A multi-stack fuel cell cooling system and its hydrothermal management method

Abstract

This invention proposes a multi-stack fuel cell cooling system and its hydrothermal management method. The system includes a cooling water tank and a water pump. The inlet of the water pump is connected to the cooling water tank, and the outlet of the water pump is connected to three cooling branches. The three cooling branches are connected to the cooling water tank via return pipes. The first and second cooling branches each include a switching valve, a fuel cell stack, a three-way solenoid valve, an intercooler, and a check valve. The third cooling branch includes a switching valve, a check valve, a fuel cell stack, a thermostat, and an intercooler. The first and second cooling branches, as well as the second and third cooling branches, are connected by check valves. This system can recover and utilize the exhaust heat from the front-end fuel cell stack, enabling rapid startup of the back-end fuel cell stack without consuming additional electrical energy, thus improving the system's energy utilization rate. This hydrothermal management method achieves precise control of both preheating and operating temperatures, ensuring the stability of system operation.

Description

Technical Field

[0001] This invention belongs to the field of fuel cells, and particularly relates to a multi-stack fuel cell cooling system and its hydrothermal management method. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) offer superior performance and are widely used in transportation, military, and other fields. Currently, most fuel cell systems in new energy vehicles utilize single, high-power fuel cell systems. However, high-power fuel cells suffer from drawbacks such as high cost, rapid stack aging, and inability to operate for extended periods due to incomplete technological and material breakthroughs. Furthermore, frequent power fluctuations accelerate fuel cell aging, and damage to individual fuel cell cells within the stack can cause the entire system to malfunction. To address these issues, multi-stack fuel cell systems (MFCSs) are commonly used to meet high-power requirements. MFCSs consist of several low-power fuel cell systems, rather than a single high-power stack, avoiding the problem of insufficient stack durability and enhancing system stability.

[0003] Multi-stack fuel cell systems typically employ independent parallel hydrothermal management structures, where each fuel cell stack is paired with its own independent cooling water pipeline. This structure is costly and cannot effectively utilize waste heat in the cooling water. While connecting multiple fuel cell stacks in series within a single cooling water loop can effectively utilize waste heat, it cannot effectively control the operating temperature of subsequent fuel cells and can lead to heat accumulation in the last fuel cell stack, causing it to malfunction.

[0004] Currently, energy management in multi-stall fuel cells primarily determines the activation of a specific stack based on the current power demand. When power demand is low, only a few stacks need to operate. However, since vehicle power fluctuates in real time, more stacks are required to supply power when demand increases. Furthermore, fuel cell startup takes time, especially in cold environments, where a cold start without preheating can take 2-5 minutes. This can cause the multi-stall fuel cell system to be unable to quickly meet the vehicle's real-time energy needs, resulting in insufficient power. While electric heating can be used to maintain the fuel cell temperature, this method consumes additional electrical energy. Summary of the Invention

[0005] This invention addresses the technical problems of high cost and complex control of existing multi-stack fuel cell system hydrothermal management structures by proposing a low-cost multi-stack fuel cell cooling system and hydrothermal management method that can fully utilize the waste heat of the fuel cell stack to preheat the individual fuel cell stacks at the downstream end.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A multi-stack fuel cell cooling system includes a cooling water tank, a water pump, and a battery controller. The water pump's inlet is connected to the cooling water tank, and the water pump's outlet is connected to three cooling branches. The three cooling branches are connected to the cooling water tank via return pipes.

[0008] The first cooling branch includes a switching valve 1, a PTC heater, a fuel cell stack 1, a three-way solenoid valve 1, an intercooler 1, and a check valve 1 connected in sequence via piping. Temperature sensor 1 is connected to fuel cell stack 1. The second cooling branch includes a switching valve 2, a check valve 5, a fuel cell stack 2, a three-way solenoid valve 2, an intercooler 2, and a check valve 2 connected in sequence via piping. Temperature sensor 2 is connected to fuel cell stack 2. The third cooling branch includes a switching valve 3, a check valve 6, a fuel cell stack 3, a thermostat, and a check valve 3 connected in sequence via piping. The third port of the thermostat is connected to intercooler 3. Intercooler 3 is connected to the return water pipe via check valve 4. Temperature sensor 3 is connected to fuel cell stack 3.

