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Technical Dialogue

Wireless Charging

D25.4 - Analysis and Design of Capacitive Coupling Wireless Power Transfer System using Load-Independent Class-EF Inverter

Thursday, March 20, 2025
11:30 AM – 1:30 PM ET
Location: Level One, Hall A3
This study proposes a capacitive-coupling wireless power transfer (WPT) system using a load-independent (LI) class-EF inverter. The proposed system consists of an LI class-EF inverter, two pairs of coupling capacitors, an LCCL filter, and a class-D rectifier. Conventional capacitive-coupling WPT system using an LI class-E inverter has issues: one is the switch's high voltage stress, and another is the limited design freedom by the identical input-output voltage gain by determining the unique duty-ratio. The proposed system uses a class-EF inverter to reduce the voltage stress on the switches and an LCCL filter to convert the LI constant-current (CC) output characteristic of the class-EF inverter to a constant-voltage (CV) characteristic, thereby achieving zero voltage switching (ZVS) and constant output voltage regardless of load variations. The output voltage can also be adjusted arbitrarily depending on the design of the LCCL filter. This study analytically demonstrates the design method of the proposed circuit and shows the effectiveness of the proposed circuit through actual device verification.