Fuel cell cold start system and control method
By introducing a combination of COD heater and PTC heater into the fuel cell system, the problem of difficulty in responding to and icing risks during cold start in low temperature environments is solved, and the effect of quickly responding to power battery power requirements and effective start is achieved.
Patent Information
- Application Number
- CN202411788475.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-04-01
AI Technical Summary
The existing fuel cell cold start system is difficult to quickly respond to the power demand of the vehicle's power battery in a low-temperature environment, and cannot be effectively restarted when the fault is urgently stopped or the cold start failed due to icing in a low-temperature environment, which affects the life of the fuel cell.
A fuel cell cold start system is designed, including stack module, vehicle control unit and fuel cell unit. The COD heater consumes the electric energy generated by the stack to heat the coolant, and combines the external heating function of the PTC heater to achieve rapid cold start and heat start when the risk of icing is present.
The COD heater consumes the stack's electrical energy to heat the coolant, significantly reducing the time required for cold start, reducing the power limit of the fuel cell system in a low-temperature environment, increasing the difficulty of controlling the cold start process, ensuring that the fuel cell can quickly respond to the power demand of the power battery in a low-temperature environment, and effectively start when the risk of icing occurs.
Smart Images
Figure CN119742400A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of fuel cells, in particular to a fuel cell cold start system and a control method. Background Art
[0002] The adaptability of fuel cells to low-temperature environments is an important factor affecting their large-scale commercial application. In low-temperature environments below 0°C, the freezing of liquid water in the membrane electrode and gas diffusion layer inside the fuel cell system will cause irreversible mechanical damage to the proton membrane. The freezing of liquid water in the gas flow channel will block the flow channel, resulting in a lack of reactants in the electrochemical reaction of the fuel cell, and damage the catalyst and carbon carrier. Therefore, in order to ensure that the fuel cell responds to the power demand of the vehicle and minimize the impact on the life of the fuel cell, a special structure and corresponding strategy will be designed to realize the cold start process of the fuel cell in a low-temperature environment.
[0003] Currently, there are two main types of fuel cell cold start system architectures: the first is a system without any auxiliary heating, which relies on the fuel cell's own heat generation capacity to achieve cold start. This system architecture is relatively simple and cost-effective. However, if the fuel cell stops suddenly due to a fault or the cold start process fails in a low-temperature environment, resulting in internal ice, the system itself cannot be restarted, causing the entire vehicle to break down. In addition, the power battery limits the fuel cell input power at low temperatures, resulting in the inability to increase the operating power of the cold start process, which makes it difficult to control the fuel cell. The second is a system with a PTC heater in the water circulation. This system architecture can increase the water temperature and shorten the start-up time through the PTC heater. The disadvantage is that it requires a stable external power supply and the cost is higher than the first type. Summary of the invention
[0004] In order to overcome the deficiencies of the prior art, the present invention provides a fuel cell cold start system and a control method.
[0005] To achieve the above-mentioned purpose, a fuel cell cold start system is designed, including a fuel cell stack module, wherein the hydrogen inlet of the fuel cell stack module is connected to the hydrogen supply subsystem, the air inlet of the fuel cell stack module is connected to the air supply subsystem, and the coolant outlet of the fuel cell stack module is divided into two paths, one path is connected to the PTC heater and the COD heater in sequence, and the other path is connected to the radiator. The COD heater and the radiator are converged into one path through a three-way valve and are connected to one end of a water pump, and the other end of the water pump is connected to the coolant inlet of the fuel cell stack module.
[0006] It also includes a vehicle control unit and a fuel cell unit. The vehicle control unit sends demands to the fuel cell unit, and the fuel cell unit controls the switches of the PTC heater, COD heater, radiator, three-way valve, and water pump according to the demands.
[0007] A first temperature sensor is provided on the pipeline between the coolant inlet of the battery stack module and the water pump; a second temperature sensor is provided on the pipeline between the coolant outlet of the battery stack module and the PTC heater.
[0008] The coolant coming out of the coolant outlet of the stack module passes through the second temperature sensor, PTC heater, COD heater, three-way valve, water pump, and first temperature sensor in sequence to heat the coolant during the cold start process, and passes through the radiator, three-way valve, and water pump in sequence to dissipate the coolant during normal operation.
