Direct Single-Phase AC–AC Converters Based on Series Impedance Networks

In this paper, a novel direct ac–ac converter based on the coupled inductor Z-source networks is proposed that offers a wide range of buck–boost operation. A total of two Z-source networks, called the coupled switched inductor and the modified switched coupled inductor, are employed that enable the ac–ac converter to deliver a wide voltage range. The proposed converter with both networks provides free-wheeling current paths for the inductors currents during the state transitions, which results in solving the commutation problems and the need for snubber circuits. A simple switching strategy is then proposed that helps to share a common magnetic core between the coupled inductors. For any particular voltage gain, the proposed structures require a smaller duty cycle compared to the conventional ones; therefore, a smaller inductance is required. Simulation and experimental results are provided to confirm the theoretical achievements.