Fuel Cell Water Level Sensor Failure Detection
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Solution Overview
Problem
In fuel cell systems, a failure in the water level sensor makes it impossible to estimate the state of water in the gas liquid separator, necessitating a method to easily and accurately detect sensor failures.
Innovation Solution
A failure detection processing method that determines a failure in the water level sensor by monitoring the presence of water, power generation current values, and the state of the drain valve, with conditions satisfied for a time period exceeding a threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water level sensor is installed to detect water accumulation in the gas liquid separator, then water discharge control is improved, but the system cannot detect sensor failures
Solution Approach 1:
The system uses feedback from multiple sensors (water level sensor, drain valve state sensor, and power generation current sensor) to continuously monitor the water discharge process. By comparing the expected system state (based on sensor readings and valve positions) with the actual state, the control unit can detect when the water level sensor fails to provide accurate feedback, thereby identifying sensor failures while maintaining reliable water discharge control.
2Ease of operation
If simple sensor monitoring is used to detect failures, then the detection method is easy to implement, but the detection accuracy is insufficient
Solution Approach 1:
The control unit performs multiple functions: it controls the drain valve operation, monitors water level sensor readings, detects sensor failures, and manages power generation current. By integrating these functions into a single control system, the patent achieves accurate failure detection without requiring separate complex monitoring systems, thus maintaining ease of implementation while improving detection accuracy through multi-parameter analysis.
3Measurement precision
If multiple parameters are monitored to improve failure detection accuracy, then detection precision is improved, but system complexity increases
Solution Approach 1:
The control unit utilizes existing system components (drain valve, power generation current measurements) to assist in water level sensor failure detection. The system serves itself by using its own operational data (valve state, current consumption patterns) to validate sensor readings, thereby improving detection precision without adding separate complex monitoring equipment or increasing overall system complexity.
Data Source
AI summary
A fuel cell system includes a fuel cell stack, a gas liquid separator, a water level sensor, a drain valve, and a control unit. When a failure detection processing method is performed, a control unit makes a determination of main conditions where the water level sensor determines that water is present, a power generation current value of the fuel cell stack is not more than a predetermined current threshold value, a drain valve for discharging water in the gas liquid separator is open. Then, the control unit counts elapsed time when the main conditions are satisfied, and in the case where the main conditions are kept satisfied for the elapsed time which is larger than a time threshold value, the control unit determines that the water level sensor has a failure.