Fuel Cell Contactor Failure Detection via DC/DC Voltage Monitoring
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Solution Overview
Problem
Existing fuel cell systems lack a reliable method to detect closing failures of contactors, which can occur due to melting adhesion between movable and fixed contacts, leading to inefficiencies and potential system downtime.
Innovation Solution
A contactor failure detecting apparatus that includes a DC/DC converter and a control device, which transmits an opening command to the contactor and monitors changes in voltage, current, or electrical power on the fuel cell and load sides to quickly detect closing failures, preventing overloading and system downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contactor is used to connect or disconnect the load with the fuel cell, then the system can control power flow and protect the fuel cell, but the contactor may suffer from melting adhesion between movable and fixed contacts, leading to closing failures
Solution Approach 1:
The system performs preliminary actions by controlling the contactor to open before changing operating conditions or stopping the fuel cell. The control device monitors contactor status and executes opening commands proactively to prevent melting adhesion from occurring in the first place, rather than waiting for failure to detect and respond.
Solution Approach 2:
The control device continuously monitors the contactor's closing status and provides feedback to detect closing failures. By monitoring whether the contactor properly closes after an opening command, the system can identify melting adhesion issues and take corrective action, creating a closed-loop control system that improves reliability through continuous verification.
2Productivity
If the contactor closes properly under load, then power flow is maintained, but undetected closing failures can lead to overloading of the fuel cell and system downtime
Solution Approach 1:
The control device uses feedback monitoring to detect whether the contactor has properly closed by checking voltage, current, or power signals after issuing a closing command. This continuous feedback loop allows the system to identify closing failures immediately and prevent overloading conditions, maintaining both productivity and reliability.
Solution Approach 2:
The system takes preliminary anti-action by detecting closing failures before they can lead to overloading or system damage. The control device monitors contactor status and can prevent harmful effects by identifying improper closing and taking corrective action before the fuel cell is overloaded or system downtime occurs.
3Device complexity
If traditional failure detection methods are used, then system complexity is minimized, but detection time is extended and response to contactor failures is delayed
Solution Approach 1:
The control device performs multiple functions: it controls the contactor opening/closing operations, monitors system operating parameters, and detects contactor failures all through a single integrated device. This multi-functionality eliminates the need for separate dedicated detection hardware, maintaining low system complexity while enabling rapid failure detection through its existing monitoring capabilities.
Solution Approach 2:
The control device uses its existing feedback monitoring of voltage, current, or power signals to detect contactor failures. By leveraging the feedback already present in the control system for normal operation, the patent achieves rapid failure detection without adding complex dedicated detection circuitry, thus minimizing device complexity while reducing detection time.
Data Source
AI summary
A contactor electrically connects and disconnects a fuel cell from a load. When a failure-detecting mode for detecting a closing failure of a contactor is initiated, an opening command is transmitted to the contactor, and a DC/DC converter connected to a motor changes the load voltage. Then, the load voltage and a fuel cell voltage are compared with each other. If the contactor is in a normal open state, as a result of the opening command, the fuel cell voltage is constant, whereas the load voltage of the DC/DC converter decreases, thereby producing a voltage difference. A closing failure of the contactor is determined when it is detected that the fuel cell voltage is substantially equal to the load voltage.