Simulation method for fuel cell thermal management based on cascade PID control

Abstract

The application discloses a simulation method of fuel cell thermal management based on cascade PID control and specifically relates to the field of fuel cell control. The method comprises the following steps: constructing a stack thermal physical model, a cooling water thermal physical model, a radiator model and a water pump model, and acquiring a heat generation power, real-time temperatures of the two models and an ambient temperature; when the temperature of the stack is high, the water pump opening is increased; the cooling water heat dissipation is determined according to the temperature difference of the two models and a stack heat exchange coefficient; the real-time temperature of the stack is updated according to the heat generation power, the cooling water heat dissipation and a stack heat capacity parameter; when the temperature of the cooling water is high, the radiator opening is increased; the radiator heat dissipation is determined according to the temperature difference of the cooling water and the ambient and a radiator heat exchange coefficient; and the real-time temperature of the cooling water is updated according to the cooling water heat dissipation, the radiator heat dissipation and a cooling water heat capacity parameter. Based on the above method, the service life of the stack can be prevented from being shortened due to long-time overheating.

Description

Technical Field

[0001] This invention relates to the field of fuel cell control, and in particular to a simulation method for fuel cell thermal management based on cascade PID control. Background Technology

[0002] The optimal operating temperature for proton exchange membrane fuel cells (PEMFCs) is typically around 60°C. Excessive temperature can lead to membrane dehydration and catalyst degradation, while excessively low temperatures can negatively impact electrochemical reaction rates. Traditional thermal management often employs single-variable control (such as controlling only the fan or only the pump) or simple on / off control, making it difficult to achieve rapid and stable temperature regulation under drastic load changes. Furthermore, existing control schemes often neglect the smoothness of pump and fan operation, resulting in large fluctuations in energy consumption and severe mechanical wear. Summary of the Invention

[0003] The main objective of this application is to provide a simulation method for fuel cell thermal management based on cascade PID control, which aims to solve the problem that existing thermal management methods are difficult to achieve fast and stable temperature regulation.

[0004] To achieve the above objectives, this application provides a simulation method for fuel cell thermal management based on cascade PID control, comprising: constructing a fuel cell stack thermophysical model, a cooling water thermophysical model, a radiator model, and a water pump model, and obtaining the heat generation power of the fuel cell stack thermophysical model; obtaining a first real-time temperature of the fuel cell stack thermophysical model, a second real-time temperature of the cooling water thermophysical model, and the ambient temperature; comparing the first real-time temperature with a first target temperature, and when the first real-time temperature is higher than the first target temperature, outputting a command signal to increase the water pump opening of the water pump model; obtaining the current water pump opening, and determining the fuel cell stack heat transfer coefficient based on the water pump opening; determining the difference between the first real-time temperature and the second real-time temperature, and using it as the first temperature difference; determining the cooling water heat dissipation based on the fuel cell stack heat transfer coefficient and the first temperature difference; determining the difference between the heat generation power and the cooling water heat dissipation; and determining the fuel cell stack heating rate based on the difference and the fuel cell stack heat capacity parameters. The process involves updating the first real-time temperature based on the fuel cell stack heating rate, comparing it again with the first target temperature until the first real-time temperature is lower than or equal to the first target temperature; comparing the second real-time temperature with the second target temperature, and if the second real-time temperature is higher than the second target temperature, outputting a command signal to increase the heat dissipation opening of the radiator model and obtaining the current heat dissipation opening; determining the radiator heat transfer coefficient based on the heat dissipation opening; determining the difference between the second real-time temperature and the ambient temperature as the second temperature difference; determining the radiator heat dissipation based on the radiator heat transfer coefficient and the second temperature difference; determining the difference between the cooling water heat dissipation and the radiator heat dissipation, and determining the cooling water heating rate based on the difference and the cooling water heat capacity parameter; and updating the second real-time temperature based on the cooling water heating rate, comparing it again with the second target temperature until the second real-time temperature is lower than or equal to the first target temperature.

[0005] Optionally, the heat transfer coefficient of the fuel cell stack is determined based on the pump opening, including: determining the cooling water flow rate based on the pump opening; and determining the heat transfer coefficient of the fuel cell stack corresponding to the current cooling water flow rate based on the correspondence between the cooling water flow rate and the convective heat transfer coefficient.

