Four level AC converter and application

With the development of power electronics technology, the three-level converter has been proposed with the low switch voltage and low output voltage harmonics. Multilevel AC - AC converter circuit topology has many advantages and has been used extensively in high output voltage field. This paper deals with the study of a thin multi-level AC-AC converter, the operating and control scheme are analyzed in detail and mathematical expressions are worked out by using circuit analysis principle. In the control circuit, the inverter is controlled by instantaneous voltage value loop. The system can be used in reactive power compensation, which will realize a wide range of dynamic capacitive VAR control without using a dc/ac inverter stage. Simulation results reveal that the proposed main circuit topology and operation principle is feasible and efficient.