Modelling, Harmonic Compensation, and Current Sharing Between Winding Sets of Asymmetric Nine-Phase PMSM

Several modelling approaches of multiphase machines have been proposed in literature to control the machine in healthy or faulty conditions. The variety of the models may confuse the researchers to select the proper ones. In this paper, vector space decomposition (VSD), multi-star (MS), and decoupled MS (DMS) models are developed with detailed explanations for triple three-phase (or asymmetric nine-phase) permanent magnet synchronous machine (PMSM). It is shown that the machine differential equations are not fully decoupled in DMS modelling. The presented approaches can be extended to any types of multiple three-phase PMSM. Also, two new models are introduced with the use of specific transformation matrices in order to provide the current sharing between different three-phase winding sets and for compensation of current harmonics arising from inverter nonlinearities or machine structure. These models are necessary to design the parameters of the control system in order to have the optimum dynamic response.