Thermal management subsystem of liquid-cooled fuel cell and control method of thermal management subsystem

Abstract

The invention relates to the technical field of battery thermal management, in particular to a liquid-cooled fuel cell thermal management subsystem and a control method thereof.The liquid-cooled fuel cell thermal management subsystem comprises a fuel cell body, a cooling liquid circulation system, a temperature sensor, a flow sensor and a thermal management system controller; the heat management system controller is electrically connected with the temperature sensor, the flow sensor, the water pump, the radiator, the heater and the control valve, calculates the pile temperature of the fuel cell main body through load current, and continuously monitors the inlet temperature and the outlet temperature of the fuel cell main body and the outlet flow of the water pump at the same time; and the working state of the cooling liquid circulation system is controlled according to the monitored and calculated data, so that the temperature of the fuel cell main body is accurately controlled.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery thermal management, in particular to a liquid-cooled fuel cell thermal management subsystem and a control method thereof. BACKGROUND

[0002] As a high-efficiency and clean energy conversion device, fuel cells have shown great application potential in the fields of transportation and distributed power generation. In particular, in the field of automobiles, fuel cell vehicles are considered as one of the important development directions of future new energy vehicles due to their zero emission and long cruising range.

[0003] Proton exchange membrane fuel cells (PEMFC) have attracted widespread attention due to their high energy efficiency. The output performance of a PEMFC depends on factors such as reaction gas pressure, humidity, and reaction temperature. In terms of temperature, PEMFC is a low-temperature reaction system, and the ideal working temperature is generally 60-90℃. Within this range, the performance and lifespan of the proton exchange membrane are optimal. When the temperature is too low, the polarization losses in the stack increase, the evaporation rate of liquid water decreases, and the gas mass transfer is limited, thereby limiting the performance of the stack and resulting in low efficiency. When the temperature is too high (exceeding 100℃), the proton exchange membrane may dry out, even break, the electrical conductivity decreases, the catalyst degrades, and the performance and lifespan of the stack are both impaired. Therefore, a corresponding thermal management subsystem is provided for the PEMFC to quickly raise the reaction temperature of the stack to the optimal reaction temperature range when the reaction temperature is low. When the heat generation efficiency of the stack is too high during operation and the temperature exceeds the range, the cooling system is used to remove the excess heat, thereby ensuring the efficient and stable operation of the system.

[0004] Currently, the common fuel cell thermal management methods mainly include air cooling and liquid cooling. The air cooling method uses air flow to remove the heat generated by the stack, and has the advantages of simple structure and low cost, but the heat dissipation efficiency is relatively limited, and it is suitable for small-power and low-heat fuel cell systems. The liquid cooling method uses cooling liquid to circulate in the cooling channels inside the stack to transfer heat to the heat sink for heat dissipation, and has the advantages of high heat dissipation efficiency and good temperature control precision, and is particularly suitable for high-power and high-heat fuel cell systems, so it has been more widely used in current fuel cell vehicle applications.

[0005] Deficiencies of existing liquid cooling thermal management technology:

[0006] Single control strategy: Many existing liquid-cooled fuel cell thermal management systems use relatively simple control strategies, such as on-off control based on fixed temperature thresholds. This control method cannot dynamically adjust according to the actual working conditions and load changes of the fuel cell, making it difficult for the system to achieve optimal thermal management under different operating conditions. For example, when the load suddenly changes, the system may not respond in time, causing large fluctuations in the stack temperature and affecting the performance and life of the fuel cell.

[0007] Lack of accurate modeling: Some thermal management systems do not fully consider the complex coupling relationships between fuel cell stacks, cooling systems, and other components during design and control, lacking accurate system models. This makes it difficult for the controller to accurately predict the thermal behavior of the system under different operating conditions, and it is difficult to achieve precise temperature control. For example, factors such as the flow characteristics of the cooling liquid and the heat conduction inside the stack may be ignored during modeling, resulting in a large deviation between the model and the actual system, thereby affecting the control effect.

[0008] Poor dynamic response: Some thermal management systems lack dynamic response capability when facing rapid load changes of the fuel cell. When the load suddenly increases, the system may not be able to increase the heat dissipation capacity in time, causing the stack temperature to rise rapidly; when the load suddenly decreases, the system may not be able to adjust the heat dissipation power in time, causing energy waste. This lack of dynamic response capability severely limits the stable operation of the fuel cell under different operating conditions.

[0009] Lack of comprehensive control strategy: Existing thermal management methods often only focus on temperature control, ignoring the coordinated control with other systems (such as air supply systems, hydrogen supply systems, etc.). In fact, the various subsystems of the fuel cell interact and restrict each other, for example, changes in air flow and hydrogen flow will affect the heat generation of the stack, and the operation of the thermal management system will also affect the gas supply of the stack. Lack of comprehensive control strategy leads to suboptimal overall system performance.

[0010] The fuel cell system thermal management method, system and fuel cell vehicle disclosed in Chinese patent publication CN118269769A mainly focus on adjusting the flow and temperature of the cooling liquid to achieve temperature control of the fuel cell stack. However, its control strategy is relatively simple and does not fully consider the dynamic characteristics of the fuel cell under different operating conditions and the coupling relationships between the various subsystems. Compared with the present application, this prior art lacks in-depth construction and analysis of the system model, and cannot achieve precise control and dynamic optimization based on the model. The adaptability and control precision in dealing with complex operating conditions need to be improved.

[0011] The fuel cell thermal management control method and fuel cell thermal management system disclosed in Chinese Patent Publication No. CN115101788A mainly control the operation of the cooling equipment by setting different temperature intervals. However, it still has the problem of insufficient control strategy, and does not dynamically adjust in real time according to the load change of the fuel cell. Moreover, the prior art does not fully consider the influence of the heat exchange efficiency between the cooling system and the stack and the flow characteristics of the cooling liquid on thermal management. The present application can more accurately analyze the system operating state by constructing a detailed fuel cell thermal management system model, including a stack model, a heat balance model, and a cooling system model, to achieve more precise and efficient thermal management control.

[0012] The fuel cell thermal management test system and test method disclosed in Chinese Patent Publication No. CN110632523A mainly focus on the fuel cell thermal management test system and test method, and emphasize performance testing and evaluation of the fuel cell thermal management system, rather than providing an effective thermal management control method. Although the test results can provide a reference for the design and optimization of the thermal management system, it does not directly solve the thermal management control problem of fuel cells in actual operation. The present application focuses on the thermal management control method, and realizes real-time and accurate control of the fuel cell thermal management system by establishing a model and developing a comprehensive control strategy, thereby improving the performance and reliability of the fuel cell.

[0013] In summary, the existing liquid-cooled fuel cell thermal management technology has many shortcomings and cannot meet the demand for efficient and accurate thermal management of fuel cells under different operating conditions. Therefore, the liquid-cooled fuel cell thermal management subsystem modeling and control method proposed in the present application has important practical significance, aiming to optimize the control of the fuel cell thermal management system by constructing an accurate system model and developing a comprehensive control strategy, thereby improving the performance and reliability of the fuel cell and promoting the further development of fuel cell technology. SUMMARY

[0014] To solve the above problems, a liquid-cooled fuel cell thermal management subsystem and its control method are provided, aiming to solve the problems of single control strategy, lack of accurate modeling, and poor dynamic response of existing liquid-cooled fuel cell thermal management control strategies. By constructing a system model and a comprehensive control strategy, accurate and efficient control of fuel cell thermal management is achieved, and the performance and reliability of the fuel cell are improved.

