The investigation of the load and frequency influences on the quality of three phases voltage source inverter current with SHEM modulation pattern

M. Asadi, Sh. Rezaei Borjlou, H. F. Farahani, A. Shoulaie

Abstract

Today the voltage source inverters are used in UPS, small and large induction motor drivers and etc. One of the important points in voltage source inverters is the output current quality or the output current harmonics. The voltage modulation is used for increasing the  quality of the current in the inverters. One of the modulation methods is SHEM modulation (Selected Harmonic Elimination Modulation) in voltage source inverters. Output harmonics are depending on the load and the operational frequency in this modulation.

In this paper by means of the made laboratory inverter, the influence of the freqquency and different loads (pure resistance, resistance-inductance, pure inductance) have been investigated on the inverter output harmonics. For this purpose different operational modes has been defined for the inverter and the influence of the different frequency have been investigated and evaluated by means of the passive filter (for decreasing of the current harmonics aplitude) on the quality of the inverter output current. Mentioned inverter has been modeled and simulated in PSPICE sofware too. The simulated and the experimental results confirm together.