Influence of unbalanced magnetic pull on the radial stability of flexible-shaft induction machines

An accurate assessment of the critical speed and the electromechanical damping is necessary to avoid the possibility of excessive vibrations and damage under operating conditions. Nowadays these problems are even more important, as the speed of induction motors may be varied using static inverters. 2-pole machines are very interesting when used with these inverters, because, f or a given frequency range of the inverter, the absolute speed range covered is twice the range of a 4-pole machine. Therefore the unbalanced magnetic pull and its relationship with the homopolar flux is analysed.