CN114639850A

CN114639850A - Concentration optimization control method for liquid fuel cell

Info

Publication number: CN114639850A
Application number: CN202011487948.6A
Authority: CN
Inventors: 孙海; 甘海波; 孙公权
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2022-06-17
Anticipated expiration: 2040-12-16
Also published as: CN114639850B

Abstract

The invention relates to a concentration optimization control method for a liquid fuel cell, which optimizes the operation concentration of the liquid fuel cell in real time by dividing a voltage-temperature interval or a current-temperature interval on a two-dimensional plane and based on a power-concentration step response relation, so that the liquid fuel cell always operates near the optimal concentration. The method comprises the following steps: setting and initializing fuel cell system parameters; starting a temperature rise process of the fuel cell system; the fuel cell regulates and controls the discharge process; a fuel cell system steady state operation concentration control process; a concentration self-learning adjustment optimization process; concentration optimization exploration process. Compared with the prior art, the invention breaks through the constant concentration operation mode; the scheme of the invention can gradually optimize the system operation concentration according to the state of the galvanic pile and the state of the load working condition in the system, and improve the power/efficiency of the galvanic pile; meanwhile, the scheme is suitable for various liquid feeding fuel cells, new and old systems with different attenuation degrees and different load working conditions; in addition, the algorithm has a self-learning characteristic and can automatically update the controlled concentration.

Description

Concentration optimization control method for liquid fuel cell

Technical Field

The invention relates to a fuel cell, in particular to a concentration optimization control method of a liquid fuel cell.

Background

The fuel cell has the advantages of high specific energy, sustainable power generation, low noise, small pollution and the like, and can play an important role in aspects of power sources, electronic power sources and the like. The liquid fuel cell has the advantages of easy fuel storage, convenient fuel carrying, simple fuel filling and the like, and has wide application prospect in the aspect of portable power supply.

To balance the performance and stability of liquid fuel cells, high concentration fuel is typically diluted and supplied to the stack. Therefore, how to control the fuel concentration in the stack becomes a key issue. The traditional method is based on an empirical or theoretical model, and a constant concentration value C is artificially set_setAnd the system is operated at constant concentration through feedback control. The concentration value was 0.1mol L based on the membrane electrode characteristics^-1～3mol L^-1In between. Other methods associate concentration with stack operating parameters, such as voltage, voltage vibration amplitude, temperature, power, etc., and then implement indirect control of concentration by setting a range of stack operating parameters associated with concentration, thereby causing concentration to fluctuate within a certain range.

However, due to fuel permeation, etc., the system is usually corresponding to an optimal concentration C under a certain condition_best. If the concentration is higher, the permeation is increased and the performance of the galvanic pile is reduced. If the concentration is lower, the anode polarization is intensified, and the performance of the galvanic pile is reduced. Generally, the optimum concentration for system operation tends to be slightly different at different temperatures, discharge voltages (or discharge currents). Optimum concentration (C)_best) Is influenced by multiple factors such as voltage, current, temperature, membrane electrode water content, membrane permeability coefficient, cathode/anode inlet/outlet pressure, etc. Therefore, how to realize real-time online optimization of concentration remains one of the key problems of the liquid fuel cell.

Disclosure of Invention

Aiming at the problem of concentration optimization control of the liquid fuel cell in the operation process, the invention provides a method for realizing concentration optimization control in the operation process of the fuel cell by dividing a voltage-temperature interval (or a current-temperature interval) on a two-dimensional plane and constructing an optimal concentration matrix, and gradually updating the optimal concentration matrix based on the response characteristic of the stack power to the concentration step change.

The technical scheme adopted by the invention for solving the technical problem is as follows:

a concentration optimization control method for a liquid fuel cell is characterized in that a voltage-temperature interval or a current-temperature interval is divided on a two-dimensional plane, and the operation concentration of the liquid fuel cell is optimized in real time based on a power-concentration step response relation; the method comprises the following steps:

setting system parameters of the fuel cell and constructing an optimal concentration matrix; adjusting the increase or decrease of the voltage or the current of the electric pile according to the residual electric quantity of the battery pack so as to regulate and control the discharge process of the fuel cell and enable the electric pile to operate in the range of the stable threshold values of the voltage/the current and the temperature;

further dividing stable operation intervals of voltage/current and temperature, and judging whether the system operates stably in the intervals; if the fuel cell stack is not in a stable state, the fuel cell stack outputs the maximum power within a specified temperature and voltage/current interval by optimizing the fuel concentration value in the optimal concentration matrix during the operation of the stack; and controlling the speed of the first liquid pump according to the optimal concentration value corresponding to the maximum power, thereby realizing the optimal control of the fuel cell.

The method is implemented based on a fuel cell system comprising: the fuel pump comprises a fuel tank, a mixing tank, a fuel concentration sensor, a first liquid pump, a second liquid pump, an air pump, a controller, a temperature sensor, a galvanic pile, a battery pack and a circuit adjusting module;

the fuel concentration sensor is immersed in the solution of the mixing tank or a circulating pipeline of the solution of the mixing tank and is used for monitoring the concentration of the solution in the mixing tank and representing the fuel concentration in the galvanic pile; the temperature sensor is attached to the surface of the galvanic pile or embedded in the galvanic pile and used for monitoring the temperature of the galvanic pile;

the first liquid pump is respectively connected with the fuel tank and the mixing tank and is used for injecting the fuel in the fuel tank into the mixing tank; the second liquid pump is respectively connected with the mixing tank and the galvanic pile and is used for supplying the solution in the mixing tank to the galvanic pile; the air pump is connected with the electric pile and used for supplying air to the electric pile;

the circuit adjusting module is respectively connected with the battery pack, the galvanic pile and the user electric equipment and is used for monitoring the voltage of the galvanic pile, the current of the galvanic pile, the residual electric quantity SOC of the battery pack, the charging current and the discharging current of the battery pack and the voltage and the current of the user electric equipment, controlling the discharging voltage or the current of the galvanic pile and adjusting the output voltage or the current of the fuel cell system according to the power demand of the user;

the controller is respectively connected with the first liquid pump, the second liquid pump, the air pump, the fuel concentration sensor, the temperature sensor and the circuit adjusting module; the controller obtains a galvanic pile voltage value, a galvanic pile current value, a battery pack charging or discharging current value and a battery pack residual electric quantity value SOC through the circuit adjusting module.

The method comprises the following steps:

STEP1, setting and initializing fuel cell system parameters;

step2. fuel cell system start-up temperature rise process:

for voltage-temperature feedback control/current-temperature feedback control, if the stack voltage U_stackCurrent of galvanic pile I_stackAnd temperature T of the stack_stackWhen the voltage subinterval and the temperature subinterval which correspond to the steady-state operation of the galvanic pile are both in, entering a steady-state operation control STEP STEP 4;

otherwise, the speed of the first liquid pump is controlled based on the fuel concentration value feedback, and the discharging process is controlled to STEP 3; after the program returns from the STEP3, the STEP2 is repeatedly executed until the voltage/current of the galvanic pile and the temperature of the galvanic pile enter a defined voltage/current and temperature interval corresponding to the steady-state operation of the galvanic pile;

STEP3. Fuel cell regulated discharge Process:

if the SOC of the residual electric quantity of the battery pack is lower than the set lower threshold value SOC_DOWNAdjusting the voltage or current of the electric pile to try to increase the output power of the electric pile; if the SOC of the residual electric quantity of the battery pack is higher than the set upper threshold SOC_UPAnd the electric power P of the user equipment_outLower than the output power P of the electric pile_stackAdjusting the voltage or current of the electric pile to reduce the output power of the electric pile; for maintaining the remaining charge SOC of the battery pack between the set battery pack charge threshold ranges;

STEP4. Fuel cell System Steady State operation concentration control Process:

monitoring the temperature T of the stack_nowFuel concentration value C, stack discharge voltage U_stackDischarge current I of the cell stack_stack；

Searching a voltage subinterval/current subinterval or a temperature subinterval corresponding to the current electric pile running state: if the current running state of the galvanic pile meets U_s1-1≤U_stack<U_s1/I_s1-1≤I_stack<I_s1And T_s2-1≤T_stack<T_s2If the current cell stack operation state is in the s1 voltage/current subinterval and the s2 temperature subinterval;

the corresponding concentration value C in the optimum concentration matrix is then read_opt(s1, s2) and based on the real-time fuel concentration values C and C_opt(s1, s2) feedback-controlling the first liquid pump (2) rate for a fuel concentration value C close to C_opt(s1, s2) corresponding concentration values;

judging whether the electric pile system enters a stable state, if so, jumping to STEP5, otherwise, repeatedly executing STEP 4;

STEP5. concentration self-learning adjustment optimization process:

the process is realized by the current power P of the galvanic pile_coptThe value P of corresponding element in the high-concentration electric pile power matrix_c,high(s1, s2) and the value P of the corresponding element in the low concentration stack power matrix_c,low(s1, s2) comparing, gradually adjusting the element value C corresponding to the present voltage/current subinterval and temperature subinterval in the optimal density matrix_opt(s1, s2) for causing the stack to operate at C when the stack is operating in the present voltage/current subinterval and temperature subinterval_opt(s1, s2) output Power P at Density running_coptSatisfies the following conditions: p_copt>P_c,high(s1, s2) and P_copt>P_c,low(s1,s2)；

STEP6. concentration optimization exploration procedure:

by testing the operation of the fuel cell stack in the present voltage/current subinterval and temperature subintervalHigher input concentration C_opt(s1, s2) + dC or lower input concentration C_opt(s1, s2) -dC_c,high(s1, s2) and P_c,low(s1, s2) for optimizing the density matrix C_optThe adjustment of the corresponding parameters provides reference basis.

