High Frequency Three–level Inverter–based Inductive Wireless Power Transfer (IWPT) System with Double LCC Resonance

This paper presents an inductively coupled wireless power transfer (IWPT) system with a new circuit topology featuring three level high frequency inverter (TLHF– INV) and double LCC compensation tank. Different from a conventional IWPT system, this system provides phase shift pulse–width–modulation (PS–PWM) for output power control. Since this system targets an EV charging application, accordingly its operation frequency is defined in 85 kHz by Society of Automotive Engineers (SAE). The proposed IWPT system is analyzed by the state space equations for proving its Lyapunov stability and its anti–interference capability on simulation is given with various load value. The soft switching conditions are discussed such as zero voltage turn–on in outer switches and complete zero current switching in outer switches (Q1 and Q4). Moreover, a hybrid modulation method for tracking the ZCS at inner switches (Q2 and Q3) is mentioned. The performance of the proposed system which is designed for various load is investigated and evaluated by experiment. The experimental results reveal high conversion efficiency and certain loss reduction with variable frequency VFPS–PWM.