AC Uninterruptible Power Supply Fuel Cell Start Control
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Solution Overview
Problem
Conventional uninterruptible power supply systems with fuel cells experience unstable start and stop control due to fluctuations in storage battery output voltage, primarily caused by changes in internal resistance and load current, leading to repeated start and stop cycles, especially with smaller capacity batteries.
Innovation Solution
An alternating current uninterruptible power supply system that includes a switch, power feed lines from both the commercial AC power source and a fuel cell, a converter, inverter, and a control unit that determines power failure duration and adjusts the fuel cell's operation accordingly, ensuring stable start and stop control by switching between power sources based on predefined time thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel cell is started depending on the output voltage of the storage battery, then the fuel cell can be activated when battery charge decreases, but both start control and stop control of the fuel cell become unstable
Solution Approach 1:
The patent introduces a commercial power source as an intermediary to stabilize the storage battery's output voltage. By connecting the commercial power source in parallel with the storage battery through a switch, the system uses the stable commercial power to compensate for voltage fluctuations in the storage battery, thereby preventing unstable fuel cell start/stop control while maintaining the ability to activate the fuel cell when needed.
2Volume of moving object
If a storage battery with small capacity is employed to reduce size, then the internal resistance of the storage battery increases, but the fluctuation in output voltage becomes more remarkable
Solution Approach 1:
The patent merges the storage battery with the commercial power source to form a hybrid power supply system. This combination allows the system to benefit from both the portability of a small storage battery and the voltage stability of the commercial power source, effectively resolving the contradiction between miniaturization and voltage stability.
Solution Approach 2:
The commercial power source acts as a mediator that compensates for the voltage instability caused by the small-capacity storage battery's high internal resistance. The switch controls the connection between these two power sources, allowing the system to maintain stable output voltage while using a compact battery configuration.
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 system stabilizes the start and stop control of the fuel cell, preventing repeated cycles and ensuring reliable emergency power supply by accurately determining power failure and resumption durations.
Implementation Method 1
a stack constructed from a plurality of unit battery cells generating electric power by means of a reaction between fuel gas and oxidation gas
Implementation Method 2
a converter connected between the first power feed line and the second power feed line
Implementation Method 3
an inverter connected to the second power feed line between the battery and the second input part
Data Source
AI summary
An alternating current uninterruptible power supply system includes a first power feed line, a second power feed line, a switchover relay, a converter, a power switch, a fuel cell, a system control board, a battery, and an inverter. If it is determined that electric power supply from a commercial alternating current power source has stopped for a first time or longer, a system control part of the system control board switches the switchover relay from a first state to a second state. Then, on the basis of the state of the electric power of the first power feed line, the system control part determines whether or not stopping of the electric power supply from the commercial alternating current power source has continued for a second time or longer. After that, if it is determined that the stopping of the electric power supply from the commercial alternating current power source has continued for the second time or longer, the system control part starts power generation of the stack.