[0015] To solve the problems in the prior art, the application provides a liquid-cooled fuel cell thermal management subsystem, which comprises: a fuel cell main body for providing electric energy for a load; a cooling liquid circulation system comprising a water tank, a water pump, a radiator, a heater, a control valve and a cooling liquid pipeline, the cooling liquid circulation system being connected with the fuel cell main body and being used for circulating cooling liquid to adjust the temperature of the fuel cell main body; wherein the cooling liquid circulation system comprises a main circulation (large circulation) flowing through the radiator and an auxiliary temperature-rising circulation (small circulation) flowing through the heater; a temperature sensor arranged at the inlet and outlet of the fuel cell main body and used for monitoring the inlet temperature and outlet temperature of the cooling liquid in real time respectively; a flow sensor arranged on the cooling liquid pipeline at the outlet of the water pump and used for monitoring the cooling liquid flow at the outlet of the water pump in real time; and a thermal management system controller electrically connected with the temperature sensor, the flow sensor, the water pump, the radiator, the heater and the control valve, the thermal management system controller being used for obtaining the stack temperature of the fuel cell main body through load current calculation, continuously monitoring the inlet temperature, outlet temperature and water pump outlet flow of the fuel cell main body, and controlling the working state of the cooling liquid circulation system according to the monitoring and calculation data, so as to realize accurate temperature control of the fuel cell main body.

[0016] As a specific embodiment of the application, the thermal management system controller comprises: a data acquisition module used for acquiring the data fed back by the temperature sensor and the flow sensor in real time and obtaining load current information; a calculation module used for calculating the stack temperature of the fuel cell main body according to the obtained load current information; a modeling analysis module used for establishing the stack model, the heat balance model and the cooling system model of the fuel cell main body based on the acquired data and the calculated stack temperature, and analyzing the thermal state of the fuel cell main body and the performance of the cooling liquid circulation system; and a control strategy module used for formulating and executing the control strategy of the cooling liquid circulation system according to the output of the modeling analysis module, including adjusting the rotating speed of the water pump, the rotating speed of the radiator fan, the power of the heater and the opening degree of the control valve, so as to maintain the fuel cell main body in the suitable temperature range.

[0017] As a specific embodiment of the present application, the control strategy module specifically comprises: a flow following unit, which dynamically determines the target flow of the coolant according to the real-time temperature requirement of the fuel cell body and the output of the modeling analysis module; a PID control unit, which accurately controls the rotating speed of the water pump through a PID algorithm according to the target flow determined by the flow following unit and the real-time flow data fed back by the flow sensor, so as to realize accurate adjustment of the flow of the coolant; a temperature adjustment unit, which controls the start of the heater and adjusts the flow of the auxiliary heating circulation (small circulation) when the temperature of the stack is too low, and simultaneously adjusts the distribution of the coolant between the main circulation (large circulation) and the auxiliary heating circulation (small circulation) by means of the control valve, so as to quickly raise the temperature of the stack to the ideal working temperature; under specific working conditions, the power change rate limiting strategy of the circulating water pump and the intelligent adjustment strategy of the rotating speed of the radiator fan are implemented, so as to optimize the thermal management effect and prevent system oscillation and overheating / overcooling phenomenon.

[0018] As a specific embodiment of the present application, the thermal management system controller further comprises: a fault diagnosis and protection module, which is used for real-time monitoring of the operating state of the coolant circulation system and the fuel cell body, and combines the calculated value of the stack temperature and the sensor-monitored inlet temperature, outlet temperature and flow data, and automatically takes protective measures such as reducing the rotating speed of the water pump, shutting down the heater or the radiator, and issuing an alarm signal when an abnormality is detected, so as to prevent system damage and ensure operation safety; a communication interface module, which is used for data exchange with external devices or systems, realizes remote monitoring, parameter setting and fault diagnosis functions, and improves the maintainability and intelligent level of the system; at the same time, external load current information or other related instructions can be received through the communication interface module, so as to optimize the control strategy of the thermal management system controller.

[0019] As a specific embodiment of the present application, when the temperature adjustment unit controls the start of the heater, the heating power of the heater is dynamically adjusted according to the difference between the temperature of the stack and the ideal working temperature, and the flow of the auxiliary heating circulation (small circulation) is adjusted through the control valve, so as to realize rapid and smooth rise of the temperature of the stack; at the same time, the flow of the main circulation (large circulation) and the rotating speed of the radiator fan are adjusted according to the heat dissipation requirement, so as to ensure that the fuel cell body can maintain the optimal working temperature under different working conditions.

[0020] A liquid-cooled fuel cell thermal management control method applied to a liquid-cooled fuel cell thermal management subsystem, comprising the following steps: a data acquisition step: using temperature sensors to collect fuel cell stack temperature, fuel cell cooling liquid inlet and outlet temperature in real time, obtaining cooling liquid flow data through a flow sensor, and transmitting these data to a thermal management system controller; a model construction and analysis step: the thermal management system controller analyzes the current system operating state based on the obtained data, determines the key factors affecting the stack temperature and the coupling relationship between the factors, and combines the fuel cell thermal management system model, which covers the stack model, the heat balance model and the cooling system model; a control decision and execution step: according to the model analysis result, the cooling system control strategy based on flow following is executed, the cooling or heating mode is determined according to the current fuel cell stack temperature, the circulating water pump and the radiator are adjusted, so that the power battery temperature reaches the target temperature; at the same time, the supplementary control strategy is executed, including circulating water pump power change rate limiting, thermostat opening degree adjustment and radiator fan speed control.

[0021] As a specific embodiment of the present application, the cooling system control strategy based on flow following is specifically: PID controller input and output determination: the PID controller takes the load current and the stack inlet and outlet temperature difference as the input, and outputs the cooling liquid flow set value; PID controller parameter setting: set the proportional coefficient Kp, the integral coefficient Ki and the differential coefficient Kd, and adjust them through simulation or real vehicle calibration to meet the dynamic response and steady state accuracy requirements of the system under different conditions; PID control logic execution: when the stack inlet and outlet temperature difference exceeds the set threshold value, the PID controller calculates the required cooling liquid flow set value according to the current temperature difference and load current to improve the heat dissipation capacity; when the stack temperature approaches the target value, the cooling liquid flow change rate is reduced to avoid temperature overshoot; the cooling liquid flow is adjusted in advance according to the change trend of the load current to improve the dynamic response performance of the system; in low temperature environment, the cooling liquid flow set value is appropriately reduced to prevent the stack temperature from falling too fast; in high temperature and high load conditions, the cooling liquid flow set value is increased to ensure stable operation of the stack.

[0022] As a specific embodiment of the present application, the circulating water pump power change rate limiting strategy is: the thermal management system controller monitors the circulating water pump power change in real time, and when the water pump power rises or falls in unit time exceeds the preset limiting value, the controller limits the change rate of the water pump power to prevent the system from being impacted by power mutation; the preset limiting value is set according to different working conditions of the fuel cell and system stability requirements, and different limiting values are used in different stages such as starting, accelerating and decelerating.

