Design of wireless power transfer system with inputfilter

For power electronic systems, adding filters to eliminate harmonic interferenceis a general and effective method, but the position and parameters of filters inwireless power transmission (WPT) system will greatly affect the systemcharacteristics of WPT. The main reason for the harmonic interference in WPT isthat the harmonics in the output square wave are loaded on the resonant coil ofthe transmitter, so in this study, a method of harmonic elimination by adding asecond‐order LCR filter to the resonant part (LCR‐WPT) is studied. However, theWPT resonant part is precisely matched and designed; if a filter is added at theresonant part, it inevitably affects the resonance state, system output powerand efficiency of the WPT. To ensure that the LCR‐WPT has good systemcharacteristics, this study analyses the mathematical model of the LCR‐WPT anddeduces a design method for the filter and an efficiency optimisation formula.This study also introduces LCR‐WPT applications in two different controlschemes. The experimental results show that the harmonic interference of thesystem is significantly attenuated after the filter is added; additionally, theefficiency of the system decreases by <10%, and the system still maintainssufficient output power.