Over-Modulated Reference for 12-Sided Polygonal Space Vector Strategy Based Modified Pulse Pattern for CHB MLI

Abstract

In this paper, a new pulse pattern is designed for multilevel dodecagonal space vector modulation with over modulated reference. This 12-sided polygonal or Dodecagonal Space Vector Modulation is a sub-sectional strategy for the Hexagonal Space Vector Modulation. In this Hexagonal Space Vector Modulation, the pulse durations are calculated based on present position and magnitude of reference. For the proper sharing of present and future sectors in the duration of pulses are decides with reference position and magnitude. But over modulated reference gives a single and specified level throughout the sector duration because reference crosses the space hexagonal region. Over modulating reference simplifies the computational complexity of pulse time calculations in hexagonal space vector, the same strategy is implemented and analyzed for eliminating harmonic distortions in output waveform with sinusoidal approximation in 12-sided polygonal modulation. The proposed over modulated reference implementation eliminates the present position estimation, calculations for sharing of present and future sectors and repetitive pulse generation. The over modulating reference implementation is done with 12-sided polygonal space vector modulation for 7-level cascaded multilevel inverter. Detailed simulation and experimental results for proposed over modulating reference based 12-sided polygonal space vector modulated 7-level Cascaded H-Bridge Multilevel Inverter are presented to validate the better performance of proposed strategy.