Isolated three-phase AC-to-DC bidirectional converter with a small number of switches

A bidirectional converter that converts three-phase AC to DC or vice versa by using a high-frequency transformer has been investigated. The main feature of the circuit is that it does not need as many switches as the conventional converter. Suitable operating conditions and design considerations for the circuit were clarified by analyzing the steady-state characteristics and resonant reset of the transformer. Circuit operation was verified by simulation, and it was confirmed that AC currents can be controlled as sinusoidal waveforms by using a simple control circuit.