Investigation of the unbalanced magnetic pull damping effect in squirrel cage induction machines

摘要

The unbalanced magnetic pull (UMP) in electrical machines is due to the existence of additional $p pm 1$p +/- 1 magnetic flux waves. When squirrel cage induction machine (SCIM) running below its rated slip, most of the additional magnetic flux waves can be damped by the counteracting flux waves produced by its parallel-connected rotor bars. Here, this UMP damping effect is comprehensively discussed by comparing the UMP and the air-gap flux of SCIMs and wound rotor induction machines. Subsequently, a UMP damping coefficient is proposed to be included in the conventional UMP analytical model, in which the damping of UMP caused by the counteracting flux waves can be taken into account. Lastly, the UMP of SCIM at different excitation frequencies and rotor resistance are investigated to further verify the UMP damping effect.