[0009] A one-way valve seven is also connected between the third port of the three-way solenoid valve one and the fuel cell stack two, and a one-way valve eight is also connected between the third port of the three-way solenoid valve two and the fuel cell stack three.

[0010] A hydrothermal management method for a multi-stall fuel cell cooling system includes a preheating cold start-up phase and a multi-stall operation phase, specifically comprising the following steps:

[0011] S1. When cold start, the preheating cold start circuit is run. The FCU controls the three-way solenoid valve one to open the circuit to the one-way valve seven and close the circuit to the intercooler one.

[0012] S2, the three-way solenoid valve two opens the circuit to the one-way valve eight and closes the circuit to the intercooler two;

[0013] S3. Once the switch valve is opened, the cooling water pump and PTC heater start to preheat the fuel cell stack.

[0014] S4. Determine the outlet water temperature of the three fuel cell stacks and the minimum opening temperature T of the thermostat's main circulation. min The size, when the outlet water temperature of all three fuel cells is greater than T min If the cold start is complete, run S5 to enter the normal operation phase of the multi-stack system; otherwise, run S3.

[0015] S5 and PTC heaters are stopped, while fuel cell stack 1 is operating normally.

[0016] S6, FCU determines the number of fuel cell stacks to be activated based on the vehicle's energy requirements. When both fuel cell stack one and fuel cell stack two need to operate, S7 is activated. Otherwise, FCU controls the opening and closing of the two outlets of three-way solenoid valve one and three-way solenoid valve two, ensuring that the outlet water temperature of fuel cell stack two and fuel cell stack three is greater than T. min And less than the optimal operating temperature T best And run S5;

[0017] S7. Close the circuit from the three-way solenoid valve 1 to the one-way valve 7, and open the circuit to the intercooler 1.

[0018] S8. Open switch valve two, and fuel cell stack two begins normal operation;

[0019] S9, FCU determines the number of fuel cell stacks to be activated based on the vehicle's energy requirements. When all three fuel cell stacks need to operate, S10 is executed; otherwise, FCU controls the opening and closing of the two outlets of the three-way solenoid valve two to ensure that the outlet water temperature of fuel cell stack three is greater than T. min And less than the optimal operating temperature T best and run S6;

[0020] S10. Close the circuit from the three-way solenoid valve 2 to the one-way valve 8, and open the circuit to the intercooler 2.

[0021] S11. Open switch valve three, and fuel cell stack three will start normal operation.

[0022] Preferably, in step S6, the opening degree of the two outlets of the three-way solenoid valve one and the three-way solenoid valve two is controlled by the following method.

[0023] S61. When fuel cell stacks two and three are not operating, the temperature T2 of fuel cell stack two is measured by temperature sensor two. Initially, both three-way solenoid valves one and two are at their maximum opening, causing the temperature T2 of fuel cell stack two to gradually approach (T... min +T best ) / 2;

[0024] S62. Preliminary calculation of the opening degree of the three-way solenoid valve 1, real-time opening degree D. 1_ori D 1_ori =k1(λ)T2 / T min , where k1(λ) is the nonlinear coefficient of the valve opening;

[0025] S63, compare T2 with the target temperature of the fuel cell stack (T) min +T best The difference between 1 / 2 is used as the input value of the PID controller to obtain the fine adjustment amount D of the valve opening of the three-way solenoid valve. 1_pid The final real-time opening degree of the three-way solenoid valve is D1 = D 1_ori +D 1_pid ;

[0026] S64. Temperature sensor three measures the temperature T3 of fuel cell stack three, and preliminarily calculates the real-time valve opening D of three-way solenoid valve two. 2_ori ,

[0027] D 2_ori =k2(λ)T3 / T min , where k2(λ) is the nonlinear coefficient of the valve opening;

[0028] S65, compare T3 with the three target temperatures of the fuel cell stack. min The difference is used as the input value of the PID controller to obtain the fine adjustment D of the valve opening of the three-way solenoid valve. 2_pid The final real-time opening degree of the three-way solenoid valve 2, D2 = D 2_ori +D 2_pid .

[0029] Preferably, the opening degree of the outlet of the three-way solenoid valve two in step S9 is controlled by the following method.