[0006] Optionally, the cooling water heat dissipation is determined based on the heat transfer coefficient of the fuel cell stack and the first temperature difference, including determining the cooling water heat dissipation based on the product of the heat transfer coefficient of the fuel cell stack and the first temperature difference.

[0007] Optionally, the heat transfer coefficient of the radiator is determined based on the heat dissipation opening, including: determining the airflow through the radiator based on the heat dissipation opening; and determining the radiator heat transfer coefficient corresponding to the current radiator fan opening based on the correspondence between the airflow through the radiator and the radiator heat transfer coefficient.

[0008] Optionally, the heat dissipation of the radiator is determined based on the heat transfer coefficient of the radiator and the second temperature difference, including: determining the heat dissipation of the radiator based on the product of the heat transfer coefficient of the radiator and the second temperature difference.

[0009] To achieve the above objectives, this application also provides a simulation system for fuel cell thermal management based on cascade PID control, comprising: a model building module for building a fuel cell stack thermophysical model, a cooling water thermophysical model, a radiator model, and a water pump model; a step signal source module for acquiring the heat generation power of the fuel cell stack thermophysical model; a temperature acquisition module for acquiring a first real-time temperature of the fuel cell stack thermophysical model, a second real-time temperature of the cooling water thermophysical model, and the ambient temperature; a first PID controller module for comparing the first real-time temperature with a first target temperature, outputting an instruction signal to increase the water pump opening when the first real-time temperature is higher than the first target temperature, and acquiring the current water pump opening; a first heat transfer coefficient gain module for acquiring the current water pump opening and determining the fuel cell stack heat transfer coefficient based on the water pump opening; a heat exchange coupling module for determining the difference between the first real-time temperature and the second real-time temperature as a first temperature difference; determining the cooling water heat dissipation based on the fuel cell stack heat transfer coefficient and the first temperature difference; and determining the heat generation power and cooling water heat dissipation... The system comprises the following modules: a first gain module for determining the fuel cell stack heating rate based on the difference between the heat generation power and the cooling water heat dissipation, and the fuel cell stack heat capacity parameters; a first integrator module for updating the first real-time temperature based on the fuel cell stack heating rate; a second PID controller module for comparing the second real-time temperature with a second target temperature, and outputting an instruction signal to increase the heat dissipation opening of the radiator model when the second real-time temperature is greater than the second target temperature, and obtaining the current heat dissipation opening; a second heat transfer coefficient gain module for determining the radiator heat transfer coefficient based on the heat dissipation opening; a heat exchange coupling module for determining the difference between the second real-time temperature and the ambient temperature as the second temperature difference; determining the radiator heat dissipation based on the radiator heat transfer coefficient and the second temperature difference; determining the difference between the cooling water heat dissipation and the radiator heat dissipation; a second gain module for determining the cooling water heating rate based on the difference between the cooling water heat dissipation and the radiator heat dissipation, and the cooling water heat capacity parameters; and a second integrator module for updating the second real-time temperature based on the cooling water heating rate.

[0010] Optionally, the heat exchange coupling module includes: a first subtractor for determining the difference between a first real-time temperature and a second real-time temperature, and using it as the first temperature difference; a first multiplier for determining the cooling water heat dissipation based on the product of the stack heat transfer coefficient and the first temperature difference; a second subtractor for determining the difference between the heat generation power and the cooling water heat dissipation; a third subtractor for determining the difference between the second real-time temperature and the ambient temperature, and using it as the second temperature difference; a second multiplier for determining the radiator heat dissipation based on the product of the radiator heat transfer coefficient and the second temperature difference; and a fourth subtractor for determining the difference between the cooling water heat dissipation and the radiator heat dissipation.

