Eccentric Rotors Research Articles

Calculation and measurement of unbalanced magnetic pull in cage induction motors with eccentric rotors. Part 1: Analytical model

The paper describes an analytical model for cage induction motors with a static eccentric rotor. The method is based on an airgap permeance approach including stator and rotor MMF harmonics. The stator windings are resolved into harmonic conductor density distributions that allow different series/parallel winding connections to be accommodated in a straightforward manner. Sinusoidal and homopolar airgap field components are identified and the total airgap field distribution is used to determine the radial forces on the rotor. The model examines the principal harmonic interactions that influence the unbalanced magnetic pull.

Harmonious and Transient Behavior of Rotors

The paper presents an analytical solution to predict the behavior of eccentric rotors, both during the transient motion as well as the conditions for self-synchronization. Hamilton’s principle is applied to predict the condition of self-synchronization of two rotors arranged in arbitrary configuration. The transient behavior of two electric motors with eccentric rotors is presented. It is shown that the motors may not attain the final operating speed and be locked at a resonant frequency of the system unless they possess sufficient power.

Radial Magnetic Pull in Salient Pole Machines with Eccentric Rotors

A new simple analytical method for radial magnetic pull force in salient pole machines with eccentric rotors is presented. Calculation results are verified by experiments. As this method presents the precise calculation of flux density in the air gap of the entire circumference and the saturation effect of magnetization, the estimation of radial magnetic pull has been improved.

Radial Magnetic Pull in Salient Pole Machines with Eccentric Rotors

Radial Magnetic Pull in Salient Pole Machines with Eccentric Rotors

Wear-induced profiles of brushes on eccentric rotors

Brushes in electrical machines are worn to a profile that is modified by rotor eccentricity. As a result, conventional values of applied contact force produce only fractional contact of the nominal interface area. The local contact position shifts as the rotor turns, to include the entire brush face in the wear process. The steady state profile is determined by two requirements: that the wear per cycle is equal for all points on the brush face and that the brush face is tangential to the rotor surface at the point of contact. These conditions are applied to two examples in the calculation of wearinduced brush profiles.

誘導電動機の偏心時主磁束分布の均一化作用

誘導電動機の偏心時主磁束分布の均一化作用

Unbalanced Magnetic Pull in Induction Motors with Eccentric Rotors [includes discussion

Unbalanced Magnetic Pull in Induction Motors with Eccentric Rotors [includes discussion