[0030] S91. Temperature sensor three measures the temperature T3 of the fuel cell stack three, and preliminarily calculates the real-time valve opening D of the three-way solenoid valve two. 2_ori D 2_ori =k2(λ)T3 / T min k2(λ) is the nonlinear coefficient of the valve opening;

[0031] S92, with T3 and the three target temperatures of the fuel cell stack T min The difference is used as the input value of the PID controller to obtain the fine adjustment D of the valve opening of the three-way solenoid valve. 2_pid The real-time opening degree of the three-way solenoid valve 2, D2 = D 2_ori +D 2_pid .

[0032] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0033] The multi-stack fuel cell cooling system described in this invention can recover and utilize the exhaust heat from the front-end fuel cell stack through a reasonable cooling pipeline design, thereby improving the system's energy utilization rate. After the front-end stack is operating normally, the multi-stack fuel cell can maintain its temperature above the preheating temperature, enabling rapid startup of the back-end stack without consuming additional electrical energy, and its normal heat dissipation function is not affected when the back-end stack is operating normally.

[0034] This hydrothermal management algorithm maintains the fuel cell system above its preheating temperature, reducing the cold start time of the fuel cell stack and enabling rapid startup without additional energy heating. This efficient and practical hydrothermal management method precisely controls the preheating and operating temperatures of multiple fuel cell stacks, ensuring system stability. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the multi-stack fuel cell cooling system of the present invention;

[0036] Figure 2 This is a control network connection diagram of the multi-stack fuel cell cooling system of the present invention;

[0037] Figure 3 This is a logic diagram of the hydrothermal management method of the present invention;

[0038] In the above diagrams: 1. Cooling water tank; 2. Water pump; 3. Switch valve one; 4. PTC heater; 5. Fuel cell stack one; 6. Temperature sensor one; 7. Three-way solenoid valve one; 8. Intercooler one; 9. Check valve one; 10. Switch valve two; 11. Check valve five; 12. Fuel cell stack two; 13. Temperature sensor two; 14. Three-way solenoid valve two; 15. Intercooler two; 16. Check valve two; 17. Switch valve three; 18. Check valve six; 19. Fuel cell stack three; 20. Temperature sensor three; 21. Thermostat; 22. Check valve three; 23. Intercooler three; 24. Check valve four; 25. Check valve seven; 26. Check valve eight; a. First interface; b. Second interface; c. Third interface. Detailed Implementation

[0039] To better understand the present invention, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, a multi-stack fuel cell cooling system includes a cooling water tank 1 and a water pump 2. The water inlet of the water pump 2 is connected to the cooling water tank 1, and the water outlet of the water pump 2 is connected to three cooling branches. The three cooling branches are connected to the cooling water tank 1 via return water pipes.

[0042] The first cooling branch includes a switching valve 3, a PTC heater 4, a fuel cell stack 5, a three-way solenoid valve 7, an intercooler 8, and a check valve 9 connected in sequence via pipelines. A temperature sensor 6 is connected to the fuel cell stack 5. The first port a of the three-way solenoid valve 7 is connected to the fuel cell stack 5, and its second port b (which is the first outlet) is connected to the intercooler 8.

[0043] The second cooling branch includes a second switching valve 10, a fifth check valve 11, a second fuel cell stack 12, a second three-way solenoid valve 14, an intercooler 15, and a second check valve 16 connected in sequence via pipelines. A second temperature sensor 13 is connected to the second fuel cell stack 12. The first port a of the second three-way solenoid valve 14 is connected to the second fuel cell stack 12, and its second port b (i.e., the first outlet) is connected to the second intercooler 15.

[0044] The third cooling branch includes a switch valve 17, a check valve 18, a fuel cell stack 19, a thermostat 21, and a check valve 22 connected in sequence via pipes. The third interface c of the thermostat 21 is connected to the intercooler 23. The intercooler 23 is connected to the return water pipe via a check valve 24. A temperature sensor 20 is connected to the fuel cell stack 19.

[0045] A one-way valve 25 is also connected between the third port c (i.e., the second outlet) of the three-way solenoid valve 17 and the fuel cell stack 12, and a one-way valve 26 is also connected between the third port c (i.e., the second outlet) of the three-way solenoid valve 14 and the fuel cell stack 19.

