Symmetrical six-phase induction machines: a solution for multiphase direct control strategies

Abstract

Six-phase induction machines are considered an interesting multiphase option because they can benefit from the well-known three-phase converter technology. These multiphase machines can be classified according to the spatial distribution of their windings into two main groups: asymmetrical and symmetrical six-phase machines. In the case of symmetrical sixphase machines, some sets of voltage vectors show an important advantage from the point of view of the 𝒙-𝒚 current mitigation. They provide an active production in the 𝜶 - 𝜷 plane with a completely null injection of 𝒙-𝒚 components. This fact is a desired feature for direct control strategies, such as standard model predictive control (MPC), where a single switching state is applied during the entire sampling period. Based on these statements, this work proposes an MPC strategy for symmetrical six-phase induction machines using voltage vectors with null 𝒙-𝒚 voltage production in order to obtain the flux/torque generation with minimum 𝒙-𝒚 currents. Simulated results have been included to validate the goodness of the developed control scheme.