UPS Control System Transformer Magnetization via Back-Feed
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Solution Overview
Problem
Existing ECOMODE UPS systems without an output isolation transformer suffer from high efficiency losses due to inefficiencies in the bypass and inverter operations, and line-interactive UPSs struggle to maintain output voltage quality during variable mains frequency.
Innovation Solution
A control system for UPSs that includes a bypass feed path and an inverter feed path with an output isolation transformer, where the transformer is magnetized via back-feed from the bypass path when the load is fed by the bypass path, and the inverter is switched on only after a detected fault, optimizing efficiency and maintaining battery charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the load is fed by the bypass feed path in ECOMODE, then efficiency is improved, but the transformer becomes demagnetized causing operational problems when switching to inverter path
Solution Approach 1:
The control system performs preliminary action by detecting when the bypass feed path is active and initiating a back-feed current through the transformer before switching to inverter mode. This preliminary magnetization prevents the transformer from being demagnetized during bypass operation, ensuring reliable operation when switching between modes while maintaining high efficiency during bypass feeding.
2Reliability
If the rectifier is kept on to maintain battery charge, then battery health is improved, but efficiency decreases due to continuous rectifier operation
Solution Approach 1:
The control system implements periodic action by switching the rectifier on and off based on battery charge state rather than continuous operation. The rectifier is activated only when battery charge is needed, creating a periodic operation pattern that maintains battery health while avoiding continuous energy loss, thereby improving overall system efficiency.
3Loss of energy
If line-interactive UPS is used to feed load by mains, then efficiency is improved, but output voltage quality cannot be maintained when mains frequency is variable
Solution Approach 1:
The control system employs feedback by continuously monitoring mains frequency and quality parameters. When variable frequency or quality degradation is detected, the system automatically switches from mains feeding to inverter feeding, maintaining output voltage quality. This feedback mechanism allows the system to operate in efficient mains-feeding mode under normal conditions while ensuring voltage quality through automatic switching when needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves an efficiency greater than 98% with minimal efficiency decrease, maintaining battery health and improving output voltage quality by continuously monitoring power quality and switching to the inverter path upon fault detection, while keeping the rectifier on to charge the battery.
Implementation Method 1
The control system is configured for facilitating magnetization of the transformer via a back-feed from the first feed path
Data Source
AI summary
A control system for an uninterruptible power supply (UPS) for servicing a load is disclosed. The UPS includes a first feed path and a second feed path, where the first feed path is operable in parallel with the second feed path. The first feed path is engagable via a first switch to deliver a bypass current to the load. The second feed path includes a rectifier, an inverter responsive to a control signal and in electrical communication with the rectifier, and an output transformer in electrical communication with the inverter. The second feed path is engagable via a second switch to deliver an inverter current to the load. The control system is configured for facilitating magnetization of the transformer via a back-feed from the first feed path in response to the load being fed by the first feed path, the rectifier being off, and the inverter being off.