Study of optimum design on magnetizing fixtures for the ring magnet in spindle motors

The magnetization profiles of the ring magnet in spindle motors have been i nvestigated theoretically by a computer-aided simulation with two dimension al modeling processes of finite element analysis. Under the three topologie s of magnetizing fixture, the current was varied below 15 kA. The double-si ded fixture shows a minimum cogging torque near 8 kA. However, the single-s ided fixture internal to the magnet shows a maximum torque constant near 8 kA. Experimental data are in good agreement with theoretical calculation. A high efficiency and low cogging torque spindle motor has been achieved by optimum design of the magnetizing fixture to magnetize the ring magnet in a spindle motor. (C) 1999 American Institute of Physics. [S0021-8979(99)6170 8-X].