Modelling of phase-shift modulated bidirectional CLLC resonant converter

The study proposes the application of two modelling techniques for analysis of bidirectional CLLC resonant converters. The state-variable and cyclic-averaging techniques are applied for converters operating under two types of phase-shift modulation: single-phase-shift and pulse-phase modulation. The converter is analysed considering forward and reverse power flow directions and a state-variable equation description is obtained for both modes. The models are first validated through simulation, comparing the state-variable and cyclic-averaging results to a simulation program with integrated circuit emphasis (SPICE)-based simulation. Additionally, a low power prototype is built, experimental results are presented and the influence of parasitic elements and system delays is discussed. Simulation and experimental results show the models can accurately represent the behaviour of CLLC converters for both types of phase-shift modulation. In addition, using the cyclic-averaging technique results in a considerably faster execution compared to state-variable and SPICE-based models.