WO2022048660A1

WO2022048660A1 - Dynamic control method for fuel cell system

Info

Publication number: WO2022048660A1
Application number: PCT/CN2021/116645
Authority: WO
Inventors: 丁天威; 黄兴; 赵洪辉; 赵子亮; 曲禄成; 王宇鹏; 都京; 马秋玉
Original assignee: 中国第一汽车股份有限公司
Priority date: 2020-09-07
Filing date: 2021-09-06
Publication date: 2022-03-10
Also published as: CN112072143B; CN112072143A

Abstract

The present application provides a dynamic control method for a fuel cell system. The dynamic control method comprises a load control process and a load shedding control process; the load control process comprises: by means of demand power and power load change rate, checking a logic table to determine a performance coefficient and, according to the size of the performance coefficient, controlling an air measurement ratio, a hydrogen/air pressure difference target value, a water discharge valve work energy threshold, and a water discharge valve start time of an air compressor; the load shedding control process comprises: by means of a power shedding change rate, controlling a deceleration slope and a water discharge valve work state of the air compressor, discharging excess moisture, maintaining a stable hydrogen/air pressure difference.

Description

A kind of dynamic control method of fuel cell system

This application claims the priority of the Chinese Patent Application No. 202010931073.8 filed with the China Patent Office on September 7, 2020, the entire contents of which are incorporated herein by reference.

technical field

The present application belongs to the technical field of dynamic control of fuel cells, and relates to a dynamic control method of a fuel cell system, for example, a dynamic control method of a fuel cell system including dynamic loading control and dynamic load shedding control.

Background technique

In today's world, energy development, energy and environment are issues of common concern to the whole world and all mankind, and are also important issues for my country's social and economic development. Energy is the material basis of human activities, the most basic driving force for the development and economic growth of the entire world, and an important indicator for measuring the comprehensive strength of a country and people's living standards. In a sense, the development of human society is inseparable from the emergence of high-quality energy and the use of advanced energy technologies. The issue of energy security has arisen since the Industrial Revolution. Today, with the rapid development of the global economy, international energy security has risen to the level of a country, and all countries have formulated energy policies with energy supply security as the core. On the premise of stable energy supply, the world economy has achieved large-scale growth. However, while energy brings economic growth and technological progress, it also brings a series of unavoidable energy security crises. It is precisely because of problems including resource shortage, energy competition and environmental pollution caused by excessive use of energy that human survival and development are facing threats. One aspect of solving the energy problem depends on the continuous discovery of new energy sources, and the other is energy saving. Energy saving includes two aspects: one is to improve energy utilization efficiency, and the other is to reduce energy consumption. Energy conservation has become a comprehensive indicator to measure the quality of a country's energy utilization, and it is also an important symbol of a country's high level of science and technology. Therefore, the development of efficient, clean, safe and environmentally friendly new energy has attracted more and more countries' attention.

Fuel cell is a new type of electrochemical power generation device, which breaks the mode of generating power through the heat engine process, that is, the traditional power generation mode of burning fuel to obtain its heat, but directly converts the fuel through the chemical reaction of the electrolyte. The chemical energy stored in the fuel and oxidant is converted into electrical energy. Its advantages are: (1) high energy conversion efficiency; (2) environmental friendliness; (3) high reliability; (4) no noise; (5) high flexibility.

However, in the current fuel cell, there are problems such as uneven distribution of hydrogen pressure in the stack, insufficient air flow, and local flooding caused by excessive instantaneous water production during the dynamic loading process. Due to the decrease of the metering ratio and other conditions, the water produced before the load reduction cannot be discharged in time; at the same time, the risk of excessive hydrogen-air pressure difference caused by the sudden increase of hydrogen pressure due to the instantaneous reduction of the load.

CN110069033A discloses a double-layer predictive control method for an air compressor of a full-power fuel cell electric vehicle. The upper-layer predictor predicts the vehicle speed in real time, calculates and obtains the power required by the fuel cell vehicle at the corresponding speed, and uses the fuel calculated by the upper-layer predictor. The power required by the battery is calculated by the fuel cell cathode flow model to calculate the required output air flow of the fuel cell air compressor, which is used as the reference flow of the underlying predictive controller. The bottom prediction controller predicts the air flow required by the fuel cell air compressor according to the reference flow, and obtains the control voltage of the air compressor, thereby realizing the control of the output flow of the air compressor and satisfying the oxygen required by the fuel cell stack reaction. quantity. However, this solution cannot solve the problem of uneven local gas distribution inside the stack caused by rapid changes in vehicle power.

