End Ring Resistance Calculation for Line-Start Synchronous Reluctance Machines with Non-Standard Rotor Cage Geometries

Abstract:
Modern designs of Line-Start Synchronous Reluctance Machines include geometries where the rotor bars are placed within the empty areas of the flux barriers. Compared to standard Induction Machines, this results in a highly deformed cage geometry where adjacent rotor bars have different shapes and can be very deep. When trying to parameterize the end rings of this type of cage for circuit-coupled 2D Finite Element Analyses or models with distributed parameters, it becomes a huge challenge. Most known analytical or 2D numerical approaches either fail or are too complex to implement. Hence, this paper proposes a 3D Finite Element assisted approach for calculating the resistances of the individual ring segments. The influence of the skin effect in the rotor bars on the ring parameters is also investigated by applying a multi-layer model. The method is validated with locked rotor measurements for two different Line-Start Synchronous Reluctance Machines.