[0023] As a specific embodiment of the application, the thermostat opening adjustment strategy is that the thermal management system controller adjusts the thermostat opening in real time according to the change of the stack temperature, when the stack temperature is lower than the lower limit of the ideal working temperature, the thermostat opening is reduced, the auxiliary heating cycle (small cycle) cooling liquid flow is increased, and the main cycle (large cycle) heat dissipation is reduced, so as to quickly raise the stack temperature; when the stack temperature is higher than the upper limit of the ideal working temperature, the thermostat opening is increased, the main cycle (large cycle) cooling liquid flow is increased, and the heat dissipation capacity is enhanced, so that the stack temperature is maintained within a reasonable range; during the adjustment of the thermostat opening, the controller adopts a gradual adjustment mode according to the temperature change rate and the target temperature difference, so as to avoid the impact on the system caused by sudden change of the opening.

[0024] As a specific embodiment of the application, the radiator fan speed control strategy is that the thermal management system controller adjusts the radiator fan speed in real time according to the stack inlet temperature, when the stack inlet temperature exceeds the set threshold, the fan speed is increased, and the heat dissipation efficiency is enhanced; when the stack inlet temperature is lower than the set threshold, the fan speed is reduced, and the energy consumption is reduced; the fan speed adjustment adopts a hierarchical control mode, different speed levels are set according to the temperature interval, and precise heat dissipation control is realized.

[0025] The application has the following beneficial effects compared with the prior art:

[0026] 1. Precise temperature control and dynamic response: the application realizes precise control of the temperature of the fuel cell stack by constructing a detailed model including the stack, heat balance and cooling system, and combining with the PID control strategy of flow following. At the same time, the system can quickly adjust the cooling liquid flow according to the load change, effectively suppress the temperature fluctuation, significantly improve the dynamic response performance, and ensure the stable operation of the fuel cell under various working conditions.

[0027] 2. High efficiency and energy saving and multi-working condition adaptation: the power limiting, thermostat opening adjustment and radiator fan speed optimization in the supplementary control strategy enable the system to maintain the best thermal management effect with minimum energy consumption under different working conditions. Whether it is low-temperature starting, high-temperature high-load or variable load working condition, the system can automatically adapt to realize high-efficiency energy-saving operation.

[0028] 3. Intelligent protection and remote management: the integrated fault diagnosis and protection module can monitor system abnormalities in real time and automatically trigger the protection mechanism to prevent equipment damage. The communication interface supports remote monitoring, parameter adjustment and fault diagnosis, greatly improves the maintainability and intelligent level of the system, and provides reliable guarantee for the large-scale application of fuel cells. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a system diagram of a liquid-cooled fuel cell thermal management subsystem of the application.

[0030] Figure 2 is a flow following based cooling system control flow chart in a liquid-cooled fuel cell thermal management subsystem of the present application.

[0031] Figure 3 is a water pump control model in a liquid-cooled fuel cell thermal management subsystem of the present application.

[0032] Figure 4 is a radiator control model in a liquid-cooled fuel cell thermal management subsystem of the present application.

[0033] Figure 5 is a simulation result of the liquid-cooled fuel cell thermal management subsystem of the present application for the change of the stack inlet and outlet temperature.

[0034] Figure 6 is a simulation result of the liquid-cooled fuel cell thermal management subsystem of the present application for the change of the stack inlet and outlet temperature difference. DETAILED DESCRIPTION

[0035] In order to further understand the features, technical means and specific purposes and functions achieved by the present application, the present application will be described in further detail below with reference to the drawings and specific embodiments.

[0036] Referring to Figure 1 a liquid-cooled fuel cell thermal management subsystem shown in the figure, which comprises a fuel cell body (PEMFC), a cooling liquid circulation system, a temperature sensor, a flow sensor and a thermal management system controller. The fuel cell body is used to provide electric energy for the load; the cooling liquid circulation system contains a water tank, a water pump, a radiator, a heater, a control valve and a cooling liquid pipeline, which is connected with the fuel cell body and used to circulate the cooling liquid to adjust the temperature of the fuel cell body; wherein the cooling liquid circulation system includes a main circulation (large circulation) flowing through the radiator and an auxiliary heating circulation (small circulation) flowing through the heater; the temperature sensor is arranged at the inlet and outlet of the fuel cell body, respectively, for real-time monitoring of the inlet temperature and outlet temperature of the cooling liquid; the flow sensor is arranged on the cooling liquid pipeline at the outlet of the water pump, for real-time monitoring of the cooling liquid flow at the outlet of the water pump; the thermal management system controller is electrically connected with the temperature sensor, the flow sensor, the water pump, the radiator, the heater and the control valve, the thermal management system controller obtains the stack temperature of the fuel cell body through load current calculation, continuously monitors the inlet temperature, outlet temperature and water pump outlet flow of the fuel cell body, and controls the working state of the cooling liquid circulation system according to the monitoring and calculation data, so as to realize accurate temperature control of the fuel cell body.

[0037] The liquid-cooled fuel cell thermal management subsystem of the present application is a precise and highly integrated temperature control solution designed to optimize fuel cell performance and extend service life, capable of flexibly switching between main circulation (large circulation) and auxiliary heating circulation (small circulation) according to the working state of the fuel cell and environmental conditions, ensuring that the coolant circulates in the optimal path to achieve precise regulation of the fuel cell temperature. Whether it is heat dissipation in high temperature environment or rapid heating in low temperature start-up, this system can handle it with ease.

[0038] The thermal management system controller, as the "wisdom center" of the entire system, bears the heavy responsibility of data processing, strategy formulation and actuator regulation. It can not only accurately calculate the stack temperature of the fuel cell body according to the data feedback from the temperature sensor and flow sensor, combined with the load current information, but also continuously monitor and analyze various parameters of the cooling system. Based on these analyses, the thermal management system controller uses a cooling system control strategy based on flow following, combined with the precise adjustment of the PID controller, to dynamically adjust the coolant flow, radiator fan speed and thermostat opening degree and other key actuators. This intelligent control strategy ensures that the fuel cell maintains a stable temperature under different load conditions, avoiding performance degradation or damage caused by temperature fluctuations.

[0039] In addition, a number of supplementary control strategies are also incorporated, such as circulation pump power change rate limiting, thermostat opening degree fine adjustment and radiator fan speed intelligent control. These strategies further enhance the response speed and stability of the system by limiting the mutation of pump power, optimizing the circulation ratio of coolant and improving the cooling efficiency. Simulation and real vehicle test results show that the system can quickly respond to variable load conditions, stabilizing the stack inlet temperature and temperature difference within the ideal range, significantly reducing the average response time and temperature overshoot. These advantages not only improve the reliability and efficiency of the fuel cell system, but also significantly extend its service life, providing strong technical support for the commercialization of liquid-cooled fuel cells.

[0040] wherein, Figure 5 The simulation results of the liquid-cooled fuel cell thermal management subsystem of the present application for the temperature change of the stack inlet and outlet can be seen that during 0-50s, the stack inlet and outlet temperatures rise rapidly at the same speed, because the stack temperature is low at this time and has not reached the heat dissipation temperature, the radiator does not work, the cooling system only realizes the rapid heating of the stack through the small circulation, and the temperature difference between the stack inlet and outlet is also small, and the circulation pump works at the lowest speed. When the stack inlet temperature reaches 60℃, the radiator starts to dissipate heat, and when the load changes, the fan speed can be quickly adjusted to stabilize the inlet temperature at 60℃, with small overshoot. Figure 6is a simulation result of a liquid-cooled fuel cell thermal management subsystem of the present application aiming at the temperature difference between the inlet and outlet of the stack. Comparison Figure 5 It can be seen that from 50s to 94s, the temperature rise rate of the stack outlet slows down, and the temperature difference between the inlet and outlet of the stack gradually increases. When the temperature difference is greater than 10℃, the circulating water pump controller starts to work. After a period of adjustment, the temperature difference is controlled again within 10℃, and the average response time is about 100s. Due to the time delay in the start of the water pump controller, a maximum overshoot of +5℃ occurs, but it is within the safe range of the battery temperature. In summary, the controller designed in the present patent can achieve good control effect when the current changes in steps, and the inlet temperature is controlled within the range of 60±1℃, and the temperature difference is controlled within the range of 10±2℃.