The set parameters include:

setting the upper limit value U of the discharge voltage of the galvanic pile based on the voltage-temperature feedback control_maxLower limit value U_minAnd is in U_max、U_minM voltage subintervals U are divided between₀～U₁，U₁～U₂,，U₂～U₃，…，U_m-1～U_mWherein U is_min＝U₀<U₁<U₂<…<U_m-2<U_m-1<U_m＝U_max；

Setting the upper limit value I of the discharge current of the galvanic pile based on the current-temperature feedback control_maxLower limit value I_minAnd is in I_max、I_minM current subintervals I are divided between₀～I₁，I₁～I₂，I₂～I₃，…，I_m-1～I_mIn which I_min＝I₀<I₁<I₂<…<I_m-2<I_m-1<I_m＝I_max；

Setting the upper limit value T of the operating temperature of the electric pile_maxLower limit value T_minAnd at T_max、T_minN temperature intervals T are divided among₀～T₁，T₁～T₂，T₂～T₃，…，T_n-1～T_nWherein T is_min＝T₀<T₁<T₂<…<T_n-2<T_n-1<T_n＝T_max；

Empirically setting the initial concentration value C of the electric pile₀；

Creating an optimal density matrix C of m rows and n columns_optThe matrix C_optElement of the s1 th row and s2 th columnValue C_opt(s₁,s₂) Represents when the electric pile runs in the s1 th voltage interval (U)_s1-1～U_s1) Or the s1 th current interval (I)_s1-1～I_s1) And the s2 th temperature interval (T)_s2-1～T_s2) Then, the optimal concentration value calculated by the method is adopted;

setting an upper limit SOC of a battery pack electric quantity threshold_UPLower limit SOC of electric quantity threshold of battery pack_DOWNUpper limit value I of charging current of battery pack_BinUP；

Setting the step length dC of single adjustment of concentration, and the step length dU of voltage adjustment_stackStep length dI of current regulation_stack；

Setting a lag time delta t1 of the response of the galvanic pile to the concentration change, a lag time delta t2 of the response of the galvanic pile to the voltage (or current) change and a time span delta t3 of the stable operation judgment of the galvanic pile;

temperature fluctuation upper limit delta T corresponding to stable operation of electric pile_xUpper limit of concentration fluctuation DeltaC_xUpper limit of voltage fluctuation DeltaU_xAnd the upper limit of current fluctuation DeltaI_x；

Constructing a high-concentration power matrix P of m rows and n columns_c,highLow concentration power matrix P_c,low；P_c,high(s1, s2) for the fuel concentration C when the stack voltage is in the s1 voltage subinterval, the stack temperature is in the s2 temperature subinterval_opt(s1, s2) + dC, discharge power of the stack; p_c,low(s1, s2) for the fuel concentration C when the stack voltage is in the s1 voltage subinterval, the stack temperature is in the s2 temperature subinterval_opt(s1, s2) -dC, the discharge power of the stack.

The STEP3 specifically includes:

for voltage-temperature-based feedback/current-temperature-based feedback:

1) if the SOC of the residual electric quantity of the battery pack is less than the lower limit SOC of the threshold value_DOWNWhen it is, let P_old＝P_stack(ii) a The controller reduces the discharging voltage of the galvanic pile by dU through the circuit adjusting module_stack(reduction of pile discharge Current dI_stack) And wait for a duration of Δ t 2; the current of the pile is then tested and countedCalculating new output power P of the stack after voltage change_new(ii) a If P_new>P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≤P_oldThe controller increases the discharge voltage of the electric pile by 2 × dU through the circuit regulating module_stack(increase in pile discharge current by 2 × dI_stack) And wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new>P_oldIf the current control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≤P_oldThen the controller reduces the discharge voltage of the electric pile by dU through the circuit adjusting module_stack(reduction of the discharge Current dI of the cell_stack) Maintaining the original discharge voltage (original discharge current) of the galvanic pile, then leaving the current regulation and control discharge process, and returning to the previous step;

2) if the residual electric quantity SOC of the battery pack is larger than the SOC_UPAnd the power of the galvanic pile is higher than the power (P) of the electricity used by the user_stack>P_out) When it is, let P_old＝P_stack(ii) a Then, the controller increases the discharge voltage of the electric pile by dU through the circuit adjusting module_stack(increase of pile discharge Current dI_stack) And wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new<P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≥P_oldThe controller reduces the discharge voltage of the electric pile by 2 × dU through the circuit regulating module_stackReduction of the discharge current of the galvanic pile by 2 dI_stackAnd wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new<P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≥P_oldThen the controller increases the discharge voltage of the electric pile by dU through the circuit adjusting module_stackIncrease of discharge current of galvanic pile dI_stackI.e. maintaining the stack's original discharge voltage (original discharge)Current) and then leave the current regulation and control electron discharge process and return to the previous step.

The STEP4 is to determine whether the system enters a stable state, and specifically includes:

condition 1, the temperature change amplitude of the galvanic pile is lower than delta T in a continuous delta T3 time period_x；

Condition 2: the fuel concentration variation amplitude is lower than Δ Cx for the continuous Δ t3 time period;

condition 3: in the continuous time period of delta t3, the voltage change amplitude of the galvanic pile is lower than delta Ux;

condition 4: in a continuous time period of delta t3, the current change amplitude of the galvanic pile is lower than delta Ix;

when the above conditions are not completely met, the system is determined not to enter a stable state; when all the above determination conditions are established, the system is considered to have entered a steady state.

The STEP5 concentration self-learning adjustment optimization process specifically comprises the following STEPs:

1) if P_c,high(s1, s2) is 0 or P_c,low(s1, s2) is 0, then go into the concentration optimization exploration process to obtain P_c,high(s1,s2)、P_c,low(s1, s2), namely entering STEP6, then returning to STEP4, and waiting for the cell stack to enter a stable state again;

2) if P_c,high(s1, s2) and P_c,low(s1, s2) are not 0, then according to the current power value P of the electric pile_coptAnd P_c,high(s1, s2) and P_c,low(s1, s2) adjusting the corresponding element C in the optimal density matrix respectively_opt(s1, s 2).

Respectively adjusting corresponding elements C in the optimal concentration matrix_optThe values of (s1, s2) are:

i. if P_copt≥P_c,high(s1, s2) and P_copt≥P_c,low(s1, s2) indicating that the current system is working near the optimal concentration, maintaining and continuing to operate the galvanic pile at the corresponding position element C in the current optimal concentration matrix_opt(s1, s2) concentration operation, i.e. back to STEP 4;

if P is_c,low(s1,s2)<P_copt<P_c,high(s1, s2), and calculating the element value (C) of the corresponding position of the current optimal density matrix_opt(s1, s2)) increased dC; at the same time, P is synchronously updated_c,low、P_c,highThe values of the corresponding elements in the matrix; the current stack power P_coptImpartation of P_c,low(s1,s2)；

And calibrating the output power of the galvanic pile at higher concentration in the current voltage or current subinterval and temperature subinterval: will P_c,highCorresponding element P in the matrix_c,high(s1, s2) is set to zero, and then STEP6 is entered, namely, the concentration optimization exploration process; then returning to STEP4, controlling the speed of the first liquid pump according to the concentration values of elements corresponding to the current voltage (or current) subinterval and temperature subinterval in the new optimal concentration matrix, and waiting for the galvanic pile to enter a stable state again;

if P is iii_c,low(s1,s2)>P_copt>P_c,high(s1, s2), and converting the element value (C) of the corresponding position of the current optimal density matrix into the element value (C)_opt(s1, s2)) decreasing dC; at the same time, updating P synchronously_c,low、P_c,highThe values of the corresponding elements in the matrix; the current stack power P_coptImpartation of P_c,high(s1,s2)；

Calibrating the output power of the electric pile at lower concentration in the current voltage (or current) subinterval and temperature subinterval: will P_c,lowCorresponding element P in the matrix_c,low(s1, s2) is set to zero, and then STEP6 is entered, namely, the concentration optimization exploration process; and returning to STEP4, controlling the speed of the first liquid pump according to the concentration values of the elements corresponding to the current voltage (or current) subinterval and temperature subinterval in the new optimal concentration matrix, and waiting for the electric pile to enter a stable state again.

