Post-fault Model of Six-phase PMSMs with an Open-circuit Fault

A post-fault model of six-phase PMSMs with an open-circuit fault is presented. First, the two key properties of the well-known vector space decomposition transformation for the healthy machine, namely decoupling and orthogonality, are discussed. Then a dedicated transformation with similar properties for a faulty machine with one open-circuit fault is derived. It maps the phasedomain variables on a new five-dimensional space; the current which builds the magnetomotive force vector in the airgap is mapped on a separate sub-plane, and the currents which do not affect the magnetomotive force vector on the three remaining dimensions called zero-sequence axes. The proposed transformation is generic and can be applied to different star connections, i.e., grounded, connected, and isolated star points. Then, the model of the machine linked with equivalent circuit diagrams is developed. Simulation results are provided to illustrate the properties of the transformation and show the validity of the proposed model.