Modeling of High-Efficiency Nonsalient Pole Transmitter in High-Power Dynamic Wireless Charging System for Electric Vehicles

In high-power dynamic wireless charging applications, the bipolar magnetic coupler is continuously developed due to its strong coupling ability. The latest proposed bipolar-non-salient-pole (BNSP) transmitter has shown significant improvements in performance, cost, and modularization. In this article, the efficiency of BNSP transmitter is further analyzed. A quantitative loss model is proposed to reduce the dependence of analysis on finite element simulation. The model of winding loss based on squared magnetic field analysis is introduced, and a concept of flat Litz winding design suitable for BNSP transmitter is proposed, which has lower loss and fewer nonideal loss factors. The model of core loss is established by the magnetic circuit model of BNSP transmitter and Steinmetz formula of the core material. In the experiment of 40 kW power, the proposed loss model is verified to describe loss components in BNSP transmitter accurately. Compared with bipolar-salient-pole transmitter of the same power level, BNSP transmitter is quite smaller in size and more compact in structure, with 28.2% shorter Litz wire and 27.6% smaller volume of cores. The rated efficiency of BNSP transmitter is 97.9%, and the dynamic efficiency of the magnetic coupler with BNSP transmitter is 94.4%-96.3%.