A three-stage heat exchange fuel cell platform water cooling temperature control system and method

Abstract

The application discloses a kind of three-stage heat exchange fuel cell platform water-cooling temperature control system and method, system includes water-cooling system test platform, outer ring incremental PID and inner ring incremental PID, fuel cell inner circulation loop (1) and test platform in circulation loop (2) are connected by first plate heat exchanger E1, test platform in circulation loop (2) and test platform outer circulation loop (3) are connected by second plate heat exchanger E2, circulation loop (2) is set on test platform in circulation loop (2) three-way proportional valve SV1;The engine outlet temperature of the fuel cell system FAT to be measured and the engine outlet temperature set value difference input outer ring incremental PID, the output of outer ring incremental PID and the output temperature of second plate heat exchanger E2 difference input to inner ring incremental PID;The application has the advantages that: the temperature of the fuel cell system to be measured is accurately and quickly tracked control adjustment.

Description

Technical Field

[0001] This invention relates to the field of fuel cell system control, specifically to a water-cooled temperature control system and method for a three-stage heat exchange fuel cell platform. Background Technology

[0002] High-power fuel cell system design is a growing trend. To ensure reliable and stable optimal performance output of high-power fuel cell systems, the testing system must guarantee optimal operating conditions for three flow fields: hydrogen flow, air flow, and water flow, providing a basis for product performance evaluation. However, currently, under low load or low temperature conditions, fuel cells heat up slowly, requiring the circulating water temperature to reach a specific level before the stack can be gradually loaded for performance testing. Furthermore, due to differences in fuel cell technology routes, the requirements for fuel cell thermal management characteristics also differ, necessitating a higher degree of adaptability from fuel cell system test benches. Firstly, differences in the internal structure of fuel cell systems lead to significant variations in internal cold flow resistance. Secondly, different temperature and temperature difference control ranges for fuel cell systems make it difficult to simultaneously meet the hardware configuration and software control methods of the fuel cell system test bench. Therefore, existing fuel cell test benches suffer from limited test power coverage and narrow temperature difference control ranges.

[0003] In summary, current PEMFC proton exchange membrane testing platforms, such as the proton exchange membrane fuel cell testing and control platform disclosed in Chinese Patent Publication No. CN103199284A, suffer from problems such as severe overshoot of the target temperature of the circulating water and slow response to the target temperature when the stack is operating under high-power sudden load conditions during the testing of high-power fuel cell systems. This is because the stack heats up slowly and must wait for the circulating water temperature to rise to a specific temperature before the stack can be gradually loaded for performance testing. Summary of the Invention

[0004] The technical problem to be solved by this invention is that the existing fuel cell system temperature control methods have problems such as serious overshoot of the target temperature of the circulating water and slow response of the target temperature.

[0005] The present invention solves the above-mentioned technical problems through the following technical means: a three-stage heat exchange fuel cell platform water-cooled temperature control system, including a water-cooled system test platform, an outer loop incremental PID and an inner loop incremental PID. The water-cooled system test platform includes an inner circulation loop (1) of the fuel cell, a middle circulation loop (2) of the test platform and an outer circulation loop (3) of the test platform. The inner circulation loop (1) of the fuel cell and the middle circulation loop (2) of the test platform are connected through a first plate heat exchanger E1. The middle circulation loop (2) of the test platform and the outer circulation loop (3) of the test platform are connected through a second plate heat exchanger E2. A three-way proportional valve SV1 is set on the loop where the middle circulation loop (2) of the test platform is located. The difference between the engine outlet temperature of the fuel cell system FAT under test and the engine outlet temperature set value is input to the outer loop incremental PID. The difference between the output of the outer loop incremental PID and the output temperature of the second plate heat exchanger E2 is input to the inner loop incremental PID. The output of the inner loop incremental PID is added to the set feedforward opening and acts on the three-way proportional valve SV1.

[0006] Furthermore, the water-cooled temperature control system of the three-stage heat exchange fuel cell system platform also includes a first subtractor, a second subtractor, and an adder. The engine outlet temperature of the fuel cell system under test (FAT) and the engine outlet temperature setpoint are input to the first subtractor. The first subtractor, the outer loop incremental PID, the second subtractor, the inner loop incremental PID, the adder, and the three-way proportional valve SV1 are connected in sequence. The output temperature of the second plate heat exchanger E2 is fed back to the second subtractor.

