A study on the design method of the light weight coils for a high power contactless power transfer systems

A contactless power transfer system has a lot of attention in many advantages such as the electric shock free and the short circuit. Moreover, if assuming the electric supply to a moving vehicle, a contactless power transfer system is advantageous in respect of less maintenance. So a contactless power transfer system is expected to be applied to the power feeding to the electric vehicles and the railway vehicles are expected. The contactless power transfer through a large air gap causes lower power factor. So, the contactless power transfer system has resonant capacitors, to correct the power factor. When increasing the power of the system, there are the problems with the higher reactive power of the power feeding coils, higher voltage and over-current of the resonant capacitors. In addition, the loss with the converter becomes more major problem by raising the frequency of the power converter. This paper deals with a 300kW contactless power transfer system for charging the energy storage device, for instance, for supplying power to the hybrid railway vehicles. The characteristics such as power feeding coils-reactive power and loss property are analyzed, to downsize the power feeding coils.