The impact of sampling frequency and amplitude modulation index on low order harmonics in a 3-phase SV-PVM voltage source inverter

Abstract

Nowadays, variable speed AC motors are widely used in industry and there are many speed adjustment techniques available. In the last decade there has been a trend towards the use of space vector PWM-IGBT inverters, due to easier digital realization and better utilization of the DC bus. Every power inverter produces a total harmonic distortion (THD) on its output that causes extra losses in stator of induction motors. By eliminating a number of low order voltage/current harmonics it is possible to reduce harmonic losses (stator losses) and mechanical oscillations in general. This could be achieved by implementing filters in the output of inverters or by applying a modern modulation technique such as space vector pulse width modulation (SV-PWM). The objective of this paper is focused on using general techniques of SV-PWM in 2-level 3-phase voltage source inverters for inductive load tempting to eliminate the low order voltage/current harmonics, by varying sampling frequency and amplitude modulation index, without using filters.