Patent ID: 9214849
Filing Date: 2015-12-15
Classification: H02K

Abstract:
1. A stepper motor, comprising: a rotor with a plurality of rotor teeth, the rotor fitting within a stator winding assembly and seated by bearings on an axial shaft so as to rotate within the stator winding assembly; and the stator winding assembly including a stator with a set of stator poles wound with coils that can be driven in a series of phases so as to magnetically interact with the rotor, the stator poles having sets of stator teeth that are selectively magnetized by energizing of the stator coils, the stator characterized by having a permanent ring magnet sandwiched between outer portions of two stator stack elements of the stator outside of the coils, the permanent ring magnet having a ring interior with magnetic flux from the permanent ring magnet passing axially through the ring interior to remotely magnetize the rotor and its rotor teeth, such that magnetic flux in an air gap between rotor and stator teeth is dominated by the flux generated by Ampere-turns of energized stator coils with reduced flux interactions from non-energized poles.