Self-Tuning LCC Receiver for Improved Efficiency and EMI Mitigation in Spread-Spectrum Wireless Power Transfer

The wireless power transfer (WPT) technology can benefit from the use of spread-spectrum frequency modulation to reduce electromagnetic interference (EMI) levels. However, this technique can come at the cost of reduced system efficiency due to the mistuning of the resonant frequency of the receiver (RX) network. To address this challenge, this paper proposes a self-tuning LCC compensation RX with improved overall system efficiency and EMI suppression for WPT systems. The proposed design uses a tuning MOSFET for soft switching operation and analytical expressions are derived to guide the design of the proposed LCC RX, resulting in improved system efficiency through enhanced reflected resistance. A 3.3kW prototype has been built to validate the proposed topology, demonstrating an improvement in overall efficiency by 8~10% point in spread-spectrum frequencies ranging from 80~90 kHz, and a 14 dB reduction in EMI.