[0007] Furthermore, the internal circulation loop (1) of the fuel cell includes an electric valve EV2, a pressure sensor P2, a temperature sensor T2, a conductivity sensor CS, an electric valve EV1, a pressure sensor P1, a temperature sensor T1, and a flow sensor F1. The electric valve EV2, pressure sensor P2, temperature sensor T2, and conductivity sensor CS are installed on the pipeline from the outlet of the fuel cell system FAT under test to the first inlet of the first plate heat exchanger E1. The electric valve EV1, pressure sensor P1, temperature sensor T1, and flow sensor F1 are installed on the pipeline from the first outlet of the first plate heat exchanger E1 to the inlet of the fuel cell system FAT under test.

[0008] Furthermore, the water-cooled temperature control system of the three-stage heat exchange fuel cell system platform also includes a water replenishment circuit. The water replenishment circuit includes an electric valve EV3, an electric valve EV4, and a water replenishment tank. One outlet of the fuel cell system under test (FAT) is connected to the inlet of the water replenishment tank through the electric valve EV4. The outlet of the water replenishment tank is connected to the pipeline where the first outlet of the first plate heat exchanger (E1) is located through the electric valve EV3.

[0009] Furthermore, the water replenishment tank is equipped with an exhaust port.

[0010] Furthermore, the circulating loop (2) in the test platform includes a temperature sensor T3, a pressure sensor P3, a flow sensor F2, a water pump 1, a three-way proportional valve SV1, a temperature sensor T4, a pressure sensor P4, a heater H1, and a temperature sensor T5. The temperature sensor T3, pressure sensor P3, flow sensor F2, water pump 1, and three-way proportional valve SV1 are installed on the pipeline between the second outlet of the first plate heat exchanger E1 and the first inlet of the second plate heat exchanger E2. The temperature sensor T4, pressure sensor P4, heater H1, and temperature sensor T5 are installed on the pipeline between the first outlet of the second plate heat exchanger E2 and the second inlet of the first plate heat exchanger E1. One interface of the three-way proportional valve SV1 is connected to the pipeline between the heater H1 and the first outlet of the second plate heat exchanger E2.

[0011] Furthermore, the external circulation loop (3) of the test platform includes a filter Y1, a temperature control valve SV2, a temperature sensor T6, a pressure sensor P5, and a flow meter F3. The filter Y1, the temperature control valve SV2, the temperature sensor T6, and the pressure sensor P5 are installed on the pipeline where the second inlet of the second plate heat exchanger E2 is located and the outlet of the cooling tower is located. The flow meter F3 is installed on the pipeline where the second outlet of the second plate heat exchanger E2 is located and the inlet of the cooling tower is located.

[0012] Furthermore, the external circulation loop (3) of the test platform also includes a manual ball valve V1 and a manual ball valve V2, which are installed on the pipeline between the filter Y1 and the temperature control valve SV2.

[0013] This invention also provides a method for a water-cooled temperature control system for a three-stage heat exchange fuel cell platform. The difference between the engine outlet temperature of the fuel cell system under test (FAT) and the set engine outlet temperature is input to an outer-loop incremental PID controller. The difference between the output of the outer-loop incremental PID controller and the output temperature of the second plate heat exchanger (E2) is input to an inner-loop incremental PID controller. The output of the inner-loop incremental PID controller is added to the set feedforward opening and applied to a three-way proportional valve (SV1), thereby adjusting the water flow rate in the loop containing the second plate heat exchanger (E2) and indirectly adjusting the temperature of the fuel cell system under test.

[0014] Furthermore, the engine outlet temperature of the fuel cell system under test (FAT) is subtracted from the engine outlet temperature setpoint by the first subtractor and input into the outer loop incremental PID controller for PID adjustment. The output of the outer loop incremental PID controller is subtracted from the outlet temperature setpoint of the second plate heat exchanger (E2) and the actual outlet temperature of the second plate heat exchanger (E2) by the second subtractor and input into the inner loop incremental PID controller for PID adjustment. The output of the inner loop incremental PID controller is added to the set feedforward opening value by the adder and applied to the three-way proportional valve (SV1).

[0015] The advantages of this invention are:

[0016] (1) The present invention adjusts the three-way proportional valve SV1 by coordinating the outer loop incremental PID and the inner loop incremental PID, thereby adjusting the water flow in the loop where the second plate heat exchanger E2 is located, and indirectly performs precise and rapid tracking control adjustment of the temperature of the fuel cell system under test, avoiding the problem of severe overshoot of the target temperature of the circulating water and slow response of the target temperature.

