Research On Single Phase AC/AC Onverters Based On Simple Topologies

The research of direct AC/AC converters derived from DC-DC topologies by using bi-directional power devices is a hotspot in recent years. The thesis presents a group of direct AC/AC topologies including single and three phases AC/AC converters which are based on simple DC-DC topologies and realized by using the single-power tube four-quadrant switches. With only two power switches, these single or three phases AC/AC converters can achieve high quality four-quadrant AC/AC conversion by simple configurations and simple control schemes. The thesis mainly researches on the single phase AC/AC converter in the topologies including AC_Buck and AC_Cuk.Firstly, the operating principles of the two converters are analyzed in detail and the rules of their parameters design are educed; The commutation of their power switches which is the key of these topologies to realize is analyzed in detail and a feasible solution which can be named RCD-Commutation mode is presented and proved effectual by theory analyses and simulation results.Secondly the control schemes for the single phase AC/AC converters are researched Based on AC_Buck converter. The single-voltage-loop instantaneous control scheme is researched and the sample machine of"Single phase AC_Buck with RCD commutation mode Controlled by Single-voltage-loop Instantaneous control scheme"is developed. The final experimental results shows that RCD-Commutation mode can solve the commutation problem, and that by single-voltage-loop instantaneous control scheme, the converter can achieve high quality four-quadrant AC/AC conversion and has excellent performances on resisting the fluctuations of the power supply and load. Nevertheless, the converter with this control scheme has an inevitable defect of across-zero-aberration.As a reformative control scheme, the One-Cycle control policy is presented in the latter research of AC_Cuk converter. Based on AC_Cuk, the performances of the converter controlled by One-Cycle control scheme is researched by simulations and the results shows that with One-Cycle control , the single phase AC/AC converters based on simple topologies can not only avoid the across-zero-aberration but also has better performance on resisting the fluctuations of power supply.