CN102891329A discloses a method for controlling the air end of a fuel cell system. When the demand current is increased from I _old to I _dem , it is judged whether the current demand current I _dem causes the system to be “deficient in oxygen”, and if so, the current demand current I _dem is set to drop to the critical current value I _crit ; otherwise, the current demand current I _dem is used as the target value of current control, and is directly applied to the fuel cell stack; when the demand current is reduced from I _old to I _dem , other inputs of the system are kept unchanged. Change, the air compressor control voltage is directly reduced to the voltage value corresponding to the current demand current I _dem , and the current I _st is drawn according to the air flow. However, in this scheme, the demand current command is mainly considered for the supply of air flow. If the demand current may cause the stack to be "anoxic", the actual current output will be limited. When the air supply of the air compressor meets the demand, the current Pull load. This process can be slow to respond.

CN110061263A discloses a hybrid fuel cell air subsystem, a vehicle and a control method. The vehicle includes a fuel cell stack and an air subsystem. The air subsystem includes an air supply branch, an air supply branch and an air storage branch. The air inlet of the air branch is connected to the fuel cell air compressor, the air outlet of the air supply branch is connected to the air inlet end of the air supply branch, and the air outlet end of the air supply branch is connected to the fuel cell stack to deliver air to the stack. The outlet of the air branch is connected to the intake end of the air supply branch, and the inlet of the air storage branch is connected to the auxiliary air intake device. The air supply method using the fuel cell air compressor mixed with the auxiliary air intake device can meet the requirements of the fuel cell in practical use. The air demand of automobiles when running at different powers reduces the performance requirements for fuel cell air compressors, so that low-power fuel cell air compressors can be used, thereby reducing the noise of the entire vehicle.

CN105633436B discloses a fuel cell system, a fuel cell vehicle, and a control method of the fuel cell system. The fuel cell system installed in the vehicle includes: a fuel cell for supplying electric power to an electric motor that drives the vehicle; a pump for supplying oxygen supply to the fuel cell; an accelerator position detection unit that detects an accelerator depression amount of the vehicle; and a control unit that calculates, based on the accelerator depression amount, electric power required to be generated by the fuel cell and required for driving the pump and control the pump based on the power required for the drive, wherein the control unit calculates the power required for the drive such that when the calculated need to generate the power increases, the power required for the drive increases The rate of increase in power exceeds the rate of increase in power that needs to be generated.

In general, none of the currently known dynamic control schemes for fuel cells can effectively solve the problems of uneven distribution of hydrogen pressure in the stack, insufficient air flow, and local flooding caused by excessive instantaneous water production during the dynamic loading process. At the same time, it cannot effectively solve the technical problems in the dynamic load shedding process, such as the inability to drain water in time due to the decrease of the load shedding ratio and other conditions, and the risk of excessive hydrogen-air pressure difference caused by the sudden increase of hydrogen pressure due to the instantaneous reduction of the load.

SUMMARY OF THE INVENTION

The present application provides a dynamic control method for a fuel cell system, which effectively solves the problems of uneven distribution of hydrogen pressure in the stack, insufficient air flow and local flooding caused by excessive instantaneous water production during the dynamic loading process; During the dynamic load shedding process, there are technical problems such as the inability to drain water in time due to the decrease of the load shedding ratio and other conditions, and the risk of excessive hydrogen-air pressure difference caused by the sudden increase of hydrogen pressure due to the instantaneous reduction of the load.

This application adopts the following technical solutions:

In a first aspect, the present application provides a dynamic control method for a fuel cell system, the dynamic control method includes a loading control process and a load shedding control process.

The loading control process includes: determining the coefficient of performance by querying the logic table of required power and power loading change rate, and controlling the air metering ratio of the air compressor, the target value of the hydrogen-air pressure difference, the working energy threshold of the drain valve and the drain valve according to the size of the performance coefficient. opening time.

The load shedding control process includes: controlling the deceleration slope of the air compressor and the working state of the drain valve through the power shedding rate of change, discharging excess water, and maintaining a stable hydrogen-air pressure difference.

