Single-Stage Three-Phase AC–AC Matrix Converter for Inductive Power Transfer Systems

Abstract

A direct three-phase ac–ac matrix converter for inductive power transfer (IPT) systems with soft-switching operation is introduced. The proposed topology is expected to have a high reliability and extended lifetime due to the soft-switching operation and elimination of short-life electrolytic capacitors. The soft-switching operation will also reduce switching stress, switching loss, and electromagnetic interference of the converter. A variable-frequency control strategy based on the energy-injection and free-oscillation technique is used to regulate the resonant current, the resonant voltage, and the output power. With the use of reverse-blocking switches, the proposed converter can be built with a reduced number of switches (only seven), which will consequently increase the reliability and efficiency and reduce the cost of the converter. The converter operates in eight modes, which are described in detail. With the use of the proposed converter as the primary converter, simulation analysis and experimental implementations on a case study IPT system show that the current regulation control method can fully regulate the output current and output power around user-defined reference values, thus making it suitable for dynamic IPT applications, where the system has inherent variations.