Switching Loss Optimization of Inverter Using Different Switching Schemes

Abstract

Inverters are widely used in AC motor drives and uninterruptible AC power supplies which require a sinusoidal output where frequency and magnitude can be controlled. Inverters can be either Voltage Source Inverters (VSI) or Current Source Inverters (CSI). In this project VSI has been used where input to the inverter is a DC voltage source. In order to obtain a variable voltage, either the DC voltage can be varied or the modulation index of the inverter can be varied. If the DC voltage is fixed, the modulation index can be varied by using Pulse Width Modulation (PWM) control. PWM techniques provide a better sinusoidal approximate waveform which reduces the size of the filter. These techniques differ in terms of output voltage, waveform shape quality, switching losses and complexity in implementation.

In this project different switching techniques have been explored and then some of these techniques have been simulated using PSIM software for a three phase inverter. These switching schemes are analyzed and compared for different parameters like switching losses, harmonic performance, DC bus utilization and complexity in implementation. The best of those techniques has been selected and tested on the prototype. The results are compared with the conventional scheme.