Decomposition and investigation of torque components of dual‐PM machines

This paper proposes a multi-torque component decomposition method combining with frozen permeability method, and for the first time, accurately decomposes six torque components of dual-PM (DPM) machines. Based on the decomposition results, the characteristics of torque components are investigated. It is found that for average torque, the components generated by armature field interacting with PM fields and iron cores have positive contributions, while the components generated by the interactions between stator PMs, rotor PMs, and iron cores have negative contributions and are affected by magnetic saturation. The phases of torque ripple of torque components are different, resulting in a low resultant torque ripple of DPM machines. Moreover, for cogging torque, the component generated by the interaction between stator PMs and rotor PMs is the major source, and the components generated by the interactions between PMs and iron poles have a cancelling effect. Finally, a DPM machine is prototyped and tested to verify the analyses.