New concept on sinusoidal modulation for three-phase DC/AC Converters: Analysis and experiments

Abstract

Various modulation schemes have already been developed for conventional three-phase buck-type converters such as sinusoidal pulse-width modulation and space vector modulation (SVM). However, SVM is not applicable to boost-type converters. This study proposes a new concept on sinusoidal modulation for both buck and boost-type three-phase DC-AC converters. A novel optimised modulation technique is introduced by using basic equations of conventional buck and boost. By solving the optimisation problem, pulse widths will be obtained for a given modulation index. The significant point is that the optimisation problem should not be solved for every modulation index because the answer of the optimisation problem obeys a certain pattern. Also, this method has a positive effect on reducing losses, especially in boost-converters. Analysis and simulations are first introduced for three-phase boost-converters, and then is extended to a buck converter. Furthermore, practical verification takes place on two implemented 1 kVA boost and buck-converters in order to confirm the proposed technique as well as theoretical analysis and simulations. The experiments and simulations both verify the suggested optimised modulation technique. ©The Institution of Engineering and Technology 2014.