Digital Space Vector Approach to Eliminate Overcharging of DC-link Capacitor in Asymmetrical VSI Fed Open End Winding Induction Motor Drive

Abstract

Dual inverter topology with asymmetrical input voltage (2:1) is the simple and most economical solution to fabricate four-level output voltage. Due to the lack of switching status selections, the asymmetric configuration of the dual inverter suffers from overload of the DC link capacitor. The present work compares few exiting decoupled and coupled PWM techniques with implementation using multilevel carrier comparison approach and digital space vector approach. It is proved that proposed coupled PWM with the digital space vector approach provide easy path for switching state selection to eliminate the problem “overcharging of DC link capacitor”. The other decoupled PWM techniques may eliminate the problem, but generate poor quality of output voltage. In addition, the proposed digital space vector approach provides freedom in the choice of different voltage vectors to achieve good output voltage quality.