| Permanent magnet(PM)machines have a series of excellent performances such as high power density,high efficiency,wide speed range,and fast response ability,which have a good application prospect.However,PM machines have rich magnetic field harmonics in the air gap.The interaction between the spatial and temporal magnetic harmonics produces profuse harmonic spectrum distribution of electromagnetic force,which has a significant impact on the electromagnetic vibration performance of PM machines.The traditional vibration analysis model for PM machines equates the stator to a cylindrical structure,which makes it difficult to consider the stator teeth modulation effect on electromagnetic force and vibration,resulting in large calculation errors in electromagnetic vibration of PM machines.Hench the traditional vibration analysis model is difficult to accurately guide the optimal design of electromagnetic vibration of PM machines.Therefore,the innovative research around the electromagnetic force modulation mechanism and electromagnetic vibration suppression design of PM machines are carried out in this paper.The basic characteristics of electromagnetic force and vibration in PM machines are explored,the mechanisms of electromagnetic force modulation effect and multiple types of excitation forces on electromagnetic vibration under different operating conditions are revealed.The impact of structural parameters of PM machine on electromagnetic force and its modulation effects are researched,and the internal relationship and constraints between electromagnetic force harmonics and torque quality are analyzed.A collaborative design method for electromagnetic vibration suppression and torque quality improvement are proposed,and the universal rules for the design of high-quality,low-vibration PM machines are summarized.The main research findings of this paper are as follows:(1)The mathematical model of the air gap magnetic field of PM machine is established,and the temporal and spatial distribution of the air gap magnetic field is explored.The mathematical expressions of electromagnetic force under no-load and load conditions are derived,and the mapping relationship between air gap magnetic field harmonics and electromagnetic force is explored.A mathematical model for electromagnetic vibration of PM machines is established,and the mechanism of the "three elements" of electromagnetic force space-time harmonics on electromagnetic vibration is revealed.(2)Based on the Shannon sampling theorem,a theoretical model of electromagnetic force modulation effect for PM machines is established,and the modulation mechanism of highorder electromagnetic force to low order electromagnetic force is revealed,In addition,the influence of magnetic field modulation effect,armature reaction magnetic field,and tangential electromagnetic force on electromagnetic vibration under different operating conditions is investigated,and a refined analysis model for electromagnetic vibration of PM machines is established.(3)The influence of dual three-phase winding structure and its phase shift angle on the electromagnetic force and vibration of PM machines is investigated,and the mathematical expression of phase shift angle on the armature reaction magnetic field and electromagnetic force is derived.A design method for electromagnetic vibration suppression of PM machines based on dual three-phase winding with phase shift structure is proposed.The effectiveness of vibration reduction measures is verified using finite-element method and experimental method.(4)The influence mechanism of the structural parameters of PM machines on the main excitation sources is explored,and the effect of electromagnetic force modulation on different slot-pole combinations of PM machines is revealed.Corresponding technical measures are proposed from three aspects: stator slot opening width,stator tooth number,and slot opening position to suppress the main excitation sources,and effective suppression of electromagnetic vibration of PM machines is achieved.(5)The influence mechanism of rotor PM structure on electromagnetic force and vibration is explored.According to the mechanism of harmonic magnetic field on electromagnetic vibration of PM machines with different winding structures,PM segmented technology and PM shaping technology based on electromagnetic force modulation are proposed to optimize the electromagnetic vibration performance of PM machines.The research on electromagnetic force and vibration of consequent pole PM machines is carried out,and the generation mechanism and suppression methods of unbalanced electromagnetic force are summarized.The effective improvement of electromagnetic vibration performance of consequent pole PM machines is achieved. |
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