A Dynamic Transition Algorithm Integrated with Hybrid Modulation for CLLC Resonant Converters

Abstract

The CLLC resonant converter is a widely used bidirectional power converter known for its high energy transfer efficiency. To extend its operating range, the converter often employs a hybrid modulation strategy, which is valued for its simplicity and efficiency. However, at the critical transition point between pulse frequency modulation and phase-shift modulation, instability in the output can be observed due to repetitive and unnecessary mode changes caused by noise. In order to address this issue, this paper introduces a dynamic transition algorithm integrated with hybrid modulation. This approach adaptively updates the controller parameters to mitigate oscillations resulting from improper initial parameter settings. Additionally, it incorporates error analysis and hysteresis comparison to prevent false triggers caused by noise, enabling intelligent mode adjustments. Finally, a 1 kW prototype is designed to conduct experiments, demonstrating an approximately 50% improvement in dynamic performance when the converter operates with the dynamic transition algorithm.

Keywords

• dynamic transition algorithm
• CLLC resonant converters
• hybrid modulation
• fundamental harmonic approximation method
• control loop deign