Abstract
Resent suspension control system adopts stepping motor to achieve fine positioning, and expensive rare earth magnet, which has high maximum energy product, is used to keep directed position with high detent torque not with electric supply. We developed auxiliary poles technology by finding out generating mechanism of detent torque of permanent magnet type stepping motor through three-dimensional magnetic field analysis using finite element method. This technology makes detent torque of stepping motor increase or decrease as desired and allows stepping motor for suspension control use ferrite magnet instead of rare earth magnet.