Design-Oriented Comprehensive Time-Domain Model for CLLC Class Isolated Bidirectional DC-DC Converter for Various Operation Modes

A comprehensive time-domain model of a CLLC class isolated bidirectional dc-dc converter (IBDC) is proposed in this article. Based on the circuit analysis and the solution of the state equations, analytical expressions of the state variables are provided. The model is a piecewise time-domain analytical model and can accurately describe the transformer currents and capacitor voltages under almost all basic types of control strategies, e.g., phase-shift control and frequency modulation control. With the model, the steady-state analysis of the IBDC can speed up evidently (up to 330 times faster compared to MATLAB/Simulink and more than 10 times compared to SIMPLIS and PLECS), which gives great support to parameter sweep and case comparison in the design procedure. By assigning specific parameters, the presented model can also be applied to the analysis of the LLC resonant IBDC or typical DAB IBDC since the LLC converter and DAB converter are similar to the CLLC converter in the circuit topology. The transformation of the model from CLLC to LLC/DAB is provided and several application examples are given. Finally, the simulation and experimental results are presented, verifying the effectiveness of the model.