[0011] Compared with the prior art, the beneficial effects of this application are as follows:

[0012] The present invention provides a simulation method for fuel cell thermal management based on cascade PID control. This method compares the real-time temperature of the fuel cell stack thermophysical model with the corresponding target temperature. When the target temperature is exceeded, a first temperature difference is determined, and the water pump opening is increased. The cooling water heat dissipation is determined based on the first temperature difference and the fuel cell stack heat transfer coefficient. The difference between the heat generation power and the cooling water heat dissipation is processed to obtain the adjusted real-time temperature of the fuel cell stack thermophysical model, thus achieving fuel cell stack thermal balance regulation in the main control loop. Furthermore, the method compares the real-time temperature of the cooling water thermophysical model with the corresponding target temperature. When the target temperature is exceeded, a second temperature difference is determined, and the heat dissipation opening is increased. The radiator heat dissipation is determined based on the second temperature difference and the radiator heat transfer coefficient. The difference between the radiator heat dissipation and the cooling water heat dissipation is processed. The system simulates the dynamic response of cooling water temperature to obtain the real-time temperature of the adjusted cooling water thermophysical model, thereby achieving cooling water thermal balance regulation in the secondary control loop. Through the synergistic effect of the dual closed-loop PID regulation of fuel cell stack thermal balance and cooling water thermal balance, the change curves of pump opening and fan opening exhibit a smooth "climbing-falling" characteristic, avoiding frequent start-stop and violent fluctuations of the actuator near steady state, and extending the mechanical life of the pump and fan. The secondary loop control strategy ensures that the cooling fan only intervenes when the cooling water temperature is too high, and the opening is automatically adjusted according to the actual temperature difference, significantly reducing the parasitic power consumption of the system compared to a constant-speed fan. It can stabilize the fuel cell stack temperature in a short time, effectively preventing the fuel cell stack from having a reduced lifespan due to prolonged overheating. Attached Figure Description

[0013] Figure 1 This is a schematic flowchart illustrating a simulation method for fuel cell thermal management based on cascade PID control according to this application.

[0014] Figure 2 This is a schematic diagram of the structure of a simulation system for thermal management of a fuel cell based on cascade PID control, as described in this application.

[0015] Figure 3 The waveform diagram shows the simulation results of Example 1 under the step heat generation condition.

[0016] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] The first embodiment of the present invention provides a simulation method for fuel cell thermal management based on cascade PID control, such as... Figure 1 As shown, the specific steps include:

[0019] Step S1: Construct the thermophysical model of the fuel cell stack, the thermophysical model of the cooling water, the radiator model, and the water pump model;

[0020] Specifically, based on the thermodynamic law of conservation of energy, a thermophysical model of the fuel cell stack, a thermophysical model of the cooling water, and a radiator model are established in the Simulink simulation environment; and a dual closed-loop control model and a heat exchange coupling model are built to achieve thermal management of the fuel cell stack thermophysical model by adjusting the water pump opening and the radiator opening, as detailed below.

[0021] Step S2: Obtain the heat generation power of the fuel cell stack thermophysical model and input it into the fuel cell stack thermophysical model;

[0022] In this embodiment, the heat generation power of the fuel cell stack is simulated by a step signal source module in the Simulink simulation environment, and the fuel cell stack thermophysical model is input.

[0023] Step S3: Obtain the first real-time temperature of the fuel cell stack thermophysical model and the second real-time temperature of the cooling water thermophysical model;

[0024] It is worth noting that initially, the first and second real-time temperatures can be obtained directly through simulation software without the need for simulation calculations.

[0025] The dual-closed-loop control model includes a main control loop and a secondary control loop. Through a "temperature-flow-heat dissipation" dual-closed-loop cascade control strategy, the heat dissipation process can be regulated in stages, as detailed below:

[0026] Step S4: Compare the first real-time temperature with the first target temperature. When the first real-time temperature is higher than the first target temperature, output an instruction signal to increase the pump opening of the pump model and obtain the current pump opening (i.e., the increased pump opening).

[0027] The main control loop focuses on stabilizing the fuel cell stack temperature. It inputs the first real-time temperature to the first PID controller module in the dual-closed-loop control model, compares this first real-time temperature with a first target temperature, and outputs a command signal to the pump model to increase the pump opening when the first real-time temperature exceeds the first target temperature. The increased pump opening is then acquired and displayed in real-time on an oscilloscope. For example, the logic of the first PID controller module is configured as follows: the proportional element rapidly outputs a command signal to increase the pump opening; the integral element eliminates static errors; and the output signal is limited (0-100%) by a limiting module before driving the pump model.

[0028] During simulation, the heat transfer relationship between the electric stack thermophysical model and the cooling water thermophysical model is established through a heat exchange coupling model, as detailed below.

