This work presents detailed analysis of LLC resonant converter to accurately predcit the voltage gain of the converter. Nowadays, Lithium-ion battery cells are mostly preferred for on-board electrical vehicle (EV) battery chargers due to their high power density. This results in wide range output voltage regulation for battery charger. The output voltage regulation of LLC resonant converter is provided by the changing of switching frequency. However, conventional first harmonic approximation (FHA) method applying for resonant power converters produces error below resonance frequency. Therefore, the objective of this paper is accurate prediction of the voltage gain characteristic for LLC resonant converter using in EV battery charge applications. The detailed theoretical anlysis of the LLC resonant converter is presented and the presented analysis is compared with a simulation study with 2.7 kW output power and 250 V-450 V output voltage range.
Accurate Prediction of Voltage Gain of the LLC Resonant Converter for EV battery Charge Applications