[0017] (2) This invention is mainly used for factory calibration testing of fuel cell systems. Under the conditions of closed-loop power control and open-loop water cooling system of fuel cell system, it can achieve precise control of thermal management system through fuel cell test bench. Compared with the temperature control system of traditional test platform, it not only has the advantages of rapid drainage, water addition and replacement, and low pressure resistance pipeline design, but more importantly, it can quickly achieve target temperature tracking of circulating water, meeting the test requirements of 1~2℃ / S temperature rise of circulating water under high power stack test conditions. At the same time, it can also provide fuel cell system developers with special test conditions that simulate the air cooling heat dissipation control requirements of the whole vehicle, which is more in line with the operating conditions of fuel cell test system on the whole vehicle, and meets the test requirements of manufacturers as much as possible. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a water-cooled temperature control system for a three-stage heat exchange fuel cell platform disclosed in an embodiment of the present invention;

[0019] Figure 2 This is a PID control principle diagram of a water-cooled temperature control system for a three-stage heat exchange fuel cell platform disclosed in an embodiment of the present invention;

[0020] Figure 3 This is a temperature control curve of the fuel cell system power change process in a water-cooled temperature control system of a three-stage heat exchange fuel cell platform disclosed in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figure 1 and Figure 2As shown, this invention provides a three-stage heat exchange fuel cell platform water-cooled temperature control system, including a water-cooled system test platform, an outer-loop incremental PID controller, and an inner-loop incremental PID controller. The water-cooled system test platform includes an inner circulation loop 1, a middle circulation loop 2, and an outer circulation loop 3. The inner circulation loop 1 and the middle circulation loop 2 are connected by a first plate heat exchanger E1, and the middle circulation loop 2 and the outer circulation loop 3 are connected by a second plate heat exchanger E2. A three-way proportional valve SV1 is installed on the middle circulation loop 2. The engine outlet temperature of the fuel cell system under test (FAT) and the engine outlet temperature setpoint are input to a first subtractor. The first subtractor, the outer-loop incremental PID controller, the second subtractor, the inner-loop incremental PID controller, the adder, and the three-way proportional valve SV1 are connected sequentially. The output temperature of the second plate heat exchanger E2 is fed back to the second subtractor. The difference between the engine outlet temperature of the fuel cell system under test (FAT) and the engine outlet temperature setpoint is input to the outer loop incremental PID controller. The difference between the output of the outer loop incremental PID controller and the output temperature of the second plate heat exchanger (E2) is input to the inner loop incremental PID controller. The output of the inner loop incremental PID controller is added to the set feedforward opening and applied to the three-way proportional valve (SV1). Figure 2 The engine in the middle is the engine of the fuel cell system FAT under test. The structure and principle of each part are described in detail below.

[0023] The internal circulation loop 1 of the fuel cell consists of the fuel cell system FAT and the first plate heat exchanger E1 connected by stainless steel pipes. It includes an electric valve EV2, a pressure sensor P2, a temperature sensor T2, a conductivity sensor CS, an electric valve EV1, a pressure sensor P1, a temperature sensor T1, and a flow sensor F1. The electric valve EV2, pressure sensor P2, temperature sensor T2, and conductivity sensor CS are installed on the pipe from the outlet of the fuel cell system FAT to the first inlet of the first plate heat exchanger E1. The electric valve EV1, pressure sensor P1, temperature sensor T1, and flow sensor F1 are installed on the pipe from the first outlet of the first plate heat exchanger E1 to the inlet of the fuel cell system FAT to be tested.

[0024] The water-cooled temperature control system of the three-stage heat exchange fuel cell system platform also includes a water replenishment circuit. This water replenishment circuit includes electric valves EV3 and EV4, and a water replenishment tank. One outlet of the fuel cell system under test (FAT) is connected to the inlet of the water replenishment tank via electric valve EV4. The outlet of the water replenishment tank is connected to the pipeline containing the first outlet of the first plate heat exchanger (E1) via electric valve EV3. The water replenishment tank is equipped with an exhaust port.

