Abstract
The saturation effect of permanent magnet magnetic property such as the flux density, on electromagnetic characteristics of a double stator (DS) permanent magnet (PM) machine is investigated in this study. The studied parameters are: flux linkage, induced voltage, torque characteristics and total harmonic distortion (THD). Maxwell-2D software is employed to predict the results using Finite Element Analysis (FEA) procedure.
The FEA-calculated flux linkage value of the studied machine at magnetic flux densities of 1 Tesla, 2 Tesla, 3 Tesla and 4 Tesla are 0.0085 Wb, 0.0106 Wb, 0.0086 Wb and 0.0067 Wb. The corresponding maximum static torque of the machine are 2.0427 Nm, 2.5596 Nm, 2.2377 Nm and 1.8306 Nm. Optimum value of magnetic flux density would yield large value of flux linkage and a corresponding large amount of torque, provided the machine is not saturated; in other words, the best machine performance is predicted under normal working conditions of rated speed, load and optimal magnetic flux density value. It is revealed that, for a given permanent magnet machine having neodymium-iron-boron magnet, its optimal electromagnetic performance is obtained when its magnetic flux density magnitude is about 2 Tesla; beyond this value of magnetic flux density, the machine’s performance tends to reduce, owing to the saturation effect of the implemented magnetic material.

Key words: Machine, magnetic property, saturation, torque ripple and voltage distortions.