Discontinuous Space Vector Pulse Density Modulation Scheme for Multilevel Inverter using abc Coordinates

Abstract

Space Vector Pulse Density Modulation (SVPDM) schemes based on Sigma Delta Modulation (SDM) are digital modulation schemes. A Discontinuous SVPDM (DSVPDM) scheme applicable for any n-level inverter topology is proposed in this article. To reduce the switching the pole voltage is clamped to negative DC bus for a period of 1200. The DSVPDM scheme uses abc coordinates and thus it does not require sector information and coordinate transformation. The cross switching associated with direct vector quantized SVPDM is less in the proposed scheme. The DSVPDM is validated for a four-level inverter realized by a 3hp open end winding induction motor fed by 11.5 kVA two-level inverter on both sides with asymmetric DC link voltage. The performance of DSVPDM is compared with space vector based modulation schemes and the results are presented.