The STEP6 concentration optimization exploration specifically comprises the following STEPs:

i. firstly, the air pump and the second liquid pump are kept running, and the voltage or the current of the galvanic pile is controlled to be unchanged by the circuit adjusting module;

if P is_c,low(s1, s2) is equal to 0, the first liquid pump is adjusted by the controller so that the fuel concentration for the operation of the cell system is close to C_opt(s1, s2) -dC and wait a period of time Δ t 1; periodic monitoringTemperature T of the stack_stackFuel concentration C, stack discharge voltage U_tackDischarge current I of the cell stack_stackAnd calculating the stack power P_nowUntil the electric pile system enters a stable state;

writing the current stack power value into P_c,lowIn a matrix, i.e. P_c,low(s1,s2)＝P_stack. The first liquid pump is then regulated by the controller to cause the cell system to operate at a fuel concentration close to C_opt(s1, s2) and back to STEP4, re-wait for the stack to enter steady state;

if P is iii_c,low(s1,s2)>0 and P_c,high(s1, s2) is equal to 0, the first liquid pump is adjusted by the controller so that the fuel concentration for the operation of the cell system is close to C_opt(s1, s2) + dC and wait for a period of time Δ t 1; regular monitoring of the temperature T of the cell stack_stackFuel concentration C, stack discharge voltage U_tackDischarge current I of the pile_stackAnd calculating the stack power P_nowUntil the electric pile system enters a stable state;

writing the current pile power value into P_c,highIn a matrix, i.e. P_c,high(s1,s2)＝P_stack(ii) a The first liquid pump is then regulated by the controller to cause the cell system to operate at a fuel concentration close to C_opt(s1, s2) and back to STEP4, again waiting for the stack to enter steady state.

The invention has the following beneficial effects and advantages:

1. the invention breaks through the constant concentration operation mode and adopts the gradual optimization operation mode.

2. The scheme is suitable for various liquid fuel cells.

3. The scheme is suitable for systems with different attenuation degrees and different load working conditions.

4. The invention can gradually optimize the operation concentration along with the change of the state of the galvanic pile and the load working condition.

5. The algorithm has an automatic learning characteristic and can automatically update the controlled concentration.

6. The algorithm can control and improve the operation power and efficiency of the fuel cell system.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

FIG. 2 is a flow chart of a concentration self-learning voltage-temperature feedback optimization control main algorithm of the present invention;

FIG. 3 is a flow chart of a concentration self-learning current-temperature feedback optimization control main algorithm of the present invention;

FIG. 4 is a flow chart of a sub-algorithm for regulating the discharge process with voltage-temperature feedback according to the present invention;

FIG. 5 is a flow chart of a current-temperature feedback regulated discharge process sub-algorithm of the present invention;

FIG. 6 is a flow chart of the concentration self-learning adjustment optimization process algorithm of the present invention;

FIG. 7 is a graph of battery system operating power versus time, in accordance with an embodiment of the present invention;

FIG. 8 is a graph of battery system operating concentration versus time, in accordance with an embodiment of the present invention;

wherein, 1: fuel tank, 2: first liquid pump, 3: mixing tank, 4: fuel concentration sensor, 5: controller, 6: air pump, 7: second liquid pump, 8: storage battery, 9: circuit adjusting module, 10: temperature sensor, 11: and (4) electric pile.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as modified in the spirit and scope of the present invention as set forth in the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

As shown in fig. 1, the liquid fuel cell system includes a fuel tank 1, a mixing tank 3, a fuel concentration sensor 4, a first liquid pump 2, a second liquid pump 7, an air pump 6, a controller 5, a temperature sensor 10, a cell stack 11, a cell stack 8, and a circuit adjusting module 9. The fuel concentration sensor 4 is immersed in the mixing tank solution or the circulation pipeline of the mixing tank solution and is used for monitoring the concentration of the solution in the mixing tank and representing the fuel concentration in the electric pile. The temperature sensor 10 is attached to the surface of the galvanic pile or embedded in the galvanic pile and used for monitoring the temperature of the galvanic pile. The circuit adjusting module 9 has functions of monitoring and controlling discharge voltage and current of the electric pile 11, monitoring residual capacity (SOC) of the battery pack 8, charging current and discharge current of the battery pack, and adjusting output voltage or current of the battery system and monitoring output current and voltage of the battery system according to power demand of a user. The circuit adjusting module 9 usually includes a plurality of chips and circuits to realize its functions, such as control of stack discharge voltage or current and control of battery system output voltage or current through circuits such as boost, buck, etc., and such as monitoring functions of stack voltage, stack current, battery pack charging current and battery pack discharge current through sampling resistor and analog quantity detection chip, such as monitoring input and output electric quantity of the battery pack 8 through electric quantity test circuit or current integration test circuit, and further calculating the residual electric quantity of the battery pack 8 by combining the battery pack capacity.

In terms of fluid pipelines, the first liquid pump 2 is respectively connected with the fuel tank 1 and the mixing tank 3 and is used for injecting fuel in the fuel tank 1 into the mixing tank 3; the second liquid pump 7 is respectively connected with the mixing tank 3 and the electric pile 11 and is used for supplying the solution in the mixing tank 3 to the electric pile 11; the air pump 6 is connected to the stack 11 for supplying air (oxidant) to the stack 11.

In the aspect of circuit connection, the circuit adjusting module 9 is respectively connected to the battery pack 8, the battery pack 11 and the user electric equipment, and is configured to monitor a voltage of the battery pack 11, a current of the battery pack, a remaining battery capacity (SOC) of the battery pack 8, a charging current and a discharging current of the battery pack 8, and a voltage (i.e., a battery system output voltage) and a current of the user electric equipment, control the discharging voltage or the current of the battery pack (8), and adjust the output voltage or the current of the fuel cell system according to a user power demand. The controller 5 is respectively connected with the first liquid pump 2, the second liquid pump 7, the air pump 6, the fuel concentration sensor 4, the temperature sensor 10 and the circuit adjusting module 9. The controller 5 obtains a cell stack voltage value, a cell stack current value, a battery pack charging (or discharging) current value and a battery pack residual charge value (SOC) through the circuit adjusting module 9. The controller 5 acquires a temperature value of the electric pile through a temperature sensor 10. The controller 5 acquires a fuel concentration value by a fuel concentration sensor 4. The controller 5 controls the discharge voltage or current of the galvanic pile through the circuit adjusting module 9 based on the patent algorithm; the controller 5 obtains the fuel concentration value to be set under the cell operation condition according to the algorithm of the patent. Then, the controller 5 controls the rotation speed or the opening time of the first liquid pump 2 according to the set value and the fuel concentration value fed back by the concentration sensor (4) to realize the control of the fuel input rate, so that the fuel concentration approaches the set concentration value.

The implementation process of the concentration optimization control scheme of the liquid fuel cell comprises the following steps: a. and configuring basic parameters of the algorithm.

Firstly, dividing a stack voltage or stack current subinterval during steady-state operation of a cell system according to factors such as the electrode characteristics of a fuel cell stack, the operating condition of the stack, the operating environment state of the stack and the like. The algorithm can be divided into two optimized control schemes of voltage-temperature feedback-based and current-temperature feedback-based. For the first scheme, namely based on voltage-temperature feedback control, the upper limit value U of the discharge voltage of the fuel cell stack is set empirically according to the characteristics of the fuel cell stack and the environmental working conditions_maxLower limit value U_minAnd is in U_max、U_minM voltage subintervals U are divided between₀～U₁，U₁～U₂,，U₂～U₃，…，U_m-1～U_mWherein U is_min＝U₀<U₁<U₂<…<U_m-2<U_m-1<U_m＝U_max. Generally, the lower limit of the voltage is in the range of 0.1V/node & lt U_minNot more than 0.6V/node, and the upper limit of voltage is not more than 0.3V/nodeU_maxIs not more than 0.9V/node, and the number m of the voltage intervals is not less than 3 and not more than 500. In the present embodiment, the upper voltage limit U_max0.5V/node is taken, and the lower limit of the voltage is U_minTaking 0.2V/node, 15 (m is 15) voltage intervals are evenly divided in the voltage range. That is, the voltage subintervals are: 0.2-0.22V, 0.22-0.24V, 0.24-0.26V, …, 0.46-0.48V, 0.48-0.5V. For the second scheme, namely based on current-temperature feedback control, the upper limit value I of the discharge current of the fuel cell stack needs to be set empirically according to the characteristics of the fuel cell stack and the environmental working conditions_maxLower limit value I_minAnd is in I_max、I_minM current subintervals I are divided between₀～I₁，I₁～I₂，I₂～I₃，…，I_m-1～I_mIn which I_min＝I₀<I₁<I₂<…<I_m-2<I_m-1<I_m＝I_max. Generally, the lower limit of the current is in the range of 0.01Acm^-2≤I_min≤2Acm^-2Within the upper current limit range of 0.05Acm^-2≤I_max≤5Acm^-2The number m of the current intervals is more than or equal to 3 and less than or equal to 500.