[0029] Step S5: Obtain the current water pump opening degree, determine the fuel cell stack heat transfer coefficient based on the water pump opening degree; determine the difference between the first real-time temperature and the second real-time temperature, and use it as the first temperature difference; determine the cooling water heat dissipation based on the fuel cell stack heat transfer coefficient and the first temperature difference.

[0030] Specifically, the first real-time temperature and the second real-time temperature are input into the first subtractor to calculate the difference between them, i.e., the first temperature difference. In the first heat transfer coefficient gain module, the cooling water flow rate is determined based on the current water pump opening, and the fuel cell stack heat transfer coefficient is generated in real-time based on the cooling water flow rate. The correspondence between the cooling water flow rate and the fuel cell stack heat transfer coefficient is preset; once the cooling water flow rate is determined, the fuel cell stack heat transfer coefficient can be obtained. Therefore, the water pump opening is input into the first heat transfer coefficient gain module to obtain the dynamic fuel cell stack heat transfer coefficient. The first temperature difference and the fuel cell stack heat transfer coefficient are input into the first multiplier to output the cooling water heat dissipation. , , The dynamic heat transfer coefficient of the fuel cell stack. The first temperature difference is used in this formula to reflect the dynamic impact of flow rate changes on heat exchange efficiency. Specifically, the heat transfer coefficient of the fuel cell stack represents the heat exchange capacity between the fuel cell stack and the cooling water, and its value depends on the specific heat capacity of the cooling water and the hardware parameters of the cooling water pump.

[0031] Step S6: Determine the difference between the heat generation power and the heat dissipation of the cooling water. Based on the difference and the heat capacity parameters of the fuel cell stack, determine the heating rate of the fuel cell stack. Update the first real-time temperature according to the heating rate of the fuel cell stack and return to step S4 until the first real-time temperature is lower than or equal to the first target temperature.

[0032] Specifically, the difference between the heat generation power and the heat dissipation of the cooling water is calculated by the second subtractor, and the difference is input into the first gain module. Based on the difference and the heat capacity parameters of the fuel cell stack, the heating rate of the fuel cell stack is determined. Then, the heating rate of the fuel cell stack is integrated by the first integrator module to obtain a new first real-time temperature. This adjustment is repeated until the first real-time temperature is lower than or equal to the first target temperature, thus achieving thermal balance of the fuel cell stack.

[0033] Step S61: Determine the fuel cell stack heating rate based on the difference between the heat generation power and the cooling water heat dissipation, and the fuel cell stack heat capacity parameters; the calculation formula is as follows: ,in For the fuel cell stack heating rate, For the heat capacity of the fuel cell stack, For heat generation power, This refers to the heat dissipation of the cooling water.

[0034] Step S62: Integrate the data according to the heating rate of the fuel cell stack to obtain a new first real-time temperature; and return to step S4 until the first real-time temperature is lower than or equal to the first target temperature.

[0035] The process involves introducing a fuel cell heat capacity parameter to characterize the fuel cell's thermal inertia. By loading a preset fuel cell heat capacity parameter (in this embodiment, the fuel cell heat capacity parameter is the reciprocal of the fuel cell heat capacity) into the first gain module, a low thermal inertia parameter is set to simulate the rapid heating characteristics of a high power density fuel cell. By inputting the heat generation power into the first gain module and comparing it with the reciprocal of the fuel cell heat capacity, the fuel cell heating rate can be determined. The fuel cell heating rate is then input into the first integrator module to simulate the temperature change of the fuel cell, and its initial condition is set as the initial temperature of the fuel cell, thus obtaining the real-time temperature of the fuel cell thermophysical model.

[0036] Step S7: Compare the second real-time temperature with the second target temperature. When the second real-time temperature is greater than the second target temperature, output an instruction signal to increase the heat dissipation opening of the heat sink model and obtain the current heat dissipation opening.

[0037] Specifically, the secondary control loop uses stabilizing the cooling water temperature as an auxiliary objective: it monitors a second real-time temperature in real time and compares it with a second target temperature. When the second real-time temperature exceeds the second target temperature, the second PID controller activates and outputs a command signal to increase the heat dissipation opening of the radiator model, and obtains the heat dissipation opening. This loop ensures that the cooling water is always maintained at a low temperature with sufficient heat exchange temperature difference, avoiding heat dissipation failure of the fuel cell stack due to excessively high water temperature. For example, in this embodiment, the heat dissipation opening is the opening of the cooling fan.

