On-Load Analytical Modeling of Slotted Interior Magnet Synchronous Machines Using Magnetic Islands Method

In general, the Magnetic Circuit (MC) is an effective and valuable tool for calculating the PM flux and predicting machine behavior during the no-load operation. Since the rotor PMs are the sole source of the flux, the flux path and the respective MC model is independent of the rotor position. However, this is not the case for the loaded operating condition. As the rotor spins, the path of the armature flux necessarily changes to pass through the rotor with minimum reluctance. Therefore, the MC model would vary at every rotor position and is no longer a feasible solution particularly, for cases with complex rotor structure. To resolve this, an analytical solution procedure based on the concept of the Magnetic Islands (MI) is presented to predict the on-load response of the motor such as armature flux and the winding inductance. The air-gap is defined as a function along the perimeter of the stator to include the stator slotting effect. In addition, the presented method accounts for the magnetic saturation. To assess the accuracy of the model, analytical results are compared against the finite element results.