[0041] As a specific embodiment of the liquid-cooled fuel cell thermal management subsystem, the thermal management system controller comprises a data acquisition module, a calculation module, a modeling analysis module and a control strategy module.

[0042] The data acquisition module is used to acquire the data fed back by the temperature sensor and the flow sensor in real time, and to acquire the load current information

[0043] Specifically, the data acquisition module is the "sensing organ" of the thermal management system controller, which is responsible for capturing the key parameters in the operation process of the fuel cell in real time. It continuously monitors the inlet and outlet temperatures of the fuel cell stack and the flow changes of the cooling liquid in the system through the temperature sensor and the flow sensor. At the same time, the data acquisition module is also connected with the load current monitoring interface of the vehicle or system, and acquires the load current information in real time, providing basic data support for subsequent temperature calculation and strategy making. The accuracy and timeliness of these data are directly related to the accurate judgment of the thermal state of the fuel cell by the thermal management system.

[0044] The calculation module is used to calculate the stack temperature of the fuel cell body according to the acquired load current information.

[0045] Specifically, the calculation module is the "calculation center" of the thermal management system controller, which calculates the stack temperature of the fuel cell body accurately according to the load current information provided by the data acquisition module, combined with the electrochemical characteristics and thermal physical parameters of the fuel cell. This calculation process not only considers the influence of current on the heat generation of the stack, but also combines the contribution of environmental temperature, cooling liquid flow and other factors to the heat dissipation of the stack, ensuring the accuracy and reliability of the calculation results. The accurate calculation of the stack temperature provides an important basis for subsequent modeling analysis and strategy making.

[0046] The modeling analysis module is used to establish the stack model, thermal balance model and cooling system model of the fuel cell body based on the collected data and the calculated stack temperature, and to analyze the thermal state of the fuel cell body and the performance of the cooling liquid circulation system.

[0047] Specifically, the modeling analysis module is the "analysis brain" of the thermal management system controller, which builds the stack model, heat balance model, and cooling system model of the fuel cell main body based on the real-time data provided by the data acquisition module and the stack temperature obtained by the calculation module. The stack model describes the relationship between the electrochemical reaction and heat generation inside the stack; the heat balance model reveals the dynamic balance between heat generation and heat dissipation of the stack; and the cooling system model simulates the circulation path and heat dissipation efficiency of the cooling liquid in the system in detail. Through the joint analysis of the three models, the modeling analysis module can comprehensively evaluate the thermal state of the fuel cell and the performance of the cooling liquid circulation system, providing a scientific basis for subsequent strategy making.

[0048] The control strategy module is used to formulate and execute the control strategy of the cooling liquid circulation system according to the output of the modeling analysis module, including adjusting the water pump speed, radiator fan speed, heater power, and controlling the opening of the valve, to maintain the fuel cell main body operating within the appropriate temperature range.

[0049] Specifically, the control strategy module is the "decision executor" of the thermal management system controller, which formulates and executes the control strategy of the cooling liquid circulation system according to the output of the modeling analysis module. Specifically, the control strategy module controls the flow of cooling liquid by adjusting the water pump speed to ensure that the temperature difference between the inlet and outlet of the stack is within a reasonable range; adjusts the radiator fan speed to optimize the heat dissipation efficiency and prevent the stack from overheating; and adjusts the heater power according to the changes in ambient temperature and stack temperature to achieve rapid heating or temperature maintenance function. In addition, the control strategy module also optimizes the circulation path of the cooling liquid by controlling the opening of the valve (such as the thermostat and three-way valve), further improving the thermal management performance of the system. The precise execution of these control strategies ensures that the fuel cell can maintain the optimal temperature range under various working conditions, thereby improving the reliability and efficiency of the system.

[0050] As a specific embodiment of the liquid-cooled fuel cell thermal management subsystem, the control strategy module specifically includes a flow following unit, a PID control unit, and a temperature adjustment unit.

[0051] The flow following unit dynamically determines the target flow of the cooling liquid according to the real-time temperature requirements of the fuel cell main body and the output of the modeling analysis module.

[0052] Specifically, the flow following unit is the "lookahead" of the control strategy module, which dynamically determines the target flow of the coolant based on the real-time temperature demand of the fuel cell body and the output results of the modeling analysis module. This process not only considers the current heat production and heat dissipation balance demand of the stack, but also combines the prediction of the impact of future load changes on the stack temperature. By adjusting the target flow in real time, the flow following unit ensures that the coolant circulation system can quickly respond to changes in the stack temperature, providing accurate target values for subsequent PID control.

[0053] The PID control unit accurately controls the speed of the water pump through the PID algorithm based on the target flow determined by the flow following unit and the real-time flow data feedback by the flow sensor, to achieve precise regulation of the coolant flow.

[0054] Specifically, the PID control unit is the "precision guidance system" of the control strategy module, which uses the PID control algorithm to accurately calculate and adjust the speed of the water pump based on the target flow determined by the flow following unit and the real-time flow data feedback by the flow sensor. The PID control algorithm effectively eliminates the influence of system inertia, lag and other factors on flow control through the synergistic effect of proportional, integral and differential, achieving rapid and accurate regulation of coolant flow. In this process, the PID control unit continuously compares the deviation between the target flow and the actual flow, and adjusts the control signal of the water pump accordingly, ensuring that the coolant flow is always close to the target value, providing stable heat dissipation conditions for the stack.

[0055] The temperature regulation unit controls the start of the heater and adjusts the flow of the auxiliary heating cycle (small cycle) when the stack temperature is too low, and adjusts the distribution of the coolant between the main cycle (large cycle) and the auxiliary heating cycle (small cycle) through the control valve to quickly raise the stack temperature to the ideal working temperature. In certain conditions, the power change rate limiting strategy of the circulating water pump and the intelligent speed adjustment strategy of the radiator fan are implemented to optimize the thermal management effect and prevent system oscillation and overheating / overcooling phenomena.

[0056] Specifically, the temperature regulation unit is the "intelligent temperature controller" of the control strategy module, which is responsible for quickly starting and adjusting related actuators when the stack temperature deviates from the ideal range to restore the stack to the optimal working temperature. Specifically, when the stack temperature is too low, the temperature regulation unit controls the start of the heater and adjusts the flow of the auxiliary heating cycle (small cycle), and adjusts the optimal distribution of the coolant between the main cycle (large cycle) and the auxiliary heating cycle (small cycle) through the control valve (such as the thermostat). In this process, the temperature regulation unit not only considers the demand for rapid heating, but also takes into account the system energy efficiency and stability, avoiding performance degradation or damage caused by excessive temperature fluctuations.

