2-MHz Compact Wireless Power Transfer System With Voltage Conversion From 400 V to 48 V

In many industrial applications, wireless power transfer (WPT) systems with small transmitting and receiving coils and compact secondary sides are required. This asks for high switching frequencies to achieve sufficiently large power densities. At the same time, a conversion from higher to lower voltages is often desirable, and thus different transmitting and receiving coils must be used. This work presents an inductive WPT system addressing both challenges. It uses small transmitting and receiving coils with a surface area of only 20 cm2, achieving a power transfer of 500W. The design of the coils allows for a voltage conversion from 400V to 48 V. To simplify the receiving circuit, operation is similar to an LLC converter so that the compensation capacitor on the secondary side can be omitted. First experimental results of a prototype system show a peak efficiency of 92% at 2 MHz while transmitting 400 W.