UPS Power Failure Detection via Waveform Analysis
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Solution Overview
Problem
Uninterruptible power supplies (UPS) face challenges in detecting power failures or abnormalities quickly and efficiently, as existing methods require higher capacitance capacitors that are expensive and take up more space, limiting the speed of transfer to backup power sources.
Innovation Solution
The implementation of a method in UPS systems to detect waveforms of primary power inputs, specifically focusing on portions less than a half-cycle, such as quarter-cycles, using input voltage and current detection circuits, and calculating root mean square or average values to determine threshold conditions for transferring to secondary power inputs, allowing for earlier detection and potentially reducing the required capacitance of DC bus capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If higher capacitance capacitors are used in the DC bus, then the UPS can maintain power during longer detection periods, but the cost and space requirements increase
Solution Approach 1:
The system performs preliminary detection actions by monitoring voltage and current waveforms during the incoming half-cycle before the power failure occurs. This preliminary detection allows the system to identify power abnormalities early, enabling a faster transfer to backup power and reducing the duration for which the DC bus capacitor must maintain power.
2Duration of action of stationary object
If higher capacitance capacitors are used in the DC bus, then the UPS can maintain power during longer detection periods, but the cost increases
Solution Approach 1:
The control circuit performs preliminary analysis of voltage and current waveforms during the incoming half-cycle to detect power failures or abnormalities before they occur. This early detection reduces the required power maintenance duration, allowing for the use of lower capacitance capacitors and thereby reducing manufacturing costs.
Solution Approach 2:
The system changes the detection parameter from monitoring full cycles or near-full cycles to monitoring only the incoming half-cycle or quarter-cycle. This parameter change in detection timing allows for faster power failure detection, reducing the required capacitor capacitance and associated costs.
3Speed
If the detected waveform is less than a half-cycle, then the power failure detection speed increases, but the accuracy of voltage and current measurement may be affected
Solution Approach 1:
The control circuit uses feedback from both voltage and current detection circuits to cross-validate power failure conditions. By monitoring the relationship between voltage and current waveforms during the incoming half-cycle, the system can accurately detect power failures even with limited waveform data, maintaining measurement precision while achieving fast detection.
Data Source
AI summary
In accordance with presently disclosed embodiments, uninterruptable power supplies and a method for detecting power failures for a UPS are provided. In one embodiment, the method comprises: detecting at least a portion of a waveform of a primary power input of an uninterruptable power supply; calculating at least one of a detected voltage value and a detected current value, based, at least in part, on the detected waveform by calculating at least one of a root mean square, an average, or a summation of the detected waveform; and transferring the uninterruptable power supply to a secondary power input in response to at least one of the following conditions: the detected voltage value is lower than a minimum threshold voltage value, the detected voltage value is higher than a maximum threshold voltage, or the detected current value is higher than an over current value.