Vacuum Circuit Breaker UPS Switching to Prevent Input Backfeed
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Solution Overview
Problem
Existing power supply apparatuses experience malfunctions due to the transmission of AC output voltage from the snubber circuit to the input terminal during AC power failures, leading to repeated output and stop cycles, and the use of high-speed mechanical switches increases costs while vacuum circuit breakers struggle with rapid on-off operations during power failure and recovery.
Innovation Solution
A power supply apparatus with multiple mechanical switches and a bypass circuit, where a different mechanical switch is turned off during each power failure, preventing AC output voltage from reaching the input terminal and employing a semiconductor switch with a snubber circuit to quickly disconnect AC power, and using two vacuum circuit breakers in series to enable fast and stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a semiconductor switch with snubber circuit is used to quickly disconnect AC power supply, then the disconnection speed is improved, but AC output voltage is transmitted to the input terminal causing erroneous determination
Solution Approach 1:
The patent divides the mechanical switch function into multiple vacuum circuit breakers (first and second vacuum circuit breakers) connected in series. This segmentation allows the system to prevent AC output voltage from reaching the input terminal by ensuring that at least one vacuum circuit breaker remains closed during power failure, thereby maintaining reliability while using fast semiconductor switches for disconnection.
2Ease of manufacture
If vacuum circuit breakers are used as mechanical switches, then cost is reduced, but rapid on-off operation during power failure and recovery is difficult
Solution Approach 1:
The patent implements dynamic control of multiple vacuum circuit breakers where the control device selectively opens different vacuum circuit breakers based on the state (power failure or recovery). During power failure, the first vacuum circuit breaker is opened while the second remains closed. During recovery, the second is opened while the first remains closed. This dynamic switching strategy enables rapid response using inexpensive vacuum circuit breakers.
3Ease of manufacture
If mechanical switches are used instead of semiconductor switches, then cost is reduced, but disconnection time increases
Solution Approach 1:
The patent merges the advantages of both mechanical and semiconductor switches by combining vacuum circuit breakers (inexpensive mechanical switches) with semiconductor switches in the bypass circuit. The vacuum circuit breakers provide cost-effective isolation, while the semiconductor switches in the bypass circuit enable rapid disconnection when AC power supply fails, thus reducing disconnection time while maintaining cost-effectiveness.
Data Source
AI summary
An uninterruptible power supply includes a plurality of vacuum circuit breakers and a bypass circuit connected in series between a commercial AC power supply and a load, a control device that turns on both of the plurality of vacuum circuit breakers and the bypass circuit when the commercial AC power supply is normal and turns off a vacuum circuit breaker different from a vacuum circuit breaker turned off on the occurrence of previous power failure of the plurality of vacuum circuit breakers and turns off the bypass circuit when the commercial AC power supply fails, and a power converter that converts DC power of a battery into AC power and supplies AC power to the load when the commercial AC power supply fails.