UPS Back-Feed Detection Through Output Power Adjustment
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Solution Overview
Problem
Existing uninterruptible power supply (UPS) systems face challenges in detecting back-feed and mis-wiring events, which can lead to inadequate protection of loads and potential damage to equipment, as conventional methods may fail to accurately identify these conditions, especially when voltage and frequency sensing circuits malfunction.
Innovation Solution
The implementation of a UPS system with a controller that adjusts parameters such as voltage, frequency, and phase of the output AC power, and monitors both input and output AC power to detect faults, including mis-wiring or back-feed conditions by analyzing changes in current and voltage thresholds, and using active and passive methods to determine if relay contacts are welding or shorted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage and frequency sensing circuits are used to detect back-feed and mis-wiring events, then the system structure remains simple, but the detection reliability is insufficient and may fail to accurately identify faults
Solution Approach 1:
The patent replaces conventional voltage and frequency sensing circuits with an advanced detection method that uses current measurements and mathematical calculations. The controller measures current through the relay coil and determines back-feed or mis-wiring conditions by analyzing whether the measured current matches expected values during specific operational states (battery mode vs. line mode), eliminating the need for separate voltage and frequency sensing hardware.
Solution Approach 2:
The patent introduces an intermediary detection approach by using the relay coil current as a proxy indicator for system state verification. Instead of directly measuring voltage and frequency to detect faults, the system uses the relay coil current waveform characteristics as an intermediate parameter to infer whether back-feed or mis-wiring conditions exist, providing more reliable fault detection.
2Measurement precision
If the UPS system continuously monitors and adjusts output parameters to detect faults, then the detection precision improves, but the energy consumption increases
Solution Approach 1:
The patent implements self-service by using the existing relay coil current measurements, which are already being taken for normal UPS operation, to simultaneously perform fault detection. The system leverages measurements that would otherwise be discarded or used for basic control purposes, extracting additional diagnostic information without requiring separate dedicated measurement circuits or increasing overall energy consumption.
Solution Approach 2:
The patent applies partial action by performing fault detection using a subset of available information (relay coil current measurements) rather than continuously monitoring all possible parameters (voltage, frequency, current, power). This selective approach achieves sufficient detection precision while minimizing the energy and computational resources required for fault detection.
Data Source
AI summary
Power supplies and methods of use thereof are provided, where a power supply includes an input configured to receive input AC power an output configured to provide output AC power to a load, at least one power converter coupled to the input and configured to convert the input AC power into the output AC power, a controller coupled the at least one power converter. The controller is configured to adjust at least one parameter of the output AC power provided by the at least one power converter, detect, in response to adjusting the at least one parameter of the output AC power, at least one of an adjusted input AC power or an adjusted output AC power, and determine that a fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power.