A Novel Transformerless Asymmetrical Fifteen Level Inverter Topology for Renewable Energy Applications

In the field of medium and high power applications Multilevel Inverter (MLI) topology is an alternative concept. It has the capability to generate the high voltage staircase pseudo-sinusoidal waveform with less distortion and high quality. But it requires more number of Switching Components (SC) with complex PWM (Pulse Width Modulation) strategies hence the cost and size of inverter becomes high. So, in view of this authors investigated a novel asymmetrical transformerless MLI topology of fifteen level inverter is presented in this paper, with an attempt of reduction in overall device count (switches, diodes, capacitors, dc voltage sources, etc.,) compared to all existing multilevel inverters. The basic structure and operating modes of proposed MLI is explained clearly. It requires seven power switches (IGBT), three diodes and three DC-bus capacitors are required to generate fifteen level 1-֠voltage. Furthermore, an efficient PWM technique is implemented with seven reference signals whose magnitude is equal to carrier signal. The performance of proposed MLI is accomplished in terms of Total Harmonic Distortion (THD) at modulation index M=0.9. The evaluation of MLI is carried out through MATLAB/SIMULINK environment.