[0046] The system also includes a fuel cell controller (FCU). The fuel cell controller (FCU), water pump 2, on / off valves 1-3, PTC heater 4, temperature sensors 1-3, three-way solenoid valve 7, three-way solenoid valve 14, fuel cell controller, and fuel cell stacks 1-3 all communicate and are controlled via a CAN network. The CAN network is as follows: Figure 2 As shown;

[0047] The operation process of the multi-stack fuel cell cooling system is as described in Example 2.

[0048] The multi-stall fuel cell cooling system described in this embodiment can recover and utilize the exhaust heat from the front-end fuel cell stack through a reasonable cooling pipeline design, thereby improving the system's energy utilization rate. After the front-end stack is operating normally, the multi-stall fuel cell can maintain its temperature above the preheating temperature, enabling rapid startup of the back-end stack without consuming additional electrical energy, and its normal heat dissipation function is not affected when the back-end stack is operating normally.

[0049] Example 2

[0050] A hydrothermal management method for a multi-stacking fuel cell cooling system includes a preheating cold start phase, a multi-stacking operation phase, and a shutdown phase, such as... Figure 3 As shown, the specific steps include the following:

[0051] S1. Run the preheating cold start step during cold start.

[0052] When the vehicle is cold-started, the fuel cell stack temperature is too low to function properly. The vehicle is powered by low voltage, and the FCU controls the three-way solenoid valve to open the circuit to the one-way valve 725 and close the circuit to the intercooler 8.

[0053] S2, the three-way solenoid valve 14 opens the circuit to the one-way valve 26 and closes the circuit to the intercooler 15.

[0054] S3. Switch valve 1 (3) opens, cooling water pump 2 starts, and cooling water begins circulating in the circuit. At this time, PTC heater 4 is activated to heat the cooling water, which then passes through fuel cell stack 1 (5) to preheat it. Afterward, cooling water flows out from the outlet of fuel cell stack 1 (5), enters three-way solenoid valve 1 (7), and flows through one-way valve 7 (25) into fuel cell stack 2 (12) to preheat it. Cooling water then flows out from the outlet of fuel cell stack 2 (12) and passes through three-way solenoid valve 2 (14) and one-way valve 8 (26) into fuel cell stack 3 (19) to preheat it. If the outlet temperature of fuel cell stack 3 (19) is lower than the minimum opening temperature T of the thermostat 21 for the large circulation cycle... min Then, the cooling water flows through the small circulation channel of thermostat 21 into check valve 3 22, and finally into water pump 2. If at this time the outlet temperature of fuel cell stack 2 12 is greater than or equal to the minimum opening temperature T of the large circulation channel of thermostat 21... min Then, the cooling water flows into the intercooler through the large circulation channel of the thermostat 21, and finally flows into the water pump 2 through the one-way valve 24.

[0055] S4. Based on the temperature value T1 of fuel cell stack 5 returned by temperature sensor 6, the temperature value T2 of fuel cell stack 12 returned by temperature sensor 13, and the temperature value T3 of fuel cell stack 19 returned by temperature sensor 20, when the temperature values ​​of T1, T2, and T3 are all greater than T... min When the system preheating is complete, the fuel cell can start normally and output electrical energy. Afterwards, run S5 to complete the cold start and enter the normal multi-stack operation phase; otherwise, run S3.

[0056] S5 and PTC heater 4 are stopped, while fuel cell stack 5 is operating normally.

[0057] S6, FCU determines the number of fuel cell stacks to be activated based on the vehicle's energy requirements. When both fuel cell stack 1 (5) and fuel cell stack 2 (12) need to operate, S7 is activated. Otherwise, FCU controls the opening and closing of the two outlets of three-way solenoid valve 1 (7) and three-way solenoid valve 2 (14) to ensure that the outlet water temperature of fuel cell stack 2 (12) and fuel cell stack 3 (19) is greater than T. min And less than the optimal operating temperature T best And run S5;