As an optional technical solution of the present application, the loading control process includes:

S100, according to the required power of the fuel cell system and the power load change rate query logic table to determine that the coefficient of performance is 1, 2 or 3, when the coefficient of performance is 1, go to step S110; when the coefficient of performance is 2, go to step S120; When the performance coefficient is 3, go to step S130;

S110, increasing the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, maintaining the working energy threshold of the drain valve and the opening time of the drain valve in a normal working state, and entering step S111;

S111, query the logic table to re-determine the coefficient of performance and determine whether the coefficient of performance is maintained, and in response to the judgment result that the coefficient of performance is maintained, return to step S110, and in response to the judgment result that the coefficient of performance is not maintained, end the process;

S120, increasing the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, lowering the working energy threshold of the drain valve and prolonging the opening time of the drain valve, and proceeding to step S121;

S121, query the logic table to re-determine the coefficient of performance and determine whether the coefficient of performance is maintained, in response to the judgment result that the coefficient of performance is maintained, return to step S120, and in response to the result of the judgment that the coefficient of performance is not maintained, end the process;

S130, increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, lower the working energy threshold of the drain valve, open the drain valve immediately and prolong the opening time of the drain valve;

S131 , query the logic table to re-determine the performance coefficient and determine whether the performance coefficient is maintained, and return to step S130 in response to the judgment result that the performance coefficient is maintained, and end the process in response to the judgment result that the performance coefficient is not maintained.

As an optional technical solution of the present application, in step S100, the query rule of the logic table is:

When the required power is 10-30% of the rated power, and the power load change rate is less than or equal to 10kw/s, the performance coefficient is determined to be 1;

When the required power is 10-30% of the rated power, and 10kw/s < power load change rate ≤ 20kw/s, the performance coefficient is determined to be 2;

When the required power is 30-60% of the rated power, and the power loading change rate is less than or equal to 5kw/s, the performance coefficient is determined to be 1;

When the required power is 30-60% of the rated power, and 5kw/s < power load change rate ≤ 10kw/s, the performance coefficient is determined to be 2;

When the required power is 30-60% of the rated power, and 10kw/s < power loading change rate ≤ 20kw/s, the performance coefficient is determined to be 3;

When the required power is 60% to 100% of the rated power, and the power load change rate is within the range of ≤5kw/s, the performance coefficient is determined to be 2;

When the required power is 60-100% of the rated power, and the range of 5kw/s < power load change rate ≤ 20kw/s, the performance coefficient is determined to be 3.

This application comprehensively considers the required power and the power load change rate of the fuel cell system, and constructs the performance coefficient, which reflects the driving intention of the driver of the vehicle, and establishes the required power and power load change rate and performance coefficient. The logical relationship between them, based on the logical relationship, a logical table is designed, which is divided into three levels according to the required power, namely low power state (10-30% of rated power, including 10% but not including 30%), medium power Power state (30 to 60% of rated power, including 30% but not including 60%) and high power state (60 to 100% of rated power, including 60% but not including 100%); The actual power and loading time are calculated to calculate the power loading change rate (power loading change rate = (required power - actual power)/loading time), and then divided into three grades according to the size of the power loading change rate, respectively, the power change is gentle (power Loading change rate≤5kw/s), moderate power change (5kw/s<power loading change rate≤10kw/s) and power change urgent (10kw/s<power loading change rate≤20kw/s). The coefficient of performance is determined by querying the logic table according to the three levels of the required power and the three levels of the power load change rate.

As an optional technical solution of the present application, in step S110, the air metering ratio of the air compressor is increased by 20-40%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26% %, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40% but not limited to those listed value, other non-recited values within this value range also apply.

Optionally, the target value of the hydrogen-air pressure difference is increased to 1.5-3.5 bar, for example, it can be 1.5 bar, 1.6 bar, 1.7 bar, 1.8 bar, 1.9 bar, 2.0 bar, 2.1 bar, 2.2 bar, 2.3 bar, 2.4bar, 2.5bar, 2.6bar, 2.7bar, 2.8bar, 2.9bar, 3.0bar, 3.1bar, 3.2bar, 3.3bar, 3.4bar or 3.5bar, but not limited to the listed values, other values within the range The same applies to non-recited values.

Optionally, under normal working conditions, the working energy threshold of the drain valve is maintained at 300-900kJ, for example, it can be 300kJ, 350kJ, 400kJ, 450kJ, 500kJ, 550kJ, 600kJ, 650kJ, 700kJ, 750kJ, 800kJ, 850kJ or 900kJ, but is not limited to the recited values, other unrecited values within this range of values also apply.

Optionally, under normal working conditions, the opening time of the drain valve is maintained at 0.1-2s, such as 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, 0.7s, 0.8s, 0.9s s, 1.0s, 1.1s, 1.2s, 1.3s, 1.4s, 1.5s, 1.6s, 1.7s, 1.8s, 1.9s or 2.0s, but not limited to the recited values, other The values listed also apply.

