Soft Start-up Current Control of an LCC-S Compensated Inductive Charging System

Starting an inductive power transmission (IPT) system requires regulation of the inverter current. Otherwise, overcurrent or hard-switching may occur. This publication discusses the soft-start of a full-bridge inverter powering stationary inductive charging of an electric vehicle (EV) battery. Compensation by the LCC-S network is used for this purpose, as well as the controllable dc link voltage on the primary side. The control strategy also takes advantage of variable frequency and phase shift. A transient state model of the circuit serves as the simulation environment for verification. It is shown that the inclusion of the dc link voltage simplifies the starting conditions and helps keeping zero voltage switching (ZVS) throughout the whole charging process.