Fuel Cell Stack Voltage Drop Control During Stop Mode
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Solution Overview
Problem
In fuel cell systems, the output voltage of the fuel cell stack may not be reduced during stop control mode due to the presence of excess hydrogen and air, leading to potential deterioration of the stack.
Innovation Solution
A fuel cell system with a converter and a controller that adjusts the output voltage by using a bi-directional high voltage DC converter and air compressor/adjustment valve to maintain the voltage within predefined limits, even during stop control mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fuel cell stack enters stop control mode to reduce power consumption, then energy efficiency is improved, but the output voltage may not be reduced due to excess hydrogen and air, causing stack deterioration
Solution Approach 1:
The patent introduces a converter as an intermediary device between the fuel cell stack and the load. The converter actively regulates the output voltage of the fuel cell stack during stop control mode by converting excess electrical energy, thereby preventing voltage buildup that would otherwise cause stack deterioration while maintaining the low power consumption state.
Solution Approach 2:
The patent changes the electrical parameter (voltage) by introducing a converter that actively regulates and reduces the output voltage of the fuel cell stack. This parameter change allows the system to maintain stop control mode benefits while preventing the harmful effect of excessive voltage on the stack.
2Reliability
If the air compressor and air adjustment valve are used to control the output voltage, then voltage regulation is achieved, but the device complexity increases
Solution Approach 1:
The patent makes the converter a multi-functional device that simultaneously performs voltage regulation and power management functions. By integrating these functions into a single device, the system achieves voltage regulation without proportionally increasing device complexity, as the converter serves multiple purposes in the fuel cell system.
Solution Approach 2:
The patent replaces the mechanical control system (air compressor and air adjustment valve) with an electrical control system (converter). This substitution eliminates the need for mechanical moving parts and complex mechanical regulation mechanisms, thereby achieving voltage regulation with reduced device complexity.
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
Prevents overvoltage-induced deterioration of the fuel cell stack by forcibly dropping the output voltage to predefined limits, ensuring stable operation and extending the stack's lifespan.
Implementation Method 1
a converter connected to a high voltage line and a battery while being located therebetween and configured to control a voltage at the high voltage line
Implementation Method 2
A fuel cell is a device that receives hydrogen and air from the outside space and generates electrical energy through an electrochemistry reaction inside a fuel cell stack
Data Source
AI summary
A fuel cell system includes a fuel cell stack and a battery that are connected to a high voltage line in parallel, a converter connected to the high voltage line and the battery while being located therebetween and configured to control a voltage at the high voltage line, and a controller, in a stop control mode of the fuel cell stack, when an error occurs in a drop control of an output voltage of the fuel cell stack, the controller dropping the voltage at the high voltage line under the output voltage of the fuel cell stack by the converter to drop the output voltage of the fuel cell stack.