Modeling of a Permanent Magnet Synchronous Machine With Internal Magnets Using Magnetic Equivalent Circuits

The design of control strategies for permanent magnet synchronous machines (PSM) is almost exclusively based on classical dq0-models. These models are, however, not able to systematically describe saturation or nonhomogenous air gap geometries typically occurring in PSM. This paper deals with a framework for the mathematical modeling of PSM based on magnetic equivalent circuits. Different to existing works, the model equations are derived by means of graph theory allowing for a systematic choice of a minimal set of state variables of the model and a systematic consideration of the electrical connection of the coils of the motor. The resulting model is calibrated and verified by means of measurement results. Finally, a magnetically linear and a dq0-model are derived and their performance is compared with the nonlinear model and measurement results.