Secondly, the upper limit value T of the working temperature of the fuel cell stack is set empirically according to the characteristics and the working condition environment of the fuel cell stack_maxLower limit value T_minAnd at T_max、T_minIs divided into n temperature intervals T₀～T₁，T₁～T₂，T₂～T₃，…，T_n-1～T_nWherein T is_min＝T₀<T₁<T₂<…<T_n-2<T_n-1<T_n＝T_max. Generally, the upper limit range of the working temperature of the galvanic pile is more than or equal to 50 ℃ and less than or equal to T_maxThe lower limit of the working temperature of the galvanic pile is between 10 and T_minThe temperature is less than or equal to 65 ℃, and the number n of the electric pile working temperature intervals is less than or equal to 3 and less than or equal to 300. In the present embodiment, the upper limit T of the stack operating temperature_maxTaking the temperature of 85 ℃, the lower limit T of the working temperature of the galvanic pile_minTaking 55 ℃, evenly dividing 15 (n-15) temperature subgroups in the temperature rangeAn interval. Namely, the sub-intervals of the operating temperature of the electric pile are respectively as follows: 55-57 ℃, 57-59 ℃, 59-61 ℃, …, 81-83 ℃ and 83-85 ℃.

Thirdly, manually setting the initial concentration value C of the operation of the galvanic pile₀。C₀Represents a concentration that can be empirically controlled to maintain stable operation of the stack prior to optimization of the concentration using the algorithm of this patent. C₀The range is as follows: 0.01mol L^-1≤C₀≤10molL^-1. In the examples, C₀Set to 0.4mol L^-1。

At the same time, an optimal density matrix C of m rows and n columns corresponding to m voltage subintervals (or m current subintervals) and n temperature subintervals is created_optAnd records it into the memory chip of the controller 5. Optimal concentration matrix C_optRepresenting the concentration optimized in real time after the algorithm of the patent is adopted. Matrix C_optThe element value of the s1 th row and s2 th column, namely C_opt(s₁,s₂) Represents when the electric pile runs in the s1 th voltage interval (U)_s1-1～U_s1) Or the s1 th current interval (I)_s1-1～I_s1) And the s2 th temperature interval (T)_s2-1～T_s2) And then, the optimal concentration value calculated by the algorithm is adopted. The value of each element in the optimal concentration matrix can be initialized to C₀. In this embodiment, since the number of the voltage subintervals m and the temperature subintervals n are both 15, C is_optA matrix of 15 rows and 15 columns. Meanwhile, in this embodiment, C_optAll the elements in the solution are initially 0.4mol L^-1。

Then, empirically setting the upper limit SOC of the battery charge threshold_UPAnd the lower limit SOC of the electric quantity threshold of the battery pack_DOWN. Upper limit value of charging current of battery pack I_BinUP. In the algorithm of the present embodiment, SOC_UPAnd SOC_DOWNAre decision parameters for different discharge strategies. In general, SOC_UPThe range is 0 percent<SOC_set≤100％。SOC_DOWNThe range is 0 percent<SOC_DOWNLess than or equal to 100 percent. The upper limit of the charging current of the battery pack is determined by the type and the capacity of the battery in the battery pack, and the upper limit of the charging current can be realized by setting the upper limit of the charging multiplying powerIs set. The upper limit value of the charging rate is usually in the range of 0.1 to 20. In this embodiment, SOC_UPSet to 90%, SOC_DOWNThe setting was 70%. When the capacity of the battery pack is 5 ampere, the upper limit of the charging multiplying power is set to be 1, so that the upper limit I of the charging current of the battery pack_UPIs 5A.

Subsequently, the step size dC of a single adjustment of the concentration is empirically set; empirically setting the step size dU of the voltage adjustment_stackStep size dI of (based on voltage-temperature feedback control) or current regulation_stack(based on current-temperature feedback control). dC represents the amount of change in concentration that the controller regulates at each time during concentration optimization. dC in the range of 0mol L^-1<dC≤3mol L^-1. In this example, dC was 0.02mol L^-1。dU_stackIt is represented that the controller adjusts the amount of change in the stack voltage each time during the adjustment of the discharge when the control (voltage-temperature-based feedback control) is performed using the first scheme of this patent. dU_stackIn the range of 0V/node<dU_stackLess than or equal to 0.2V/node. dU in this example_stackThe value is 0.005V/node. dI_stackIt is represented that the controller adjusts the amount of change in the stack current each time during the adjustment of the discharge when the control (based on the current temperature feedback control) is performed by the second scheme of this patent. dI_stackIn the range of 0A cm^-2<dI≤0.5Acm^-2。

Then, the lag time Δ t1 of the cell stack response to the concentration change and the lag time Δ t2 of the cell stack response to the voltage (or current) change are empirically set. Because the time constants of various mass transfer and reaction processes in the electric pile are different, the response of the electric pile to a parameter change usually has a certain delay, and the time span corresponding to the delay is related to the structural parameters and the operation state of the electric pile. Therefore, after changing the concentration or adjusting the voltage (or current), it is necessary to wait for a certain period of time before performing the test. Generally, Δ t1 and Δ t2 are artificially set based on the system response characteristics. The range of the delta t1 is that the delta t1 is less than or equal to 5s and less than or equal to 10min, and the range of the t2 is as follows: 0s < Δ t2<2 min. In this embodiment, Δ t1 is set to 5min, and Δ t2 is set to 30 s.

Then, the time span Δ t3 for the stable operation determination of the stack, is empirically setUpper limit of temperature fluctuation Δ T corresponding to stable operation_xUpper limit of concentration fluctuation Δ C_xUpper limit of voltage fluctuation DeltaU_xAnd the upper limit of current fluctuation DeltaI_x. In the present patent solution, Δ t3 is an artificially set minimum stabilization period length. That is, the difference between the maximum value of the temperature of the electric pile and the minimum value of the temperature of the electric pile is less than delta T only when the electric pile is in continuous delta T3 time periods_xThe difference between the maximum fuel concentration value and the minimum fuel concentration value is less than Delta C_xThe difference between the maximum value of the electric pile voltage and the minimum value of the electric pile voltage is less than delta U_xThe difference between the maximum value of the electric pile current and the minimum value of the electric pile current is less than delta I_xWhen the four conditions are simultaneously met, the program judges that the galvanic pile operates in a stable state, and can execute a concentration optimization exploration step. Typically, the range of Δ T3 is 10s ≦ Δ T3 ≦ 30min, Δ T_xThe range is as follows: delta T is more than or equal to 0_x≤5℃，ΔC_xΔ C of 0. ltoreq_x≤0.1mol L^-1，ΔU_xIn the range of 0 to less than or equal to delta U_xLess than or equal to 0.05V/node, delta I_xWithin the range of 0 to DELTA I_x≤0.03A cm^-2. In this embodiment, Δ T3 is 5min, Δ T_xAt 1 deg.C or less, delta C_xTaking 0.02mol L^-1，ΔU_xTake 0.01V/node, Δ I_xTaking 0.01A/cm^-2。

Finally, a concentration matrix C is constructed and optimized_optMatrices P with the same number of rows and columns (m rows and n columns)_c,high(high concentration power matrix), P_c,low(low density power matrix). P_c,highThe elements in the middle s1 th row and s2 th column (s1 is not less than 1 and not more than m, s2 is not less than 1 and not more than n, s1 and s2 are integers), namely P_c,high(s1, s2) for the voltage of the stack at the s1 th voltage subinterval (U)_s1-1≤U<U_s1) The temperature of the electric pile is in the s2 th temperature subinterval (T)_s2-1≤T<T_s2) And the fuel concentration is C_opt(s1, s2) + dC, the discharge power of the stack. P_c,lowThe elements in the middle s1 th row and s2 th column (s1 is not less than 1 and not more than m, s2 is not less than 1 and not more than n, s1 and s2 are integers), namely P_c,low(s1, s2) for the voltage of the stack at the s1 th voltage subinterval (U)_s1-1≤U<U_s1) The temperature of the electric pile is in the s2 th temperature subinterval (T)_s2-1≤T<T_s2) And burnMaterial concentration of C_opt(s1, s2) -dC, the discharge power of the cell stack. Each time the battery system is started, P_c,high,P_c,lowEach element of (1) is initially set to 0. In the steady-state operation stage of the battery, P is updated according to the algorithm of the patent_c,high，P_c,lowCorresponding to the voltage sub-interval and the temperature sub-interval in which the galvanic pile operates in real time.

b. Concentration on-line optimization control

Fig. 2 and 3 are algorithm flow charts corresponding to concentration optimization control schemes based on voltage-temperature feedback and current-temperature feedback. As shown in fig. 2 and fig. 3, the operation and concentration optimization control of the liquid fuel cell system includes the following steps:

STEP1. initialization of fuel cell system start-up parameters. The fuel cell system is connected with the electric equipment, and the electric equipment is started. The air pump 6 and the second liquid pump 7 are started. Reading the optimal concentration matrix C from the controller storage chip_opt. Initializing the boundary values (i.e., U) of the voltage subintervals in turn based on the terms in the algorithm's basic parameter configuration₀、U₁、U₂…U_m-1、U_m) Or the boundary value of each current sub-interval (i.e. I)₀、I₁、I₂…I_m-1、I_m) And boundary value of each temperature sub-interval (i.e. T)₀、T₁、T₂…T_m-1、T_m) And the upper limit SOC of the electric quantity threshold of the battery pack_UPLower limit SOC of electric quantity threshold of battery pack_DOWNInitial concentration value C of electric pile operation₀A lag time delta t1 of the response of the electric pile to the concentration change, a lag time delta t2 of the response of the electric pile to the voltage (or current) change, a concentration single adjustment step dC, a pile voltage single adjustment step dU (or pile current single adjustment step dI), and a high concentration power matrix P_c,highLow concentration power matrix P_c,low. Time span delta T3 for judging stable operation of electric pile and temperature fluctuation upper limit delta T corresponding to stable operation of electric pile_xConcentration fluctuation upper limit Delta C corresponding to stable operation of electric pile_xVoltage fluctuation upper limit delta U corresponding to stable operation of electric pile_xCorresponding to stable operation of the stackUpper limit of current fluctuation Δ I_x. And then to STEP2.

