Control of six-phase voltage source converters using dynamic voltage vectors

Abstract

The use of a single switching state during the whole sampling period in the current regulation of six-phase voltage source converters (VSCs) inevitably generates undesired parasitic 𝒙-𝒚 currents. Aiming to solve this problem, the creation of virtual/synthetic voltage vectors (VVs) has been recently proposed to ensure zero average 𝒙-𝒚 voltage production. However, the off-line calculation of VVs makes them static and suboptimal. This paper introduces new approach where the virtual voltages are created on-line within a model predictive control (MPC) based current regulation strategy. Since the selection of the switching states and the dwell times varies each sampling period, the resulting vector are termed dynamic voltage vectors (DVVs). This new concept allows an online optimization of the output voltage production depending on the operating point at the expense of a higher computational cost. Simulation results confirm that six-phase VSCs can be successfully regulated using DVVs in an MPC-based current control scheme.