CN112652794B - Cathode open type fuel cell thermal management system and method using time lag information - Google Patents

Abstract

The invention relates to a cathode open type fuel cell heat management system and method using time lag information.A galvanic pile temperature dynamic description model considering the relation between the voltage and the water content of a fuel cell galvanic pile is established in the system, and the temperature of the fuel cell galvanic pile is controlled by combining a fuel cell galvanic pile temperature and change rate observation system thereof and using the time lag information; the fuel cell stack temperature and change rate observation system is used for estimating the fuel cell stack temperature and change rate thereof, the fuel cell thermal management controller is designed through time lag information of measurable physical quantities in a temperature dynamic description model, uncertainty of a fuel cell thermal model and known interference and unknown disturbance including ambient temperature and working current are eliminated, the fuel cell thermal management controller is combined with the fuel cell stack temperature and change rate observation system to accurately estimate the fuel cell stack temperature and change rate thereof under noise interference, and influence of temperature measurement noise on thermal stability is reduced so as to better control the stack temperature.

Description

A thermal management system and method for an open-cathode fuel cell utilizing time-lag information

technical field

The invention relates to the field of fuel cell heat management, in particular to a cathode open fuel cell heat management system and method using time-lag information.

Background technique

At present, global energy and environmental problems are becoming more and more serious, and countries all over the world are actively seeking solutions, and the purpose of vigorously promoting new energy vehicles in the automotive field is exactly the same. There are different types of new energy vehicles. Among them, fuel cell vehicles can not only completely replace fuel in fuel, but also have "zero emissions", high energy conversion efficiency, diverse fuel sources, and flexible renewable energy sources. Therefore, it is considered to be one of the important directions to realize the sustainable development of the automobile industry in the future, and also one of the ideal solutions to solve global energy and environmental problems.

A fuel cell is an energy conversion device that converts the chemical energy of fuel and oxidant into electrical energy by electrochemical reaction. At present, a variety of high-performance fuel cell vehicle products around the world have initially entered the stage of commercial application. Among them, proton exchange membrane fuel cells have the advantages of high specific power, fast start-up, non-corrosiveness, low reaction temperature, and low oxidant demand, and are currently the first choice for fuel cell vehicles. Among them, the cathode open proton exchange mode fuel cell has a minimal auxiliary system, which is very suitable for portable mobile power applications. However, the suitable working temperature range of proton exchange membrane is relatively narrow. If the stack temperature is too low, the evaporation of water in the proton exchange membrane will be reduced, resulting in slower electrochemical reaction rate and lower battery performance. However, if the temperature of the stack is too high, the water in the proton exchange membrane will evaporate excessively, resulting in a decrease in humidity, which will not only reduce the proton conductivity, but also damage the proton exchange membrane.

Therefore, the correct control strategy can provide a suitable working temperature for the proton exchange membrane fuel cell. This is very important for improving the power and prolonging the life of the fuel cell, and it is also a problem that those skilled in the art need to solve at present.

Contents of the invention

In view of this, the object of the present invention is to provide a cathode open fuel cell thermal management system and method using time-lag information, so as to realize effective thermal management of the fuel cell.

The present invention is realized by the following scheme: a cathode open fuel cell thermal management system utilizing time-delay information, including an open cathode fuel cell, an external load, a PC upper computer, an Arduino Nano development board, a temperature sensor, and a DC motor PWM speed regulation module and a DC fan group; the cathode open fuel cell is connected with an external load to supply power for the external load; the temperature sensor is used to read the temperature information of the cathode open fuel cell; the ArduinoNano development board is connected with The temperature sensor is connected with the host computer, in order to upload the temperature information read by the temperature sensor to the PC host computer through the Arduino Nano development board for real-time monitoring, and through the PC host computer will bring The controller calculation program of time-delay information is downloaded to the Arduino Nano development board to calculate the control rate in real time; the Arduino Nano development board is also connected with the DC motor PWM speed regulation module, and the DC motor PWM speed regulation module is also Connected with the DC fan group, it is used to transmit the control rate calculated in real time by the Arduino Nano development board to the DC motor PWM speed regulation module to control the speed of the DC fan group, and then effectively control the stack temperature to achieve Fuel cell thermal management.

