UPS Backfeed Detection via Voltage Comparison
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Solution Overview
Problem
Existing uninterruptible power systems (UPS) face malfunctions and inaccurate backfeed failure detection due to current transformer failures, leading to unnecessary shutdowns and increased costs.
Innovation Solution
The implementation of a UPS system with a power conversion apparatus, a switch unit, a first voltage detection unit, a second voltage detection unit, and a comparison unit, which compares input and output voltage signals to accurately determine backfeed failure by identifying coincident frequency, amplitude, and phase relationships, eliminating the need for current transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If current transformers are used for backfeed detection, then detection function is achieved, but costs increase and circuit design becomes complex
Solution Approach 1:
The patent removes the current transformer from the circuit and extracts only the essential voltage detection function. This simplification eliminates the complexity of current transformer integration while maintaining the core backfeed detection capability through direct voltage monitoring.
Solution Approach 2:
The patent replaces the expensive and complex current transformer with a simpler, more cost-effective voltage detector. This substitution achieves the same detection function with lower cost and reduced circuit complexity, aligning with the principle of using simpler components when possible.
2Measurement precision
If current transformers detect large current for backfeed failure, then backfeed detection is enabled, but malfunctions occur due to interruption of detection leading to wrong operation confirmation
Solution Approach 1:
The patent extracts the detection function from the unreliable current transformer system and implements it through direct voltage monitoring. This approach maintains measurement precision for backfeed failure detection while eliminating the reliability issues caused by large-current detection interruptions.
Solution Approach 2:
The patent substitutes the mechanical/electromagnetic current transformer system with an electronic voltage detection system. This replacement eliminates the physical limitations and malfunctions of current transformers while maintaining accurate detection capability through electronic voltage monitoring at the input terminal.
Data Source
AI summary
An uninterruptible power system and a method of operating the same are disclosed. The uninterruptible power system includes a power conversion apparatus, a switch unit, a first voltage detection unit, a second voltage detection unit, and a comparison unit. The power conversion apparatus receives an AC power source and converts the AC power source to supply an AC load. The first voltage detection unit detects an input voltage of the power conversion apparatus and produces a first voltage signal. The second voltage detection unit detects an output voltage of the switch unit and produces a second voltage signal. Under the AC power source is disabled and the power conversion apparatus provides a backup power to supply the AC load, the switch unit is detected in a fault operation when the first voltage signal is compared by the comparison unit to equal to the second voltage signal.