Analysis and Design of Multiphase Receiver With Reduction of Output Fluctuation for EV Dynamic Wireless Charging System

The multiphase receiver for more steady output is proposed in this paper. The conventional power supply rail with multipole such as I-type, S-type, and n-type for dynamic wireless charging (DWC) system has a main drawback: the induced voltage of the double-D coil of receiver has a sinusoidal fluctuation along the driving direction and the fluctuation factor is 1.0. Therefore, the multiphase receivers including two-phase, three-phase, and four-phase receiver are proposed to solve the problem. The fluctuation factor, effective value (rms) of induced voltage and mutual inductance, cost, and loss of different numbers of phase in different connection modes are analyzed and compared. The applicable conditions of different types are given. The structure size of single-phase coil is optimized to achieve larger coupling coefficient. The influence of distance between phases on fluctuation factor and induced voltage (rms) are calculated and the design principle of the distance between phases is determined. Based on above research, design guideline for the multiphase receiver is proposed including the constraints of installation environment and the distribution of different phases. The structure size of single-phase coil and the distance between phases are optimized to improve the coupling coefficient and reduce cost, loss, and voltage level of resonator. Considering the practical application environment, a four-phase receiver of 10-kW DWC system is designed. A prototype system is also established and the analysis and simulation are verified. In the dynamic 10-kW experiment, the fluctuation factor is reduced to 0.146 from 0.3 of two-phase receiver and 1.0 of single-phase receiver.