Investigation for high output of 2.5MHz power supply constructed from multi-core transformers and a multi-phase inverter and application for wireless power transfer

This paper discusses a development for high output of 2.5 MHz inverter without fast-switching semiconductor switches. This inverter consists of a multi-phase inverter using conventional silicon semiconductor switches and multiple core transformers. In this paper, a principle of drop in inverter output voltage which reduces the inverter output voltage due to a relationship between dead-time and a leakage inductance of a transformer is clarified. In addition, two methods which are bifilar wound transformers and a LC series resonance are applied to the proposed circuit in order to achieve higher output power. The validity of two methods for higher output power is confirmed by experiments. Finally, the proposed circuit is applied to a wireless power transfer when a lamb bulb is used as a load.