Control Strategy for Modular-Structured Series-Resonant Converters: Unifying Pulse-Density Modulation and Phase-Shift Control

Abstract

The study proposes an advanced control technique for modular-structured series-resonant converters, unifying pulse-density modulation (PDM) and phase-shift control to mitigate output current amplitude fluctuations. Series-resonant converters, widely utilised for their efficiency in various applications, typically employ PDM to achieve zero-voltage and quasi-zero-current switching, minimising switching losses. However, these converters often encounter challenges with amplitude fluctuations in the output current, particularly during deep current regulation, which can compromise performance and lead to increased electromagnetic interference and overvoltage issues. The presented control strategy combines PDM with phase-shift control, significantly reducing these fluctuations and maintaining higher minimum peak currents. This unified approach ensures greater stability and efficiency in the converter's operation. Detailed experimental validation confirms the theoretical benefits, highlighting the proposed method's superiority over traditional PDM control techniques in achieving stable and efficient converter performance.