Control method of input-parallel and output-series connected inverters for plasma generator

In this paper, the control method of output-series-connected inverter for plasma generator, which operates at the high switching frequency, is proposed. In the previous studies about control methods of output-series-connected inverters, all of switches in connected inverters are turned on and turned off at the same time. Therefore, the output voltage is always square wave or quasi square wave. However, each inverter module in this paper is sequentially controlled with phase differences by applying the proposed control method. Thus, the output voltage contains less harmonics, which means that the proposed method has advantage in terms of the output power quality. Finally, the validity of the proposed control method is verified by simulation and experimental results.