Cascaded Dual-Buck AC–AC Converter With Reduced Number of Inductors

This paper proposes a new type of cascaded ac-ac converter with phase-shift control and reduced number of inductors. It can attain high voltage levels by using standard low-voltage rating semiconductor devices. The proposed converter is resistant to current shoot-through and does not require pulse-width modulation (PWM) dead-time; these lead to greatly enhanced system reliability and effective utilization of PWM voltages. Moreover, it does not require current/voltage polarity sensors, lossy snubbers, or dedicated PWM strategies for commutation. These features make it possible to design the converter with reduced control complexity, and obtain output voltage with less distortion. The cascaded units in the proposed converter share the inductors; therefore, number of inductors, inductors footprints, and magnetic volume can be reduced. The phase-shift PWM control is also presented. It increases the effective frequency of the converter by the number of cascaded units, which decreases the size of the passive components and/or the current and voltage ripples. In order to demonstrate the advantages of the proposed converter, detailed comparative simulations and experimental results of the proposed 2-unit, 3-unit, and 4-unit cascaded converters are provided.