Permanent magnets are used extensively in synchronous machines that produce high power density, wide speed range and high efficiency. It is important therefore to determine the qualityof the magnetic material before the assembly and magnetization in the electrical machines.Once they are installed, they cannot be removed. Thus, if the quality of the magnets is inadequate, the rotor assembly is unusable.In this thesis, different types of magnetometers are reviewed before pulsed field magnetometer system is chosen due to its simplicity, quick and smaller size to measure the magnetic hysteresis for characterization. A pulsed magnetometer is useful for testing high performance magnets due to their ability to produce magnetic fields, high enough to saturate the rare earth permanent magnets. The basic geometry, coil winding configuration and input currents of the pulsed field magnetometer are calculated using Finite Element Method andMATLAB/Simulink. The whole coil arrangement combined with power electronic circuitry is designed and built. The control is implemented using LabView and the results are post processed using MATLAB.The first part of the work is to plot the measured hysteresis loop using two current pulses with magnet position at 0° and 180° at different temperatures after compensating for open-loop demagnetization factor. Three different Neodymium-Iron-Boron magnets: Nickel plated,Aluminum coated and Black painted magnets are used for this test.The second part of the work is to distinguish between good and bad raw material of the permanent magnets used in PMAC machines. For this, the magnetic field is applied to good raw material magnet such that the negative peak forces the magnet operating point to fall slightlyabove or close to the knee of the hysteresis curve. It is used as reference and compared to the magnets with some amount of impurities. The magnets with bad raw material trail different minor loops and recoil line when compared to the magnets with good raw material.On the whole, the pulsed field magnetometer, coupled with minor loops and recoil lines, is used as a successful technique to distinguish between good and bad raw material of the permanent magnets used in PMAC machines.
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