Offline UPS DOE Mode Exit via Battery Voltage Slope Detection
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Solution Overview
Problem
Conventional offline UPS designs fail to meet new market requirements for efficiency indicators, leading to energy loss and unreliable standby duration due to DOE mode failures, particularly when the AC/DC converter is damaged, causing rapid battery voltage drop.
Innovation Solution
An offline UPS with a control unit that monitors the rechargeable battery voltage slope, exiting the DOE mode when the slope exceeds a preset threshold, thereby avoiding energy loss by turning on the transformer and bidirectional converter, disabling the DOE function, and saving the failure in a historical record, without requiring additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the offline UPS operates in DOE mode with transformer and bidirectional converter turned off, then energy efficiency is improved, but reliability deteriorates due to undetected battery failures causing rapid voltage drop
Solution Approach 1:
The control unit continuously monitors battery voltage and calculates the rate of change (slope). When the slope exceeds a preset threshold, the system automatically exits DOE mode and activates the transformer and bidirectional converter. This feedback mechanism ensures reliable detection of battery failures while maintaining energy efficiency during normal operation.
2Reliability
If additional hardware circuits are added for failure detection, then reliability is improved, but device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it controls the transformer and bidirectional converter, monitors battery voltage, calculates voltage slope, and manages DOE mode operation. By making the control unit multi-functional, the patent achieves reliable failure detection without adding dedicated hardware circuits, thus avoiding increased device complexity.
3Reliability
If the control unit continuously monitors battery voltage slope, then reliability is improved through quick failure detection, but use of energy increases
Solution Approach 1:
The control unit performs voltage slope calculations at periodic intervals by sampling battery voltage at different time points. This periodic monitoring approach enables timely failure detection while minimizing energy consumption compared to continuous monitoring, as the control unit can enter low-power states between sampling intervals.
Data Source
AI summary
An offline uninterruptible power supply (UPS) is provided, including: a transformer, configured to output a utility power voltage to a load; a bidirectional converter, configured to convert alternating current from the transformer into direct current to charge a rechargeable battery, and convert direct current from the rechargeable battery into alternating current to be outputted to the transformer; and a control unit, configured to control operation of the offline UPS, where when the utility power voltage is within a normal range and the rechargeable battery is fully charged, the offline UPS enters a design of energy (DOE) mode, in the DOE mode, the transformer and the bidirectional converter are turned off, and in the DOE mode, the control unit is configured to detect a voltage of the rechargeable battery, and calculate a slope of decrease in the voltage of the rechargeable battery, and when the slope of decrease in the voltage is greater than a preset first threshold, the control unit controls the offline UPS to delete the DOE mode.