A generalized hexagonal co-ordinate based SVPWM algorithm for multilevel inverters

Abstract

In recent years, Multilevel Inverters have drawn tremendous interest due to increase in medium and high power applications with their better performance. The performance of multilevel inverter depends on number of output levels and type of modulating technique used. Space vector pulse width modulation strategy is well-liked than carrier comparison approach due to superior performance. However, conventional space vector pulse width modulation approach is tolerable up to three level inverter after which it becomes computational intense. With the aim to reduce complexity at higher levels, a generalized hexagonal co-ordinate based space vector pulse width modulation algorithm for multilevel inverter is proposed in this paper. In the present work emphasis is made on non-orthogonal coordinate system to identify adjacent three switching states and compute their residing times. With the proposed algorithm number of steps entailed in identifying the three adjacent vectors, corresponding switching states and their residing times are maintained same irrespective of the output levels of the inverter. After identifying switching states, they are mapped to original switching states by using a reverse transformation approach. This algorithm is computationally efficient and is applicable to ‘n’ level inverters. In this proposed algorithm is explained for five level operation and performance is verified on five, eleven level neutral point clamped inverter fed induction motor drive through computer aided simulation and results are presented.