Fuel Cell System Relay Insulation Safety Control
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Solution Overview
Problem
Conventional fuel cell systems face insulation decrease issues due to increased conductivity of cooling liquids, which can form high voltage paths between the cooling circuit and high voltage circuit outside the fuel cell system, potentially leading to unsafe high voltage applications when starting the fuel cell.
Innovation Solution
A fuel cell system with a relay, conductivity reduction unit, and control unit that performs conductivity reduction on the cooling liquid before connecting the relay, ensuring no high voltage path is formed outside the fuel cell system, allowing safe startup and preventing electrical leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductivity reduction process is performed on cooling liquid before relay connection, then insulation safety is improved, but system startup time increases
Solution Approach 1:
The conductivity reduction process is performed in advance before the relay connects the fuel cell to the high voltage circuit. The control unit executes the conductivity reduction process upon receiving a start request and before establishing electrical connection, ensuring cooling liquid conductivity is reduced to safe levels prior to potential high voltage exposure that could occur if an outer current path exists.
Solution Approach 2:
The system dynamically adjusts the startup sequence based on detected insulation decrease locations. When insulation decrease is detected outside the fuel cell region, the system activates the conductivity reduction process and delays relay connection until completion. When insulation decrease occurs within the fuel cell region, the system can proceed with immediate relay connection, optimizing startup time while maintaining safety.
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
Enables quick and safe startup of the fuel cell without forming external high voltage paths, effectively managing insulation decreases and maintaining system safety.
Implementation Method 1
a conductivity reduction unit disposed on the cooling circuit, the conductivity reduction unit configured to reduce conductivity of the cooling circuit
Data Source
AI summary
A fuel cell system FCS includes a fuel cell 10, a high voltage circuit 21 for driving an electromotor 42, and a relay 41 for electrically connecting or blocking the fuel cell 10 to or from the high voltage circuit 21. A control unit 50 obtains insulation decrease information in accordance with a request for starting the fuel cell, and performs, when a specified insulation decrease occurred region is not a fuel cell region SE1 including the fuel cell and the cooling circuit, conductivity reduction process on cooling liquid using a conductivity reduction unit 113 before having a relay 41 connect, and has the relay 41 connect after completing the conductivity reduction process.