Efficiency Analysis and Optimization Control for Input-Parallel Output-Series Wireless Power Transfer Systems

Abstract

Wireless power transfer (WPT) technology has shown its significant role in various applications, such as electric vehicles and consumer electronics. In this paper, an input-parallel output-series circuit topology based on a compact double-sided decoupled coupler is presented to upgrade the power capacity of the WPT system with low-power and low-cost semiconductors. To avoid the potential risk of magnetic saturation, the phase difference between the transmitter currents is controlled to be 90° to achieve a symmetrical magnetic flux distribution for the magnetic coupler. Most importantly, an analytical model, which illustrates the relation between the efficiency and the ratio of the output voltages of the transmitter-side inverters under various misalignments, has been derived. Based on this, a control strategy is developed to maximize the energy efficiency under various misalignment conditions. The experimental results based on a 2.5-kW laboratory prototype show that, in comparison with the traditional method with identical inverters output voltages, the overall efficiency is improved by 2.32% by using the proposed method.