Low Spikes and Low Harmonic Distortion Multilevel Inverter for Induction Motor Implementation

Different Modulation techniques are suggested for use in electronic converters' applications for getting minimized Total Harmonic Distortion (THD). One of such techniques a Selective Harmonics Elimination Pulse Width Modulation (SHE-PWM) scheme. Specific odd harmonics can be mitigated by operating the semiconductor switches in H-bridge inverters at optimized switching angles of the PWM signals. These switching angles are determined by calculating a set of nonlinear equations. Multilevel converters operated by PWM, suffer from the issue of harmonic spikes in the output voltage. In this paper, an improved scheme of SHE-PWM is proposed for multilevel converter to mitigate THD and supress the harmonic spikes of the system. To investigate and confirm the proposed technique, a five-level cascade multilevel inverter is simulated, and experimentally implemented. It is seen that the simulation results are verified experimentally by eliminating low order harmoinics in getting a THD of 23.20% without using filter. The experimental results of the developed multilevel converer is validated with the simulation results under different performance conditions which show a complete agreement between them in terms of shapes and values.