Influence of ferromagnetic bridges in dq-equivalent-circuit modeling of interior permanent-magnet machines

To reach energy efficiency goals the demand to high efficient motors, among which Permanent Magnet Motors, is increasing. In order to analyze and to predict the performance, equations based on equivalent circuits are generated. Lumped parameters have to be estimated and for simplicity often coarse assumptions are made, affecting the accuracy of the model. In this paper flux-linkage and inductance variations in (LineStart) Interior Permanent-Magnet Synchronous Machines are discussed. Attention is given to the influence of the behavior of the ferromagnetic material caused by load angle and current variations and more specific to the geometric design parameters, in particular to the magnetic conductance of the bridges. Finite Element Method is used for parameter estimations and detailed magnetic field research.