EMI Suppression in Inductive Power Transfer Systems Using Class E Inverters

The coupler's antenna-like structure introduces electromagnetic interference (EMI) challenges in inductive power transfer systems. This letter leverages the spread spectrum technique in a class E inverter-driven, highly resonant system to address these challenges. However, a conventional class E inverter would be optimized toward a single frequency, and directly leading to hard switching issue when applying spread spectrum. By examining original classical class-E design method, it enriches the understanding of the design under frequency modulation scenarios. Through simulation, it investigates the tradeoffs among various goals, including efficiency, voltage stress, output ripple, and EMI reduction. It develops an IPT system according to the design strategy, achieving zero-voltage switching across a frequency modulation range of 0.95–1.05 MHz and maintaining an efficiency of 87%. This approach resulted in a 13-dB EMI reduction compared to a 1 MHz classical class E design.