A rapid warm-up control strategy for a fuel cell system

Abstract

The present invention relates to the field of fuel cells, specifically a rapid warm-up control strategy for a fuel cell system. It includes the following steps: S1, receiving a power-on command and performing a power-on self-test; S2, pulling the load to the idle current and identifying whether there is a fault: if not, identifying whether the coolant temperature requires a warm-up operation, and if so, executing a rapid warm-up strategy, pulling the load to the warm-up current, and executing steps A1-A3: A1, the air path adjusts the air flow into the stack through the throttle opening, limits the average potential cooling path, turns on the PTC heater, and controls the inlet and outlet water temperature of the stack through the water pump and thermostat; A2, identifying whether the stack temperature and the thermostat opening meet the free loading requirements of the stack, and if so, exiting the rapid warm-up state, turning off the PTC heater, and restoring normal air flow and water pump speed; A3, entering the normal operating state. The present invention can quickly warm up the fuel cell system in the cold state, freely pull the load after warming up, and quickly respond to power requirements.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to an extremely fast warm-up control strategy for a fuel cell system. Background Art

[0002] Currently, existing fuel cell systems require a series of warm-up and slow loading processes to start from a cold state and run at full power, which is time-consuming. In addition, this process is generally subject to system power limitations, making it impossible to quickly respond to upstream power demands in a short period of time. Summary of the Invention

[0003] The purpose of the present invention is to address the problems existing in the background technology and propose a fuel cell system rapid warm-up control strategy that can achieve rapid warm-up of the fuel cell system in a cold state, perform free loading after warm-up, and quickly respond to power requirements.

[0004] The technical solution of the present invention is a fuel cell system rapid warm-up control strategy, comprising the following steps:

[0005] S1. Accept the power-on command and perform power-on self-test;

[0006] S2, pull the load to the idle current, and identify whether there is a fault:

[0007] If so, shut down the machine and purge;

[0008] If not, the coolant temperature is determined to determine whether a warm-up operation is required. If so, a rapid warm-up strategy is implemented, the load is increased to the warm-up current, and steps A1-A3 are executed:

[0009] A1. The air path adjusts the air flow into the stack through the throttle opening to limit the average potential. The cooling path turns on the PTC (positive temperature coefficient thermistor) heater and controls the stack inlet and outlet water temperatures through the water pump and thermostat.

[0010] A2. Identify whether the stack water temperature and thermostat opening meet the stack free load requirements. If so, exit the rapid warm-up state, turn off the PTC heater, and restore normal air flow and water pump speed.

[0011] A3. Enter the normal operating state and realize free load increase and decrease according to the required power.

[0012] Preferably, in step S2, if the water temperature at the fuel cell stack inlet is lower than 50°C, a warm-up operation needs to be performed; if the water temperature at the fuel cell stack inlet is higher than 50°C, no warm-up operation needs to be performed.

[0013] Preferably, in step S2, the warm-up current is 0.8A / cm 2 The corresponding current at the current density.

[0014] Preferably, in step A1, the average cell voltage of the stack is controlled to be maintained at 0.3V.

[0015] Preferably, in step A1, the temperature difference between the water temperature at the inlet and outlet of the fuel cell stack is in the range of 7-10°C.

[0016] Preferably, if the water temperature of the fuel cell stack to be identified reaches above 65°C and the thermostat opening is higher than 60, the free loading requirement of the fuel cell stack is met.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects:

[0018] This invention enables rapid warm-up of a fuel cell system from a cold state, followed by free loading and rapid response to power demands. The warm-up process accelerates stack heat generation by operating in a reduced cathode stoichiometric ratio mode, while simultaneously operating the PTC heater to heat the coolant. This significantly shortens the warm-up time and enables faster response to upstream power demands. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic structural diagram of a fuel cell system according to an embodiment of the present invention;

[0020] Figure 2 This is a flow chart of the warm-up control strategy according to an embodiment of the present invention.

[0021] Figure numerals: 1. Air filter; 2. Air compressor; 3. Intercooler; 4. Humidifier; 5. Throttle a; 6. Throttle b; 7. Back pressure valve; 8. Fuel cell stack; 9. Water pump; 10. PTC heater; 11. Radiator; 12. Thermostat. DETAILED DESCRIPTION

[0022] This embodiment proposes a fuel cell system rapid warm-up control strategy, such as Figure 1 As shown, the fuel cell system includes an air filter 1, an air compressor 2, an intercooler 3, a humidifier 4, a throttle, a backpressure valve 7, a fuel cell stack 8, a water pump 9, a PTC heater 10, a radiator 11, and a thermostat 12. The air filter 1, air compressor 2, intercooler 3, humidifier 4, and throttle are connected in sequence. The air filter 1 filters impurities from the air. The filtered air then enters the air compressor 2 and is compressed to the required system pressure. The heat generated during the compression process is exchanged through the intercooler 3, and then the air is humidified by the humidifier 4. The throttle includes a throttle a5 that controls whether the humidified air from the humidifier 4 is directed into the fuel cell stack 8 or a throttle b6 that directs it into the exhaust. The reacted gas from the fuel cell stack 8 enters the exhaust through the backpressure valve 7, which can be used to adjust the pressure within the fuel cell stack 8.

