Characteristics of high efficiency and low distortion single phase 7 level inverter without using LC filter

Recently, the problem of global warming and environmental deterioration, depletion of fossil fuel are remarkable, and the method of power generation and energy conversion with efficient using the natural energy is proposed. This technology will be quickly commercialized in future and the popularization is widely expected for the reduction of CO2. In this paper, new single phase inverter circuit which efficiently converts DC voltage generated from natural energy into AC voltage is proposed. The voltage output from conventional bridge type inverter circuit was generally controlled by the PWM control. The sum of loss in the switching and loss by the LC filter for the removal of high frequency component occupied the most part of the loss, and there was a limit for the efficiency improvement. Then, by generating the quasi-sine wave without using PWM control, the frequency of the switching was reduced. The improvement on the efficiency was attempted by reduction of the switching loss and LC filter loss. And, the optimization of the switching was attempted on the generation method of quasi-sine wave by the coexistence of stability and low distortion of the voltage. Here, circuit configuration, operation principle, and the optimization of switching phase of proposing circuit is described. © 2010 IEEE.