Unbalanced magnetic forces in permanent magnet brushless machines with diametrically asymmetric phase windings
ABSTRACT A general analytical model, formulated in 2-D polar coordinates, is developed to predict the unbalanced magnetic force which results in permanent magnet brushless AC and DC machines having a diametrically asymmetric disposition of slots and phase windings. It is shown that the unbalanced magnetic force can be significant in machines having a fractional ratio of slot number to pole number, especially when the electric loading is high. The developed model is validated by finite element calculations on 9-slot/8-pole and 3-slot/2-pole machines.
Article: Effect of Pole and Slot Combination on Noise and Vibration in Permanent Magnet Synchronous Motor[show abstract] [hide abstract]
ABSTRACT: This paper investigates the effect of pole and slot combination on the vibration and noise in permanent magnet synchronous motor (PMSM). Two PMSMs that have the same performances but different pole and slot combinations are studied. A numerical analysis process for the vibration is introduced. First, by using the electromagnetic field finite element analysis (FEA) and Maxwell stress tensor method, the radial forces of these two motors are analyzed. In order to evaluate the effect of the radial force on the vibration, then the equivalent magnetizing current method is used to calculate the local force which then is employed in the mechanical FEA analysis. Finally, an experiment is processed to test the vibration and noise of these two motors, and verify the proposed analysis process. The effect of the pole and slot combination on the noise and vibration are revealed.IEEE Transactions on Magnetics 06/2011; · 1.36 Impact Factor
Conference Proceeding: Unbalanced Magnetic Pull in Fractional-Slot Brushless PM Motors[show abstract] [hide abstract]
ABSTRACT: This paper reports on an investigation into the unbalanced magnetic pull in brushless PM motors due to either magnetic asymmetry or rotor eccentricity. Several machines are investigated. These have different slot and pole number combinations. Some of the windings contain sub-harmonics and these are found to be more susceptible to UMP when there is rotor eccentricity and also to produce vibrating UMP. Consequent rotor poles are also found to produce high UMP under rotor eccentricity conditions.Industry Applications Society Annual Meeting, 2008. IAS '08. IEEE; 11/2008
Article: Force Calculations in 3-D Cylindrical Structures Using Fourier Analysis and the Maxwell Stress TensorIEEE Transactions on Magnetics 01/2013; 49(1):536 -545. · 1.36 Impact Factor