It should be noted that the conventional drainage scheme mainly controls the opening or closing of the drainage valve according to the water production of the stack. When the energy integral reaches the upper limit energy threshold of the stack water storage, the drainage valve is opened. When the energy integral is less than or equal to the stack storage When the water volume upper limit energy threshold is reached, the drain valve is closed. However, the water production of the stack itself is related to the energy integral of the product of the actual current and voltage of the stack, and the upper limit energy threshold of the water storage capacity of the stack is related to the characteristics of the stack itself. The process parameters are limited, so the opening time of the drain valve cannot be limited. In addition, when the drain valve is opened, the opening time is related to the hydrogen pressure. When the hydrogen pressure is higher, the drainage time is shorter, and when the hydrogen pressure is lower, the drainage time is longer.

As an optional technical solution of the present application, in step S120, the air metering ratio of the air compressor is increased by 20-40%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26% %, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40% but not limited to those listed value, other non-recited values within this value range also apply.

Optionally, the working energy threshold of the drain valve is reduced to 100-300kJ, such as 100kJ, 110kJ, 120kJ, 130kJ, 140kJ, 150kJ, 160kJ, 170kJ, 180kJ, 190kJ, 200kJ, 210kJ, 220kJ, 230kJ, 240kJ , 250kJ, 260kJ, 270kJ, 280kJ, 290kJ or 300kJ, but are not limited to the recited values, and other unrecited values within this range of values are also applicable.

Optionally, the opening time of the drain valve is extended to 2-4s, for example, it can be 2.0s, 2.1s, 2.2s, 2.3s, 2.4s, 2.5s, 2.6s, 2.7s, 2.8s, 2.9s, 3.0s, 3.1s, 3.2s, 3.3s, 3.4s, 3.5s, 3.6s, 3.7s, 3.8s, 3.9s or 4.0s, but not limited to the listed values, other values not listed within the range The same applies to numerical values.

As an optional technical solution of the present application, in step S130, the air metering ratio of the air compressor is increased by 20-40%, for example, it can be 20%, 21%, 22%, 23%, 24%, 25%, 26% %, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40% but not limited to those listed value, other non-recited values within this value range also apply.

Optionally, the threshold value of the working energy of the drain valve is reduced to 100kJ to 300kJ, such as 100kJ, 110kJ, 120kJ, 130kJ, 140kJ, 150kJ, 160kJ, 170kJ, 180kJ, 190kJ, 200kJ, 210kJ, 220kJ, 230kJ, 240kJ , 250kJ, 260kJ, 270kJ, 280kJ, 290kJ or 300kJ, but are not limited to the recited values, and other unrecited values within this range of values are also applicable.

As an optional technical solution of the present application, the load shedding control process includes:

S200, reduce the output power according to the required power of the fuel cell system and calculate the power load shedding change rate, and logically determine whether the power load shedding change rate is lower than the power load shedding change rate threshold, and respond that the power load shedding change rate is lower than the power load shedding change rate In response to the judgment result of the power load shedding rate threshold, go to step S210, and in response to the judgment result that the power load shedding change rate is higher than or equal to the power load shedding change rate threshold, go to step S220;

S210, the deceleration slope of the air compressor is slowed down, and the slowing down process of the deceleration slope is timed, and when the timing time reaches the preset drainage time, go to step S211;

S211, logically determine whether the hydrogen-air pressure difference is higher than the pressure difference threshold, in response to the judgment result that the hydrogen-air pressure difference is higher than the pressure difference threshold, go to step S212, in response to the judgment result that the hydrogen-air pressure difference is lower than or equal to the pressure difference threshold , enter step S213;

S212, open the drain valve of the fuel cell system, and return to step S211 after discharging excess water;

S213. After the delay for a specific time, the air compressor reduces the load according to the normal deceleration slope until the required power is reached, and the process ends;

S220, the air compressor sheds the load according to the normal deceleration slope until the required power is reached, and the process ends.

As an optional technical solution of the present application, in step S200, the threshold value of the power load shedding change rate is -3kw/s.

Optionally, in step S210, the deceleration slope of the air compressor is slowed down to -500rpm/s.

Optionally, the slowing down process of the deceleration slope of the air compressor is maintained for 2-5s, for example, it can be 2.0s, 2.2s, 2.4s, 2.6s, 2.8s, 3.0s, 3.2s, 3.4s, 3.6s s, 3.8s, 4.0s, 4.2s, 4.4s, 4.6s, 4.8s or 5.0s, but are not limited to the recited values, and other non-recited values within this range of values also apply.

