A Dynamical Model of Full Bridge LLC Resonant Converter Which Incorporates Power Loss Coefficients for Controller Design

Abstract

DC-DC converters play important role in smart grids and electric vehicles. A practical model is needed for effective controller design of full bride LLC resonant converter, a topology of DC-DC converter. This paper proposes a new practical model of full bridge LLC resonant converter which incorporates power loss coefficients. Power losses due to MOSFET on-resistance, equivalent serial resistance (ESR), and voltage drop of diode are expressed using power loss coefficients. A practical linear model in state space equation is obtained using Jacobian matrices. A physical model inSimulink/Simscape Electrical®environment is builtbased on a prototype of LLC converter which has nominal input voltage of 120 V, nominal output voltage of 240 V, and nominal switching frequency of 100 kHz. In order to validate the proposed practical model, transient responses comparison between the practical linear model and the physical model was carried out through computer simulation. From the simulation results, it can be concluded that the proposed practical linear model represents well dynamics of the physical model. Therefore, the proposed practical linear model can be used for controller design in an effective manner based on analytical approach.