[0057] Meanwhile, under certain working conditions, such as high temperature and high load or low temperature start-up, the temperature regulation unit also implements a series of supplementary control strategies, such as circulating water pump power change rate limiting strategy, radiator fan speed intelligent adjustment strategy, etc. The circulating water pump power change rate limiting strategy effectively prevents the system from shaking or becoming unstable due to power impact by limiting the mutation rate of water pump power; the radiator fan speed intelligent adjustment strategy adjusts the fan speed in advance according to the change trend of the stack inlet temperature, improves the heat dissipation efficiency and reduces the energy consumption. The implementation of these supplementary control strategies further optimizes the thermal management effect and ensures the stable operation of the fuel cell system under various extreme working conditions.

[0058] As a specific embodiment of the liquid-cooled fuel cell thermal management subsystem, the thermal management system controller further comprises a fault diagnosis and protection module and a communication interface module.

[0059] The fault diagnosis and protection module is used to monitor the operating state of the cooling liquid circulation system and the fuel cell body in real time, and in combination with the calculated value of the stack temperature and the sensor-monitored inlet temperature, outlet temperature and flow data, when an abnormality is detected, automatically take protective measures such as reducing the water pump speed, turning off the heater or radiator, issuing an alarm signal, to prevent system damage and ensure safe operation.

[0060] Specifically, the fault diagnosis and protection module is the "safety guard" of the system, which monitors the operating state of the cooling liquid circulation system and the fuel cell body in real time. In combination with the calculated value of the stack temperature and the sensor-monitored inlet temperature, outlet temperature and flow data, it quickly identifies abnormal conditions in the system, such as excessively high temperature, abnormal flow, etc. Once an abnormality is detected, it will automatically take protective measures such as reducing the water pump speed, turning off the heater or radiator, issuing an alarm signal, etc. to prevent system damage and ensure safe operation. The implementation of these protective measures effectively improves the reliability and stability of the system.

[0061] The communication interface module is used for data exchange with external devices or systems, realizing remote monitoring, parameter setting and fault diagnosis functions, improving the maintainability and intelligent level of the system; at the same time, external load current information or other related instructions can be received through the communication interface module to optimize the control strategy of the thermal management system controller.

[0062] Specifically, the communication interface module is the "external contact window" of the system, which is responsible for data exchange with external devices or systems. Through this communication interface module, the thermal management system controller can realize remote monitoring, parameter setting and fault diagnosis functions, greatly improving the maintainability and intelligent level of the system. At the same time, the communication interface module can also receive external load current information or other related instructions to optimize the control strategy of the thermal management system controller, making it more adaptable to the operating requirements under different working conditions. This open and extensible design provides convenient conditions for the future upgrade and expansion of the fuel cell system.

[0063] As a specific embodiment of a liquid-cooled fuel cell thermal management subsystem, the temperature regulation unit dynamically adjusts the heating power of the heater according to the difference between the stack temperature and the ideal working temperature when starting the heater, and adjusts the flow of the auxiliary heating cycle (small cycle) through the control valve to realize the rapid and smooth rise of the stack temperature; at the same time, according to the heat dissipation demand, the flow of the main cycle (large cycle) and the speed of the radiator fan are adjusted to ensure that the fuel cell main body can maintain the best working temperature under different working conditions.

[0064] A liquid-cooled fuel cell thermal management control method applied to a liquid-cooled fuel cell thermal management subsystem, comprising the following steps:

[0065] Data acquisition step: real-time acquisition of fuel cell stack temperature, fuel cell cooling liquid inlet and outlet temperature by temperature sensor, cooling liquid flow data acquisition by flow sensor, and transmission of these data to thermal management system controller.

[0066] Specifically, the data acquisition step as the starting point of the whole control method, uses multiple sensors to real-time collect fuel cell stack temperature, cooling liquid inlet and outlet temperature and flow, etc. Key data, and accurately transmits these data to the thermal management system controller, providing rich and accurate information source for subsequent analysis and decision-making.

[0067] Model construction and analysis step: the thermal management system controller analyzes the current system running state based on the obtained data, combined with the fuel cell thermal management system model, which covers the stack model, heat balance model and cooling system model, determines the key factors affecting the stack temperature and the coupling relationship between each factor.

[0068] Specifically, the model construction and analysis step is the core theoretical support of the control method. The controller, based on the real-time data obtained, combines the comprehensive fuel cell thermal management system model to conduct a comprehensive and in-depth analysis of the current system running state. By determining the key factors affecting the stack temperature and their coupling relationship, the internal law of system operation is revealed, providing a solid basis for formulating a scientific and reasonable control strategy.

[0069] Control decision and execution step: according to the model analysis result, the cooling system control strategy based on flow following is executed, the cooling or heating mode is determined according to the current fuel cell stack temperature, the circulating water pump and the radiator are adjusted, and the power battery temperature reaches the target temperature; at the same time, the supplementary control strategy is executed, including the circulating water pump power change rate limiting, the thermostat opening adjustment and the radiator fan speed control.

[0070] Specifically, the control decision and execution step is the key link of converting theoretical analysis into actual control action. According to the model analysis result, first, the cooling system control strategy based on flow following is executed, the circulating water pump and the radiator are dynamically adjusted according to the stack temperature demand, and the preliminary accurate control of the stack temperature is realized. At the same time, in order to further optimize the thermal management effect, a series of supplementary control strategies are executed, including circulating water pump power change rate limiting, thermostat opening adjustment and radiator fan speed control. These supplementary strategies cooperate with each other, effectively prevent the occurrence of system oscillation and overheating / overcooling phenomenon, and ensure that the fuel cell can stably and efficiently operate under various working conditions.

[0071] In summary, the liquid-cooled fuel cell thermal management control method of the application forms a complete and closed-loop control system through the organic combination of the three steps of data acquisition, model construction and analysis, and control decision and execution, can dynamically adjust and optimize according to the real-time thermal state of the fuel cell, provides a strong guarantee for the safe and reliable operation of the fuel cell, and has significant application value and popularization prospect.

[0072] As a specific embodiment of the liquid-cooled fuel cell thermal management control method, the cooling system control strategy based on flow following is specifically:

[0073] PID controller input and output determination: the PID controller takes the load current and the temperature difference between the inlet and outlet of the stack as the input, and outputs the cooling liquid flow set value;

[0074] PID controller parameter setting: the proportional coefficient Kp, the integral coefficient Ki and the differential coefficient Kd are set, and are adjusted through simulation or real vehicle calibration to meet the dynamic response and steady state accuracy requirements of the system under different working conditions;

[0075] PID control logic execution: when the temperature difference between the inlet and outlet of the stack exceeds the set threshold, the PID controller calculates the required coolant flow rate set value based on the current temperature difference and load current, increasing the heat dissipation capacity; when the stack temperature approaches the target value, the coolant flow rate change rate is reduced to avoid temperature overshoot; according to the change trend of the load current, the coolant flow rate is adjusted in advance to improve the dynamic response performance of the system; in low temperature environment, the coolant flow rate set value is appropriately reduced to prevent the stack temperature from dropping too fast; in high temperature and high load conditions, the coolant flow rate set value is increased to ensure stable operation of the stack.

[0076] Specifically, in combination with Figure 2 , the flow following cooling system control strategy aims to dynamically adjust the coolant flow rate of the cooling system according to the real-time operating state of the fuel cell (PEMFC) to ensure that the fuel cell operates within the optimal temperature range, thereby improving its performance and lifespan. This strategy monitors load current, inlet temperature and other parameters in real time, and combines a PID control algorithm to accurately control the operation of the circulating water pump and radiator. Specifically, the following processes are included:

[0077] Data acquisition and processing:

[0078] The temperature sensor collects the inlet temperature T in of the fuel cell coolant in real time and transmits it to the thermal management system controller. At the same time, the flow sensor monitors the actual coolant flow rate W real in real time. The load current I is also obtained in real time for calculating the design coolant flow rate (i.e. target coolant flow rate) W cl,design = f(I, ΔT), specifically, W cl,design is a function of load current I and temperature difference ΔT. ΔT set is the set temperature difference (usually 10℃) for comparison with the actual temperature difference as an important reference value in the control strategy. T in,set is the set coolant inlet temperature as the target value for temperature control.

