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Passive diode bridge rectifier with LC filter is widely used in wireless power transfer (WPT) system due to its simple structure and uncontrolled characteristics. However, as the load resistance decreases, its input phase angle will also decrease rapidly until it shows obvious capacitive. Therefore, a novel rectifier topology with an input-series inductor (hereafter called ISIR) is proposed in this article to solve this problem. What is more, the ISIR can avoid the duty cycle loss and improve the dc–dc efficiency. First, the mechanism of ISIR is analyzed in detail combined with the operating status of topology. Then, the inductance and compensation parameters are determined based on theoretical calculation and simulation results. Finally, a prototype with a maximum load of 7 Ω is built to validate the feasibility and effectiveness of ISIR, and 88% efficiency is achieved under this condition. Compared with the traditional method, it has increased by 1.05%. The maximum efficiency of WPT system is as high as 91.14% with the proposed ISIR. [ABSTRACT FROM AUTHOR]

With the increase of load resistance, the impedance angle of the rectifier with passive C filter also increases, which may have some negative effects on the characteristics of the inductive power transfer (IPT) system. This article presents an impedance analysis method for C-filter rectifiers in continuous conduction mode. The calculation formula of critical load resistance is given and the relevant values are calculated. An improved C-filter rectifier circuit is proposed to reduce the phase angle of the IPT system. A very tiny capacitance is connected in parallel at the input end of the rectifier to reduce the impedance angle as load resistance changes, with hardly increased costs. This improved method not only improves the system efficiency, but also reduces the fluctuation of output voltage or current. Simulation and experiment results verify the feasibility of the proposed topology. A 1 kW prototype with primary series, secondary series compensation topology was built. The maximum system efficiency from dc power supply to the load is 94.5%. The efficiency under rated load is as high as 93%. Compared with traditional method, it has increased by 0.6%. [ABSTRACT FROM AUTHOR]

The capability of misalignment tolerance is vital for an inductive power transfer system. The conditions satisfied by the high-misalignment-tolerant compensation topology are proposed in the article. It is proven that all compensation topologies with secondary parallel compensation component have a strong capability of misalignment tolerance if the parameters of the compensation circuit are properly designed. And, their misalignment-tolerant capability was analyzed. The impedance characteristics of the simple S/T compensation topology are analyzed. Two prototypes of approximately 300 W used S/SP (primary series, secondary series–parallel) compensation topology with strong misalignment tolerance were designed to verify the system performance. They have the characteristics of constant-voltage and constant-current output, respectively. [ABSTRACT FROM AUTHOR]