LLC Resonant Converter Input Voltage Balance Circuit
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Solution Overview
Problem
Resonant converters with interleaving LLC circuits face input voltage imbalances, leading to excessive voltage ratings for components and potential operational issues due to unaddressed differences in input voltages between parallel-connected modules.
Innovation Solution
A converter circuit design incorporating multiple modules and switching circuits, where each module has a first and second input/output, with switching circuits connecting voltage sources to regulate input voltages within a desired range by switching between open and conductive states based on input voltage levels, ensuring balanced operation across modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple LLC resonant converters are connected in parallel with series-connected inputs to share a common input voltage source, then power conversion efficiency is improved and output current ripple is reduced, but input voltage imbalance occurs between modules causing excessive voltage ratings for components
Solution Approach 1:
The patent implements a feedback mechanism where the controller monitors the input voltages of parallel-connected LLC resonant converters and adjusts the switching frequencies of individual modules accordingly. This feedback control ensures that input voltages remain balanced across all modules, preventing excessive voltage ratings while maintaining the efficiency benefits of parallel operation.
Solution Approach 2:
The patent changes the switching frequency parameter of individual LLC resonant converter modules based on their input voltage conditions. By dynamically adjusting switching frequencies, the system maintains input voltage balance across parallel-connected modules, resolving the voltage imbalance issue while preserving the overall system efficiency.
2Ease of operation
If input voltages of parallel-connected LLC resonant converters are allowed to differ significantly, then current balance among modules can be achieved automatically, but voltage ratings of components become excessively high affecting normal operation
Solution Approach 1:
The controller continuously monitors input voltages and switching frequencies of parallel-connected modules, providing feedback to adjust operating parameters. This feedback mechanism maintains input voltages within acceptable ranges, preventing excessive voltage ratings while preserving automatic current balance through controlled frequency adjustments.
Solution Approach 2:
The patent introduces dynamic adjustment of switching frequencies based on real-time input voltage conditions. This dynamic control ensures that while current balance is maintained automatically, input voltages remain within safe operating limits, preventing excessively high voltage ratings on components.
3Device complexity
If switching frequencies of LLC resonant converters are kept the same to simplify control, then control complexity is reduced, but input voltage imbalance cannot be corrected
Solution Approach 1:
The patent implements a feedback control system where the controller monitors input voltages and automatically adjusts switching frequencies of individual modules. This feedback mechanism maintains input voltage balance without requiring complex manual intervention, as the controller autonomously makes frequency adjustments based on real-time conditions.
Solution Approach 2:
The control system performs self-adjustment by automatically detecting input voltage imbalances and correcting them through frequency modulation. This self-service capability maintains voltage balance without requiring external intervention or complex control logic, simplifying overall system operation while ensuring reliability.
Data Source
AI summary
In one aspect of the present invention, a converter circuit with input voltage balance includes a plurality of modules having inputs electrically series-connected to each other and outputs electrically parallel-connected to each other and a plurality of switching circuits with each electrically connected to an input connection node of a corresponding module and its immediate next module, and configured such that when an input voltage of the corresponding module or its immediate next module is in a desired range from a first predetermine value to a second predetermined value greater than the first predetermined value, the switching circuit operates in an open state, while when the input voltage is out of the desired range, the switching circuit operates in a conductive state so as to regulate the input voltage of the corresponding module or its immediate next module in the desired range.