Analysis of the contactless power transfer system using modelling and analysis of the contactless transformer

In this paper, the electrical characteristics of the contactless transformer is presented using conventional coupled inductor theory. Compared with the conventional transformer, a contactless transformer has large airgap, long primary wire and multi-secondary wire. So contactless transformer has large leakage inductance, small magnetizing inductance and poor coupling coefficient. Therefore, large magnetizing current flows through entire primary system due to small magnetizing inductance and the overall system efficiency will be low. In high power applications, contactless transformer is so bulky and heavy that it should be split by some light and small transformers. So contactless transformer needs several small transformer modules which are connected series or parallel to transfer the primary power to the secondary one. This paper shows analysis and measurement results of the each contactless transformer module and comparison results between series-connection and parallel-connection of the contactless transformer. The results are verified on the simulation based on the theoretical analysis and the 30 kW experimental prototype.

I. Introduction

Nowadays, Contactless Power Transfer System(CPTS) is widely used in many industry applications such it automated guided vehicles and medical applications. Conventional one drags long power cables directly to transfer power and produces many particles because of mechanical friction between power cables and surface of the nearby instruments, whereas CPTS delivers electrical power to load with the help of contactless transformer that has no mechanical contact. In this method, CPTS doesn't produce particles, thereby making it adaptable to the industry applications where clean circumstances are needed such it semi-conductor, LCD, and PDP manufacturing factory.