Push-Pull Feedback Control for Parallel Power Converter Load Sharing
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Solution Overview
Problem
Conventional power converters are not designed to be connected in parallel, limiting their ability to share load and increase output power beyond their maximum rating, which is a challenge in applications where output power and load current exceed the converter's specifications.
Innovation Solution
The implementation of parallel connected power converters using push-pull feedback networks, where load-dependent signals control the switching frequency to adjust voltage regulation and equalize output current, allowing power converters to share the load and increase output power by connecting them in parallel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power converters are connected in parallel, then output power and load sharing capability are improved, but conventional converters cannot operate in parallel due to design limitations
Solution Approach 1:
The patent implements a feedback mechanism where the output current of each power converter is sensed and fed back to its controller. This feedback signal, combined with a load-dependent signal, dynamically adjusts the switching frequency to enable automatic load sharing among parallel-connected converters without requiring complex inter-converter communication or synchronization circuits.
Solution Approach 2:
The patent changes the switching frequency parameter dynamically based on load conditions. By adjusting the switching frequency in response to load-dependent signals and feedback from output current sensing, each converter adapts its operating parameters to achieve proper load sharing when connected in parallel, enabling converters designed for standalone operation to function in parallel configurations.
2Power
If switching frequency is adjusted to equalize output current, then load sharing is improved, but control complexity increases
Solution Approach 1:
The control circuit automatically adjusts the switching frequency based on locally available information (output current feedback and load-dependent signals) without requiring external intervention or complex coordination with other converters. Each converter independently regulates its own output current by modifying its switching frequency, achieving load sharing through self-service control that minimizes overall system complexity.
Data Source
AI summary
Parallel connected power converters using push-pull feedback networks are described herein. The power converters may be switch-mode (switching) power converters (SMPSs) controlled by load dependent signals such that switching frequency increases as a function of load. The load dependent signals (i.e., controller signals) may drive the push-pull feedback networks to adjust the voltage regulation feedback signals and to equalize the output current (i.e., output power) from the parallel-connected power converters.