[0009] In order to achieve the above object, a control method for a fuel cell cold start system is designed, comprising the following steps: S1, when the fuel cell needs to be cold-started in a low-temperature environment, the vehicle control unit sends a power demand instruction, and the fuel cell unit determines the current coolant temperature after receiving the demand; S2, if the coolant temperature is higher than 0°C, execute the normal startup process; if the coolant temperature is lower than 0°C, execute the low temperature startup process; S3, when the FCU fuel cell unit is judged to have a risk of icing, the PTC heater is started for external heating; S4: When the fuel cell unit is judged to have no risk of icing and the required power is lower than the net output power of the fuel cell unit during the startup process, the COD heater is started to consume excess power to heat the coolant for a cold start; when the fuel cell unit is judged to have no risk of icing and the required power is higher than or equal to the net output power of the fuel cell unit during the startup process, a self-start without external heating is performed.
[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with a system without auxiliary heating, the present invention can accelerate the cold start process by consuming the electricity generated by the battery stack through the COD heater to heat the coolant and respond more quickly to the power demand of the vehicle's power battery.
[0011] 2. Compared with a fuel cell system that only contains PTC, the COD heater can directly consume the electricity generated by the fuel cell stack, participate in the shutdown process to consume the remaining power of the fuel cell stack, act as a discharge resistor, and consume hydrogen from the fuel cell stack.
[0012] 3. In low temperature environments, the power input of the power battery is limited. The presence of the COD heater and the PTC heater can relax some of the power restrictions of the fuel cell system during the cold start process, reducing the difficulty of controlling the cold start process of the fuel cell system.
[0013] 4. When the inside of the fuel cell is frozen, the coolant temperature can be heated to above zero by the heater to enable the system to start normally. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a structural schematic diagram of the present invention.
[0015] Figure 2 It is a flow chart of the present invention. DETAILED DESCRIPTION
[0016] The present invention will be further described below with reference to the accompanying drawings.
[0017] like Figure 1 As shown, the hydrogen inlet of the fuel cell module 1 is connected to the hydrogen supply subsystem 2, the air inlet of the fuel cell module 1 is connected to the air supply subsystem 3, and the coolant outlet of the fuel cell module 1 is divided into two paths, one path is connected to the PTC heater 4 and the COD heater 5 in sequence, and the other path is connected to the radiator 6. The COD heater 5 and the radiator 6 are converged into one path through a three-way valve 7 and are connected to one end of a water pump 8. The other end of the water pump 8 is connected to the coolant inlet of the fuel cell module 1.
[0018] It also includes a vehicle control unit 9 and a fuel cell unit 10. The vehicle control unit 9 sends a demand to the fuel cell unit 10, and the fuel cell unit 10 controls the switches of the PTC heater 4, the COD heater 5, the radiator 6, the three-way valve 7, and the water pump 8 according to the demand.
[0019] A first temperature sensor 11 is provided on the pipe between the coolant inlet of the stack module 1 and the water pump 8; a second temperature sensor 12 is provided on the pipe between the coolant outlet of the stack module 1 and the PTC heater 4. When in use, the temperature of the coolant is obtained with the cooperation of the first temperature sensor 11 and the second temperature sensor 12.
[0020] The coolant coming out of the coolant outlet of the stack module 1 passes through the second temperature sensor 12, the PTC heater 4, the COD heater 5, the three-way valve 7, the water pump 8, and the first temperature sensor 11 in sequence to heat the coolant during the cold start process, and passes through the radiator 6, the three-way valve 7, and the water pump 8 in sequence to dissipate the coolant during normal operation.
[0021] The COD heater 5 and the PTC heater 4 are used in series, which can reduce the requirements for the PTC selection. First, the use frequency of the PTC is reduced, and second, the power demand for the PTC is smaller.
[0022] In specific use, when the fuel cell unit 10 is in a low temperature environment, and the system starts and identifies that the coolant water temperature is lower than 0°C, the fuel cell system performs a cold start process, controls the opening of the three-way valve 7, and allows the coolant to flow in the small circulation branch of the fuel cell. During the cold start process, when the net output power of the fuel cell unit 10 is higher than the power required by the vehicle power battery, the COD heater 5 consumes the remaining power of the stack to heat the coolant, so that the small circulation water temperature rises rapidly; when the fuel cell unit 10 fails to start cold or there is a risk of icing inside and cannot start normally, the PTC heater 4 is used to heat the small circulation water temperature, and the normal startup process is carried out after the water temperature is higher than 0°C.
