Sinusoidal Rotor Core Shape for Low Torque Ripple in Hollow-Cup Machines

Liu Zhang, Zhanpeng Cui, Pengfei Song, Liming Wang and Xikai Liu ()
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Liu Zhang: Ningbo Institute of Technology, Beihang University, Ningbo 315800, China
Zhanpeng Cui: School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China
Pengfei Song: Ningbo Institute of Technology, Beihang University, Ningbo 315800, China
Liming Wang: Ningbo Institute of Technology, Beihang University, Ningbo 315800, China
Xikai Liu: Ningbo Institute of Technology, Beihang University, Ningbo 315800, China

Energies, 2024, vol. 17, issue 13, 1-16

Abstract: Due to the configuration of coreless stators and two synchronously rotated rotors, hollow-cup machines (HCMs) enjoy the merits of negligible cogging torque and core loss. Consequently, HCMs have been successfully employed as high-speed electric machines in the aerospace field, which requires high precision and low thermal dissipation. However, the permanent magnet (PM) thickness and air-gap length of conventional HCM are uniform, resulting in various harmonics in the air-gap flux density as well as back-EMF. These harmonics inevitably produce an electromagnetic torque ripple, which has not met the increasing demand for ultraprecision in recent years. Since the inner rotor of HCMs only consists of an iron core, this paper proposes a novel sinusoidal-shaped inner rotor, which can change the harmonics of air-gap permeance, to adjust the harmonics of air-gap flux density and back-EMF. HCMs with the proposed inner rotors have a significant 87% reduction in torque ripple compared to conventional HCMs. Meanwhile, compared to conventional methods, HCMs with the proposed inner rotor exhibit comparable torque ripple and higher average torque.

Keywords: hollow-cup machine; permanent magnet machine; rotor shaping; torque ripple (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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