[0079] Temperature control loop:

[0080] The set coolant inlet temperature T in,set is compared with the actual monitored inlet temperature T in to obtain the temperature deviation. The temperature deviation is input into the PID controller. The PID controller calculates the control voltage according to the size of the deviation, the rate of change and the historical deviation information. The control voltage is filtered and adjusted by the transfer function (where T is the time constant and s is the Laplace operator) and then output to the radiator to adjust the heat dissipation capacity of the radiator to control the inlet temperature of the coolant.

[0081] Flow following control loop:

[0082] According to the load current I and the set temperature difference ΔT set , the design coolant flow rate is calculated by the formula W cl,design = f(I, ΔT). The design coolant flow rate W cl,design is compared with the actual coolant flow rate W real , and the flow rate deviation is obtained. The flow rate deviation is input into another PID controller, which calculates a frequency control signal according to the deviation. After the frequency control signal is processed by a transfer function , it is output to the circulating water pump to adjust the speed of the water pump, thereby changing the actual flow rate of the coolant to follow the design flow rate, achieving flow rate following control.

[0083] The temperature control loop and the flow rate following control loop cooperate with each other. The flow rate following control ensures that the coolant flow rate can be dynamically adjusted according to the load and temperature requirements, and the temperature control further precisely adjusts the inlet temperature of the coolant, so that the fuel cell can always be kept within the appropriate temperature range. Through this cooperative control method, the cooling system can quickly respond to load changes and temperature fluctuations, effectively avoiding performance degradation or damage of the fuel cell due to excessively high or low temperature, and improving the stability and reliability of the fuel cell system.

[0084] As a specific embodiment of the liquid-cooled fuel cell thermal management control method, the circulating water pump power change rate limiting strategy is:

[0085] The thermal management system controller monitors the circulating water pump power change in real time. When the water pump power rises or falls by more than the preset limiting value per unit time, the controller limits the change rate of the water pump power to prevent system shocks caused by sudden power changes. The preset limiting value is set according to different working conditions of the fuel cell and system stability requirements, and different limiting values are used in different stages such as starting, accelerating, and decelerating.

[0086] Specifically, as shown in Figure 3 , the water pump control model is a key part of the fuel cell thermal management system. Its main function is to accurately control the speed of the circulating water pump according to the heat generation and temperature requirements of the fuel cell, thereby adjusting the flow rate of the coolant to ensure stable operation of the fuel cell within the appropriate temperature range. This model realizes precise control of the water pump frequency through comprehensive consideration of multiple input parameters, function calculation, and PID control. Figure 3 The correlation function is introduced as follows:

[0087] Q gen(W): Heat generated by the fuel cell. It reflects the heat production rate during the operation of the fuel cell and is an important parameter for determining cooling demand. The more heat is produced, the larger the cooling liquid flow rate is usually required.

[0088] Q gas (W): Heat carried away by the gas. During the operation of the fuel cell, part of the heat is carried away by the gas flow, and this parameter is used to correct the total heat balance calculation.

[0089] : Indicates the rate of change of a certain parameter related to mass flow over time. It can be used to reflect the dynamic changes of mass flow in the system, and has reference significance for adjusting the cooling liquid flow rate.

[0090] T st (℃): Temperature of the fuel cell stack. The stack temperature is a key indicator of thermal management, directly determining whether to increase or decrease the cooling liquid flow rate.

[0091] δ T (℃): Temperature deviation, which can be the difference between the set temperature and the actual stack temperature, used to measure the deviation of the current temperature from the target temperature.

[0092] W cl (kg / s): Mass flow rate of the cooling liquid, which is the output adjustment object of the water pump control model.

[0093] Function f(u): This is a comprehensive calculation function that integrates multiple input parameters (Q gen (W), Q gas (W), ΔtΔw , T st (℃), δ T (℃)) to calculate an intermediate value W cool related to the cooling liquid flow rate. The specific form of this function can be determined according to the thermal characteristics of the fuel cell, system structure, etc., aiming to comprehensively consider various factors affecting the cooling liquid flow rate.

[0094] W design : Designed cooling liquid flow rate, which is a flow rate value set in advance according to the design requirements and expected operating conditions of the fuel cell.

[0095] W real : Actual cooling liquid flow rate, measured in real time by a sensor.

[0096] PID controller: Proportional-Integral-Derivative controller, which calculates the control signal according to the deviation between the designed cooling liquid flow rate W design and the actual cooling liquid flow rate W real . The output formula of the PID controller is: u(t) = Kp e(t) + K i ∫ 0t e(τ)dτ + K d dtde(t) , where u(t) is the output of the controller, e(t) = W design -W real is the error, K p , K i , K d are the proportional, integral, and derivative coefficients, respectively. By adjusting these three coefficients, the response speed, stability, and accuracy of the control system can be optimized.

[0097] Control frequency range limitation: Limit the frequency range of the control signal output by the PID controller, ensuring that the water pump operates within a safe and reasonable frequency range, preventing damage to the water pump or affecting system stability due to excessively high or low frequencies.

[0098] Frequency p ump(Hz): The control frequency of the water pump, which is the final output of the water pump control model, used to directly control the speed of the water pump.

[0099] The specific process of the water pump control model is as follows:

[0100] (1) Data acquisition and input: Real-time acquisition of the heat generated by the fuel cell Q gen (W), the heat carried away by the gas Q gas (W), the mass flow rate change rate , the stack temperature T st (℃), and the temperature deviation δ T (℃), and input these parameters into the function f(u).

[0101] (2) Intermediate value calculation: The function f(u) calculates the intermediate value W cool according to the input parameters, which reflects the required coolant flow rate after considering various factors (equivalent to: design coolant flow rate W design ).

[0102] (3) Flow deviation calculation and PID control: Compare the design coolant flow rate W design with the actual coolant flow rate W real to obtain the flow deviation. Input the flow deviation into the PID controller, and the PID controller calculates the control signal according to the size of the deviation, the trend of change, and the historical deviation information.

[0103] (4) Frequency limitation and water pump control: Limit the control frequency range of the control signal output by the PID controller to ensure that the output signal is within a safe and effective range. The final control frequency Frequencyp ump(Hz) is used to control the rotation speed of the water pump, so as to adjust the flow of the cooling liquid, so that the actual cooling liquid flow W real As close as possible to the design cooling liquid flow W design , to achieve precise control of the temperature of the fuel cell.

[0104] The advantages of this water pump control model: through the function f(u), various factors such as fuel cell heat generation, heat carried away by gas, mass flow variation, and temperature are comprehensively considered, making the control of cooling liquid flow more comprehensive and accurate. Using the PID control algorithm, the control signal can be adjusted in real time according to the flow deviation, realizing precise control of the rotation speed of the water pump, and then accurately adjusting the cooling liquid flow. The control frequency range limiting link ensures that the water pump operates within a safe frequency range, improves the reliability and stability of the system, and prolongs the service life of the water pump.