Further, the temperature sensor is a miniature thermocouple.

Further, the PWM speed regulation module of the DC motor adopts a speed regulation module whose model is XH-M222.

Further, the present invention also provides a method for thermal management of an open-cathode fuel cell using time-lag information, comprising the following steps:

Step S1: Aiming at the thermal characteristics of the open-cathode fuel cell, build a dynamic description model of the stack temperature considering the relationship between the stack voltage and water content of the open-cathode fuel cell to describe the dynamic change characteristics of the stack temperature;

Step S2: Design the fuel cell stack thermal management controller by using the measurable physical quantities in the dynamic description model of the stack temperature, including the stack temperature and the time-delay information of the control input, and use the time-delay information to eliminate the uncertainty in the mathematical model of the fuel cell temperature and known and unknown disturbances including ambient temperature and operating current;

Step S3: Use the fuel cell stack temperature and its change rate observation system to estimate the fuel cell stack temperature and its change rate, and substitute the observed stack temperature and its change rate into the fuel cell stack thermal management controller control rate to reduce the effect of temperature measurement noise on the thermal stability of an open-cathode fuel cell.

Further, the relationship between the cathode open fuel cell stack voltage and water content in step S1 is:

Among them, V _act is the activation polarization voltage, R, a, n, and F are system constants, i _ref is the internal current density, T _ref is the reference ambient temperature, A _opt and S _opt are the optimum electrode surface roughness, respectively and optimal liquid water saturation, ΔG is the cell activation impedance.

Further, the dynamic description model of the cathode open fuel cell stack temperature in step S1 is:

和

分别为电堆热传递速率、总产热速率、辐射散热速率和对流散热速率。Among them, m _st and C _st are fuel cell stack mass and specific heat capacity respectively,

and

They are stack heat transfer rate, total heat production rate, radiation heat dissipation rate and convection heat dissipation rate.

Further, in step S2, the content of designing the thermal management controller of the fuel cell stack through the stack temperature dynamic description model including the stack temperature and the delay information of the control input is as follows:

Step Sa: write the fuel cell stack temperature dynamic description model as follows:

Among them, f(T _st (t), t) is the dynamic change function of the stack temperature, u(t) is the control input of the stack temperature, B(T _st (t), t) is the control input function, d(t) Control the amount of disturbance for the stack temperature;

f(T _st (t),t)＝-5.971824×10 ^-6 I _st T _st -2.932364×10 ^-6 T _st ² -2.38557×10 ^-3 T _st

B(T _st (t),t)＝(T _amb -T _st )/3137.4

u(t)＝64.92898u _fan ² +81.48939u _fan +3.9394

The working current I _st and the ambient temperature T _amb are the known disturbance quantities of the temperature control system, and d(t) is the unknown disturbance;

Step Sb: the selected temperature reference model according to the requirements of the performance index is:

Among them, M is an integer, r(t) is the tracking variable, T _ref (t) and T _m (t) are the tracking temperature and the reference model temperature, respectively;

得出初始控制率u₀(t)为：Step Sc: Find the u(t) of the control action to make the system state track the error e of the reference model state, satisfying the error dynamic equation

The initial control rate u ₀ (t) is obtained as:

_u0 (t)＝B ⁺ ( _Tst (t),t)(- _MTst (t)+ _MTref (t)-d(t));

Step Sd: Design an external disturbance observer based on time-delay information:

And substitute it into the initial control rate u ₀ (t) to get the control rate u ₁ (t) of the controller.

