In-depth analysis of magnetic flux concentration indicator in novel curved slots of multi-tooth dual-PM doubly salient machine

Multi-tooth structure in dual-PM doubly salient machine (MT-DDSPM) has discovered large flux leakage with a non-concentrated magnetic flux due to many square teeth and many edges at teeth and poles. To overcome these shortcomings, this paper proposed a novel design of the curved slots applied in the MT-DDSPM. In addition, the magnetic flux concentration indicator (MFCI) was originally formulated to measure the magnetic flux concentration at the stator teeth, focused mainly on the edge and slots. These aimed to optimize the design of curved slots applied in the 12/3/35-pole MT-DDSPM for superior torque production. The electromagnetic performance of the designed MT-DDSPM was deeply investigated using the finite element method in comparison to traditional square-slot design. The invented MT-DDSPM with curved slots revealed the highest MFCI of 25.47 compared to 19.16 obtained with the square slots. The results indicated an enhanced magnetic flux concentration of MT-DDSPM, leading to higher flux linkage and other electromagnetic performances. Especially, the rated torque obtained from the curved-slot design was 66.01% higher than the square one at the same rated current, providing a better profile even at overload current. The minimum ripple torque of 1.35% was found with the curved-slot MT-DDSPM. In conclusion, this work highlighted the superior performance of a novel curved-slot MT-DDSPM and provided a reliable alternative to evaluate the quality of magnetic flux concentration in terms of MFCI, which can be essential for the in-depth analysis of the multi-tooth family of electrical machines and relevant applications.