[0105] As a specific embodiment of a liquid-cooled fuel cell thermal management control method, the thermostat opening adjustment strategy is:

[0106] The thermal management system controller adjusts the thermostat opening in real time according to the change of the stack temperature. When the stack temperature is lower than the lower limit of the ideal working temperature, the thermostat opening is reduced, the auxiliary heating cycle (small cycle) cooling liquid flow is increased, and the main cycle (large cycle) heat dissipation is reduced to quickly raise the stack temperature. When the stack temperature is higher than the upper limit of the ideal working temperature, the thermostat opening is increased, the main cycle (large cycle) cooling liquid flow is increased, and the heat dissipation capacity is enhanced to maintain the stack temperature within a reasonable range. During the adjustment of the thermostat opening, the controller uses a gradual adjustment method according to the temperature change rate and the target temperature difference to avoid sudden changes in the opening that may cause shocks to the system.

[0107] The thermostat is essentially a three-way valve, but its opening size can change with temperature, and the valve opening is adjusted at different temperatures to achieve the distribution of large and small cycle cooling liquids. Currently, there are two common types of thermostats: electronic thermostats and paraffin thermostats. Electronic thermostats have the characteristics of fast response and high control accuracy, while paraffin thermostats have the characteristics of safety and reliability, simple structure, and low cost. This patent uses an electronic thermostat. After the cooling liquid is divided by the thermostat, the flow rates of the radiator branch and the bypass pipe can be represented as:

[0108]

[0109] In the formula, k is the opening of the thermostat, which varies from 0 to 1. The ratio of the current flow area of the valve to the maximum flow area is defined as the opening of the thermostat:

[0110]

[0111] The motor thermostat selected in the patent controls the flow area of the thermostat by changing the valve angle, uses the valve angle θ to obtain the opening degree k of the thermostat, and further controls the flow of the large and small circulating cooling liquids.

[0112] Due to the shunt effect of the thermostat, the temperature of the cooling liquid flowing back to the inlet of the stack is the temperature value after mixing of the large and small circulating cooling liquids, which can be expressed as:

[0113] T st,in (t+t pipe )=(W bypass T st,out +W rad T rad,out ) / W cool ;

[0114] In the formula, t pump represents the time delay of the cooling pipeline.

[0115] The optimal temperature of the stack in the patent is 70℃, the initial opening temperature of the thermostat is set to 55℃, and the full opening temperature is 65℃. When the temperature reaches 55℃, the thermostat gradually opens, and when the temperature rises to 65℃, the thermostat is fully opened, and the cooling liquid flows through the large circulation. When the load changes, the radiator can achieve better heat dissipation effect, and the thermostat will not be frequently opened and closed, which is beneficial to prolong the service life of the thermostat.

[0116] As a specific embodiment of a liquid-cooled fuel cell thermal management control method, the radiator fan speed control strategy is: the thermal management system controller adjusts the radiator fan speed in real time according to the stack inlet temperature, increases the fan speed when the stack inlet temperature exceeds the set threshold, and enhances the heat dissipation efficiency; when the stack inlet temperature is lower than the set threshold, reduce the fan speed to reduce energy consumption; the fan speed adjustment adopts a hierarchical control mode, different speed levels are set according to the temperature interval, and precise heat dissipation control is realized.

[0117] Specifically, as shown in Figure 4 , the radiator control model plays a crucial role in the fuel cell thermal management system. Its main purpose is to accurately control the control voltage of the radiator according to the inlet temperature of the fuel cell stack, so as to adjust the heat dissipation capacity of the radiator and ensure that the fuel cell works in the appropriate temperature range. The model receives the deviation signal of the temperature set value and the actual inlet temperature, passes through the PID controller and the control voltage range limiting link, and realizes effective control of the radiator. Figure 4 The correlation function is introduced as follows:

[0118] T st_in ((℃): the inlet temperature of the fuel cell stack. It is an important parameter reflecting the current thermal state of the fuel cell, which is measured in real time by a temperature sensor.

[0119] T st_design (℃): Design inlet temperature of fuel cell stack. It is a temperature value set in advance according to the performance requirements and optimal working conditions of the fuel cell as the target temperature of the radiator control.

[0120] Control voltage range limitation: Range limitation on the control signal output by the PID controller. Since the control voltage of the radiator has a certain allowable range, this link ensures that the control voltage U fan (V) output to the radiator is within the safe and effective range, preventing damage or affecting the normal work of the radiator due to excessively high or low voltage.

[0121] U fan (V): Control voltage of the radiator. It is the final output of the radiator control model, and by adjusting this voltage, the fan speed of the radiator can be changed, thereby adjusting the heat dissipation capacity of the radiator.

[0122] The specific process of the radiator control model is as follows:

[0123] (1) Temperature data acquisition and deviation calculation

[0124] The temperature sensor collects the inlet temperature T st_in (℃) of the fuel cell stack in real time and transmits it to the control model. The actual inlet temperature T st_in (℃) is subtracted from the design inlet temperature T st_design (℃) to obtain the temperature deviation signal.

[0125] (2) PID control calculation

[0126] The temperature deviation signal is input into the PID controller. The PID controller calculates a preliminary control signal according to the preset proportional, integral, and derivative coefficients based on the size, trend of change, and historical deviation information of the deviation.

[0127] (3) Control voltage range limitation and radiator control

[0128] The control signal output by the PID controller is subjected to control voltage range limitation to ensure that the output voltage is within the allowable working voltage range of the radiator.

[0129] The limited control voltage U fan (V) acts on the radiator, adjusting the fan speed of the radiator and changing the heat dissipation efficiency of the radiator. When the actual inlet temperature is higher than the design inlet temperature, the control voltage adjusts accordingly to increase the fan speed and enhance the heat dissipation capacity; conversely, when the actual inlet temperature is lower than the design inlet temperature, the fan speed is reduced to reduce heat dissipation, thereby gradually approaching the design inlet temperature of the fuel cell stack.

[0130] The advantages of the radiator control model: using PID control algorithm, can real-time, accurate adjustment of the control voltage of the radiator according to temperature deviation, realize the precise control of the inlet temperature of fuel cell, ensure the fuel cell in the best temperature range operation. Control voltage range limit link ensures that the radiator works in the safe voltage condition, avoids the damage caused by abnormal voltage to the radiator, improves the reliability and stability of the system. The model can adapt to different fuel cell working conditions and environmental conditions, by adjusting the parameters of PID controller, can optimize the control effect, meet the heat management demand in different situations.

[0131] The above examples only express one or several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A liquid-cooled fuel cell thermal management subsystem, characterized in that: include: A fuel cell body, used to provide electrical energy to a load; A coolant circulation system, comprising a water tank, a water pump, a radiator, a heater, a control valve, and coolant piping, connected to the fuel cell body and configured to circulate coolant to regulate the temperature of the fuel cell body; the coolant circulation system comprises a main circulation (large circulation) through the radiator and an auxiliary heating circulation (small circulation) through the heater; Temperature sensors are provided at the inlet and outlet of the fuel cell body, respectively, for real-time monitoring of the inlet temperature and outlet temperature of the coolant; A flow sensor is installed on the coolant pipeline at the water pump outlet to monitor the coolant flow at the water pump outlet in real time; The thermal management system controller is electrically connected to the temperature sensor, flow sensor, water pump, radiator, heater and control valve. The thermal management system controller obtains the stack temperature of the fuel cell body through load current calculation, and continuously monitors the inlet temperature, outlet temperature and water pump outlet flow of the fuel cell body, and controls the working state of the coolant circulation system according to the monitoring and calculation data to achieve precise control of the temperature of the fuel cell body.

