Analysis and Design of the LC Filter Rectifier With Zero Input Impedance Angle for IPT System

An LC filter rectifier with a diode bridge is widely used in an inductive power transfer (IPT) system. However, when the load resistance reduces, the rectifier input impedance becomes capacitive. In addition, the filtered inductor is not infinite, and its harmonic currents cause the input impedance to be biased inductively. In order to solve the above two problems, a novel LC filter rectifier is proposed in this article, which achieves zero input impedance angle of the rectifier. First, the mechanism of the traditional LC rectifier filter is analyzed in detail, and an accurate circuit model is proposed. Then, an improved LC filter rectifier is analyzed and designed, and the input impedance angle of the rectifier is zero. Finally, a prototype with the load of 8–120 Ω is built, which verified the correctness and feasibility of the improved rectifier. Compared with the traditional rectifier, the efficiency of the IPT system with an improved rectifier is increased by 1.10%, and the output voltage fluctuation is smaller.