Isolated soft-switching HFAC-link 3-phase ACAC converter using a single-phase HF transformer

A new resonant three-phase ac-ac converter with a high-frequency ac link, soft switching characteristic, unity input power factor, galvanic isolation, and bidirectional power flow is introduced in this paper. The galvanic isolation is realized with only one single-phase high-frequency transformer, which is substantially small. The converter´s ac link is formed by the magnetizing inductance of the high-frequency transformer and two considerably small ac capacitors; no bulky short-life electrolytic capacitor is used. Moreover, the converter´s switches are turned on at zero voltage and are turned off with low loss; therefore, the converter´s switching losses are significantly low, which subsequently permits the switching frequency to be high. The operation of the topology comprises 16 distinct modes and is described in detail. The analysis of the proposed topology is carried out to reveal the converter´s behavior in different operating conditions. Simulation results are also given to demonstrate the effectiveness of the power converter.