Rotor Strength Analysis of FeCo-Based Permanent Magnet High Speed Motor

Abstract

To solve the problem of tension stress caused by centrifugal force and caused by high-speed operation of permanent magnet (PM) rotor, a FeCo-based PM rotor structure model is proposed. Based on the thick-walled cylinder theory, the uniform analytical calculation formulas of strain field, displacement field, and stress field of high-speed permanent magnet rotor are derived, and the stresses of FeCo-based PM and sleeve are obtained. The correctness of analytical calculation method (ACM) is verified by finite element method (FEM). Based on the derived analytical formula, the influence of static interference, sleeve thickness, rotating shaft, and PM thermal expansion coefficient on the strength of high-speed permanent magnet rotor is analyzed, and the mechanical design law of high-speed permanent magnet rotor is summarized. Alloy sleeves are usually fitted outside the high-speed permanent magnet rotor to protect the PM from damage. In order to ensure safe operation of PM rotor under hot rotating conditions, strength calculation and check of sleeve and PM must be carried out. Based on the characteristics of slender structure of high-speed rotor, a high-speed permanent magnet motor (HSPMM) with a rated power of 100 kW and a rated speed of 18,000 r/min was produced, and a continuous operation test was carried out to verify the validity of the above theoretical analysis.

A Novel Sleeve Design to Reduce the Eddy Current Loss of High-Speed Electrical Machines

“…Figure 8a shows that the eddy current is reduced more than other tapering numbers from T n = 14 to T n = 18. In the range of T n (10)(11)(12)(13)(19)(20)(21)(22)(23)(24), it was confirmed that the effect on the tapering model was not significantly affected when considering the number of slots. Figure 8b shows the minimum safety factor through mechanical stiffness analysis for each parameter.…”

“…As a result, the equivalent stress derived by equating the directional stress state to a scalar amount is used to assess the structure's safety. This equivalent stress is also referred to as von Mises stress [24], and is equivalent to a uniaxial tensile or compressive stress of a composite load from multiple directions. The expression for this is:…”

Comparative analysis of dual stator machines

“…The average UMF values of the investigated machines are also listed in It should be noted amount of UMF in any given electric machine can lead to unwanted vibration and noise in such machine and this is similar to the effect of torque pulsation (Sung et al, 2013) and (Shi et al, 2020). Moreover, the noise and vibration levels in an electric machine would be a function of the adopted magnetic core materials, as established in Hou et al, (2022). Furthermore, negative effect of magnetic forces could also be felt on the stator especially around its teeth; however, the magnitude of this effect can be reduced by adopting appropriate winding topology through improved winding factors (Farshadnia et al, 2018).…”

Influence of Electric Motor Manufacturing Tolerances on End-of-Line Testing: A Review

“…Conversely, the e-motor with the smallest magnet surface to generate active magnetic flux produced the lowest torque. Moreover, variations in magnet dimensions from tolerances affect the mechanical integrity and strength of the rotor structure, limiting the maximum safe operating speed [38].…”