DEVELOPMENT OF ACTIVE CONVERTER TO GENERATE SPLIT DC FOR MULTI LEVEL INVERTER

Abstract

Applications of power electronic equipment continue to increase because of their ability of better control for traditional and new processes and energy conservation. The inherent non linear nature of solid state equipment places harmonic current demands from the power distribution systems. In order to control these harmonics stringent harmonic standards IEEE Std 519-1992 have been set by IEEE in May 1993. Prepared by experts in the Industry Applications Group, it is a valuable reference document around the world. There are various techniques such as Active filtering, Passive filtering to reduce the harmonics produced by non-linear loads to meet above standards. However a converter system can mitigate harmonics by itself and adjust the power factor with modification in control strategy. Such a converter is termed as Active Power Factor correction converter (APFC). Multi Level Inverter (MLI) systems are in common use for high power applications because of better waveform, reduced voltage stresses for the devices. However the major challenge is to produce a balanced DC voltage set for MLIs. It requires again a harmonic free and efficient conversion from the AC mains. In this thesis work Active converters have been developed to maintain power factor at utility, and provide a regulated DC voltage suitable to drive 3-level and 5-level MLIs.