[0025] The test platform's circulation loop 2 consists of a cold side of the first plate heat exchanger E1, a water pump 1, a three-way proportional valve SV1, a heater H1, and a hot side of the second plate heat exchanger E2, connected by stainless steel pipes. It mainly includes a temperature sensor T3, a pressure sensor P3, a flow sensor F2, a water pump 1, a three-way proportional valve SV1, a temperature sensor T4, a pressure sensor P4, a heater H1, and a temperature sensor T5. Temperature sensor T3, pressure sensor P3, flow sensor F2, water pump 1, and three-way proportional valve SV1 are installed on the pipe between the second outlet of the first plate heat exchanger E1 and the first inlet of the second plate heat exchanger E2. Temperature sensor T4, pressure sensor P4, heater H1, and temperature sensor T5 are installed on the pipe between the first outlet of the second plate heat exchanger E2 and the second inlet of the first plate heat exchanger E1. One port of the three-way proportional valve SV1 is connected to the pipe between the heater H1 and the first outlet of the second plate heat exchanger E2.

[0026] The external circulation loop 3 of the test platform is connected to the cold side of the second plate heat exchanger E2 via a stainless steel pipe from the external cooling tower. It mainly includes a filter Y1, a temperature control valve SV2, a temperature sensor T6, a pressure sensor P5, and a flow meter F3. The filter Y1, temperature control valve SV2, temperature sensor T6, and pressure sensor P5 are installed on the pipe connecting the second inlet of the second plate heat exchanger E2 and the outlet of the cooling tower, while the flow meter F3 is installed on the pipe connecting the second outlet of the second plate heat exchanger E2 and the inlet of the cooling tower. The external circulation loop 3 also includes manual ball valves V1 and V2, which are located on the pipe between the filter Y1 and the temperature control valve SV2.

[0027] After the fuel cell system under test (FAT) starts normally, its internal heat is carried out by its internal water pump and flows into the internal circulation loop 1 of the fuel cell. Thermometers TI and T2 are used to measure the inlet and outlet coolant temperatures, pressure gauges P1 and P2 are used to measure the inlet and outlet coolant pressures, and CS1 is used to monitor the coolant conductivity. The first plate heat exchanger E1 provides the heat and mass transfer medium for the FAT's heat dissipation. Depending on its operating conditions, the FAT's coolant temperature response is adjusted in real-time through circulation loop 2 in the test platform to meet both rapid temperature tracking and steady-state control requirements. Circulation loop 2 in the test platform controls the cold-side inlet temperature of the first plate heat exchanger E1 via a three-way proportional valve SV1, and the flow rate is quickly matched by pump 1 to ensure rapid heat dissipation. This loop provides a relatively stable and rapidly adjustable operating environment for the internal circulation loop 1 of the fuel cell. The external circulation loop 3 of the test platform provides cooling to circulation loop 2 through the second plate heat exchanger E2, and the total flow rate required for the entire system circulation can be adjusted by the temperature control valve SV2.

[0028] During the experiment, only the low-pressure flow meter F1, the first plate heat exchanger E1, and the electric ball valves EV1 and EV2 were in the main loop of the fuel cell internal circulation loop 1. The overall system flow resistance was <10 kPa, and the overall system volume more closely approximates the actual on-vehicle volume of the fuel cell system, thus better reflecting the objective performance of the fuel cell system. This reduces the impact on the flow rate of the internal circulation loop, thereby avoiding affecting the inlet and outlet temperature difference of the fuel cell system. Furthermore, it reduces the lag in temperature sampling caused by heat capacity issues. Compared to traditional cooling and heat dissipation temperature control methods, where the inlet temperature and pressure of the cooling source are easily affected by external factors, and fluctuations in pressure, temperature, and flow rate can significantly impact the control of the entire system, this system method can correct for these interferences and provide stable operating conditions.

[0029] This invention also provides a method for a water-cooled temperature control system for a three-stage heat exchange fuel cell platform. The engine outlet temperature of the fuel cell system under test (FAT) and its setpoint are subtracted by a first subtractor and input to an outer-loop incremental PID controller for PID adjustment. The output of the outer-loop incremental PID controller, the setpoint outlet temperature of the second plate heat exchanger E2, and the actual outlet temperature of E2 are subtracted by a second subtractor and input to an inner-loop incremental PID controller for PID adjustment. The output of the inner-loop incremental PID controller is added to a set feedforward opening value via an adder and applied to a three-way proportional valve SV1, thereby adjusting the water flow rate in the loop containing the second plate heat exchanger E2, indirectly adjusting the temperature of the FAT in the fuel cell system under test. This system enables real-time data acquisition, device control, alarm functions, and data storage and analysis; it can also record measurements of the fuel cell system itself and related device controls. Considering that the FAT in the fuel cell system under test has a large heat capacity, meaning the system has large inertia and large delay, control is prone to significant overshoot. Therefore, preventing overshoot is the primary consideration in the control algorithm design. This system employs a PID algorithm with temperature prediction capabilities. This algorithm selects PID parameters based on the temperature deviation and its trend. Finally, the control command is calculated using both the actual and predicted temperature deviations. To ensure prediction accuracy, the model is continuously corrected in real-time based on measured values. This is achieved by introducing an SV1 feedforward reference, a reference proportional coefficient, reference offsets for different power ranges, and pump1 frequency calibrations for different power ranges. The PID control, based on traditional incremental PID, incorporates fuzzy control methods and employs segmented PI and PD control, adjusting the P value according to the difference... proportionality coefficient Current power The cooling coefficient formula is applied in advance to the SV1 proportional valve for early adjustment during high-power load changes. This enables rapid tracking of the target circulating water temperature, meeting the testing requirements of 1~2℃ / s for circulating water temperature rise under high-power fuel cell stack testing conditions.

