Design and Electromagnetic Performance Analysis of Novel Dual-Armature Π-Core Doubly Salient Permanent Magnet Machines

A novel Π-core dual-armature doubly salient PM machine (Π-core DADSPMM) is presented, in which an auxiliary armature winding is recommended to be wrapped on rotor teeth. Since this machine benefits from better space utilization compared to the existing Π-core doubly salient PM machine (Π-core DSPMM), it exhibits higher torque density. Moreover, when any one of both armature windings cannot work, this machine still can produce electromagnetic torque and thus has an inherent fault-tolerant feature. Firstly, machine structure and operation principles are investigated. Further, based on the finite element (FE) technique, both Π-core DADSPMM and Π-core DSPMM are optimized for high output torque in case of the same stator diameter, active axial length, and rated copper loss, followed by electromagnetic performance comparison. It is shown that compared to Π-core DSPMM, the proposed Π-core DADSPMM has about 67.4% higher average torque while retaining a comparable torque ripple. Furthermore, if one set of armature winding fails, Π-core DADSPMM halves its output torque, which is still about 84.2% of that in the Π-core DSPMM. Finally, a prototype is made and verified that the experimental results agree well with the simulation results.