Fuel Cell Power Net System for Rapid Emergency Voltage Reduction
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Solution Overview
Problem
Conventional fuel cell vehicles lack a rapid and efficient method to remove high voltage from the fuel cell stack during dangerous situations like collisions, posing a risk of electrical shock due to the absence of a separate device for emergency voltage reduction.
Innovation Solution
A power net system for fuel cell vehicles, comprising a fuel cell and a high-voltage battery unit connected in parallel via a main bus, with switching units and a controller that manages electrical connections to consume fuel cell power through a load device and charge the high-voltage battery, while blocking hydrogen and oxygen supply during dangerous events, and using a high-voltage converter to decrease the main bus voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If only the load device is used to decrease the voltage of the fuel cell stack, then the voltage can be reduced, but the process is slow and insufficient for emergency situations
Solution Approach 1:
The patent combines the load device with the high-voltage battery unit to create a dual-path voltage reduction system. The load device handles normal post-process voltage reduction, while the high-voltage battery unit provides rapid discharge for emergency situations, merging two functions into one integrated system that resolves the speed limitation without requiring completely separate systems.
Solution Approach 2:
The high-voltage battery unit serves multiple functions: it acts as a power source for the vehicle, provides rapid voltage reduction capability for emergencies, and can operate in parallel with the load device for enhanced voltage reduction. This multi-functionality allows the system to address emergency voltage reduction needs without adding entirely separate dedicated equipment.
2Reliability
If the fuel cell stack maintains high voltage for power output, then power availability is ensured, but the risk of electrical shock exposure increases in dangerous situations
Solution Approach 1:
The system dynamically switches between different voltage reduction modes based on operational conditions. During normal operation, the fuel cell maintains high voltage for power availability. When a dangerous situation is detected (collision, water ingress), the controller rapidly activates the high-voltage battery unit and load device to reduce voltage, creating a dynamic response that balances power needs against safety risks.
Solution Approach 2:
The high-voltage battery unit acts as an intermediary element between the fuel cell stack and the external environment. It provides a controlled discharge path that rapidly reduces voltage in emergencies, mediating the conflict between maintaining high voltage for power and reducing voltage for safety by serving as a buffer and controlled energy release mechanism.
3Productivity
If the conventional load device is used for both normal post-process and emergency voltage reduction, then device simplicity is maintained, but voltage reduction efficiency is insufficient during collisions
Solution Approach 1:
The high-voltage battery unit is pre-charged and ready to provide rapid discharge current when needed. In normal operation, it maintains charge readiness, and upon detecting a dangerous situation, it immediately activates to assist the load device in voltage reduction. This preliminary preparation allows the system to achieve high productivity in emergencies without requiring complex real-time decision-making or reconfiguration.
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
This system rapidly and efficiently reduces the high voltage of the fuel cell output terminal during collisions, preventing electrical shock by consuming fuel cell power through the load device and charging the high-voltage battery, thereby ensuring safer operation.
Implementation Method 1
a fuel cell stack configured to generate electrical energy from an electrochemical reaction of reaction gas
Implementation Method 2
a fuel cell load device for reducing and removing the voltage of the fuel cell stack... the current is consumed through the fuel cell load device
Data Source
AI summary
A power net system of a fuel cell vehicle is provided. The power net system includes a fuel cell and a high-voltage battery unit connected in parallel via a main bus and a first switching unit that is configured to form and block an electrical connection between an output terminal of the fuel cell and the main bus. A load device diverges and is connected between the output terminal of the fuel cell and the first switching unit. A reverse current blocking unit is connected between the first switching unit and a node from which the load device diverges. A second switching unit is configured to form and block an electrical connection between the output terminal of the fuel cell and the load device. A controller operates the first and second switching units and adjusts the electrical connection state between the main bus and the high-voltage battery unit.