电气工程学报

电气工程学报 ›› 2021, Vol. 7 ›› Issue (3): 42-51.doi: 10.23919/CJEE.2021.000024

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  • 收稿日期:2021-04-10 修回日期:2021-06-21 接受日期:2021-06-30 发布日期:2021-09-17

Enhancement of Torque Density in Wound Field Switched Flux Machines with Partitioned Stators Using Assisted Ferrites

Zhongze Wu1,*, Z. Q. Zhu2, Shun Cai2, Wei Hua   

  1. 1. School of Electrical Engineering, Southeast University, Nanjing 210096, China;
    2. Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield S10 2TN, UK
  • Received:2021-04-10 Revised:2021-06-21 Accepted:2021-06-30 Published:2021-09-17
  • Contact: * E-mail: zzwu@seu.edu.cn
  • About author:Zhongze Wu (S’15-M’18) received the B.E. and M.Sc. degrees in Electrical Engineering from Southeast University, Nanjing, China, in 2010 and 2013, respectively, and the Ph.D. degree in Electrical and Electronic Engineering from The University of Sheffield, Sheffield, UK, in January 2017.Since March 2021, he has been with School of Electrical Engineering, Southeast University, Nanjing, China, as a Researcher. His major research interests include the advanced electrical machines and drives for electric propulsion systems.From January 2017 to August 2018, he was with Warwick Manufacturing Group (WMG), University of Warwick, Coventry, UK, as a Research Fellow in electrical machines. From August 2018 to August 2020, he was with the Institute for Advanced Automotive Propulsion Systems (IAAPS), Department of Mechanical Engineering, University of Bath, Bath, UK, as a Prize Fellow, where he was a Lecturer between August 2020 and January 2021.
    Z. Q. Zhu (M’90-SM’00-F’09) received the B.E. and M.Sc. degrees from Zhejiang University, Hangzhou, China, in 1982 and 1984, respectively, and the Ph.D. degree from the University of Sheffield, Sheffield, UK, in 1991, all in Electrical Engineering.Since 1988, he has been with the University of Sheffield, where since 2000, he has been a Professor with the Department of Electronic and Electrical Engineering. He is currently the Royal Academy of Engineering/Siemens Research Chair, and the Head of the Electrical Machines and Drives Research Group, the Academic Director of Sheffield Siemens Gamesa Renewable Energy Research Centre, the Director of CRRC Electric Drives Technology Research Centre, and the Director of Midea Electrical Machines and Control Systems Research Centre. His current major research interests include the design and control of permanent magnet machines and drives for applications ranging from electrified transportation through domestic appliances to renewable energy.Prof. Zhu is the Recipient of the 2021 IEEE Nikola Tesla Award and the 2019 IEEE IAS Outstanding Achievement Award. He is a Fellow of Royal Academy of Engineering, UK, a Fellow of Institute of Electrical and Electronics Engineers (IEEE), USA, and a Fellow of Institute of Engineering and Technology (IET), UK.
    Shun Cai was born in Hubei, China. He received the B.E. and M.Sc. degrees from Zhejiang University, Hangzhou, China, in 2014 and 2017, respectively and the Ph.D. degree from the University of Sheffield, Sheffield, UK, in 2020, all in Electrical Engineering.Since 2021, He has been a Research Fellow with Nanyang Technological University, Singapore. His research interests include design and analysis of novel permanent magnet machines for automobile application and renewable power generation.
    Wei Hua (M’03-SM’16) received the B.Sc. and Ph.D. degrees in Electrical Engineering from Southeast University, Nanjing, China, in 2001 and 2007, respectively. From 2004 to 2005, he was with the Department of Electronics and Electrical Engineering, The University of Sheffield, UK, as a Joint-Supervised Ph.D. Student. Since 2007, he has been with Southeast University, where he is currently a Chief Professor of Southeast University and a Distinguished Professor of Jiangsu Province. From 2010, he has also worked with Yancheng Institute of New Energy Vehicles of Southeast University. He has co-authored over 150 technical papers. He holds 50 patents in his areas of interest. His teaching and research interests include design, analysis, and control of electrical machines, especially for PM brushless machines and switching reluctance machines, etc.
    Wentao Zhang received the B.E. and M.Sc. degrees in Electrical Engineering from Southeast University, Nanjing, China, in 2018 and 2021, respectively, where he has been working toward the Ph.D. degree since September 2021.His major research interests include the design, analysis, and control of the wound field switched flux machines.

Abstract: In this paper, ferrites are applied in a partitioned stator wound field switched flux (PS-WFSF) machine to increase the air-gap flux density, and hence, the average electromagnetic torque and overload capability. Introducing short-circuited ferrites in the inner stator in the PS-WFSF machine can increase the open-circuit phase fundamental back-EMF and average electromagnetic torque at a 60 W copper loss by 2.33% and 3.77%, respectively. Moreover, the proposed PS-WFSF machine with ferrites can exhibit a better overload capability than conventional PS-WFSF machines without ferrites, e.g., a 7.36% torque increment can be achieved when the copper loss is 120 W. The torque increment mechanism is analyzed and verified using finite element (FE) analysis. Moreover, the demagnetization of the ferrites in the proposed machine under rated on-load and overload conditions is investigated. Both prototypes of the proposed PS-WFSF machine with ferrites and a conventional one without ferrite are built and tested to validate the analytical and FE analyses.

Key words: Average electromagnetic torque, ferrite, flux switching, partitioned stator, switched flux, torque improvement, wound field