It should be noted that the maintenance time of the slowdown process of the air compressor deceleration slope is related to the stack power. The higher the stack power, the longer the duration of the slowdown process of the deceleration slope. For example, when the stack power is When the rated power is 10 to 100%, the time for the slowdown process of the deceleration slope to be maintained is 2 to 5 s. However, it does not mean that other possible maintenance times are not within the scope of protection and disclosure of the present application, and the maintenance time needs to be appropriately selected by those skilled in the art according to different stack characteristics.

As an optional technical solution of the present application, in step S211, the pressure difference threshold is 0.5 bar.

Optionally, in step S213, the specific time is 3 to 8s, such as 3s, 4s, 5s, 6s, 7s or 8s, but not limited to the listed values, and other unlisted values within the value range The same applies to numerical values.

As an optional technical solution of the present application, in steps S213 and S220, the normal deceleration slope matches the power load shedding change rate, and the upper limit of the normal deceleration slope is the upper limit of the air compressor deceleration.

It should be noted that the normal deceleration slope referred to in this application is a non-fixed value, which is related to the change rate of power load shedding and the upper limit of the air compressor deceleration. Reasonable selection, first of all, the normal deceleration slope should meet the power load shedding change rate of the stack, and match the power load shedding change rate of the stack, and at the same time, it should not exceed the deceleration upper limit of the air compressor. The upper limit of the deceleration is related to the characteristics of the air compressor itself. This application does not limit the characteristics and required power of the stack and the air compressor. Therefore, it is inconvenient and cannot make limitations and special requirements.

The system refers to an equipment system, a plant system or a production plant.

In the process of loading control, the application comprehensively considers the required power of the fuel cell system and the rate of change of power loading, and constructs a coefficient of performance, which reflects the driving intention of the driver of the vehicle, and establishes the required power and power The logical relationship between the loading change rate and the coefficient of performance. Based on this logical relationship, a logic table is designed. The operator can determine the coefficient of performance through a simple table look-up operation according to the required power and the rate of change of power loading, and then adjust the hydrogen supply pressure according to the coefficient of performance. , drain valve and air compressor control commands to control, to meet the fuel cell system in the case of fast power response in the cell stack voltage distribution consistency, effectively solve the dynamic loading process, the uneven distribution of hydrogen pressure in the stack, air Insufficient flow and excessive instantaneous water production cause local flooding and other problems.

In the process of load shedding control, the power shedding rate of change of the fuel cell system controls the deceleration slope of the air compressor to slow down and discharge excess water. At the same time, by opening the drain valve in time, the stability of the hydrogen-air pressure difference is ensured, which effectively improves the risk of excessive hydrogen-air pressure difference caused by the sudden increase of hydrogen pressure when the load decreases instantaneously.

Description of drawings

FIG. 1 is a control flow chart of a fuel cell system loading process provided by a specific embodiment of the present application;

FIG. 2 is a control flow chart of a load shedding process of a fuel cell system according to an embodiment of the present application.

detailed description

The technical solutions of the present application will be described below with reference to the accompanying drawings and through specific embodiments.

In a specific embodiment, the present application provides a dynamic control method of a fuel cell system, including a loading control process and a load shedding control process.

The loading control process is shown in FIG. 1 and includes control steps S100 to S131.

S100. Determine the coefficient of performance according to the required power of the fuel cell system and the power load change rate query logic table, and the query rule is:

When the demanded power is 10-30% of the rated power, it is defined as a low-power state; when the demanded power is 30-60% of the rated power, it is defined as a medium-power state; when the demanded power is 60-100% of the rated power, it is defined as for high power state;

When the power loading change rate is less than or equal to 5kw/, it is defined as a smooth power change; when 5kw/s < power loading change rate ≤ 10kw/s, it is defined as a moderate power change; when 10kw/s < power loading change rate ≤ 20kw/s When , it is defined as urgent power change, and the selection of performance coefficient follows the query rules in the following logic table:

	低功率low power	中功率medium power	高功率high power
功率变化平缓Smooth power changes	11	11	22
功率变化适中Moderate power variation	11	22	33
功率变化紧急power change emergency	22	33	33

The performance coefficient is obtained by looking up the table. When the performance coefficient is 1, go to step S110; when the performance coefficient is 2, go to step S120; when the performance coefficient is 3, go to step S130;