Step2. the fuel cell system starts a warm-up procedure. The present process is executed immediately after the initialization of the start-up parameters, and functions to gradually transition the fuel cell from the ambient state to the steady-state operation state. Firstly, a controller 5 collects signals of a fuel concentration sensor 4 to obtain a fuel concentration value C; the controller 5 collects the temperature sensor signal and obtains the temperature value T of the electric pile_stack(ii) a The controller 5 monitors the remaining charge (SOC) of the battery pack 8 through the circuit adjusting module 9. The controller 5 monitors the cell stack voltage U through the circuit adjusting module 9_stackCurrent of the cell stack I_stackAnd calculating the output power P of the electric pile_stack. The controller 5 monitors the output voltage and current of the fuel cell system through the circuit adjusting module 9 and calculates the output power P thereof_out. Output power P of fuel cell system_outAnd also the power consumption of the user equipment. Then, the following determination is performed: for the first control scheme, i.e. based on voltage-temperature feedback control, if the stack voltage U_stackAnd temperature T of the stack_stackWhen both are in the voltage subinterval and the temperature subinterval corresponding to the steady-state operation of the electric pile, namely U_min≤U_stack<U_maxAnd T_min≤T_stack<T_maxThen the steady state operation control STEP is entered, i.e. STEP4 is skipped. Otherwise, based on the fuel concentration value C and the initial concentration value C₀The rate of the first liquid pump 2 is feedback-controlled so that the fuel concentration value C approaches the initial value C of the stack operation₀. Then enters the regulated discharge process, i.e., jumps to STEP3. For the second control scheme, i.e. current-temperature feedback control, if the stack current I_stackAnd temperature T of the stack_stackWhen both are in the current subinterval and the temperature subinterval corresponding to the steady-state operation of the electric pile, i.e. I_min≤I_stack<I_maxAnd T is_min≤T_stack<T_maxThen the steady state operation control STEP is entered, i.e. STEP4 is skipped. Otherwise, based on the real-time fuel concentration value C and the initial concentration value C₀The speed of the first liquid pump 2 is feedback controlled to make the fuel concentration value C close to the initial concentration value C of the electric pile operation₀. And then enters the regulation discharge subprocess, i.e. the STEP3 is jumped to. After the program returns from STEP3, the STEPs are repeated until the voltage (or current) of the stack and the temperature of the stack enter the voltage (or current) and temperature interval corresponding to the defined steady-state operation of the stack.

Step3. the fuel cell regulates the discharge process. The purpose of this process is to maintain the remaining charge (SOC) of the battery pack 8 at the set lower limit of the battery pack charge threshold (SOC) while satisfying the demand of the user for electricity_DOWN) And upper threshold (SOC)_UP) In between. The method comprises the following steps of designing a galvanic pile discharge adjustment strategy for the following two situations: 1. if the remaining battery capacity (SOC) is lower than the set lower threshold (SOC)_DOWN) Then the stack voltage or current is adjusted in an attempt to increase the stack output power. 2. If the remaining capacity (SOC) of the battery pack is higher than the set upper threshold (SOC)_UP) And the user equipment power (P)_out) Lower than the stack output power (P)_stack) And adjusting the voltage or the current of the electric pile to reduce the output power of the electric pile. The specific regulation and control process of the galvanic pile discharge is as follows:

as shown in FIG. 4, for the first control scheme (based on voltage-temperature feedback) of this patent, if the remaining battery SOC is less than the SOC_DOWNWhen it is, let P_old＝P_stack. Then, the controller reduces the discharge voltage of the electric pile by dU through the circuit adjusting module_stackAnd waits at 2 for a duration. Then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new. If P_new>P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≤P_oldThe controller increases the discharge voltage of the galvanic pile by 2 × dU through the circuit adjusting module_stackAnd waits at 2 for a duration. Then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new. If P_new>P_oldThen, the current control discharge process is left, and the procedure returns to the previous STEP (i.e. if the procedure jumps from STEP2 to this STEP,go back to STEP 2; if the program jumps from STEP4 to this STEP, go back to STEP 4). On the contrary, if P_new≤P_oldThen the controller reduces the discharge voltage of the electric pile by dU through the circuit adjusting module_stackI.e. to maintain the original discharge voltage of the stack. Then leave this control and discharge process and return to the previous STEP (i.e. go back to STEP2 if the program jumps from STEP2 to this STEP; go back to STEP4 if the program jumps from STEP4 to this STEP). If the residual electric quantity SOC of the battery pack is larger than the SOC_UPAnd the power of the galvanic pile is higher than the power (P) of the user_stack>P_out) When it is, let P_old＝P_stack. Then, the controller increases the discharge voltage of the electric pile by dU through the circuit adjusting module_stackAnd waits for a duration at 2. Then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new. If P_new<P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≥P_oldThe controller reduces the discharge voltage of the electric pile by 2 × dU through the circuit regulating module_stackAnd waits at 2 for a duration. Then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new. If P_new<P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≥P_oldThen the controller increases the discharge voltage of the electric pile by dU through the circuit adjusting module_stackI.e. to maintain the original discharge voltage of the stack. Then, the process of this control discharging is left and returns to the previous STEP (i.e., if the program jumps from STEP2 to this STEP, it returns to STEP2, and if the program jumps from STEP4 to this STEP, it returns to STEP 4).

As shown in FIG. 5, for the second control scheme (based on current-temperature feedback) of this patent, if the remaining battery SOC is less than the SOC_DOWNWhen it is, let P_old＝P_stack. Then, after that,the controller reduces the discharging current of the galvanic pile by dI through the circuit adjusting module_stackAnd waits at 2 for a duration. Then testing the voltage of the electric pile and calculating the new output power P of the electric pile after the current changes_new. If P_new>P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≤P_oldThe controller increases the discharge current of the electric pile by 2 × dI through the circuit regulating module_stackAnd waits at 2 for a duration. Then testing the voltage of the electric pile and calculating the new output power P of the electric pile after the current changes_new. If P_new>P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≤P_oldThe controller reduces the discharge current dI of the electric pile through the circuit adjusting module_stackI.e. to maintain the original discharge current of the stack. Then leave this control and discharge process and return to the previous STEP (i.e. go back to STEP2 if the program jumps from STEP2 to this STEP; go back to STEP4 if the program jumps from STEP4 to this STEP). If the SOC of the residual electric quantity of the battery pack is larger than the SOC_UPThe power of the electric pile is higher than the power (P) of the user_stack>P_out) Let P_old＝P_stack. Then, the controller increases the discharging current of the galvanic pile by dI through the circuit adjusting module_stackAnd waits at 2 for a duration. Then testing the voltage of the electric pile and calculating the new output power P of the electric pile after the current changes_new. If P_new<P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≥P_oldThe controller reduces the discharge current of the electric pile by 2 × dI through the circuit regulating module_stackAnd waits at 2 for a duration. Then testing the voltage of the electric pile and calculating the new output work of the electric pile after the current changeRate P_new. If P_new<P_oldThen the current control electron release process is left and the process returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP 2; if the program jumps from STEP4 to this STEP, it returns to STEP 4). On the contrary, if P_new≥P_oldThe controller increases the discharge current of the electric pile by dI through the circuit adjusting module_stackI.e. maintaining the original discharge current of the stack. Then, the process of this control discharging is left and returns to the previous STEP (i.e. if the program jumps from STEP2 to this STEP, it returns to STEP2, and if the program jumps from STEP4 to this STEP, it returns to STEP 4).

