A step-up/down three-phase resonant high-frequency AC-link inverter

摘要

Parallel resonant high-frequency ac-link inverters with soft switching characteristics, step-up and step-down abilities, and bidirectional power flow are introduced in this paper. The converters' links are composed of parallel ac inductors and small ac capacitors, which are working at high frequencies. The link inductor is the main component for transferring the power from the input to the output or vice versa, and the link capacitor provides partial resonance to achieve zero voltage switching. The total number of switches of the basic unidirectional topology is as low as seven, suitable for low power applications. By adding three more switches, the converter can transfer power in both directions. A small single-phase high-frequency transformer can be employed in the converters' link to provide galvanic isolation. The basic operation of the new converters includes six modes and is described in detail. The analysis and optimal design of the proposed topologies are carried out as well. Simulation and experimental results are given to demonstrate the effectiveness of the proposed power converters.