Resonant Converter Current Balance Control via Switch On-Time Adjustment
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Solution Overview
Problem
Resonant converters in high output current applications, such as server and telecom power systems, face current imbalances due to manufacturing tolerances in their resonant tanks, leading to overcurrent or overpower issues and potential damage, especially when operating at the same switching frequency.
Innovation Solution
A controller system that receives load condition signals from multiple resonant converters and adjusts the on-time of synchronous rectifier switches to balance load distribution by reducing the on-time of switches in converters with higher loads, allowing for load balancing and reduced current imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If all resonant converters operate at the same switching frequency with equal on-times, then the control is simple and symmetric, but current imbalances occur due to manufacturing tolerances in resonant tanks
Solution Approach 1:
The patent applies parameter changes by adjusting the on-time duration of synchronous rectifier switches based on measured current levels. Converters carrying higher current receive reduced on-time adjustments, while those with lower current maintain or increase their on-time, dynamically balancing the current distribution across parallel converters without changing the switching frequency
Solution Approach 2:
The patent implements feedback control by continuously monitoring the output current of each resonant converter and using this information to adjust the on-time of synchronous rectifier switches. The controller modifies switch timing based on real-time current measurements, creating a closed-loop system that automatically corrects imbalances caused by manufacturing tolerances
2Reliability
If the on-time of synchronous rectifier switches is reduced in converters with higher load, then current balance is improved, but the control mechanism becomes more complex
Solution Approach 1:
The patent applies local quality by implementing individualized on-time adjustments for each converter's synchronous rectifier switches based on their specific current load conditions. Rather than applying a uniform control strategy to all converters, the system tailors the on-time modification to the local needs of each converter, allowing precise current balancing while maintaining relatively simple overall control logic
Data Source
AI summary
Controllers, systems and methods are presented related to resonant converters. In case of a load imbalance between the resonant converters, an on-time of a synchronous rectifier switch of one of the resonant converters is reduced.