[0030] This invention also provides fuel cell system developers with special test conditions that simulate the air-cooled heat dissipation control requirements of a complete vehicle, thus better reflecting the operating conditions of the fuel cell test system on a vehicle and meeting the manufacturer's testing needs as much as possible. Simulating the heat dissipation of the entire vehicle provides a relatively stable external condition (relatively stable inlet temperature and flow rate) for temperature control and other experiments on the internal system of the fuel cell system under test; the flow rate calibration is performed at different power levels, referencing the three-speed calibration method of a vehicle fan system.

[0031] 1) The plate heat exchanger inlet temperature TS1 in the circulation loop 2 of the test platform is automatically adjusted and closed-loop controlled by the hardware of the external circulation loop 3 of the test platform, so that the plate heat exchanger inlet temperature TS1 in the circulation loop 2 of the test platform is stabilized within a certain temperature range; the plate heat exchanger inlet temperature TS1 refers to the temperature of the second inlet of the first plate heat exchanger E1.

[0032] 2) Referring to the vehicle fan speed regulation calibration method, the flow rate in loop 2 of the test platform under different power levels of the fuel cell system is calibrated according to the power range.

[0033] Therefore, it can simulate the air-cooled heat dissipation control requirements of the whole vehicle, and provide a relatively stable external condition (relatively stable inlet temperature and relatively stable flow rate) for the internal control experiments of the fuel cell system itself (such as internal temperature control experiments).

[0034] Figure 3 The figure shows the temperature control curve during the power change process of the fuel cell system. It illustrates that the fuel cell system operates from idle to full power (105kW) for 5 minutes, followed by a 10kW (65℃) -10s to 108kW (87℃) -10s cycle acceleration for 10 minutes. Throughout the entire process, the controlled water temperature rapidly follows the target temperature, with a target temperature deviation of <2℃, and a steady-state target temperature deviation of <1℃. Temperature control provides a direct indication of the appropriate matching of the internal components of the fuel cell system, including the water pump, thermostat, and PTC device, and whether there is room for performance optimization.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A water-cooled temperature control system for a three-stage heat exchange fuel cell platform, characterized in that, The test platform includes a water-cooled system test platform, an outer-loop incremental PID and an inner-loop incremental PID. The water-cooled system test platform includes an inner circulation loop (1) of the fuel cell, a middle circulation loop (2) of the test platform and an outer circulation loop (3) of the test platform. The inner circulation loop (1) of the fuel cell and the middle circulation loop (2) of the test platform are connected through a first plate heat exchanger E1. The middle circulation loop (2) of the test platform and the outer circulation loop (3) of the test platform are connected through a second plate heat exchanger E2. A three-way proportional valve SV1 is installed on the loop where the middle circulation loop (2) of the test platform is located. The difference between the engine outlet temperature of the fuel cell system FAT under test and the engine outlet temperature setpoint is input to the outer-loop incremental PID. The difference between the output of the outer-loop incremental PID and the output temperature of the second plate heat exchanger E2 is input to the inner-loop incremental PID. The output of the inner-loop incremental PID is added to the set feedforward opening and acts on the three-way proportional valve SV1. The internal circulation loop (1) of the fuel cell includes an electric valve EV2, a pressure sensor P2, a temperature sensor T2, a conductivity sensor CS, an electric valve EV1, a pressure sensor P1, a temperature sensor T1, and a flow sensor F1. The electric valve EV2, pressure sensor P2, temperature sensor T2, and conductivity sensor CS are installed on the pipeline from the outlet of the fuel cell system FAT under test to the first inlet of the first plate heat exchanger E1. The electric valve EV1, pressure sensor P1, temperature sensor T1, and flow sensor F1 are installed on the pipeline from the first outlet of the first plate heat exchanger E1 to the inlet of the fuel cell system FAT under test. The water-cooled temperature control system of the three-stage heat exchange fuel cell platform also includes a water replenishment circuit, which includes an electric valve EV3, an electric valve EV4 and a water replenishment tank. One outlet of the fuel cell system FAT under test is connected to the inlet of the water replenishment tank through the electric valve EV4, and the outlet of the water replenishment tank is connected to the pipeline where the first outlet of the first plate heat exchanger E1 is located through the electric valve EV3. The test platform includes a circulating loop (2) comprising a temperature sensor T3, a pressure sensor P3, a flow sensor F2, a water pump 1, a three-way proportional valve SV1, a temperature sensor T4, a pressure sensor P4, a heater H1, and a temperature sensor T5. The temperature sensor T3, pressure sensor P3, flow sensor F2, water pump 1, and three-way proportional valve SV1 are installed on the pipeline between the second outlet of the first plate heat exchanger E1 and the first inlet of the second plate heat exchanger E2. The temperature sensor T4, pressure sensor P4, heater H1, and temperature sensor T5 are installed on the pipeline between the first outlet of the second plate heat exchanger E2 and the second inlet of the first plate heat exchanger E1. One interface of the three-way proportional valve SV1 is connected to the pipeline between the heater H1 and the first outlet of the second plate heat exchanger E2.

