抄録
A characteristics calculation of induction motors is rather complicated in closed-slot induction motors. The inductance of a closed-slot bridge, that is, its leakage reactance has been problematic due to saturation of a magnetic steel sheet at a bridge. In this paper, the inductance characteristics of a closed-slot induction motor are studied with an experiment and finite element method (FEM) analysis. In the experiment, the flux linkage of a model rotor was measured by a search coil and was compared with FEM results. The inductance of a closed-slot bridge and the other rotor leakage inductances of a closed-slot induction motor were also calculated with magnetic energy and magnetic co-energy obtained from FEM from slip 0.25% to 100%.
This paper makes it newly clear that a bridge inductance drastically increases around the rated speed of a closed-slot induction motor and it composes most of the rotor leakage inductance. In less than 60% speed, the bridge inductance is about half of the rotor leakage inductance. The bridge inductance of a closed-slot rotor also has a peak in small bar current region as the magnetic permeability of a magnetic steel sheet has a peak value.
