An Adaptive Fuzzy-Tuned PID and Optimal Frequency Control for Hybrid Resonant Three-Level ZCS Converter

This paper introduces an adaptive fuzzy-tuned PID control strategy for regulating the output voltage of hybrid multilevel zero current switching (ZCS) DC-DC converters. The approach focuses on controlling switches in the auxiliary circuit while maintaining a fixed $50 \%$ duty cycle in the main circuit. By integrating fuzzy logic with traditional PID control, the fuzzy gain scheduling (FGS) PID controller dynamically adjusts PID coefficients in response to varying operational conditions, enhancing control performance. Furthermore, optimal control of switching frequency mitigates current stresses on the resonant tank during startup and short circuit events, adapting frequency based on output voltage levels. Simulation results illustrate that the proposed method outperforms traditional PID and fuzzy logic controllers by reducing overshoots, achieving quicker settling times, and effectively managing current stresses during transient and fault conditions, ensuring safe converter operation.