Further, the control rate u ₁ (t) in step Sd is:

为温度变化率时滞信息。where u ₁ (tL) is the control input delay information,

is the time-lag information of the temperature change rate.

Further, the fuel cell stack temperature and its change rate observation system described in step S3 is:

r(t)＝T_ref(t)，

和

分为T_st和

的观测值。in

r(t)= _Tref (t),

and

Divided into T _st and

observation value.

Further, the final control rate u(t) after substituting the observed stack temperature and its change rate time lag information into the control rate u ₁ (t) of the fuel cell stack thermal management controller in step S3 is:

u(t)=u(tL)+B ⁺ (z1(t), _t )(- _Mz1 (t)+ _MTref (t) _-z2 (tL)).

Where z ₁ (t) is the observed stack temperature, and z ₂ (tL) is the time-lag information of the observed stack temperature change rate. Compile the obtained final control rate and write it into the Arduino Nano development board to send the real-time calculated control rate to the DC motor PWM speed control module as a PWM signal to control the speed of the DC fan group to effectively control the stack temperature, and ultimately fuel cell thermal management.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The target of the present invention is the fuel cell. Since the fuel cell stack voltage changes with the water content of the fuel cell during the operation of the fuel cell, the temperature model of the fuel cell changes. Considering the water content when modeling the fuel cell stack temperature, a more accurate fuel cell temperature model can be established to achieve a more accurate control effect.

(2) The controller adopted in the present invention designs the fuel cell stack thermal management controller through the time-lag information of the measurable physical quantity (comprising the stack temperature and control input) in the dynamic description model of the stack temperature, and is effective by establishing a temperature reference model Eliminate the influence of system disturbance on the control effect, including known and unknown disturbances such as operating current and ambient temperature, and the controller can compensate system uncertainty, reducing the controller's requirements for the accuracy of the system model, showing excellent performance Dynamic control performance and robustness can well adapt to the nonlinear characteristics of fuel cells.

(3) The present invention uses the fuel cell stack temperature and its rate of change observation system to estimate the fuel cell stack temperature and its rate of change, and substitutes the observed stack temperature and its rate of change into the control rate of the fuel cell thermal management controller Among them, it can effectively reduce the influence of temperature measurement noise on the controller, increase the thermal stability of the fuel cell, and improve the anti-interference ability of the system.

Description of drawings

FIG. 1 is a schematic diagram of an open-cathode fuel cell thermal management method using time-lag information according to an embodiment of the present invention.

Fig. 2 is a change diagram of working current, water content and stack temperature in the fuel cell temperature dynamic description model of the embodiment of the present invention.

FIG. 3 is an effect diagram for controlling temperature under noise interference according to an embodiment of the present invention.

4 is a schematic diagram of the system of the embodiment of the present invention, wherein 1 is an open-cathode fuel cell, 2 is an external load, 3 is a temperature sensor, 4 is a DC motor PWM speed control module, and 5 is a DC fan group.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

It should be pointed out that the following detailed description is exemplary and intended to provide further explanation to the present application. 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 application belongs.

It should be noted that the terminology used here is only for describing specific implementations, and is not intended to limit the exemplary implementations according to the present application. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

As shown in Figure 4, this embodiment provides an open-cathode fuel cell thermal management system using time-lag information, including an open-cathode fuel cell 1, an external load 2, a PC host computer, an Arduino Nano development board, and a temperature sensor 3 , a DC motor PWM speed control module 4 and a DC fan group 5; the open-cathode fuel cell 1 is connected to an external load 2 to provide power for the external load; the temperature sensor 3 is used to read the open-cathode fuel cell 1 temperature information; the Arduino Nano development board is connected with the temperature sensor 3 and the host computer respectively, in order to upload the temperature information read by the temperature sensor 3 to the PC by the Arduino Nano development board The upper computer performs real-time monitoring, and downloads the controller calculation program with time lag information to the Arduino Nano development board to calculate the control rate in real time through the PC upper computer; the Arduino Nano development board is also connected with the DC motor The PWM speed control module 4 is connected, and the DC motor PWM speed control module 4 is also connected with the DC fan group 5, so as to transmit the control rate calculated in real time by the Arduino Nano development board to the DC motor PWM speed control module with a PWM signal. The DC fan group 5 performs rotational speed control, and then effectively controls the stack temperature to realize a cathode open fuel cell thermal management using time-lag information.