2. A liquid-cooled fuel cell thermal management subsystem according to claim 1, characterized in that: The thermal management system controller includes: Data acquisition module, used to collect data feedback from temperature sensors and flow sensors in real time and obtain load current information; A calculation module, used to calculate the stack temperature of the fuel cell body according to the acquired load current information; The modeling and analysis module is used to establish the fuel cell stack model, thermal balance model, and cooling system model based on the collected data and the calculated stack temperature, and analyze the thermal state of the fuel cell body and the performance of the coolant circulation system; The control strategy module is used to formulate and execute the control strategy of the coolant circulation system based on the output of the modeling and analysis module, including adjusting the water pump speed, radiator fan speed, heater power and the opening of the control valve to maintain the fuel cell body operating within an appropriate temperature range.

3. The liquid-cooled fuel cell thermal management subsystem according to claim 2, characterized in that: The control strategy module specifically includes: The flow following unit dynamically determines the target flow rate of the coolant based on the real-time temperature demand of the fuel cell body and the output of the modeling and analysis module; The PID control unit uses the PID algorithm to accurately control the speed of the water pump according to the target flow determined by the flow following unit and the real-time flow data fed back by the flow sensor, so as to achieve precise regulation of the coolant flow; The temperature regulation unit controls the heater to start and adjust the flow of the auxiliary heating cycle (small cycle) when the temperature of the fuel cell stack is too low. At the same time, it combines with the control valve to adjust the distribution of the coolant between the main cycle (large cycle) and the auxiliary heating cycle (small cycle) to quickly increase the temperature of the fuel cell stack to the ideal operating temperature. Under specific working conditions, the circulating water pump power change rate limiting strategy and the radiator fan speed intelligent adjustment strategy are implemented to optimize the thermal management effect and prevent system oscillation and overheating / overcooling.

4. A liquid-cooled fuel cell thermal management subsystem according to any one of claims 1 to 3, characterized in that: The thermal management system controller further includes: The fault diagnosis and protection module monitors the operating status of the coolant circulation system and fuel cell body in real time. Combining the calculated value of the stack temperature with the inlet and outlet temperatures and flow rate data monitored by sensors, it automatically takes protective measures when an anomaly is detected, such as reducing the water pump speed, shutting down the heater or radiator, and issuing an alarm signal to prevent system damage and ensure safe operation. The communication interface module is used to exchange data with external devices or systems to realize remote monitoring, parameter setting and fault diagnosis functions, thereby improving the maintainability and intelligence level of the system. At the same time, external load current information or other related instructions can be received through the communication interface module to optimize the control strategy of the thermal management system controller.

5. The liquid-cooled fuel cell thermal management subsystem according to claim 3, characterized in that: When controlling the heater to start, the temperature regulating unit dynamically adjusts the heating power of the heater according to the difference between the stack temperature and the ideal operating temperature, and adjusts the flow of the auxiliary heating cycle (small cycle) through the control valve to achieve a rapid and steady increase in the stack temperature; at the same time, according to the heat dissipation requirements, the flow of the main cycle (large cycle) and the speed of the radiator fan are adjusted to ensure that the fuel cell body can maintain the optimal operating temperature under different working conditions.

6. A liquid-cooled fuel cell thermal management control method, applied to a liquid-cooled fuel cell thermal management subsystem according to any one of claims 1 to 5, characterized in that: The following steps are involved: Data acquisition steps: Use temperature sensors to collect real-time fuel cell stack temperature and fuel cell coolant inlet and outlet temperatures, use flow sensors to obtain coolant flow data, and transmit these data to the thermal management system controller; Model construction and analysis steps: Based on the acquired data, the thermal management system controller combines the fuel cell thermal management system model, which includes the stack model, heat balance model, and cooling system model, to analyze the current system operating status and determine the key factors affecting the stack temperature and the coupling relationship between these factors; Control decision and execution steps: Based on the model analysis results, a flow-following-based cooling system control strategy is executed. The cooling or heating mode is determined according to the current fuel cell stack temperature. The circulating water pump and radiator are adjusted to make the power battery temperature reach the target temperature. At the same time, supplementary control strategies are implemented, including limiting the circulating water pump power change rate, adjusting the thermostat opening, and controlling the radiator fan speed.

7. The method for thermal management of a liquid-cooled fuel cell according to claim 6, wherein: The cooling system control strategy based on flow following is specifically as follows: PID controller input and output determination: The PID controller takes the load current and the temperature difference between the inlet and outlet of the fuel cell stack as input and outputs the coolant flow set value; PID controller parameter setting: Set the proportional coefficient Kp, integral coefficient Ki, and differential coefficient Kd, and perform tuning through simulation or real vehicle calibration to meet the system's dynamic response and steady-state accuracy requirements under different working conditions; PID control logic execution: When the temperature difference between the inlet and outlet of the fuel cell stack exceeds the set threshold, the PID controller calculates the required coolant flow set value based on the current temperature difference and load current to improve the heat dissipation capacity; when the fuel cell stack temperature approaches the target value, the coolant flow change rate is reduced to avoid temperature overshoot; the coolant flow is adjusted in advance according to the changing trend of the load current to improve the dynamic response performance of the system; in low temperature environments, the coolant flow set value is appropriately reduced to prevent the fuel cell stack temperature from dropping too quickly; under high temperature and high load conditions, the coolant flow set value is increased to ensure stable operation of the fuel cell stack.

8. The method for thermal management of a liquid-cooled fuel cell according to claim 6, wherein: The circulating water pump power change rate limiting strategy is: The thermal management system controller monitors the changes in the circulating water pump power in real time. When the increase or decrease in the water pump power per unit time exceeds the preset limit value, the controller limits the rate of change of the water pump power to prevent the system from being impacted by sudden power changes. The preset limit value is set according to the different operating conditions of the fuel cell and the system stability requirements, and different limit values ​​are used in different stages such as startup, acceleration, and deceleration.

9. The method for thermal management of a liquid-cooled fuel cell according to claim 6, wherein: The thermostat opening adjustment strategy is: The thermal management system controller adjusts the thermostat opening in real time according to the changes in the stack temperature. When the stack temperature is lower than the ideal operating temperature limit, the thermostat opening is reduced, the coolant flow of the auxiliary heating cycle (small cycle) is increased, and the heat dissipation of the main cycle (large cycle) is reduced to quickly increase the stack temperature; when the stack temperature is higher than the ideal operating temperature limit, the thermostat opening is increased, the coolant flow of the main cycle (large cycle) is increased, and the heat dissipation capacity is enhanced to maintain the stack temperature within a reasonable range; during the thermostat opening adjustment process, the controller adopts a gradual adjustment method based on the temperature change rate and the target temperature difference to avoid sudden changes in the opening causing impact on the system.

10. The method for thermal management of a liquid-cooled fuel cell according to claim 6, wherein: The radiator fan speed control strategy is: The thermal management system controller adjusts the radiator fan speed in real time according to the stack inlet temperature. When the stack inlet temperature exceeds the set threshold, the fan speed is increased to enhance heat dissipation efficiency; when the stack inlet temperature is lower than the set threshold, the fan speed is reduced to reduce energy consumption. The fan speed is adjusted using a graded control method, with different speed levels set according to the temperature range to achieve precise heat dissipation control.

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