[0058] The outlet water temperature of fuel cell stack 2.12 and fuel cell stack 3.19 is greater than T. min And less than the optimal operating temperature T bestThis allows for quick operation when needed. Specifically, when switch valve 3 opens, cooling water flows into fuel cell stack 5, absorbs heat from stack 5, and then enters three-way solenoid valve 7. At this time, three-way solenoid valve 7 allocates the flow rate of cooling water flowing from the outlet of fuel cell stack 5 into intercooler 8 and check valve 7 25 according to the water-thermal management algorithm. Cooling water flows through three-way solenoid valve 7, passing through intercooler 8 and check valve 9 into water pump 2, and through check valve 7 25 into fuel cell stack 2. Cooling water enters fuel cell stack 2, heats it, and then flows out from the outlet into three-way solenoid valve 2 14. Three-way solenoid valve 2 14 allocates the flow rate of cooling water flowing from the outlet of fuel cell stack 2 12 into intercooler 2 15 and check valve 8 26 according to the water-thermal management algorithm. Cooling water flows through three-way solenoid valve 14, via intercooler 15 and check valve 16 into water pump 2, and via check valve 26 into fuel cell stack 19 and thermostat 21. Cooling water exiting thermostat 21 flows through intercooler 23 and check valve 24 into water pump 2, and via check valve 22 into water pump 2. The water-thermal management algorithm controls the flow rate into fuel cell stack 12 via three-way solenoid valve 7, thereby ensuring that the temperatures of fuel cell stack 12 and fuel cell stack 19 are greater than T. min And less than the optimal operating temperature T of the fuel cell best The hydrothermal management algorithm controls the flow rate into fuel cell stack 19 via a three-way solenoid valve 214, thereby ensuring that the temperature of fuel cell stack 19 is greater than T. min And less than the optimal operating temperature T of the fuel cell best .

[0059] The opening and closing degree of the two outlets of the three-way solenoid valve 17 and the three-way solenoid valve 214 are specifically controlled by the following method:

[0060] S61. When fuel cell stack 2 (12) and fuel cell stack 3 (19) are not working, the temperature T2 of fuel cell stack 2 (12) measured by temperature sensor 2 (13) is such that both three-way solenoid valve 1 and three-way solenoid valve 2 are initially at their maximum opening, causing the temperature T2 of fuel cell stack 2 (19) to gradually approach (T2). min +T best ) / 2;

[0061] S62. Preliminary calculation of the opening degree D of the three-way solenoid valve 7 (real-time opening degree). 1_ori D 1_ori =k1(λ)T2 / T min , where k1(λ) is the nonlinear coefficient of valve opening, and the specific value is obtained from bench calibration.

[0062] S63, compare T2 with the target temperature of fuel cell stack 212 (T min +T best The difference between 1 / 2 is used as the input value of the PID controller to obtain the fine adjustment amount D of the valve opening of the three-way solenoid valve 7. 1_pidThe final real-time opening degree of the three-way solenoid valve 7, D1 = D 1_ori +D 1_pid ;

[0063]

[0064] Among them, K p1 , where T is the PID proportional coefficient. i1 , where T is the PID integral coefficient. d1 , where is the PID derivative coefficient, determined during on-site debugging.

[0065] S64, temperature sensor 320 measures temperature T3 of fuel cell stack 319, and preliminarily calculates the real-time valve opening D of three-way solenoid valve 214. 2_ori ,

[0066] D 2_ori =k2(λ)T3 / T min , where k2(λ) is the nonlinear coefficient of the valve opening;

[0067] S65, Set T3 and the target temperature T of the fuel cell stack 319 min The difference is used as the input value of the PID controller to obtain the fine adjustment amount D of the valve opening of the three-way solenoid valve 214. 2_pid The final real-time opening degree D2 of the three-way solenoid valve 214 is D 2_ori +D 2_pid .

[0068]

[0069] K p1 K p2 T is the PID proportional coefficient. i1 T i2 T represents the integral coefficient of the PID controller. d1 T d2 These are the PID derivative coefficients, determined during on-site debugging.

[0070] Conventional temperature control has only one controlled object, but here there are two controlled objects: three-way solenoid valve 1 and three-way solenoid valve 2. In particular, the control of three-way solenoid valve 1 will affect the control of three-way solenoid valve 2 14, and thus affect the insulation temperature of fuel cell stack 2 12 and fuel cell stack 3 19. This method provides a temperature control solution for multiple controlled objects.