[0038] Step S8: Obtain the ambient temperature, determine the difference between the second real-time temperature and the ambient temperature as the second temperature difference; determine the heat transfer coefficient of the radiator according to the heat dissipation opening, and determine the heat dissipation of the radiator according to the heat transfer coefficient and the second temperature difference.

[0039] Specifically, the airflow through the radiator is determined based on the heat dissipation opening, and a dynamic radiator heat transfer coefficient is generated in real time based on the airflow. The correspondence between airflow and radiator heat transfer coefficient is preset; once the airflow is determined, the radiator heat transfer coefficient can be obtained.

[0040] Specifically, the radiator heat transfer coefficient is determined through the second heat transfer coefficient gain module (which includes the correspondence between airflow and radiator heat transfer coefficient, converting airflow into radiator heat transfer coefficient). The radiator heat transfer coefficient represents the efficiency coefficient of the radiator in dissipating heat to the ambient air, and its value depends on the surface area of ​​the radiator, the thermal conductivity of the radiator material, and the air convection heat transfer coefficient at the radiator's maximum rotational speed. The second real-time temperature and the ambient temperature are input into the third subtractor to calculate the difference between the second real-time temperature and the ambient temperature, i.e., the second temperature difference. The second temperature difference and the radiator heat transfer coefficient are then input into the second multiplier to output the radiator's heat dissipation. , For dynamic radiator heat transfer coefficient, This is the second temperature difference.

[0041] Step S9: Determine the difference between the heat dissipation of the cooling water and the heat dissipation of the radiator. Based on the difference and the heat capacity parameter of the cooling water, determine the cooling water heating rate. Update the second real-time temperature according to the cooling water heating rate until the second real-time temperature is lower than or equal to the first target temperature.

[0042] Specifically, the difference between the cooling water heat dissipation and the radiator heat dissipation is calculated by the fourth subtractor, and the difference is input into the second gain module. Based on the difference and the cooling water heat capacity parameter, the cooling water heating rate is re-determined. Then, the cooling water heating rate is integrated by the second integrator module to obtain a new second real-time temperature. This adjustment is repeated until the second real-time temperature is lower than or equal to the first target temperature, thus achieving cooling water thermal balance.

[0043] Step S91: Determine the cooling water heating rate based on the difference between the cooling water heat dissipation and the radiator heat dissipation, and the cooling water heat capacity parameter. The calculation formula is as follows: ,in For the cooling water heating rate, For the heat capacity of cooling water, For the heat dissipation of cooling water, This refers to the heat dissipation of the radiator.

[0044] Step S92: Integrate the cooling water temperature rate to obtain the real-time temperature of the fuel cell stack thermophysical model.

[0045] The cooling water heat capacity parameter is introduced to characterize the thermal inertia of the cooling water. By loading the preset cooling water heat capacity parameter (in this embodiment, the cooling water heat capacity parameter is the reciprocal of the cooling water heat capacity) into the second gain module, the cooling water heating rate can be determined based on the cooling water heat dissipation, radiator heat dissipation, and cooling water heat capacity. The cooling water heating rate is input into the second integrator module to simulate the cooling water temperature change, and its initial condition is set as the initial temperature of the cooling water to obtain the real-time temperature of the cooling water physical model.