STEP4. the steady state operation concentration control and the optimum concentration update learning process of the fuel cell system. The air pump 6 and the second liquid pump 7 are maintained. The controller 5 acquires signals of the fuel concentration sensor 4 to obtain a fuel concentration value C; the controller 5 collects the temperature sensor signal and obtains the temperature value T of the electric pile_stack(ii) a The controller 5 monitors the remaining charge (SOC) of the battery pack 8 through the circuit adjusting module 9. The controller 5 monitors the cell stack voltage U through the circuit adjusting module 9_stackCurrent of the cell stack I_stackAnd calculating the output power P of the electric pile_stack. The controller 5 monitors the output voltage and current of the fuel cell system through the circuit adjusting module 9 and calculates the output power P thereof_out. Fuel cell system output power P_outAnd also the power consumption of the user equipment. Then, the regulated discharge process is performed, i.e., STEP3 is entered. After the program returns from STEP3, the temperature T of the cell stack is monitored again_nowFuel concentration value C, stack discharge voltage U_stackDischarge current I of the cell stack_stackAnd searching a voltage subinterval (or a current subinterval) or a temperature subinterval corresponding to the current electric pile running state. If the current running state of the galvanic pile meets U_s1-1≤U_stack<U_s1(or I)_s1-1≤I_stack<I_s1) And T_s2-1≤T_stack<T_s2Then, the current stack operating state is in the s1 th voltage (or current) sub-interval, the s2 th temperature sub-interval (the following algorithm flows are all in the s1 th voltage (or current) sub-interval and the s2 th temperature sub-interval in the stack operating stateInterval as an example for analysis). Subsequently, the corresponding density value C in the optimum density matrix is read_opt(s1, s 2). And based on real-time fuel concentration values C and C_opt(s1, s2) feedback-controlling the first liquid pump 2 speed to bring the fuel concentration value C close to C_opt(s1, s 2). After that, whether the system enters the stable state is judged according to the following condition standards:

condition 1, the temperature change amplitude of the galvanic pile is lower than delta T within continuous delta T3 time period_x。

Condition 2: the fuel concentration change amplitude is lower than delta C in the continuous delta t3 time period_x。

Condition 3: the voltage change amplitude of the galvanic pile is lower than delta U in the continuous delta t3 time period_x。

Condition 4: the change amplitude of the current of the pile is lower than delta I in the continuous delta t3 time period_x。

When the above condition is not completely satisfied, the system is determined not to enter the steady state, STEP4 is repeatedly executed, and the system operation state is continuously monitored. When all the judgment conditions are met, the system is considered to enter a stable state, and the concentration adjustment optimization process is carried out. I.e., into STEP5.

STEP5. concentration self-learning adjustment optimization process. The aim of the process is to enable the fuel cell stack to output the maximum power within a specified temperature, voltage (or current) interval by optimizing the fuel concentration when the stack operates. Generally, the fuel cell system operated at the above-described optimum concentration has a high efficiency. The process is realized by mainly using the current power P of the galvanic pile_coptThe value P of corresponding element in the high-concentration electric pile power matrix_c,high(s1, s2) and the value P of the corresponding element in the low concentration stack power matrix_c,low(s1, s2) comparing, gradually adjusting the element value C corresponding to the current voltage (or current) subinterval and temperature subinterval in the optimal density matrix_opt(s1, s 2). So that when the stack is operating in the present voltage (or current) subinterval and temperature subinterval, the stack is at C_opt(s1, s2) output Power P at Density running_coptGreater than C_opt(s1, s2) + dC concentration operationP_c,high(s1, s2) and C_opt(s1, s2) -output Power P when operating at dC concentration_c,low(s1, s 2); i.e. P_copt>P_c,high(s1, s2) and P_copt>P_c,low(s1,s2)。

The specific execution steps are as follows: due to P_c,high、P_c,lowAll the element values are initialized to 0, so P needs to be calibrated first_c,high、P_c,lowCorresponding to the present voltage (or current) subinterval and concentration subinterval, i.e. P_c,high(s1,s2)、P_c,low(s1, s 2). Therefore, the following judgment is firstly made: if P_c,high(s1, s2) is 0 or P_c,low(s1, s2) is 0, then go into the concentration optimization exploration process to obtain P_c,high(s1,s2)、P_c,low(s1, s2), that is, into STEP6, and then back to STEP4, again waiting for the stack to enter steady state. If P_c,high(s1, s2) and P_c,low(s1, s2) are not 0, then according to the current power value P of the electric pile_coptAnd P_c,high(s1, s2) and P_c,low(s1, s2) adjusting the corresponding element C in the optimal concentration matrix_opt(s1, s 2). Since the performance of the fuel cell stack exhibits a unimodal characteristic of increasing first and then decreasing as the fuel concentration increases, P_coptAnd P_c,high(s1,s2)、P_c,high(s1, s2) exhibit only three relationships:

1. if P_copt≥P_c,high(s1, s2) and P_copt≥P_c,low(s1, s2), the current system is explained to work near the optimal density, and the corresponding position element C in the current optimal density matrix is maintained_opt(s1, s2) is unchanged and the stack continues to operate at C_opt(s1, s2) concentration operation, i.e. back to STEP4.

2. If P_c,low(s1,s2)<P_copt<P_c,high(s1, s2) then the values (C) corresponding to the present voltage (or current) and temperature sub-intervals in the present optimal concentration matrix are indicated_opt(s1, s2)) is lower than the true optimum concentration value for the fuel cell stack operating at the current voltage (or current) and temperature sub-intervals. So that the current optimum concentration momentArray element value (C) of corresponding position_opt(s1, s2)) increased dC. In order to ensure that the optimal concentration value is smoothly transited in different voltage (or current) and temperature subintervals, the corresponding optimal concentration value in the adjacent interval is adjusted. Instant meal _x1, sequentially executing the formula (1) to the formula (9) and updating the updated optimal density matrix C_optAnd writing into the memory chip. At the same time, due to C_opt(s1, s2) improved dC, requiring synchronous update of P_c,low、P_c,highThe values of the corresponding elements in the matrix. Sequentially executing the formula (10) to the formula (11) to obtain the current pile power P_coptImpartation of P_c,low(s1, s 2). Due to C_optThe concentration values corresponding to (s1, s2) are improved, and the output power of the electric pile at higher concentration is not calibrated in the current voltage (or current) subinterval and temperature subinterval. Therefore, P will be_c,highCorresponding element P in the matrix_c,highThe value of (s1, s2) is set to zero. Then, the method enters STEP6, namely a concentration optimization exploration process, so as to obtain and update an optimal concentration matrix C_optCorresponding P_c,highCorresponding to the present voltage (or current) subinterval and temperature subinterval_c,high(s1, s 2)). And then returning to STEP4, controlling the speed of the first liquid pump 2 according to the concentration values of the elements corresponding to the current voltage (or current) subinterval and temperature subinterval in the new optimal concentration matrix, and waiting for the cell stack to enter the steady state again.

3. If P_c,low(s1,s2)>P_copt>P_c,high(s1, s2) then the values (C) corresponding to the present voltage (or current) and temperature sub-intervals in the present optimal concentration matrix are indicated_opt(s1, s2)) is higher than the true optimum concentration value for the fuel cell stack operating at the current voltage (or current) and temperature sub-intervals. So as to determine the element value (C) of the corresponding position of the current optimal concentration matrix_opt(s1, s2)) decreases dC. In order to ensure that the optimal concentration value is smoothly transited in different voltage (or current) and temperature subintervals, the corresponding optimal concentration value in the adjacent interval is adjusted. Instant meal_xThe updated optimum density matrix C is obtained by executing the formula (1) to the formula (9) in order of 1_optAnd writing into the memory chip. At the same time, due to C_opt(s1, s2) reduced dC, requiring a synchronous update of P_c,low、P_c,highThe values of the corresponding elements in the matrix. Sequentially executing formula (12) to formula (13) to obtain the current pile power P_coptImpartation of P_c,high(s1, s 2). Due to C_optThe concentration values corresponding to (s1, s2) are reduced, and the output power of the galvanic pile at lower concentration is not calibrated in the current voltage (or current) subinterval and temperature subinterval. Therefore, P will be_c,lowCorresponding element P in the matrix_c,lowThe value of (s1, s2) is set to zero. Then, the method enters STEP6, namely a concentration optimization exploration process, so as to obtain and update an optimal concentration matrix C_optCorresponding P_c,lowElements (P) in the matrix corresponding to the present voltage (or current) and temperature subintervals_c,low(s1, s 2)). And then returning to STEP4, controlling the speed of the first liquid pump 2 according to the concentration values of the elements corresponding to the current voltage (or current) subinterval and temperature subinterval in the new optimal concentration matrix, and waiting for the cell stack to enter the steady state again.

C_opt(s1,s2)＝C_opt(s1,s2)+m_x*dC (1)

C_opt(s1+1,s2)＝C_opt(s1+1,s2)+m_x*dC/2 (2)

C_opt(s1,s2+1)＝C_opt(s1,s2+1)+m_x*dC/2 (3)

C_opt(s1-1,s2)＝C_opt(s1-1,s2)+m_x*dC/2 (4)

C_opt(s1,s2-1)＝C_opt(s1,s2-1)+m_x*dC/2 (5)

C_opt(s1+1,s2+1)＝C_opt(s1+1,s2+1)+m_x*dC/3 (6)

C_opt(s1+1,s2-1)＝C_opt(s1+1,s2-1)+m_x*dC/3 (7)

C_opt(s1-1,s2+1)＝C_opt(s1-1,s2+1)+m_x*dC/3 (8)

C_opt(s1-1,s2-1)＝C_opt(s1-1,s2-1)+m_x*dC/3 (9)

P_c,low(s1,s2)＝P_copt (10)

P_c,high(s1,s2)＝0 (11)

P_c,high(s1,s2)＝P_copt (12)

P_c,low(s1,s2)＝0 (13)

STEP6. concentration optimization exploration. As shown in FIG. 6, the process is directed to testing the fuel cell stack operating at the present voltage (or current) subinterval and temperature subinterval at a higher input concentration C_opt(s1, s2) + dC or lower input concentrations C_optUnder the condition of (s1, s2) -dC, the power P is output by the galvanic pile_c,high(s1, s2) and P_c,low(s1, s 2). So as to be the optimal concentration matrix C_optThe adjustment of the corresponding parameters provides reference basis. Firstly, the air pump and the second liquid pump are kept running. The voltage (or current) of the electric pile is controlled to be constant by the circuit adjusting module.

