Design and simulation of an asymmetric variable reluctance stepping millimotor

A pancake-shaped step motor, which has a geometry with an axial dimension that is much smaller than the radius, was designed and built using a combination of conventional and LIGA-based fabrication methods. Preliminary open loop dynamic testing indicated that the motor rotated normally as designed, but some abnormal phenomena were also observed at certain input frequencies. A simple model was developed to simulate the dynamic behavior of the rotor. The simulation results match the trend of abnormal behavior observed in the test. They indicate that a reliable open-loop operation is feasible for a wide range of operating frequencies.