Bipolar SHEPWM for Pure Sine Wave Single-Phase Inverter

Abstract

Modern power systems, like DC-AC inverters, use simple control strategies. However, they give rise to harmonic problems during the switching process. It impacts the total system performance.In this paper, Selective Harmonic Elimination SHEPWM was adopted to mitigate these undesirable harmonic distortions. It cancels odd harmonic at optimized switching angles. In this case, it aims to eliminate the first 100 low-order harmonics. The fsolve function was used to calculate the optimized 50 angles for the SHEPWM by solving the non-linear transcendental equations in MATLAB. The resulting SHEPWM is implemented in a low-cost high-performance PIC18F26K22 microcontroller. It controls a pure sine wave single-phase inverter in ISIS space. Finally, an LC low-pass filter is connected at the inverter output to ameliorate its response and obtain a better sinusoidal AC waveform with a lower THD.