If P_c,low(s1, s2) is equal to 0, the first liquid pump 2 is adjusted by the controller so that the fuel concentration for the operation of the cell system is close to C_opt(s1, s2) -dC and wait a period of time Δ t 1. Regular monitoring of the temperature T of the cell stack_stackFuel concentration C, stack discharge voltage U_tackDischarge current I of the cell stack_stackAnd calculating the stack power P_nowAnd until the running state of the electric pile meets the following four judgment conditions.

Condition 1, the temperature change amplitude of the galvanic pile is lower than delta T in a continuous delta T3 time period_x。

Condition 2: the concentration change amplitude of the mixing tank 3 is lower than delta C in the continuous delta t3 time period_x。

When the above conditions are not fully met, the system is deemed not to enter a new steady state and the above monitoring and determining process is repeated. When all the above-mentioned judgement conditions are met, it is considered that the system has been entered into new stable state, and the current electric pile power value is written into P_c,lowIn a matrix, i.e. P_c,low(s1,s2)＝P_stack. The first liquid pump 2 is then regulated by the controller so that the fuel concentration at which the cell system operates is close to C_opt(s1, s2) and back to STEP4, again waiting for the stack to enter steady state.

If P_c,low(s1,s2)>0 and P_c,high(s1, s2) — 0, the first liquid pump 2 is adjusted by the controller so that the fuel concentration at which the cell system operates is close to C_opt(s1, s2) + dC and wait for a period of time Δ t 1. Periodic monitoring of the temperature T of the stack_stackFuel concentration C, stack discharge voltage U_tackDischarge current I of the cell stack_stackAnd calculating the stack power P_nowAnd until the running state of the electric pile meets the following four judgment conditions.

When the above conditions are not fully met, the system is deemed not to enter a new steady state and the above monitoring and determining process is repeated. When all the above-mentioned judgement conditions are met, it is considered that the system has been entered into new stable state, and the current electric pile power value is written into P_c,highIn a matrix, i.e. P_c,high(s1,s2)＝P_stack. The first liquid pump 2 is then regulated by the controller so that the fuel concentration at which the cell system operates is close to C_opt(s1, s2) and back to STEP4, again waiting for the stack to enter steady state.

Examples

A 150W direct methanol fuel cell system was used as an example of the present invention. Fig. 7 and 8 are graphs of operation results based on the concentration self-learning algorithm control respectively. Fig. 7 is a graph of stack power versus time. FIG. 8 is a graph of methanol concentration versus time.

As can be seen from FIG. 7, the power fluctuation of the galvanic pile is large in the time period of 0-1 h after the startup; within 1-3 hours, the power change amplitude of the galvanic pile is gradually reduced; after 3 hours, the power tends to be stable and higher than P_c,high(power corresponding to higher concentration) and P_c,low(lower concentration corresponds to power). Meanwhile, fig. 8 shows that the concentration fluctuation is large in the time period of 0-1 h after the start, and the concentration gradually tends to be stable in the time period of 1-3 h. As can be seen from fig. 7 and 8, the system is in the concentration self-learning optimization phase within 3 hours after startup, and then the system is always operated near the optimal concentration. The experimental result verifies the effectiveness of the algorithm.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The concentration optimization control method of the liquid fuel cell is characterized in that the operation concentration of the liquid fuel cell is optimized in real time by dividing a voltage-temperature interval or a current-temperature interval on a two-dimensional plane and based on a power-concentration step response relation; the method comprises the following steps:

further dividing stable operation intervals of voltage/current and temperature, and judging whether the system operates stably in the intervals; if the fuel cell stack is not in a steady state, the fuel cell stack outputs the maximum power in a specified temperature, voltage/current interval by optimizing the fuel concentration value in the optimal concentration matrix during the operation of the stack; and controlling the speed of the first liquid pump according to the optimal concentration value corresponding to the maximum power, thereby realizing the optimal control of the fuel cell.

2. The liquid fuel cell concentration optimization control method according to claim 1, wherein the method is implemented based on a fuel cell system including: the fuel pump comprises a fuel tank (1), a mixing tank (3), a fuel concentration sensor (4), a first liquid pump (2), a second liquid pump (7), an air pump (6), a controller (5), a temperature sensor (10), a galvanic pile (11), a battery pack (8) and a circuit adjusting module (9);

the fuel concentration sensor (4) is immersed in the solution in the mixing tank (3) or a circulating pipeline of the solution in the mixing tank (3) and is used for monitoring the concentration of the solution in the mixing tank (3) and representing the fuel concentration in the galvanic pile (11); the temperature sensor (10) is attached to the surface of the galvanic pile (11) or embedded in the galvanic pile (11) and is used for monitoring the temperature of the galvanic pile (11);

the first liquid pump (2) is respectively connected with the fuel tank (1) and the mixing tank (3) and is used for injecting the fuel in the fuel tank (1) into the mixing tank (3); the second liquid pump (7) is respectively connected with the mixing tank (3) and the galvanic pile (11) and is used for supplying the solution in the mixing tank (3) to the galvanic pile (11); the air pump (6) is connected with the electric pile (11) and is used for supplying air to the electric pile (11);

the circuit adjusting module (9) is respectively connected with the battery pack (8), the battery pack (11) and the user electric equipment, and is used for monitoring the voltage of the battery pack, the current of the battery pack, the SOC of the residual electric quantity of the battery pack (8), the charging current and the discharging current of the battery pack (8) and the voltage and the current of the user electric equipment, controlling the discharging voltage or the current of the battery pack (11), and adjusting the output voltage or the current of the fuel cell system according to the power demand of the user;

the controller (5) is respectively connected with the first liquid pump (2), the second liquid pump (7), the air pump (6), the fuel concentration sensor (4), the temperature sensor (10) and the circuit adjusting module (9); the controller (5) obtains a galvanic pile voltage value, a galvanic pile current value, a charging or discharging current value of the battery pack (8) and a residual electric quantity value SOC of the battery pack (8) through the circuit adjusting module (9).

3. The liquid fuel cell concentration optimization control method according to claim 1, characterized by comprising:

STEP1, setting and initializing fuel cell system parameters;

STEP2. Fuel cell System Start-Up ramp-Up procedure:

for voltage-temperature feedback control/current-temperature feedback control, if the voltage U of the galvanic pile_stackElectric pile current I_stackAnd temperature T of the stack_stackWhen the voltage subinterval and the temperature subinterval which correspond to the steady-state operation of the galvanic pile are both in, entering a steady-state operation control STEP STEP 4;

otherwise, the speed of the first liquid pump (2) is controlled based on the fuel concentration value feedback, and the discharging process STEP3 is controlled; after the program returns from the STEP3, the STEP2 is repeatedly executed until the voltage/current of the galvanic pile and the temperature of the galvanic pile enter a defined voltage/current and temperature interval corresponding to the steady-state operation of the galvanic pile;

STEP3. Fuel cell regulated discharge Process:

if the residual charge SOC of the battery pack (8) is lower than the set lower threshold value SOC_DOWNAdjusting the voltage or current of the electric pile to try to increase the output power of the electric pile; if the residual charge SOC of the battery pack (8) is higher than the set upper threshold value SOC_UPAnd the electric power P of the user equipment_outLower than the output power P of the electric pile_stackAdjusting the voltage or current of the electric pile to reduce the output power of the electric pile; for maintaining the remaining charge SOC of the battery pack (8) between the set charge threshold ranges of the battery pack (8);

STEP4. Fuel cell System Steady State operation concentration control Process:

Searching a voltage subinterval/current subinterval or a temperature subinterval corresponding to the current electric pile running state: if the current running state of the galvanic pile meets U_s1-1≤U_stack<U_s1/I_s1-1≤I_stack<I_s1And T_s2-1≤T_stack<T_s2Then the current operation state of the stack is at the s1 th powerVoltage/current subintervals, the s2 th temperature subintervals;

the corresponding concentration value C in the optimum concentration matrix is then read_opt(s1, s2) and based on the real-time fuel concentration values C and C_opt(s1, s2) feedback controlling the rate of the primary liquid pump (2) for bringing the fuel concentration value C closer to C_opt(s1, s2) corresponding concentration values;

STEP5. concentration self-learning adjustment optimization process:

the realization of the process is realized by calling a concentration optimization exploration process to obtain the current power P of the galvanic pile_coptThe value P of corresponding element in the high-concentration electric pile power matrix_c,high(s1, s2) and the value P of the corresponding element in the low concentration stack power matrix_c,low(s1, s2) comparing, gradually adjusting the element value C corresponding to the present voltage/current subinterval and temperature subinterval in the optimal density matrix_opt(s1, s2) for causing the stack to operate at C when the stack is operating in the present voltage/current subinterval and temperature subinterval_opt(s1, s2) output Power P at Density running_coptSatisfies the following conditions: p_copt>P_c,high(s1, s2) and P_copt>P_c,low(s1,s2)；

STEP6. concentration optimization exploration process:

by testing the fuel cell stack operating in the present voltage/current subinterval and temperature subinterval at the higher input concentration C_opt(s1, s2) + dC or lower input concentration C_opt(s1, s2) -dC, under certain conditions_c,high(s1, s2) and P_c,low(s1, s2) for optimizing the density matrix C_optThe adjustment of the corresponding parameters provides reference basis.

