Air gap fields and pressure waves in closed-slot cage rotor induction motors

This paper describes an investigation into the effect that employing closed rotor slot designs in squirrel cage induction motors has on the air-gap flux density waves, and hence on the radial pressure waves acting on the stator. The method of analysis is firstly described, followed by tables of results which illustrate the effect of progressively closing the rotor slot and increasing the bridge depth. The results are presented in terms of the radial pressure waves, and changes to the over-all machine performance. The trends seen in the results are accounted for, and overall conclusions drawn about the possible advantages and disadvantages of using closed rotor slot designs