The ways of providing low distortion in inverter or UPS applications without using large and high cost filters are whether applying PWM technique [1] or producing several appropriate steps on the output waveform called as multilevel operation. Combining both methods multilevel PWM technique is achieved [2] [3]. But, in this method, in order to reduce harmonics, it is necessary to increase the number of pulses at the output waveform. It is obvious that it causes an increase of power losses in the switching components particularly during ON/OFF transitions. Additionally in PWM applications, the harmonic distortion depends on the pulse widths due to output regulation need.
In this study, a new three phase multilevel inverter using chopper technique will be presented.