The specific principle is: the fan is the actuator of the cathode open fuel cell thermal management system, and the fan speed is the control input of the time-delay controller, which is the quantity to be controlled. The fan speed corresponds to the heat dissipation, so the speed of the fan group is calculated here Control is to control the temperature of the stack and then perform thermal management on the fuel cell.

In this embodiment, the temperature sensor 3 is a miniature thermocouple.

In this embodiment, the DC motor PWM speed regulation module 4 adopts a speed regulation module whose model is XH-M222.

As shown in FIG. 1 , this embodiment also provides a method for thermal management of an open-cathode fuel cell using time-lag information, including the following steps:

Step S1: The heat of the fuel cell mainly comes from the irreversible heat generated by the electrochemical reaction, and this part of the heat causes the temperature of the stack to change nonlinearly. This embodiment considers the thermal characteristics of the open-cathode fuel cell and builds a battery with an open-cathode fuel cell. The stack temperature dynamic description model of the relationship between the stack voltage and the water content is used to describe the dynamic change characteristics of the stack temperature;

Step S2: Design the fuel cell stack thermal management controller by using the measurable physical quantities in the dynamic description model of the stack temperature, including the stack temperature and the time-delay information of the control input, and use the time-delay information to eliminate the uncertainty in the mathematical model of the fuel cell temperature and known and unknown disturbances including ambient temperature and operating current;

The thermal model and temperature model of the fuel cell are the existing technical terms. The mathematical model of the fuel cell temperature described here can correspond to the dynamic description model of the open cathode fuel cell stack temperature established below. The dynamic description model of the temperature here is actually A mathematical model describing the temperature of a fuel cell.

Step S3: Use the fuel cell stack temperature and its change rate observation system to estimate the fuel cell stack temperature and its change rate, and substitute the observed stack temperature and its change rate into the fuel cell stack thermal management controller control rate to reduce the effect of temperature measurement noise on the thermal stability of an open-cathode fuel cell.

In this embodiment, the relationship between the cathode open fuel cell stack voltage and water content in step S1 is:

Among them, V _act is the activation polarization voltage, R, a, n, and F are system constants, i _ref is the internal current density, T _ref is the reference ambient temperature, A _opt and S _opt are the optimum electrode surface roughness, respectively and optimal liquid water saturation, ΔG is the cell activation impedance.

In this embodiment, the dynamic description model of the cathode open fuel cell stack temperature in step S1 is:

和

分别为电堆热传递速率、总产热速率、辐射散热速率和对流散热速率。Among them, m _st and C _st are fuel cell stack mass and specific heat capacity respectively,

and

They are stack heat transfer rate, total heat production rate, radiation heat dissipation rate and convection heat dissipation rate.

In this embodiment, the measurable physical quantities in the dynamic description model of the stack temperature described in step S2 include the stack temperature and the delay information of the control input to design the fuel cell stack thermal management controller as follows:

Step Sa: write the fuel cell stack temperature dynamic description model as follows:

Among them, f(T _st (t), t) is the dynamic change function of the stack temperature, u(t) is the control input of the stack temperature, B(T _st (t), t) is the control input function, d(t) Control the amount of disturbance for the stack temperature;

f(T _st (t),t)＝-5.971824×10 ^-6 I _st T _st -2.932364×10 ^-6 T _st ² -2.38557×10 ^-3 T _st