S110. Increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference. The air metering ratio of the air compressor is increased by 20-40%, and the target value of the hydrogen-air pressure difference is increased to 1.5-3.5 bar. The working energy threshold of the drain valve and The opening time of the drain valve is maintained in a normal working state. Under the normal working state, the threshold value of the working energy of the drain valve is maintained at 300-900kJ, and the opening time of the drain valve is maintained at 0.1-2s, and the process proceeds to step S111;

S120. Increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, increase the air metering ratio of the air compressor by 20-40%, increase the target value of the hydrogen-air pressure difference to 1.5-3.5 bar, and reduce the working energy threshold of the drain valve And prolong the opening time of the drain valve, the working energy threshold of the drain valve is reduced to 100-300kJ, and the opening time of the drain valve is extended to 2-4s, and the process goes to step S121;

S130. Increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, increase the air metering ratio of the air compressor by 20-40%, increase the target value of the hydrogen-air pressure difference to 1.5-3.5 bar, and reduce the working energy threshold of the drain valve , the drain valve is opened immediately and the opening time of the drain valve is extended, the working energy threshold of the drain valve is reduced to 100-300kJ, the opening time of the drain valve is extended to 2-4s, and the process goes to step S131;

The load shedding control process is shown in FIG. 2 and includes control steps S200 to S220.

S200, reduce the output power according to the required power of the fuel cell system and calculate the power load shedding change rate, and logically determine whether the power load shedding change rate is lower than the power load shedding change rate threshold (-3kw/s), and respond to the power load shedding change rate If the judgment result is lower than the power load shedding change rate threshold, go to step S210, and in response to the judgment result that the power load shedding change rate is higher than or equal to the power load shedding change rate threshold, go to step S220;

S210, the deceleration slope of the air compressor is slowed down to -500rpm/s, and the deceleration process of the deceleration slope is timed for 2 to 5s, and when the timing time reaches the preset drainage time, go to step S211;

S211, logically determine whether the hydrogen-air pressure difference is higher than the pressure difference threshold (0.5bar), in response to the judgment result that the hydrogen-air pressure difference is higher than the pressure difference threshold, go to step S212, in response to the hydrogen-air pressure difference being lower than or equal to the pressure difference The judgment result of the threshold value goes to step S213;

S212, open the drain valve of the fuel cell system, and after discharging excess water, return to step S211;

S213. After a specific time delay, the air compressor reduces the load output according to the normal deceleration slope. The normal deceleration slope matches the power load reduction change rate. The upper limit of the normal deceleration slope is the upper limit of the air compressor deceleration until it reaches demand power, end the process;

S220. The air compressor sheds the load according to the normal deceleration slope. The normal deceleration slope matches the power load shedding change rate. The upper limit of the normal deceleration slope is the upper limit of the air compressor deceleration until the required power is reached, and the process ends. .

Example 1

This embodiment provides a loading control process for a fuel cell, and the loading control process includes the following control steps:

(1) Determine the coefficient of performance according to the required power of the fuel cell system and the power load change rate query logic table, and the query rules are:

After looking up the table, determine that the coefficient of performance is 2, and go to step (2);

(2) Increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, increase the air metering ratio of the air compressor by 30%, increase the target value of the hydrogen-air pressure difference to 2bar, reduce the working energy threshold of the drain valve and extend the drain valve. Opening time, the threshold value of the working energy of the drain valve is reduced to 200kJ, the opening time of the drain valve is extended to 3s, and the process goes to step (3);

(3) Querying the logic table to re-determine the performance coefficient and determine whether the performance coefficient is maintained, after the judgment, it is determined that the performance coefficient is not maintained, and the process is terminated.

Example 2

low power

medium power

high power

功率变化平缓Smooth power changes	11	11	22
功率变化适中Moderate power variation	11	22	33
功率变化紧急power change emergency	22	33	33

Look up the table to determine that the coefficient of performance is 3, and go to step (2);

(2) Increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, increase the air metering ratio of the air compressor by 40%, increase the target value of the hydrogen-air pressure difference to 3bar, reduce the working energy threshold of the drain valve, and the drain valve immediately Open and prolong the opening time of the drain valve, the working energy threshold of the drain valve is reduced to 300kJ, and the opening time of the drain valve is extended to 4s, and then go to step (3);

(3) Query the logic table to re-determine the coefficient of performance and determine whether the coefficient of performance is maintained. After the judgment, it is determined that the coefficient of performance is maintained. Return to step (2), increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, and lower the drain valve. Working energy threshold, the drain valve is opened immediately and the opening time of the drain valve is extended, and the process goes to step (4);

(4) Query the logic table again to re-determine the performance coefficient and determine whether the performance coefficient is maintained. After the judgment, it is determined that the performance coefficient is not maintained, and the process ends.

