The influence of magnetic saturation and armature reaction on the performance of interior permanent magnet machines

This paper investigates the combined influence of magnetic flux saturation and the stator current armature reaction on the steady-state torque capability and efficiency of an interior permanent magnet machine (IPM). These effects are reflected in the classical qdo equivalent circuit model of the machine in the following fashion: the core loss is represented with a stator flux linkage dependent core loss resistance, the armature reaction effect is accounted for by the changing magnet flux linkage and magnetic saturation effect is reflected in the changing d and q-axis inductances of the machine. The steady-state modeling and analysis of the machine, the nature of the variations of the machine parameters and how they influence the machine torque and efficiency are clearly laid out and eventually confirmed by simulation and experimental results. The balance of the paper provides finite element analysis results for an experimental 2 hp IPM to further validate the conclusions drawn from calculation and experimental results.