Power Converter Efficiency at Light Loads via Energy Storage
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Solution Overview
Problem
Existing power converter systems face inefficiencies at light loads due to increased switching and core losses, and previous techniques to improve partial-load efficiency, such as variable switching frequency, bulk-voltage reduction, and stage-shedding, suffer from limitations like increased current ripple, dynamic performance issues, and acoustic noise.
Innovation Solution
A power converter system that includes a power storage system to store energy when efficiency drops below a desired threshold, allowing the power converter to operate at optimal efficiency during charging intervals and supply power from storage during discharging intervals, thereby minimizing switching and core losses across the entire load range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power converter operates continuously at light loads, then the load is continuously supplied, but switching and core losses increase significantly reducing efficiency
Solution Approach 1:
The power converter operates in periodic intervals rather than continuously. A controller turns the power converter on during first time intervals to transfer energy to the energy storage device, and off during second time intervals when the energy storage device supplies power to the load. This periodic operation reduces switching and core losses at light loads while maintaining continuous power supply through the energy storage device.
Solution Approach 2:
Energy is pre-stored in the energy storage device during first time intervals when the power converter is active. This preliminary energy storage allows the system to operate without the power converter during second time intervals, eliminating switching and core losses during these periods while maintaining load supply.
2Loss of energy
If the power converter is turned off during second time intervals, then switching and drive losses are reduced, but the load must be supplied from energy storage
Solution Approach 1:
The energy storage device serves dual purposes: it stores energy during first time intervals and automatically supplies power during second time intervals without requiring active control during the off-periods. This self-service capability reduces control complexity while achieving loss reduction.
3Loss of energy
If previous techniques like variable switching frequency or bulk-voltage reduction are used, then light-load efficiency is improved, but current ripple increases or dynamic performance deteriorates
Solution Approach 1:
The invention extracts the power conversion function from the main power converter during second time intervals and replaces it with energy discharge from the energy storage device. This separation allows the main power converter to remain off during periods when load supply is needed, avoiding the trade-offs of other techniques while maintaining efficiency and performance.
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 approach maintains high efficiency across all load conditions, including light loads, without transient issues during load changes, and optimizes light-load efficiency by periodically turning the power converter on and off, using stored energy to support the load, thus reducing switching and drive losses.
Implementation Method 1
a power storage system coupled to the at least one power converter for receiving power supplied from the at least one power converter and storing power therein
Data Source
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AI summary
A power converter system supplies power to one or more loads. The power converter system comprises at least one power converter operating at a desired efficiency; and a power storage system coupled to the at least one power converter for receiving power supplied from the at least one power converter and storing power therein when the at least one power converter operates at an efficiency that is below the desired efficiency.