Analysis of Winding Configurations and Slot-Pole Combinations in Fractional-Slots Resolvers

Resolvers, due to their robust structure, are widely used in automation systems. The need for accurate position estimation beside the precise control of present PM motors, persuade machine designers to select a resolver with high pole numbers. By the aid of concentrated winding topologies high pole numbers is accessible. Among different topologies of concentrated windings fractional slot (FS) type has been focused by a lot of researches. FS concentrated winding (FSCW) offers high pole number under limited slots, identical on tooth coils, short end winding, and compact design. However, depending on the topology, there are major drawbacks, such as magnetic noises, high sub-harmonics, high leakage inductances, high core losses, and low fault-tolerance, resulted from inappropriate slot-pole combinations. So, in this paper after developing FSCW principles for resolvers, different configurations, including slot-pole combinations and winding layers are suggested. Then, 3-D time stepping finite element method is used to introduce five indices for evaluating the perfectness of these combinations and arrangements on the performance of resolvers. Finally, a prototype of 10-pole axial flux resolver has been constructed and tested. Good agreement between experimental and simulation results are obtained.