[0046] In this embodiment, by comparing the real-time temperature of the fuel cell stack thermophysical model with the corresponding target temperature, a first temperature difference is determined when the temperature exceeds the target temperature, and the water pump opening is increased. The cooling water heat dissipation is determined based on the first temperature difference and the fuel cell stack heat transfer coefficient. The difference between the heat generation power and the cooling water heat dissipation is processed to obtain the adjusted real-time temperature of the fuel cell stack thermophysical model, thus achieving fuel cell stack thermal balance regulation in the main control loop. Similarly, by comparing the real-time temperature of the cooling water thermophysical model with the corresponding target temperature, a second temperature difference is determined when the temperature exceeds the target temperature, and the heat dissipation opening is increased. The radiator heat dissipation is determined based on the second temperature difference and the radiator heat transfer coefficient. The difference between the radiator heat dissipation and the cooling water heat dissipation is processed to simulate the dynamic response of the cooling water temperature, thus obtaining the adjusted real-time temperature of the cooling water thermophysical model, thus achieving cooling water thermal balance in the secondary control loop. The system employs a dual-loop PID control mechanism that balances the fuel cell stack's thermal equilibrium and the cooling water's thermal equilibrium. This mechanism achieves a smooth "climb-fall" characteristic in the curves of pump and fan opening, preventing frequent starts and stops and severe fluctuations in the actuators near steady state and extending the mechanical lifespan of the pump and fan. The secondary loop control strategy ensures that the cooling fan only engages when the cooling water temperature is excessively high, and its opening is automatically adjusted based on the actual temperature difference, significantly reducing parasitic power consumption compared to a constant-speed fan. This stabilizes the fuel cell stack temperature quickly, effectively preventing the stack from experiencing reduced lifespan due to prolonged overheating. By adjusting the matching relationship between the first PID controller and the fuel cell stack's thermal capacity parameters, and between the second PID controller and the cooling water's thermal capacity parameters, the fuel cell stack temperature can be rapidly converged to the target operating temperature under step heat generation conditions.

[0047] The second embodiment of the present invention provides a simulation system for fuel cell thermal management based on cascade PID control, such as... Figure 2As shown, it includes: a model building module for building a fuel cell stack thermophysical model, a cooling water thermophysical model, a radiator model, and a water pump model; a step signal source module for acquiring the heat generation power of the fuel cell stack thermophysical model; a temperature acquisition module for acquiring the first real-time temperature of the fuel cell stack thermophysical model, the second real-time temperature of the cooling water thermophysical model, and the ambient temperature; a first PID controller module for comparing the first real-time temperature with a first target temperature, outputting an instruction signal to increase the water pump opening when the first real-time temperature is higher than the target temperature, and acquiring the current water pump opening; a first heat transfer coefficient gain module for acquiring the current water pump opening and determining the fuel cell stack heat transfer coefficient based on the water pump opening; a heat exchange coupling module for determining the difference between the first real-time temperature and the second real-time temperature as the first temperature difference; determining the cooling water heat dissipation based on the fuel cell stack heat transfer coefficient and the first temperature difference; determining the difference between the heat generation power and the cooling water heat dissipation; a first gain module for determining the fuel cell stack heating rate based on the difference between the heat generation power and the cooling water heat dissipation and the fuel cell stack heat capacity parameters; and a first integrator module for updating the first real-time temperature based on the fuel cell stack heating rate.

[0048] The second PID controller module compares the second real-time temperature with the second target temperature. When the second real-time temperature is greater than the second target temperature, it outputs a command signal to increase the heat dissipation opening of the radiator model and obtains the current heat dissipation opening. The second heat transfer coefficient gain module determines the radiator heat transfer coefficient based on the heat dissipation opening. The heat exchange coupling module also determines the difference between the second real-time temperature and the ambient temperature as the second temperature difference. Based on the radiator heat transfer coefficient and the second temperature difference, it determines the radiator heat dissipation. It also determines the difference between the cooling water heat dissipation and the radiator heat dissipation. The second gain module determines the cooling water heating rate based on the difference between the cooling water heat dissipation and the radiator heat dissipation and the cooling water heat capacity parameter. The second integrator updates the second real-time temperature based on the cooling water heating rate.

[0049] The heat exchange coupling module includes: a first subtractor for determining the difference between a first real-time temperature and a second real-time temperature, and using it as the first temperature difference; a first multiplier for determining the cooling water heat dissipation based on the product of the fuel cell heat transfer coefficient, the pump opening, and the first temperature difference; a second subtractor for determining the difference between the heat generation power and the cooling water heat dissipation; a third subtractor for determining the difference between the second real-time temperature and the ambient temperature, and using it as the second temperature difference; a second multiplier for determining the radiator heat dissipation based on the product of the second temperature difference and the radiator heat transfer coefficient; and a fourth subtractor for determining the difference between the cooling water heat dissipation and the radiator heat dissipation.

[0050] Example

[0051] A full-system simulation test was conducted based on the aforementioned Simulink model.

[0052] Initialize simulation parameters: Load the heat capacity of the fuel cell stack =4500 J / K and cooling water heat capacity Set the ambient temperature to 1500 J / K. The temperature is 25℃, and the main loop PID control is in progress. =3, =0.5; First target operating temperature The second target temperature is 60℃. The temperature is 30℃.

