods, and are not described in detail.

According to the power management method of the multi-stack hydrogen fuel cell system, through hysteresis control, the effective working time of each fuel cell stack is shortened, the starting and stopping times of each fuel cell stack are reduced, and the service life is prolonged; the aging degree of each fuel cell stack is ensured to be similar through the principle of uniform distribution of the operation time, and the maintenance is convenient.