Axial Flux Resolver Design Techniques for Minimizing Position Error Due to Static Eccentricities

This paper proposes a design solution for static eccentricity (SE) in axial flux resolvers (AFRs). There are two definitions for SE in AFRs. The first approach is based on the definition of SE in conventional radial flux resolvers, wherein the rotor axis does not coincide with the stator bore, but the rotor rotates around its own shaft. In other words, it is different in the angular inclination of the rotor and stator axis. Thus, the air gap of the motor is not uniform. In the second approach, which is more common in AFRs, when SE occurs, air-gap length remains uniform. Rotor axis remains parallel with the stator axis, although it does not coincide with the stator bore. This means that there is radial misalignment of the rotor and stator axis. In this paper, both definitions are considered, and an innovative design solution is proposed to decrease the effect of both types of SE in the accuracy of detected position. 3-D time stepping finite-element analysis is used to show the success of proposed designs. Finally, both models were evaluated using experimental results.