Analysis and Design of a Three Phase Interleaved CLL Resonant Converter with Fixed Frequency Modified PWM Control

A Three-phase interleaved CLL resonant DC-DC converter with fixed frequency modified PWM gating pattern is presented in this paper. The main benefit of the interleaving technique of the converter is to achieve higher power level, while reducing the size of filters due to lower ripples. Three identical single-phase full bridge inverter circuits with CLL resonant tank are allied in parallel on the primary of the high-frequency (HF) transformer. The operating modes of the converter for different intervals are explained with the aid of key operating waveforms. The fundamental harmonic approximation (FHA) approach is used to carry out the steady-state analysis of the converter. A 600W converter is designed and the design method is explained. PSIM simulations are done to substantiate the calculated predictions of the converter for distinct operating conditions.