A Study on the Design and Analysis of a Bidirectional IPT System for EV wireless charging by Using Switch-Controlled Capacitor /

Abstract

For loosely coupled transformers, the leakage and magnetizing inductances vary as a consequence of the changing positions for the primary and the secondary sides of the transformer windings in inductive power transfer (IPT) systems. For reducing the effects of these varying inductances, various compensation networks have been proposed. These compensation networks are used to attain a constant output voltage and unity power factor for power electronic applications. However, most of these compensation networks have a fixed compensation network designed for only a specific coupling coefficient. Therefore, a compensation network with variable components needs to be implemented to compensate for the changing inductances of the network. In this thesis, switched capacitor-based compensation network is proposed to match the resonant frequency of the network with the switching frequency of the converter. The proposed network compensates for the magnetizing inductance for coupling coefficient in the range of 0.23 to 0,35 using a switched capacitor. Moreover, the proposed converter is symmetrical so that bidirectional power flow is possible while maintaining constant output voltage and unity power factor under zero voltage switching condition (ZVS). A comparison between the two most used compensation configurations: LC-series and LCL topology is also presented. Moreover, an additional modified configuration of LCL topology with a switch-controlled capacitor is also presented under various coupling conditions. The system performance under these three configurations is presented and a comparison between LCL topology using a fixed capacitor and a switch-controlled capacitor is shown to present the system performance under the different coupling conditions