Effects of continuous rotor skewing in additively manufactured permanent magnet rotors

authored by: Stefan Urbanek, Ralf Keuter, Emma Peter, Bernd Ponick
Abstract: This paper describes the effects of skewing the rotor of a permanent magnet synchronous machine (PMSM) with buried magnets by torsion of the soft-magnetic rotor active part and maintaining the magnet pockets axially straight. The impact of this approach on the mechanical and the electromagnetic design of the rotor active part is presented. In the end, the approach leads to a reduced cogging torque with simultaneously decreased leakage flux. Using conventional manufacturing technologies, e.g. punching or laser cutting, skewing the laminated soft-magnetic rotor active part and maintaining the magnet pockets axial straight would lead to a variety of lamination cross sections. The presented approach can hence be realized usefully by means of Additive Manufacturing (AM) technologies.Therefore, a short review of metal-additive manufacturing in the field of electric machines and the common practice of skewing in PMSMs is given in a first step. After this, a PMSM with barshaped buried magnets was chosen to serve as reference. 3D electromagnetic finite element analyses (FEA) of the non-skewed reference machine, of a conventionally step-skewed rotor and of the new continuously skewed rotor concept are performed. Continuously twisting the rotor active part around the magnet pockets leads to the need of adjusting the stray paths flanking the magnet pockets. The trade-off between minimizing leakage flux and maximizing mechanical strength is pointed out and the outcome additional mechanical stress FEA is shown. The impact of the stray paths and the skewing angle on the rotor air-gap flux density distribution is investigated in detail which leads to the evaluation of the resulting cogging torque of the different rotor concepts. Finally, guidelines for designing continuously skewed PM rotors using the possibilities of AM technologies can be derived.
Organisation(s): Institute of Drive Systems and Power Electronics
Type: Conference contribution
Pages: 662-669
No. of pages: 8
Publication date: 2020
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Energy Engineering and Power Technology, Electrical and Electronic Engineering, Mechanical Engineering, Control and Optimization
Electronic version(s): https://doi.org/10.1109/speedam48782.2020.9161932 (Access: Closed)

BibTeX

@inproceedings{cbaafa79e93b4e1292c03e946b20f87f,
title = "Effects of continuous rotor skewing in additively manufactured permanent magnet rotors",
abstract = "This paper describes the effects of skewing the rotor of a permanent magnet synchronous machine (PMSM) with buried magnets by torsion of the soft-magnetic rotor active part and maintaining the magnet pockets axially straight. The impact of this approach on the mechanical and the electromagnetic design of the rotor active part is presented. In the end, the approach leads to a reduced cogging torque with simultaneously decreased leakage flux. Using conventional manufacturing technologies, e.g. punching or laser cutting, skewing the laminated soft-magnetic rotor active part and maintaining the magnet pockets axial straight would lead to a variety of lamination cross sections. The presented approach can hence be realized usefully by means of Additive Manufacturing (AM) technologies.Therefore, a short review of metal-additive manufacturing in the field of electric machines and the common practice of skewing in PMSMs is given in a first step. After this, a PMSM with barshaped buried magnets was chosen to serve as reference. 3D electromagnetic finite element analyses (FEA) of the non-skewed reference machine, of a conventionally step-skewed rotor and of the new continuously skewed rotor concept are performed. Continuously twisting the rotor active part around the magnet pockets leads to the need of adjusting the stray paths flanking the magnet pockets. The trade-off between minimizing leakage flux and maximizing mechanical strength is pointed out and the outcome additional mechanical stress FEA is shown. The impact of the stray paths and the skewing angle on the rotor air-gap flux density distribution is investigated in detail which leads to the evaluation of the resulting cogging torque of the different rotor concepts. Finally, guidelines for designing continuously skewed PM rotors using the possibilities of AM technologies can be derived. ",
keywords = "Additive Manufacturing, Finite Element Analysis, Permanent Magnet Synchronous Machine, Skewing",
author = "Stefan Urbanek and Ralf Keuter and Emma Peter and Bernd Ponick",
note = "Funding Information: This work was supported by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG).; 2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion, SPEEDAM 2020 ; Conference date: 24-06-2020 Through 26-06-2020",
year = "2020",
doi = "10.1109/speedam48782.2020.9161932",
language = "English",
isbn = "978-1-7281-7018-3",
pages = "662--669",
booktitle = "2020 International Symposium on Power Electronics, Electrical Drives, Automation and Motion, SPEEDAM 2020",
publisher = "Institute of Electrical and Electronics Engineers Inc.",
address = "United States",
}