Mitigating Unbalanced Magnetic Pull in Induction Machines Using Active Control Method

Induction machines have become one of the most widely used motor types due to their simple structure, stable operation, and relatively low cost. During operation, the problem of unbalanced magnetic pull (UMP) arising from uneven air gaps is very common, which endangers the safe and stable operation of the unit. In this article, a UMP reduction method is proposed using an active control method, which utilizes the non-linear relationship between UMP and rotor slip. Meanwhile, an analytical model to find the slip with the lowest UMP is presented, by which the UMP can be reduced by controlling the excitation voltage. In addition, the problem of UMP surge when controlling the slip during the transient state is discussed.