Three-mode One-Cycle Controlled Current-Source Single-Stage Multi-Input High-Frequency-link Inverter

A current-source single-stage multi-input high-frequency-link grid-connected inverter and a three-mode one-cycle control strategy are proposed and deeply investigated in this paper. The inverter contains multiple current-source inverting units, a multi-input high-frequency transformer, and a cycloconverter. It achieves single-stage power conversion and high-frequency galvanic isolation with a simple circuit structure. The control strategy adds a by-pass switch to the energy storage inductor. It has energy-storing, energy-releasing, and three by-pass operation modes in a low frequency cycle. Through calculating the energy-releasing duty cycle in real time, the magnetic saturation problem of current-source inverters is solved and the output waveform quality is greatly improved. Soft-switching of the converter, a transfer function block diagram, and the design of the main circuit parameters are achieved. The simulation of a three-input inverter and experiment on a two-input inverter verify the feasibility and advancement of the proposed circuit topology and control strategy.