Optimization of Output Voltage Waveform of Selective Harmonic Elimination Inverter

A selective harmonic elimination (SHE) inverter can eliminate beforehand-appoint harmonic by calculating the equations set, therefore it can eliminate harmonic effectively in theory. The connection and break of switching devices all need a little time, thus the narrow pulse of the ideal output voltage waveform is difficult to realize. For obtaining practical output voltage waveform, optimization strategies of omitting couple of switching angles and widening couple of switching angles are presented based on the material requirement of on-off time of switching device. Widening a couple of switching angles may divide into forth-widening, backwards-widening and symmetry- widening, in which symmetry-widening is more advantaged than forth-widening and backwards-widening in the way of reducing harmonic amplitude and total harmonic distortion. Theory analysis, numeral simulation and experimental results show that optimization strategies presented may reach aim to easy hardware realization and little total harmonic distortion, accordingly effective means is provided for the application of selective harmonic elimination technology to engineering.