B(T _st (t),t)＝(T _amb -T _st )/3137.4

u(t)＝64.92898u _fan ² +81.48939u _fan +3.9394

The working current I _st and the ambient temperature T _amb are the known disturbance quantities of the temperature control system, and d(t) is the unknown disturbance;

Step Sb: the selected temperature reference model according to the requirements of the performance index is:

Among them, M is an integer, r(t) is the tracking variable, T _ref (t) and T _m (t) are the tracking temperature and the reference model temperature, respectively;

得出初始控制率u₀(t)为：Step Sc: Find the u(t) of the control action to make the system state track the error e of the reference model state, satisfying the error dynamic equation

The initial control rate u ₀ (t) is obtained as:

_u0 (t)＝B ⁺ ( _Tst (t),t)(- _MTst (t)+ _MTref (t)-d(t));

Step Sd: Design an external disturbance observer based on time-delay information:

And substitute it into the initial control rate u ₀ (t) to get the control rate u ₁ (t) of the controller.

In this embodiment, the control rate u ₁ (t) in step Sd is:

为温度变化率时滞信息。where u ₁ (tL) is the control input delay information,

is the time-lag information of the temperature change rate.

In this embodiment, the fuel cell stack temperature and its rate of change observation system described in step S3 is:

r(t)＝T_ref(t)，

和

分为T_st和

的观测值。in

r(t)= _Tref (t),

and

Divided into T _st and

observation value.

In this embodiment, the final control rate u(t) after substituting the observed stack temperature and its change rate time-lag information into the control rate u ₁ (t) of the fuel cell stack thermal management controller described in step S3 )for:

u(t)=u(tL)+B ⁺ (z1(t), _t )(- _Mz1 (t)+ _MTref (t) _-z2 (tL)).

Where z ₁ (t) is the observed stack temperature, z ₂ (tL) is the time-lag information of the observed stack temperature change rate; compile the obtained final control rate and write it into the Arduino Nano development board to The real-time calculated control rate is sent to the DC motor PWM speed control module as a PWM signal, and then the speed of the DC fan group is controlled to effectively control the stack temperature, and finally realize a cathode open fuel cell thermal management using time-delay information .

According to fuel cells of different power levels, based on the control rate of the thermal management controller designed in the present invention, the temperature of the fuel cell stack can be effectively and stably controlled at a suitable temperature reference value, so as to improve the stability and durability of the fuel cell operation.

In this embodiment, the designed control rate of the time-delay controller is used as the control input to control the temperature of the fuel cell stack at the set temperature reference value. The temperature of the fuel cell stack is effectively and stably controlled at an appropriate value to improve the stability and durability of the fuel cell operation.

Among them: different from the control rate u ₁ (t), the stack temperature information (stack temperature and its time-delay change rate) at this time uses the observed value of the observation system instead of the direct measurement information of the stack temperature. The reason is that if the temperature measurement There is noise, and the control rate with noise interference will affect the stack temperature control performance and fuel cell thermal stability.

Preferably, in this embodiment, the cathode open fuel cell is connected to the hydrogen tank through the gas supply valve, and the incompletely reacted gas is discharged into the atmosphere through the exhaust valve.

Preferably, in this embodiment, the Arduino Nano development board is connected to the PC host computer through the USB interface and performs signal transmission with the host computer and can download the controller calculation program with time lag information to the Arduino Nano development board Calculate the control rate in real time.

Preferably, in this embodiment, an H-1000 cathode open fuel cell with a rated power of 1kW is taken as an example, in order to control the speed of the cathode open fuel cell fan group, in the H-1000 cathode open fuel cell system A DC motor PWM speed control module is added to change the fan speed by modulating the PWM duty cycle. The DC motor PWM speed control module is XH-M222.

In this embodiment, the temperature sensor uses a miniature thermocouple and the detection head is arranged in the internal gas channel of the fuel cell stack with an open cathode, and the read temperature information is uploaded to the PC host computer through the Arduino Nano development board for further analysis. Real-time monitoring is carried out, and the Arduino Nano development board makes further calculations based on the temperature data read in real time.

