Parallel Inverter Back-Feed Magnetization Control
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Solution Overview
Problem
Double conversion transformer-based UPS systems face inefficiencies in low-load conditions and significant load steps, as they require lengthy inverter start-ups and may expose loads to power quality events during transitions, especially in transformer-based UPSs.
Innovation Solution
A control system for parallel inverters that allows switching 'on' or 'off' based on load demand, maintaining output transformer magnetization via back-feed from another inverter, enabling instantaneous reaction to load changes without compromising power quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If inverter sections are switched off in low-load conditions to reduce UPS losses, then energy efficiency is improved, but the system cannot respond quickly to significant load steps exceeding available capacity
Solution Approach 1:
The output transformer is magnetized in advance by a back-feed path from another inverter before the inverter is switched on. This preliminary magnetization eliminates the lengthy start-up time normally required for transformer-based UPS systems, enabling the inverter to respond instantly when load increases require additional capacity.
2Use of energy by moving object
If inverter sections are switched off to improve efficiency, then energy consumption is reduced, but the load may be exposed to power quality events during transition
Solution Approach 1:
The output transformer is magnetized in advance by a back-feed path from another inverter before the inverter is switched on. This preliminary magnetization eliminates the lengthy start-up time normally required for transformer-based UPS systems, enabling the inverter to respond instantly when load increases require additional capacity.
Solution Approach 2:
A back-feed path is introduced as an intermediary mechanism that maintains magnetization of the output transformer through another inverter. This intermediary path ensures the transformer is ready for immediate operation, preventing power quality events during load transitions while still allowing inverters to be switched off for efficiency.
3Reliability
If transformer-based UPS systems are used for load isolation and power conditioning, then protection level is improved, but efficiency is reduced due to lengthy inverter start-up time
Solution Approach 1:
The output transformer is magnetized in advance by a back-feed path from another inverter before the inverter is switched on. This preliminary magnetization eliminates the lengthy start-up time normally required for transformer-based UPS systems, enabling the inverter to respond instantly when load increases require additional capacity.
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
This solution improves efficiency and dynamic response to load changes, reducing energy losses and maintaining reliable power quality by adaptively switching inverter sections 'on' or 'off' in response to load variations, especially in low-load conditions.
Implementation Method 1
The output transformer of the second inverter feed path is configured to remain magnetized via a back-feed from the output transformer of the first inverter feed path
Data Source
AI summary
A control system for parallel connected inverter legs energized by a power source and configured for servicing a load is disclosed. The invention facilitates the number of running inverter legs to adaptively react to changes in the load by dynamically switching various inverter legs “on” or “off” in response to variations in load demand, while continuing magnetization of an output transformer connected with an “off” inverter leg via a back-feed from another output transformer of an “on” inverter leg, greatly improving the dynamic response to load changes. This design enables a fast reaction to load changes with “off” inverter legs transitioning to on-line operation instantaneously.