Example 3

This embodiment provides a load shedding control process for a fuel cell, and the control process includes the following control steps:

(1) Reduce the output power according to the required power of the fuel cell system and calculate the power load shedding change rate, and logically determine whether the power load shedding change rate is lower than the power load shedding change rate threshold (-3kw/s), and determine the power reduction after the judgment. If the load change rate is higher than or equal to the power load shedding change rate threshold, go to step (2);

(2) The air compressor reduces the load output according to the normal deceleration slope. The normal deceleration slope matches the power deceleration rate of change. The upper limit of the normal deceleration slope is the upper limit of the air compressor deceleration until the required power is reached, and the end process.

Example 4

(1) Reduce the output power according to the required power of the fuel cell system and calculate the power load shedding change rate, and logically determine whether the power load shedding change rate is lower than the power load shedding change rate threshold (-3kw/s), and determine the power reduction after the judgment. If the load change rate is lower than the power load shedding change rate threshold, go to step (2);

(2) Slow down the deceleration slope of the air compressor to -500rpm/s, time the deceleration process of the deceleration slope for 3s, and enter step (3) when the timing time reaches the preset drainage time;

(3) Logically judge whether the hydrogen-air pressure difference is higher than the pressure difference threshold (0.5bar), after the judgment, determine that the hydrogen-air pressure difference is higher than the pressure difference threshold, and enter step (4);

(4) Open the drain valve of the fuel cell system, after the excess water is discharged, return to step (3), and judge again whether the hydrogen-air pressure difference is higher than the pressure difference threshold (0.5bar), and determine that the hydrogen-air pressure difference is lower than or equal to Differential pressure threshold, enter step (5);

(5) After a specific time delay, the air compressor reduces the load output according to the normal deceleration slope. The normal deceleration slope matches the power load shedding change rate. The upper limit of the normal deceleration slope is the upper limit of the air compressor deceleration until When the required power is reached, the process ends.

.

Claims

A dynamic control method for a fuel cell system, including a loading control process and a load shedding control process;

The loading control process includes: querying the logic table according to the required power and the power loading change rate to determine the coefficient of performance, and feedback control of the air metering ratio of the air compressor, the target value of the hydrogen-air pressure difference, the working energy threshold of the drainage valve and the drainage according to the size of the performance coefficient. valve opening time;

The load shedding control process includes: feedback control of the deceleration slope of the air compressor and the working state of the drain valve according to the magnitude of the power shedding change rate, so as to discharge excess water and maintain a stable hydrogen-air pressure difference.
The dynamic control method according to claim 1, wherein the loading control process comprises:

According to the demand power of the fuel cell system and the power load change rate, query the logic table to determine the coefficient of performance to be 1, 2 or 3;

When the performance coefficient is 1, increase the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, maintain the normal working state of the drain valve working energy threshold and the drain valve opening time, and query the logic table to re-determine the performance coefficient and judge the performance. Whether the coefficient is maintained, in response to the judgment result that the performance coefficient is not maintained, end the process; in response to the judgment result of the performance coefficient maintaining, return to continue to execute the target value of the air metering ratio and hydrogen-air pressure difference of the boosting air compressor, and the working energy threshold of the drain valve and the opening time of the drain valve to maintain the normal working state, query the logic table to re-determine the coefficient of performance and determine whether the coefficient of performance is maintained;

When the performance coefficient is 2, increase the air metering ratio of the air compressor and the target value of hydrogen-air pressure difference, reduce the working energy threshold of the drain valve and prolong the opening time of the drain valve, query the logic table to re-determine the performance coefficient and judge whether the performance coefficient is Maintain, in response to the judgment result that the coefficient of performance is not maintained, end the process; in response to the judgment result of maintaining the coefficient of performance, return to continue to improve the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, reduce the working energy threshold of the drain valve and Extend the opening time of the drain valve, query the logic table to re-determine the coefficient of performance and determine whether the coefficient of performance is maintained;