2. The water-cooled temperature control system for a three-stage heat exchange fuel cell platform according to claim 1, characterized in that, It also includes a first subtractor, a second subtractor, and an adder. The engine outlet temperature of the fuel cell system FAT under test and the engine outlet temperature setpoint are input to the first subtractor. The first subtractor, the outer loop incremental PID, the second subtractor, the inner loop incremental PID, the adder, and the three-way proportional valve SV1 are connected in sequence. The output temperature of the second plate heat exchanger E2 is fed back to the second subtractor.

3. The water-cooled temperature control system for a three-stage heat exchange fuel cell platform according to claim 2, characterized in that, The water supply tank is equipped with an exhaust port.

4. The water-cooled temperature control system for a three-stage heat exchange fuel cell platform according to claim 3, characterized in that, The external circulation loop (3) of the test platform includes a filter Y1, a temperature control valve SV2, a temperature sensor T6, a pressure sensor P5 and a flow meter F3. The filter Y1, the temperature control valve SV2, the temperature sensor T6 and the pressure sensor P5 are installed on the pipeline where the second inlet of the second plate heat exchanger E2 is located and the outlet of the cooling tower is located. The flow meter F3 is installed on the pipeline where the second outlet of the second plate heat exchanger E2 is located and the inlet of the cooling tower is located.

5. The water-cooled temperature control system for a three-stage heat exchange fuel cell platform according to claim 4, characterized in that, The external circulation loop (3) of the test platform also includes manual ball valve V1 and manual ball valve V2, which are installed on the pipeline between filter Y1 and temperature control valve SV2.

6. The method of using a water-cooled temperature control system for a three-stage heat exchange fuel cell platform according to claim 5, characterized in that, The difference between the engine outlet temperature of the fuel cell system under test (FAT) and the engine outlet temperature setpoint is input to the outer loop incremental PID controller. The difference between the output of the outer loop incremental PID controller and the output temperature of the second plate heat exchanger (E2) is input to the inner loop incremental PID controller. The output of the inner loop incremental PID controller is added to the set feedforward opening and acts on the three-way proportional valve SV1, thereby adjusting the water flow rate in the loop containing the second plate heat exchanger (E2) and indirectly adjusting the temperature of the fuel cell system under test.

7. The method of using a water-cooled temperature control system for a three-stage heat exchange fuel cell platform according to claim 6, characterized in that, The engine outlet temperature of the fuel cell system under test (FAT) is calculated by subtracting the engine outlet temperature setpoint from the first subtractor and input to the outer loop incremental PID controller for PID regulation. The output of the outer loop incremental PID controller is calculated by subtracting the outlet temperature setpoint of the second plate heat exchanger (E2) from the actual outlet temperature of the second plate heat exchanger (E2) and input to the inner loop incremental PID controller for PID regulation. The output of the inner loop incremental PID controller is added to the set feedforward opening value via an adder and applied to the three-way proportional valve (SV1).

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