In this embodiment, the Arduino Nano development board is connected to the PC host computer through the USB interface and performs signal transmission with the host computer. The PC host computer can download the controller calculation program with time lag information to the Arduino Nano development board for real-time calculation control rate. Described miniature thermocouple is connected with Arduino Nano development board analog interface (A), and DC motor PWM speed control module PWM input end is connected with Arduino Nano development board digital interface (D) so that the control rate calculated in real time by Arduino Nano development board is The pulse width modulation is used to control the speed of the DC fan group, and the power input terminal of the DC motor PWM speed control module needs to be connected to an external 13V DC power supply or battery to supply power to the DC fan group. The external load can be electrical equipment or a resistor, and its two ends are respectively connected to the positive and negative poles of the open-cathode fuel cell.

Preferably, this embodiment builds a temperature dynamic description model, especially considering the relationship between the stack voltage and water content of the open-cathode fuel cell, accurately describes the dynamic characteristics of the stack temperature, and describes the measurable physical quantities in the model through the dynamic description of the stack temperature (including stack temperature and control input) time-delay information to design fuel cell stack thermal management controller, the use of time-delay information can eliminate system modeling uncertainty and eliminate known disturbances including ambient temperature and operating current Unknown disturbance, and the fuel cell thermal management controller combined with the fuel cell stack temperature and its rate of change observation system can more accurately estimate the fuel cell stack temperature and its rate of change under noise interference, while reducing the temperature measurement The effect of noise on thermal stability and thus better control of the stack temperature.

Preferably, a specific example of this embodiment is as follows: Take a 1000W cathode open fuel cell as an example,

The open-cathode fuel cell stack is composed of multiple fuel cell cells connected in series, so the fuel cell stack voltage V _st can be described as follows

V _st ＝n _cell V _cell ＝n _cell (E _nernst (T _st )-V _act (T _st ,i _st ,s _CCL )-V _ohm (T _st ,i _st )-V _con (i _st ));

Among them, n _cell is the number of single fuel cells, V _cell is the voltage of single fuel cells, T _st is the stack temperature, _ist is the stack current, S _CCL is the water content of the cathode catalytic layer, E _nernst , V _act , V _ohm and V _con are the Nernst voltage, activation polarization voltage, ohmic polarization voltage and concentration polarization voltage respectively, described by the following formula

V _ohm (T _st ,i _st )=i _st (R _M (i _st ,T _st )+R _C );

V _con (i _st )=-Cln(1-i _st /i _max );

Among them, P _H2 is the pressure of hydrogen, P _O2 is the pressure of oxygen, R, a, n, C and F are system constants, R _M and R _C are the impedance when electrons and protons pass through the membrane respectively, i ₀ (T _st ,S _CCL ) is the exchange current density, determined by

Among them, R, a, n, and F are system constants, i _ref is the internal current density, T _ref is the reference ambient temperature, A _opt and S _opt are the optimum electrode surface roughness and optimum liquid water saturation, respectively, ΔG is the battery activation impedance.

Through the energy transfer equation, the fuel cell stack temperature dynamic description model can be obtained as

和

分别为电堆热传递速率、总产热速率、辐射散热速率和对流散热速率，采用以下公式描述Among them, m _st and C _st are fuel cell stack mass and specific heat capacity respectively,

and

are the stack heat transfer rate, total heat production rate, radiation heat dissipation rate and convective heat dissipation rate, described by the following formula