[0053] Step S10: The heat generation power of the electric stack thermophysical model is simulated to be 5000W through the step signal source module, and the electric stack thermophysical model is input at t=0 to obtain the first real-time temperature of 75℃.

[0054] Step S20, as follows Figure 3 As shown, the first PID controller module compares the first real-time temperature with the first target temperature and outputs a command signal to the water pump model to increase the water pump opening. The water pump model responds to the command signal, increases the water pump opening, and determines the fuel cell stack heat transfer coefficient. The first real-time temperature is updated through the heat exchange coupling model. The main control loop adjustment process is as follows: Figure 3 As shown in Figures a and b, the temperature drops rapidly from the initial 75℃. The curves show that the system settling time is approximately 20 seconds, during which the temperature smoothly converges to the target value of 60℃ without significant overshoot. After entering steady state, the temperature curve remains horizontal, indicating that the steady-state error approaches zero, thus verifying the feasibility and accuracy of the main loop control strategy.

[0055] Step S30: Obtain the real-time temperature of the cooling water model. The second PID controller compares the second real-time temperature with the second target temperature and outputs a command signal to the radiator model to increase the radiator fan opening. The radiator model responds to the command signal, increases the radiator fan opening, and updates the second real-time temperature through the heat exchange coupling model. The independent adjustment process of the secondary control loop is described in [link to relevant documentation]. Figure 3 As shown in Figures c and d, when the cooling water absorbs heat from the fuel cell stack, causing the temperature to rise and approach the 30°C setpoint, the radiator fan begins to work and eventually stabilizes at about 20% opening. This indicates that the main control loop and the secondary control loop have achieved good thermodynamic decoupling, verifying the physical feasibility of the "temperature-flow-heat dissipation" cascade control logic.

[0056] In summary, the simulation results fully demonstrate that the simulation method proposed in this invention has extremely fast response speed, extremely high control accuracy, and excellent system robustness when facing step load disturbances, and the technical solution is realistic and reliable.

[0057] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A simulation method for thermal management of fuel cells based on cascade PID control, characterized in that, include: Construct thermophysical models of the fuel cell stack, cooling water, radiator, and water pump, and... Obtain the heat generation power of the fuel cell stack thermophysics model; The first real-time temperature of the fuel cell stack thermophysical model, the second real-time temperature of the cooling water thermophysical model, and the ambient temperature are obtained. The first real-time temperature is compared with the first target temperature. When the first real-time temperature is higher than the first target temperature, an instruction signal to increase the pump opening of the pump model is output. Obtain the current pump opening and determine the fuel cell heat transfer coefficient based on the pump opening. Determine the difference between the first real-time temperature and the second real-time temperature, and use it as the first temperature difference; The cooling water heat dissipation is determined based on the heat transfer coefficient of the fuel cell stack and the first temperature difference. Determine the difference between the heat generation power and the heat dissipation of the cooling water; based on the difference and the heat capacity parameters of the fuel cell stack, determine the heating rate of the fuel cell stack. The first real-time temperature is updated according to the heating rate of the fuel cell stack, and the first real-time temperature is compared with the first target temperature again until the first real-time temperature is lower than or equal to the first target temperature. The second real-time temperature is compared with the second target temperature. When the second real-time temperature is greater than the second target temperature, an instruction signal is output to increase the heat dissipation opening of the heat sink model, and the current heat dissipation opening is obtained. The heat transfer coefficient of the radiator is determined based on the heat dissipation opening. The difference between the second real-time temperature and the ambient temperature is determined as the second temperature difference; The heat dissipation of the radiator is determined based on the heat transfer coefficient of the radiator and the second temperature difference. Determine the difference between the heat dissipation of the cooling water and the heat dissipation of the radiator, and determine the cooling water heating rate based on the difference and the heat capacity parameters of the cooling water. The second real-time temperature is updated according to the cooling water heating rate, and then compared with the second target temperature again until the second real-time temperature is lower than or equal to the second target temperature.

2. The simulation method for fuel cell thermal management based on cascade PID control according to claim 1, characterized in that, The heat transfer coefficient of the fuel cell stack is determined based on the pump opening degree, including: Determine the cooling water flow rate based on the pump opening; Based on the correspondence between cooling water flow rate and convective heat transfer coefficient, the heat transfer coefficient of the fuel cell stack corresponding to the current cooling water flow rate is determined.

