Design and implementation of single-phase modified SHEPWM unipolar inverter

Nowadays, the main target of industrial power and the utility is to save the electrical energy. With the modern industrial system such variable speed drives of the inverter, the system becomes more efficient and the control becomes way simpler. However, it will affect the harmonic in the system and gives an impact to the whole system performance. Due to this situation, some techniques are needed to eliminate this harmonic in the system. This paper presents modification made to the switching strategy of unipolar Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) inverter and tested on real resistive and inductive load to evaluate the performance of the inverter. A LC low-pass filter is implemented in this system to progressively filter the output of inverter for a better and lower total harmonic distortion (THD) level and change to better sinusoidal AC waveform before connecting to the toroidal transformer to power the normal AC loads.