**4. Conclusions**

A novel MAS-HPM machine is proposed to achieve a higher torque capability and a wider high-efficiency operation range for EV applications in this paper. The basic electromagnetic characteristics of the proposed MAS-HPM machine and the benchmark BMW i3 IPM machine are comprehensively investigated and compared by FEA. Due to the MAS effect, the difference between the optimal current angles of maximizing the magnet and reluctance torques is reduced. In addition, it was found that the back-EMF and total torque of the proposed MAS-HPM machine can be effectively improved, compared with the conventional BMW i3 IPM machine. Moreover, the proposed machine shows lower peak mechanical stress, better field-weakening capability, higher peak efficiency and comparable high-efficiency operating range, which confirms the effectiveness of the proposed MAS design concept for performance improvement. However, due to higher harmonics, the proposed MAS-HPM configuration has higher cogging torque and iron losses in a high speed operating range.

**Author Contributions:** Conceptualization, Y.L. and H.Y.; methodology, Y.L. and H.Y.; software, Y.L. and W.W.; validation, Y.L., H.Y. and H.L., formal analysis, Y.L. and H.Y.; investigation, Y.L. and H.Y.; resources, Y.L. and H.Y.; data curation, Y.L. and H.Y.; writing—original draft preparation, Y.L. and H.Y.; writing—review and editing, Y.L., H.Y., H.L. and S.F.; visualization, Y.L. and H.Y.; supervision, H.Y., H.L., and S.F.; project administration, H.Y.; funding acquisition, H.Y. and H.L.

**Funding:** This work was jointly supported in part by National Natural Science Foundations of China under Grant 51377036, in part by Natural Science Foundation of Jiangsu Province for Youth (BK20170674), in part by the Fundamental Research Funds for the Central Universities (2242017K41003) and in part by the Postgraduate Research and Practice Innovation Program of Jiangsu Province (KYCX18\_0096).

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**


© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
