Interleaved LLC Converters Current Sharing Dead-Time Control
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Solution Overview
Problem
Current isolated board-mounted power designs using LLC converters face inefficiencies due to hard switching topology limitations, leading to high output ripple currents, and interleaving converters with different resonant tank gains is challenging because of component tolerances, resulting in differing output voltages and inability to current share.
Innovation Solution
The method involves determining an expected output voltage for LLC power converters, measuring and adjusting the dead-time to equalize output currents between interleaved converters, ensuring they operate with substantially equal output currents by increasing dead-time when the measured output voltage exceeds the expected voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If multiple LLC converters are interleaved to reduce output ripple current, then output ripple current is reduced, but component tolerances cause different output voltages and prevent current sharing
Solution Approach 1:
The patent adjusts the dead-time parameter of the LLC converters to compensate for component tolerances. By varying the dead-time duration, the output voltages of converters with different resonant tank gains are equalized, enabling current sharing while maintaining the ripple reduction benefits of interleaving
Solution Approach 2:
The patent implements a feedback mechanism that measures the output voltage of each LLC converter and uses this information to adjust the dead-time. This closed-loop control ensures that despite manufacturing variations, all converters operate at the same output voltage and share current equally
2Speed
If LLC converters operate at the same frequency within tolerances, then frequency control is maintained, but output voltages differ and current sharing becomes impossible
Solution Approach 1:
The patent changes the dead-time parameter to compensate for the effects of operating at the same frequency with different component tolerances. This adjustment equalizes the output voltages of converters that would otherwise produce different voltages due to resonant tank gain variations
Solution Approach 2:
The patent makes the dead-time dynamic rather than fixed. The dead-time is continuously adjusted based on measured output voltages, allowing the system to adapt to manufacturing tolerances and maintain current sharing capability while operating at a common frequency
Data Source
AI summary
Methods and systems for current sharing using interleaved LLC power converters are described herein. The method provides for current sharing between a first LLC power converter interleaved with a second LLC power converter. The method includes determining an expected output voltage for at least one of the first and second LLC power converters and measuring an output voltage of at least one of the first and second LLC power converters. The method also includes increasing a dead-time of at least one of the first and second LLC power converters when the measured output voltage exceeds the expected output voltage. Finally, the method includes interleaving the first and second LLC power converters, wherein an output current of the first LLC power converter is substantially equal to an output current of the second LLC power converter.