Fuel Cell System Power Stop Control via Air Pump Surplus
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Solution Overview
Problem
Fuel cell systems face challenges in efficiently stopping power generation without causing deterioration of the electrolyte membrane and preventing unintended power generation due to transient currents when receiving a power generation stop request, especially when the vehicle is in operation.
Innovation Solution
A fuel cell system with a control device that executes a first control to close the stop valve and a second control to discard surplus electric power by driving an air pump using surplus power, ensuring the air pump is driven in a predetermined state once the stop valve is closed, thereby consuming transient electric power and quickly shifting the system to a power generation stop state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If air is circulated in the fuel cell system to prevent freezing after power generation stop, then freezing prevention is achieved, but electrolyte membrane deterioration progresses and durability decreases
Solution Approach 1:
The system performs preliminary drainage of water from the cathode path before power generation stop occurs. The control device activates the water discharge valve to drain water from the cathode path when water accumulation is detected, preventing freezing damage without requiring post-stop air circulation that would deteriorate the electrolyte membrane.
Solution Approach 2:
The invention extracts and removes water from the cathode path using a dedicated water discharge valve and drainage mechanism. By actively removing water before power generation stop, the system prevents freezing without needing to circulate air after stop, thereby avoiding electrolyte membrane deterioration while achieving freezing protection.
2Speed
If the output command value is rapidly lowered to stop power generation quickly, then power generation stop speed is improved, but transient current occurs causing unintended power generation
Solution Approach 1:
The system performs preliminary drainage of water from the cathode path before power generation stop. This preliminary action allows the output command value to be rapidly lowered without causing transient current, because the water drainage prevents the conditions that lead to transient current occurrence, achieving both fast stop and accurate control.
Solution Approach 2:
The invention applies preliminary anti-action by draining water from the cathode path before power generation stop. This preliminary countermeasure prevents the occurrence of transient current that would otherwise cause unintended power generation, allowing rapid reduction of the output command value without control accuracy degradation.
3Reliability
If the output command value is slowly lowered to prevent transient current, then power generation control accuracy is improved, but power generation stop time increases
Solution Approach 1:
The system performs preliminary water drainage from the cathode path before power generation stop. This preliminary action enables the output command value to be rapidly lowered without generating transient current, thereby achieving both fast power generation stop and accurate control simultaneously.
Solution Approach 2:
The invention allows the output command value to be rapidly reduced by skipping the gradual reduction process, because the preliminary water drainage has already prevented transient current occurrence. This enables quick power generation stop without sacrificing control accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively consumes surplus power and prevents fuel cell system deterioration, allowing the fuel cell system to quickly transition to a power generation stop state, even when transient electric power occurs, thereby maintaining system durability and efficiency.
Implementation Method 1
The fuel cell vehicle supplies air (including oxygen) and hydrogen gas as a fuel gas to a fuel cell. The fuel cell vehicle travels by driving an electric motor using electricity generated by the fuel cell.
Implementation Method 2
an air pump configured to supply the oxygen-containing gas to the cathode supply path
Implementation Method 3
a stop valve provided between the air pump and the fuel cell stack in the cathode supply path
Data Source
AI summary
A fuel cell system performs a first control of stopping power generation of a fuel cell stack by closing a supply-side stop valve during power generation of the fuel cell stack, and a second control of driving an air pump by using surplus power generated in a moving body to thereby discard the surplus power. If a closed state of the supply-side stop valve is detected when the first control and the second control start to be executed, the air pump is driven in a predetermined state.