3. The simulation method for fuel cell thermal management based on cascade PID control according to claim 1, characterized in that, The cooling water heat dissipation is determined based on the heat transfer coefficient of the fuel cell stack and the first temperature difference. include, The heat dissipation of the cooling water is determined by multiplying the heat transfer coefficient of the fuel cell stack by the first temperature difference.

4. The simulation method for fuel cell thermal management based on cascade PID control according to claim 1, characterized in that, The heat transfer coefficient of the radiator is determined based on the heat dissipation opening, including: Determine the airflow rate through the radiator based on the heat dissipation opening; Based on the correspondence between the airflow through the radiator and the radiator heat transfer coefficient, determine the radiator heat transfer coefficient corresponding to the current radiator fan opening.

5. The simulation method for fuel cell thermal management based on cascade PID control according to claim 1, characterized in that, The heat dissipation of the radiator is determined based on the radiator's heat transfer coefficient and the second temperature difference, including: The heat dissipation of the radiator is determined by multiplying the heat transfer coefficient of the radiator by the second temperature difference.

6. A simulation system for fuel cell thermal management based on cascade PID control, characterized in that, include: The model building module is used to build the thermophysical model of the fuel cell stack, the thermophysical model of the cooling water, the radiator model, and the water pump model. A step signal source module is used to obtain the heat generation power of the electric stack thermophysical model; The temperature acquisition module is used to acquire the first real-time temperature of the fuel cell stack thermophysical model, the second real-time temperature of the cooling water thermophysical model, and the ambient temperature. The first PID controller module is used to compare the first real-time temperature with the first target temperature. When the first real-time temperature is higher than the first target temperature, it outputs a command signal to increase the water pump opening and obtains the current water pump opening. The first heat transfer coefficient gain module is used to obtain the current water pump opening and determine the heat transfer coefficient of the fuel cell stack based on the water pump opening. A heat exchange coupling module is used to determine the difference between a first real-time temperature and a second real-time temperature, which is taken as the first temperature difference; The heat dissipation of the cooling water is determined based on the heat transfer coefficient of the fuel cell stack and the first temperature difference; the difference between the heat generation power and the heat dissipation of the cooling water is determined. The first gain module is used to determine the heating rate of the fuel cell stack based on the difference between the heat generation power and the heat dissipation of the cooling water and the heat capacity parameters of the fuel cell stack. The first integrator module is used to update the first real-time temperature according to the heating rate of the fuel cell stack; The second PID controller module is used to compare the second real-time temperature with the second target temperature. When the second real-time temperature is greater than the second target temperature, it outputs an instruction signal to increase the heat dissipation opening of the heat sink model and obtains the current heat dissipation opening. The second heat transfer coefficient gain module is used to determine the heat transfer coefficient of the radiator based on the heat dissipation opening. The heat exchange coupling module is also used to determine the difference between the second real-time temperature and the ambient temperature as the second temperature difference; to determine the heat dissipation of the radiator based on the heat transfer coefficient of the radiator and the second temperature difference; and to determine the difference between the heat dissipation of the cooling water and the heat dissipation of the radiator. The second gain module is used to determine the cooling water heating rate based on the difference between the cooling water heat dissipation and the radiator heat dissipation and the cooling water heat capacity parameter. The second integrator is used to update the second real-time temperature based on the cooling water heating rate.

7. The simulation system for fuel cell thermal management based on cascade PID control according to claim 6, characterized in that, The heat exchange coupling module includes: The first subtractor is used to determine the difference between the first real-time temperature and the second real-time temperature, and use it as the first temperature difference; The first multiplier is used to determine the heat dissipation of the cooling water based on the product of the heat transfer coefficient of the fuel cell stack and the first temperature difference. The second subtractor is used to determine the difference between the heat generation power and the heat dissipation of the cooling water; The third subtractor is used to determine the difference between the second real-time temperature and the ambient temperature, and uses it as the second temperature difference; The second multiplier is used to determine the heat dissipation of the radiator based on the product of the radiator's heat transfer coefficient and the second temperature difference. The fourth subtractor is used to determine the difference between the heat dissipation of the cooling water and the heat dissipation of the radiator.

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