Fuel Cell Stack Voltage Draining via Load Device and Battery
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Solution Overview
Problem
Fuel cell systems face challenges in preventing deterioration and diagnosing failures, particularly in draining residual voltage and oxygen from the fuel cell stack, which can lead to high voltage exposure and reduced efficiency.
Innovation Solution
A control method and system that utilize a high voltage battery and fuel cell load device to drain the fuel cell stack voltage, diagnose the operation of the fuel cell load device by monitoring current and voltage changes, and adjust the main bus terminal voltage to prevent power output to other loads until the stack reaches a safe voltage, thereby maintaining system stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel cell stack voltage is drained by connecting a fuel cell load device, then residual oxygen can be removed and carbon corrosion prevented, but the system complexity increases and diagnosis of load device failure becomes difficult
Solution Approach 1:
The fuel cell load device is designed to serve multiple functions: it acts as both a voltage draining device and an oxygen removal mechanism. By connecting the load device to the fuel cell stack, the system simultaneously reduces voltage levels and consumes residual oxygen through the electrochemical reaction, eliminating the need for separate components for each function.
Solution Approach 2:
The control unit continuously monitors the voltage level of the fuel cell stack and automatically controls the connection and disconnection of the fuel cell load device. When the voltage exceeds a predetermined threshold, the control unit connects the load device to drain the voltage; when the voltage drops below the threshold, the control unit disconnects the load device. This closed-loop feedback mechanism simplifies the overall system by using intelligent control rather than complex mechanical switching systems.
2Reliability
If the fuel cell load device is used to drain voltage, then oxygen removal is achieved, but failure diagnosis of the load device becomes difficult
Solution Approach 1:
The control unit monitors the voltage level of the fuel cell stack and uses this feedback information to diagnose the operational status of the fuel cell load device. By observing whether the voltage decreases as expected when the load device is connected, the system can detect failures in the load device without requiring separate diagnostic sensors or complex testing procedures.
Solution Approach 2:
The fuel cell load device performs self-diagnosis through its operational characteristics. When the control unit connects the load device, it expects a certain voltage drop; if the voltage does not decrease as anticipated, the system automatically detects that the load device has failed. This self-diagnostic capability eliminates the need for additional diagnostic equipment.
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
The method effectively drains residual oxygen, prevents high voltage exposure, maintains system stability during restarts, and improves fuel efficiency by ensuring the fuel cell stack is properly managed and diagnosed for potential failures.
Implementation Method 1
a fuel cell stack to generate electric power from an electrochemical reaction of reactant gases
Implementation Method 2
The oxygen flowing into the fuel cell stack 10 is removed with residual hydrogen of the anode as the fuel cell load device 20 consumes current
Data Source
AI summary
A control method and system of a fuel cell system are provided. The control method includes draining the voltage of a fuel cell stack by charging a high voltage battery. In addition, the method includes draining the voltage of the fuel cell stack by connecting a fuel cell load device to the fuel cell stack, which is performed when the voltage of the fuel cell stack decreased by the first draining process is less than a predetermined first reference voltage.