When the coefficient of performance is 3, increase the air metering ratio of the air compressor and the target value of hydrogen-air pressure difference, reduce the working energy threshold of the drain valve, open the drain valve immediately and prolong the opening time of the drain valve, and query the logic table to re-determine the performance coefficient And judge whether the performance coefficient is maintained, and end the process in response to the judgment result that the performance coefficient is not maintained; in response to the judgment result of maintaining the performance coefficient, return to continue to improve the air metering ratio of the air compressor and the target value of the hydrogen-air pressure difference, and reduce the drainage The valve working energy threshold, the drain valve is opened immediately and the opening time of the drain valve is extended, and the logic table is inquired to re-determine the performance coefficient and determine whether the performance coefficient is maintained.
The dynamic control method according to claim 2, wherein the query rule of the logic table is:

When the required power is 10-30% of the rated power, and the power loading change rate is less than or equal to 10kw/s, the performance coefficient is determined to be 1;

When the required power is 10% to 30% of the rated power, and 10kw/s < power load change rate ≤ 20kw/s, the performance coefficient is determined to be 2;

When the required power is 30-60% of the rated power, and the power load change rate is less than or equal to 5kw/s, the performance coefficient is determined to be 1;

When the required power is 30% to 60% of the rated power, and 5kw/s < power load change rate ≤ 10kw/s, the performance coefficient is determined to be 2;

When the required power is 30% to 60% of the rated power, and 10kw/s < power load change rate ≤ 20kw/s, the performance coefficient is determined to be 3;

When the required power is 60-100% of the rated power, and the power loading change rate is less than or equal to 5kw/s, the performance coefficient is determined to be 2;

In the case that the required power is 60-100% of the rated power, and 5kw/s<power loading change rate≤20kw/s, the coefficient of performance is determined to be 3.
The dynamic control method according to claim 2 or 3, wherein when the performance coefficient is 1, the air metering ratio of the air compressor is increased by 20-40%;

The target value of the hydrogen-air pressure difference is raised to 1.5-3.5 bar;

Under normal working conditions, the working energy threshold of the drain valve is maintained at 300-900kJ;

Under normal working conditions, the opening time of the drain valve is maintained at 0.1-2s.
The dynamic control method according to any one of claims 2-4, wherein, when the coefficient of performance is 2, the air metering ratio of the air compressor is increased by 20-40%;

The target value of the hydrogen-air pressure difference is raised to 1.5-3.5 bar;

The working energy threshold of the drain valve is reduced to 100-300kJ;

The opening time of the drain valve is extended to 2-4s.
The dynamic control method according to any one of claims 2-5, wherein, when the coefficient of performance is 3, the air metering ratio of the air compressor is increased by 20-40%;

The target value of the hydrogen-air pressure difference is raised to 1.5-3.5 bar;

The working energy threshold of the drain valve is reduced to 100-300kJ;

The opening time of the drain valve is extended to 2-4s.
The dynamic control method according to claim 1, wherein the load shedding control process comprises:

Reduce the output power according to the required power of the fuel cell system and calculate the power load shedding change rate to determine whether the power load shedding change rate is lower than the threshold value of the power load shedding change rate;

In response to the judgment result that the power load shedding change rate is lower than the power load shedding change rate threshold, the deceleration slope of the air compressor is slowed down, and the slowdown process of the deceleration slope is timed. When the timing time reaches the preset drainage time, the logic judgment Whether the hydrogen-air pressure difference is higher than the pressure difference threshold, in response to the judgment result that the hydrogen-air pressure difference is lower than or equal to the pressure difference threshold, after a delay of a certain time, the air compressor will reduce the load according to the normal deceleration slope until the required power is reached. , end the process; in response to the judgment result that the hydrogen-air pressure difference is higher than the pressure difference threshold, open the drain valve of the fuel cell system, after the excess water is discharged, return to continue to execute the step of judging whether the hydrogen-air pressure difference is higher than the pressure difference threshold;

In response to the judgment result that the power load shedding change rate is higher than or equal to the threshold value of the power load shedding change rate, the air compressor reduces the load according to the normal deceleration slope until the required power is reached, and the process ends.
The dynamic control method according to claim 7, wherein the power load shedding change rate threshold is -3kw/s;

The deceleration slope of the air compressor is slowed down to -500rpm/s;

The slowing down process of the deceleration slope of the air compressor is maintained for 2-5s;
The dynamic control method according to claim 7 or 8, wherein the pressure difference threshold is 0.5 bar;

The specific time is 3-8s.
The dynamic control method according to any one of claims 7-9, wherein the normal deceleration slope matches the power load shedding change rate, and the upper limit of the normal deceleration slope is the upper limit of the air compressor deceleration.