[0071] S7. Close the circuit from the three-way solenoid valve 7 to the check valve 227, and open the circuit to the intercooler 8.

[0072] S8. Open switch valve 10, and fuel cell stack 12 will start normal operation;

[0073] S9, FCU determines the number of fuel cell stacks to be activated based on the vehicle's energy requirements. When all fuel cell stacks 1 through 3 (12) need to operate, S10 is executed. Otherwise, FCU controls the opening and closing of the two outlets of the three-way solenoid valve 2 (14) to ensure that the outlet water temperature of fuel cell stack 3 (19) is greater than T. min And less than the optimal operating temperature T best The system operates in sequence S6. At this time, switching valves 3 and 2 open, and three-way solenoid valve 7 closes the circuit to check valve 227. Cooling water flows through the switching valves and PTC into fuel cell stack 5. All the cooling water passing through fuel cell stack 5 flows through intercooler 8 and check valve 9 into water pump 2. The second stream of cooling water flows through switching valve 210 and check valve 511 into fuel cell stack 12, cooling it. From the outlet of fuel cell stack 12, the water flows into three-way solenoid valve 214. Three-way solenoid valve 214, according to the water-thermal management algorithm, distributes the flow of cooling water from the outlet of fuel cell stack 12 into intercooler 215 and check valve 826, thereby ensuring that the temperature of fuel cell stack 19 is greater than T. min And less than the optimal operating temperature T of the fuel cell best The cooling water flowing out of the three-way solenoid valve 214 flows into the water pump 2 through the intercooler 215 and the check valve 216, and into the fuel cell stack 319 and the thermostat 21 through the check valve 826. The cooling water flowing out of the thermostat 21 flows into the water pump 2 through the intercooler 323 and the check valve 424, and into the water pump 2 through the check valve 322.

[0074] The opening degree of the outlet of the three-way solenoid valve 214 is controlled by the following method:

[0075] S91, temperature sensor 320 measures temperature T3 of fuel cell stack 319, and preliminarily calculates the real-time valve opening D of three-way solenoid valve 214. 2_ori D 2_ori =k2(λ)T3 / T min k2(λ) is the nonlinear coefficient of the valve opening;

[0076] S92, with T3 and target temperature T of fuel cell stack 319 min The difference is used as the input value of the PID controller to obtain the fine adjustment amount D of the valve opening of the three-way solenoid valve 214. 2_pid The real-time opening degree D2 of the three-way solenoid valve 214 is D 2_ori +D 2_pid .

[0077] S10. Close the circuit from the three-way solenoid valve 214 to the one-way valve 826, and open the circuit to the intercooler 215.

[0078] S11. Open switch valve 3 17, and fuel cell stack 3 19 begins normal operation. At this time, there is no need to consider the preheating maintenance of fuel cell stacks 1-3, only the heat dissipation of the three fuel cell stacks. Switch valves 1-3 are all open, three-way solenoid valve 1 7 closes the circuit to check valve 227, and three-way solenoid valve 2 14 closes the circuit to check valve 8 26. Cooling water flowing out from switch valve 1 flows into water pump 2 through PTC, fuel cell stack 5, three-way solenoid valve 1 7, intercooler 8, and check valve 1 9; cooling water flowing out from switch valve 2 10 flows into water pump 2 through check valve 5 11, fuel cell stack 2 12, three-way solenoid valve 2 14, intercooler 2 15, and check valve 2 16; cooling water flowing out from switch valve 3 17 flows into water pump 2 through check valve 6 18, fuel cell stack 3 19, and thermostat 21, then one path flows into water pump 2 through check valve 3 22, and another path flows into water pump 2 through intercooler 3 23 and check valve 4 24.

[0079] S12. Shutdown procedure: Water pump 2 is shut down, and all three valves are closed, thus shutting down the system.

