Modulation Technique Using Boundary-Pulse-Width for a Single-phase Power Inverter

The pulse-width-modulation technique plays a very important role in the inverter gain control. New varied-pulse width techniques for power inverters of two schemes have been introduced in this study: Small Boundary-Pulse-W idth Technique (SBPW), and Large Boundary-Pulse-Width technique (LBPW). These techniques are developed to improve the inverter operation, based on minimum harmonic contents in the output voltage. The original pulse-w idth of an inverter operation is divided into multiple pulses of variable widths per half cycle. For the SBPW method a middle pulse and several boundary pulses per half cycle are deduced. The middle pulse is given the largest width and the boundary pulses are taken small widths. For LBPW method the opposite is considered. A software-model was developed by the authors to determine the conduction angles and their gating angles required for the inverter drive. The advantage of these techniques allow a modifying in the number of pulses per half cycle and their widths, leading to an inverter operation with less generation of harmonics. The SBPW technique makes the inverter output voltage closer to a sinusoidal form. Therefore, the optimal inverter performance is obtained with this technique.