[0023] The PTC heater 10, thermostat 12, water pump 9, fuel cell stack 8, and PTC heater 10 form an internal coolant loop, heating the internal coolant through the PTC heater 10. The radiator 11, thermostat 12, water pump 9, fuel cell stack 8, and radiator 11 form an external coolant loop, exchanging heat with the outside world through the radiator 11. The thermostat 12 switches between the internal and external coolant loops. The intercooler 3 connects the cooling branches of the internal and external coolant loops. A temperature sensor a ( Figure 1 T1 in the figure), a temperature sensor b is set at the outlet of the stack 8 ( Figure 1 The system detects the temperature of the cooling path of the stack 8 in real time to achieve reasonable temperature control and ensure the normal operation of the fuel cell system.

[0024] like Figure 2 As shown in Figure 2, the warm-up control strategy includes the following steps:

[0025] S1. Receive the power-on command and perform a power-on self-test to check whether all components can respond normally.

[0026] S2. Pull the load to the idle current (zero power) or the lowest operating power point to identify whether there is a fault, such as abnormal single chip voltage, abnormal anode and cathode flow and pressure, etc.:

[0027] If so, shut down the machine for purge and troubleshoot the corresponding fault;

[0028] If not, identify whether the coolant temperature needs to be warmed up. If the water temperature at the inlet of the stack 8 (detected by temperature sensor a) reaches above 50°C, warming up is not required. If the water temperature at the inlet of the stack 8 is lower than 50°C, warming up is required. The system load is pulled to the warming-up current at the normal loading rate. The warming-up current is 0.8A / cm 2 For the current density corresponding to the current, perform steps A1-A3:

[0029] A1. Reduce the cathode stoichiometric ratio. Adjust the throttle valves (throttle a5 and throttle b6) in the air path to reduce the air flow into the stack. This maintains the average cell voltage of the stack 8 at 0.3V, accelerates heat generation, and limits the average potential. In the cooling path, turn on the PTC heater 10. The water inlet and outlet temperatures of the stack 8 are controlled by the water pump 9 and thermostat 12. The temperature difference between the inlet and outlet water temperatures of the stack 8 is 7-10°C.

[0030] A2. Identify whether the water temperature of the stack 8 and the opening of the thermostat 12 meet the free load requirement of the stack 8. If the water temperature of the stack 8 reaches above 65°C and the opening of the thermostat 12 is higher than 60°C, or if the maximum allowable current or power of the system reaches the rated value, the free load requirement of the stack 8 is met and full power operation is achieved. The rapid warm-up state is exited, the PTC heater 10 is turned off, and normal air flow and water pump speed are restored.

[0031] A3. Enter the normal operating state and realize free load increase and decrease according to the required power.

[0032] This embodiment enables rapid warm-up of the fuel cell system from a cold state, enabling free loading after warm-up, allowing for rapid response to power demands. The warm-up process accelerates heat generation in the stack by operating in a reduced cathode stoichiometric ratio mode, while simultaneously operating the PTC heater to heat the coolant, significantly shortening the warm-up time and enabling faster response to upstream power demands. Furthermore, the warm-up process can activate stacks from certain manufacturers, significantly improving fuel cell performance during subsequent normal operation.

[0033] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A fuel cell system rapid warm-up control strategy, characterized in that: The following steps are involved: S1. Accept the power-on command and perform power-on self-test; S2, pull the load to the idle current, and identify whether there is a fault: If so, shut down the machine and purge; If not, the coolant temperature is determined to determine whether a warm-up operation is required. If so, a rapid warm-up strategy is implemented, the load is increased to the warm-up current, and steps A1-A3 are executed: A1. The air path adjusts the air flow into the stack through the throttle opening to limit the average potential. The cooling path turns on the PTC heater and controls the water temperature in the stack inlet and outlet through the water pump and thermostat. A2. Identify whether the stack water temperature and thermostat opening meet the stack free load requirements. If so, exit the rapid warm-up state, turn off the PTC heater, and restore normal air flow and water pump speed. A3. Enter the normal operating state and realize the free load increase and decrease of required power; In step S2, if the water temperature at the stack inlet is lower than 50°C, a warm-up operation is required; if the water temperature at the stack inlet is higher than 50°C, no warm-up operation is required; In step A1, the average cell voltage of the stack is controlled to be maintained at 0.3V; In step A1, the temperature difference between the water temperature at the inlet and outlet of the stack is 7-10°C; If the water temperature of the fuel cell stack to be identified reaches above 65°C and the thermostat opening is higher than 60, the free loading requirement of the fuel cell stack is met.

2. A fuel cell system rapid warm-up control strategy according to claim 1, characterized in that: In step S2, the warm-up current is 0.8A / cm 2 The corresponding current at the current density.

Images