Low cogging torque and high efficient 3-phase spindle motors by reshaping magnetic circuit profiles

The dynamic characteristics of a 3-phase spindle motor with 12-poles and 9-slots can be improved by reshaping the magnetic circuit profiles. The stator cores were designed with different ratios of x/y where x is the gap angle between 2-slots and y is the expanded angle of a slot. Experiment and finite element analyses (FEA) results show that x/y ratio of 1/2.5 is an optimal design in achieving dynamic performance for DVD drives applications.