和

分别是氢气、氧气和水的质量比生成焓，Δh_H2、Δh_O2和Δh_H2O分别是氢气、氧气和水的质量比焓，h_nat和h_for分别是自然热对流系数和强制热对流系数，A_st、A_nat和A_for分别是电堆面积、自然热对流面积和强制热对流面积，ρ_air是空气密度，a₁、a₂、b₁和b₂是实验确定的常数，u_fan为散热风扇的控制电压。Wherein, T _amb is the ambient temperature, M _H2,rea , M _O2,rea and M _H2O,pro are the molar masses of hydrogen, oxygen and water respectively,

and

are the mass specific enthalpy of hydrogen, oxygen, and water, respectively, Δh _H2 , Δh _O2 , and Δh _H2O are the mass specific enthalpy of hydrogen, oxygen, and water, respectively, h _nat and h _for are the coefficients of natural heat convection and forced heat convection, respectively, A _st , A _nat and A _for are stack area, natural heat convection area and forced heat convection area respectively, ρ _air is air density, a ₁ , a ₂ , b ₁ and b ₂ are constants determined by experiments, u _fan is Cooling fan control voltage.

As shown in FIG. 2 , this embodiment presents a result graph describing the stack voltage, stack temperature and water content of a 1000W cathode open-type fuel cell by a fuel cell temperature dynamic description model.

In actual conditions, there is interference in physical quantities such as fuel cell current, voltage, and external temperature. In order to describe the fuel cell temperature more accurately, the fuel cell temperature dynamic description model is written as follows

in

f(T _st (t),t)＝-5.971824×10 ^-6 I _st T _st -2.932364×10 ^-6 T _st ² -2.38557×10 ^-3 T _st

B(T _st (t),t)＝(T _amb -T _st )/3137.4

u(t)＝64.92898u _fan ² +81.48939u _fan +3.9394

The operating current I _st and the ambient temperature T _amb are known disturbance quantities of the temperature control system, and d(t) is an unknown disturbance. According to the requirements of performance indicators, the selected reference model is

Wherein, M is a large integer, r(t) is a tracking variable, T _ref (t) and T _m (t) are tracking temperature and reference model temperature, respectively. Calculate the u(t) of the control action to make the system state track the error of the reference model state

e=T _m (t)-T _st (t);

satisfy the error dynamic equation

In order to simplify the design of the controller, take K=0. Substituting the tracking temperature and reference model temperature into the error formula, and comparing with the error dynamic equation, the initial control rate u ₀ (t) can be obtained as

u ₀ (t)＝B ⁺ (T _st (t),t)(-MT _st (t)+MT _ref (t)-d(t))

Among them, B ⁺ (T _st (t),t)=3137.4/(T _amb -T _st ) is the pseudo-inverse of B(T _st (t),t), and the following structural constraints must be satisfied to obtain a satisfactory error Dynamic performance and state tracking performance

(IB(T _st (t),t)B ⁺ (T _st (t),t))(-MT _st (t)+MT _ref (t)-d(t))=0;

Assuming that for a sufficiently small time L, the external disturbance of the system does not change much, the information of the past time t-L can be used to estimate the external disturbance at time t, and the external disturbance observer based on time-delay information is obtained as:

Substituting the external disturbance observer into the initial control rate u ₀ (t), the control rate u ₁ (t) of the controller is obtained as

进一步设计观测器如下In the process of actually controlling the temperature of the fuel cell, there is noise in the feedback information of the temperature sensor, which seriously affects the control effect of the controller. Therefore, the fuel cell temperature T _st and its change rate in the control rate of the controller

Further design the observer as follows

r(t)＝T_ref(t)，

和

分为T_st和

的观测值。in

r(t)= _Tref (t),

and

Divided into T _st and

observation value.

的观测值代入控制器的控制率u₁(t)中，得到观测后的最终控制率u(t)为Combine T _st and

The observed value of is substituted into the control rate u ₁ (t) of the controller, and the final control rate u(t) obtained after observation is

u(t)=u(tL)+B ⁺ (z ₁ (t),t)(-Mz ₁ (t)+MT _ref (t)-z ₂ (tL))

The control information output by the above controller is output to the PWM DC motor governor in the form of PWM waves, and the governor can realize the adjustment of the fan motor speed, thereby realizing the control of the cathode open fuel cell temperature.

