A Study on the Increases in the Ferrite Area of the Secondary Coil and the Number of Secondary Coils of a Railway Wireless Power Transfer System

Abstract

This paper examines a wireless power transfer (WPT) system for a railway, which utilizes an infinitely long primary cable coil without cores and a secondary coil with cores. Both of the primary and secondary circuits in the WPT system have resonant capacitors in series, and the primary circuit utilizes a constant current power source. Because the supply power required for the railway would be larger than that for electric vehicles, it is not easy to supply the required power by utilizing a single secondary coil. Therefore, the railway WPT system should utilize multiple secondary coils. Moreover, the capacity of the secondary coil should be increased in order to decrease the number of secondary coils. Because the area of the secondary coils should be large to increase their capacity, the secondary coils utilize large cores that are manufactured by bonding some small cores. Thus, the characteristics of the secondary coils utilizing bonded cores are studied. On the other hand, magnetic coupling between neighboring secondary coils should be considered to utilize multiple secondary coils. This paper examines these practical problems.