[0080] This hydrothermal management algorithm maintains the fuel cell system above its preheating temperature, reducing the cold start time of the fuel cell stack and enabling rapid startup without additional energy heating. This efficient and practical hydrothermal management method precisely controls the preheating and operating temperatures of multiple fuel cell stacks, ensuring system stability.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A hydrothermal management method for a multi-stacking fuel cell cooling system, characterized in that, This includes the preheating cold start phase and the multi-reactor normal operation phase, specifically including the following steps: S1. When cold start, the preheating cold start circuit is run. The FCU controls the three-way solenoid valve one to open the circuit to the one-way valve seven and close the circuit to the intercooler one. S2, the three-way solenoid valve two opens the circuit to the one-way valve eight and closes the circuit to the intercooler two; S3. Once the switch valve is opened, the cooling water pump and PTC heater start to preheat the fuel cell stack. S4. Determine the outlet water temperature of the three fuel cell stacks and the minimum opening temperature T of the thermostat's main circulation. min The size, when the outlet water temperature of all three fuel cells is greater than T min If the cold start is complete, run S5 to enter the normal operation phase of the multi-stack system; otherwise, run S3. S5 and PTC heaters are stopped, while fuel cell stack 1 is operating normally. S6, FCU determines the number of fuel cell stacks to be activated based on the vehicle's energy requirements. When both fuel cell stack one and fuel cell stack two need to operate, S7 is activated. Otherwise, FCU controls the opening and closing of the two outlets of three-way solenoid valve one and three-way solenoid valve two, ensuring that the outlet water temperature of fuel cell stack two and fuel cell stack three is greater than T. min And less than the optimal operating temperature T best And run S5; S7. Close the circuit from the three-way solenoid valve 1 to the one-way valve 7, and open the circuit to the intercooler 1. S8. Open switch valve two, and fuel cell stack two begins normal operation; S9, FCU determines the number of fuel cell stacks to be activated based on the vehicle's energy requirements. When all three fuel cell stacks need to operate, S10 is executed; otherwise, FCU controls the opening and closing of the two outlets of the three-way solenoid valve two to ensure that the outlet water temperature of fuel cell stack three is greater than T. min And less than the optimal operating temperature T best and run S6; S10. Close the circuit from the three-way solenoid valve 2 to the one-way valve 8, and open the circuit to the intercooler 2. S11. Open switch valve three, and fuel cell stack three begins normal operation; In step S6, the opening degree of the two outlets of the three-way solenoid valve one and the three-way solenoid valve two is controlled by the following method. S61. When fuel cell stacks two and three are not operating, the temperature T2 of fuel cell stack two is measured by temperature sensor two. Initially, both three-way solenoid valves one and two are at their maximum opening, causing the temperature T2 of fuel cell stack two to gradually approach (T... min +T best ) / 2; S62. Preliminary calculation of the opening degree of the three-way solenoid valve 1, real-time opening degree D. 1_ori D 1_ori = k1(λ)T2 / T min , where k1(λ) is the nonlinear coefficient of the valve opening; S63, compare T2 with the target temperature of the fuel cell stack (T) min +T best The difference between 1 / 2 is used as the input value of the PID controller to obtain the fine adjustment amount D of the valve opening of the three-way solenoid valve. 1_pid The final real-time opening degree of the three-way solenoid valve is D1=D 1_ori +D 1_pid ; S64. Temperature sensor three measures the temperature T3 of fuel cell stack three, and preliminarily calculates the real-time valve opening D of three-way solenoid valve two. 2_ori , D 2_ori =k2(λ)T3 / T min , where k2(λ) is the nonlinear coefficient of the valve opening; S65, compare T3 with the three target temperatures of the fuel cell stack. min The difference is used as the input value of the PID controller to obtain the fine adjustment D of the valve opening of the three-way solenoid valve. 2_pid The final real-time opening degree of the three-way solenoid valve 2, D2 = D 2_ori +D 2_pid ; In step S9, the opening degree of the outlet of the three-way solenoid valve two is controlled by the following method. S91. Temperature sensor three measures the temperature T3 of the fuel cell stack three, and preliminarily calculates the real-time valve opening D of the three-way solenoid valve two. 2_ori D 2_ori =k2(λ)T3 / T min k2(λ) is the nonlinear coefficient of the valve opening; S92, with T3 and the three target temperatures of the fuel cell stack T min The difference is used as the input value of the PID controller to obtain the fine adjustment D of the valve opening of the three-way solenoid valve. 2_pid The real-time opening degree of the three-way solenoid valve 2, D2=D 2_ori +D 2_pid .

Images