As shown in FIG. 3 , in this embodiment, a graph of the control results of a 1000W open-cathode fuel cell under temperature measurement noise with constant tracking temperature is given.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (3)

1. A method for thermal management of an open cathode fuel cell using time-lag information, characterized in that: the method is implemented using a thermal management system, and the thermal management system includes an open cathode fuel cell, an external load, a PC host computer, ArduinoNano development board, temperature sensor, DC motor PWM speed control module and DC fan group; the open cathode fuel cell is connected with an external load to supply power for the external load; the temperature sensor is used to read the open cathode fuel cell The temperature information of the battery; the ArduinoNano development board is connected with the temperature sensor and the host computer respectively, so that the temperature information read by the temperature sensor is uploaded to the PC host computer by the ArduinoNano development board for real-time monitor, and download the controller calculation program with time lag information to the ArduinoNano development board to calculate the control rate in real time through the PC host computer; the ArduinoNano development board is also connected to the DC motor PWM speed regulation module, The DC motor PWM speed regulation module is also connected with the DC fan group, so as to transmit the control rate calculated in real time by the ArduinoNano development board to the DC motor PWM speed regulation module with a PWM signal to control the speed of the DC fan group, and then The temperature of the electric stack is effectively controlled to realize the thermal management of the fuel cell; the management method includes the following steps: Step S1: Aiming at the thermal characteristics of the open-cathode fuel cell, build a dynamic description model of the stack temperature considering the relationship between the fuel cell stack voltage and water content, to describe the dynamic change characteristics of the stack temperature; Step S2: Design the fuel cell stack thermal management controller by using the measurable physical quantities in the dynamic description model of the stack temperature, including the stack temperature and the time-delay information of the control input, and use the time-delay information to eliminate the uncertainty in the mathematical model of the fuel cell temperature and known and unknown disturbances including ambient temperature and operating current; Step S3: Use the fuel cell stack temperature and its change rate observation system to estimate the fuel cell stack temperature and its change rate, and substitute the observed stack temperature and its change rate into the fuel cell stack thermal management controller for control In order to reduce the influence of temperature measurement noise on the thermal stability of the open cathode fuel cell: The relationship between the cathode open fuel cell stack voltage and the water content in step S1 is: V _st ＝n _cell V _cell ＝n _cell (E _nernst (T _st )-V _act (T _st ,i _st ,s _CCL )-V _ohm (T _st ,i _st )-V _con (i _st )); Among them, n _cell is the number of fuel cell cells, V _cell is the fuel cell cell voltage, T _st is the stack temperature, _ist is the stack current, S _CCL is the water content of the cathode catalytic layer, E _nernst , V _act , V _ohm and V _con are the Nernst voltage, activation polarization voltage, ohmic polarization voltage and concentration polarization voltage, respectively, described by the following formula:

V _ohm (T _st ,i _st )=i _st (R _M (i _st ,T _st )+R _C ); V _con (i _st )=-Cln(1-i _st /i _max ); Among them, P _H2 is the pressure of hydrogen, P _O2 is the pressure of oxygen, R, a, n, C and F are system constants, R _M and R _C are the impedance when electrons and protons pass through the membrane respectively, i ₀ (T _st ,S _CCL ) is the exchange current density, determined by the following formula:

Among them, R, a, n, and F are system constants, i _ref is the internal current density, T _ref is the reference ambient temperature, A _opt and S _opt are the optimum electrode surface roughness and optimum liquid water saturation, respectively, ΔG is the battery activation impedance. 2. A method for thermal management of an open-cathode fuel cell using time-lag information according to claim 1, wherein the temperature sensor is a miniature thermocouple. 3. A method for thermal management of an open-cathode fuel cell using time-lag information according to claim 1, characterized in that: said DC motor PWM speed control module adopts a speed control module whose model is XH-M222.

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