4. The liquid fuel cell concentration optimization control method according to claim 3, wherein the set parameters include:

setting the upper limit value U of the discharge voltage of the galvanic pile based on voltage-temperature feedback control_maxLower limit ofU_minAnd is in U_max、U_minM voltage subintervals U are divided between₀～U₁，U₁～U₂,，U₂～U₃，…，U_m-1～U_mWherein U is_min＝U₀<U₁<U₂<…<U_m-2<U_m-1<U_m＝U_max；

Setting the upper limit value T of the operating temperature of the galvanic pile_maxLower limit value T_minAnd at T_max、T_minIs divided into n temperature intervals T₀～T₁，T₁～T₂，T₂～T₃，…，T_n-1～T_nWherein T is_min＝T₀<T₁<T₂<…<T_n-2<T_n-1<T_n＝T_max；

Creating an optimal density matrix C of m rows and n columns_optMatrix C_optElement value C of s1 th row and s2 th column_opt(s₁,s₂) Represents when the electric pile runs in the s1 th voltage interval (U)_s1-1～U_s1) Or the s1 th current interval (I)_s1-1～I_s1) And the s2 th temperature interval (T)_s2-1～T_s2) Then, the optimal concentration value calculated by the method is adopted;

setting the upper limit SOC of the electric quantity threshold of the battery pack (8)_UPAnd the lower limit SOC of the electric quantity threshold value of the battery pack (8)_DOWNUpper limit value I of charging current of battery pack (8)_BinUP；

temperature fluctuation upper limit delta T corresponding to stable operation of electric pile_xUpper limit of concentration fluctuation DeltaC_xUpper limit of voltage fluctuation Δ U_xAnd the upper limit of current fluctuation DeltaI_x；

Constructing a high-concentration power matrix P of m rows and n columns_c,highLow concentration power matrix P_c,low；P_c,high(s1, s2) for the case when the stack voltage is in the s1 th voltage sub-interval, the stack temperature is in the s2 th temperature sub-interval and the fuel concentration is C_opt(s1, s2) + dC, discharge power of the stack; p_c,low(s1, s2) for the fuel concentration C when the stack voltage is in the s1 voltage subinterval, the stack temperature is in the s2 temperature subinterval_opt(s1, s2) -dC, the discharge power of the stack.

5. The method of claim 3, wherein the STEP3 specifically includes:

for voltage-temperature-based feedback/current-temperature-based feedback:

1) if the residual capacity SOC of the battery pack (8) is less than the lower limit SOC of the threshold value_DOWNWhen it is, let P_old＝P_stack(ii) a The controller (5) reduces the discharge voltage of the galvanic pile by dU through the circuit adjusting module (9)_stack(reduction of the discharge Current dI of the cell_stack) And wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new>P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≤P_oldThe controller (5) increases the discharge voltage of the electric pile by 2 × dU through the circuit regulating module (9)_stack(electric pile discharge power)Flow increase 2 × dI_stack) And wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new>P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≤P_oldThen the controller (5) reduces the discharge voltage of the galvanic pile by dU through the circuit adjusting module (9)_stack(reduction of the discharge Current dI of the cell_stack) Maintaining the original discharge voltage (original discharge current) of the galvanic pile, then leaving the current regulation and control electron discharge process, and returning to the previous step;

2) if the SOC of the residual electric quantity of the battery pack (8) is larger than the SOC_UPAnd the power of the galvanic pile is higher than the power (P) of the electricity used by the user_stack>P_out) When it is, let P_old＝P_stack(ii) a Then, the controller (5) increases the discharge voltage of the electric pile by dU through the circuit adjusting module (9)_stack(increase of pile discharge Current dI_stack) And wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new<P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≥P_oldThe controller (5) reduces the stack discharge voltage by 2 × dU through the circuit regulation module (9)_stackReduction of pile discharge current by 2 dI_stackAnd wait for a duration of Δ t 2; then testing the current of the electric pile and calculating the new output power P of the electric pile after the voltage changes_new(ii) a If P_new<P_oldIf the current regulation and control electronic discharge process is left, returning to the previous step; on the contrary, if P_new≥P_oldThe controller (5) increases the discharge voltage of the electric pile by dU through the circuit adjusting module (9)_stackIncrease of discharge current of galvanic pile dI_stackNamely, the original discharge voltage (original discharge current) of the electric pile is maintained, then the current regulation and control electron discharge process is left, and the previous step is returned.

6. The method as claimed in claim 3, wherein the STEP4 determines whether the system enters a steady state, and specifically includes:

7. The concentration optimization control method of the liquid fuel cell according to claim 3, wherein the STEP5 concentration self-learning adjustment optimization process specifically comprises:

8. The method as claimed in claim 7, wherein the adjusting the corresponding element C in the optimal concentration matrix is performed separately_optThe values of (s1, s2) are:

ii if P_c,low(s1,s2)<P_copt<P_c,high(s1, s2), and converting the element value (C) of the corresponding position of the current optimal density matrix into the element value (C)_opt(s1, s2)) increased dC; at the same time, P is synchronously updated_c,low、P_c,highThe values of the corresponding elements in the matrix; the current stack power P_coptImpartation of P_c,low(s1,s2)；

And calibrating the output power of the galvanic pile at higher concentration in the current voltage or current subinterval and temperature subinterval: will P_c,highCorresponding element P in the matrix_c,high(s1, s2) is set to zero, and then STEP6 is entered, namely, the concentration optimization exploration process; then returning to STEP4, controlling the speed of the first liquid pump (2) according to the concentration values of elements corresponding to the current voltage (or current) subinterval and temperature subinterval in the new optimal concentration matrix, and waiting for the galvanic pile to enter a stable state again;

if P is iii_c,low(s1,s2)>P_copt>P_c,high(s1, s2), and calculating the element value (C) of the corresponding position of the current optimal density matrix_opt(s1, s2)) reduce dC; at the same time, P is synchronously updated_c,low、P_c,highThe values of the corresponding elements in the matrix; the current stack power P_coptImpartation of P_c,high(s1,s2)；

Calibrating the output power of the electric pile at lower concentration in the current voltage (or current) subinterval and temperature subinterval: will P_c,lowCorresponding element P in the matrix_c,low(s1, s2) is set to zero, and then STEP6 is entered, namely, the concentration optimization exploration process; and then returning to STEP4, controlling the speed of the first liquid pump (2) according to the concentration values of the elements corresponding to the current voltage (or current) subinterval and temperature subinterval in the new optimal concentration matrix, and waiting for the galvanic pile to enter the stable state again.

9. The method of claim 3, wherein the STEP6 concentration optimization search specifically includes:

i. firstly, the air pump (6) and the second liquid pump (7) are kept running, and the voltage or the current of the galvanic pile is controlled to be unchanged through the circuit adjusting module (9);

if P is_c,low(s1, s2) is equal to 0, the first liquid pump (2) is adjusted by the controller (5) so that the fuel concentration of the battery system operation is close to C_opt(s1, s2) -dC and wait a period of time Δ t 1; regular monitoring of the temperature T of the cell stack_stackFuel concentration C, stack discharge voltage U_tackDischarge current I of the cell stack_stackAnd calculating the stack power P_nowUntil the electric pile system enters a stable state;

writing the current stack power value into P_c,lowIn a matrix, i.e. P_c,low(s1,s2)＝P_stack. The first liquid pump (2) is then regulated by the controller (5) in such a way that the fuel concentration for the operation of the cell system is close to C_opt(s1, s2) and back to STEP4, re-waiting for the stack to enter steady state;

if P is iii_c,low(s1,s2)>0 and P_c,high(s1, s2) is equal to 0, the first liquid pump (2) is adjusted by the controller (5) so that the fuel concentration of the battery system operation is close to C_opt(s1, s2) + dC and wait for a period of time Δ t 1; regular monitoring of the temperature T of the cell stack_stackFuel concentration C, stack discharge voltage U_tackDischarge current I of the cell stack_stackAnd calculating the stack power P_nowUntil the electric pile system enters a stable state;

writing the current stack power value into P_c,highIn a matrix, i.e. P_c,high(s1,s2)＝P_stack(ii) a The first liquid pump (2) is then adjusted by the controller (5) such that the fuel concentration at which the cell system operates approaches C_opt(s1, s2) and returns to STEP4, waiting again for the stack to enter steady state.