Development of wireless chargers for electric vehicles

Abstract

The objective of this dissertation project is to design an inductive power transfer (IPT) system to achieve the wireless charging for electric vehicles (EVs). A basic circuit model is set up, including high-frequency converters, a loosely-coupled transformer, resonant compensation networks and a variable load. Theoretical studies of design of the circuit parameters and electrical quantities calculation are discussed according on the corresponding circuit model. The classic charging process of EVs always includes two stages: constant-current (CC) output and constant-voltage (CV) output, thus precise control of the output is required. Several commonly used control methods and their implementation are introduced and analyzed thoroughly. Based on the inverter control scheme, the entire closed-loop feedback control system is established, and this project tries to use pulse density modulation (PDM) to modulate the primary-side inverter, for achieving the CC and CV output characteristics of the load. Simulation model is built based on an actual hardware prototype application, of which the results show the realization of stable and accurate power charging control.