[0023] like Figure 2 As shown, the control method of the fuel cell cold start system includes the following steps: S1, when the fuel cell needs to be cold-started in a low-temperature environment, the vehicle control unit 9 sends a power demand instruction, and the fuel cell unit 10 determines the coolant temperature of the current state after receiving the demand; S2, if the coolant temperature is higher than 0°C, execute the normal startup process; if the coolant temperature is lower than 0°C, execute the low temperature startup process; S3, when the FCU fuel cell unit 10 determines that there is a risk of icing, the PTC heater 4 is started for external heating; S4: When the fuel cell unit 10 is judged to have no risk of icing, and the required power is lower than the net output power of the fuel cell unit 10 during the startup process, the COD heater 5 is started to consume excess power to heat the coolant for a cold start; when the fuel cell unit 10 is judged to have no risk of icing, and the required power is higher than or equal to the net output power of the fuel cell unit 10 during the startup process, a self-start without external heating is performed.
[0024] The present invention has a simple structure, requires few parts, and is easy to control. By adding a COD heater to the small coolant circulation of the fuel cell system, the fuel cell can be operated with an output power higher than the vehicle requirement during the cold start process. The COD heater directly consumes the electric energy of the stack to heat the coolant temperature, reducing the time required for cold start. The COD heater can also be used to consume residual hydrogen in the stack during the shutdown process.
Claims
1. A fuel cell cold start system, comprising a fuel cell stack module, characterized in that: The hydrogen inlet of the stack module (1) is connected to the hydrogen supply subsystem (2), the air inlet of the stack module (1) is connected to the air supply subsystem (3), the coolant outlet of the stack module (1) is divided into two paths, one path is connected to the PTC heater (4) and the COD heater (5) in sequence, and the other path is connected to the radiator (6), the COD heater (5) and the radiator (6) are combined into one path through a three-way valve (7) and are connected to one end of a water pump (8), and the other end of the water pump (8) is connected to the coolant inlet of the stack module (1).
2. A fuel cell cold start system according to claim 1, characterized in that: It also includes a vehicle control unit (9) and a fuel cell unit (10). The vehicle control unit (9) sends a demand to the fuel cell unit (10), and the fuel cell unit (10) controls the switching of the PTC heater (4), the COD heater (5), the radiator (6), the three-way valve (7), and the water pump (8) according to the demand.
3. A fuel cell cold start system according to claim 1, characterized in that: A first temperature sensor (11) is provided on the pipeline between the coolant inlet of the stack module (1) and the water pump (8); and a second temperature sensor (12) is provided on the pipeline between the coolant outlet of the stack module (1) and the PTC heater (4).
4. A fuel cell cold start system according to claim 1, characterized in that: The coolant exiting the coolant outlet of the stack module (1) passes through the second temperature sensor (12), the PTC heater (4), the COD heater (5), the three-way valve (7), the water pump (8), and the first temperature sensor (11) in sequence, thereby heating the coolant during the cold start process; and passes through the radiator (6), the three-way valve (7), and the water pump (8) in sequence, thereby dissipating the heat of the coolant during normal operation.
5. A control method for a fuel cell cold start system, characterized in that: The steps include: S1, when the fuel cell needs to be cold-started in a low-temperature environment, the vehicle control unit (9) sends a power demand instruction, and the fuel cell unit (10) determines the current coolant temperature after receiving the demand; S2, if the coolant temperature is higher than 0°C, execute the normal startup process; if the coolant temperature is lower than 0°C, execute the low temperature startup process; S3, when the FCU fuel cell unit (10) is judged to have a risk of icing, the PTC heater (4) is started to perform external heating; S4, when the fuel cell unit (10) is judged to have no risk of freezing, and the required power is lower than the net output power of the fuel cell unit (10) during the startup process, the COD heater (5) is started to consume excess power to heat the coolant for cold starting; when the fuel cell unit (10) is judged to have no risk of freezing, and the required power is higher than or equal to the net output power of the fuel cell unit (10) during the startup process, self-starting without external heating is performed.