Starting Performance Improvement of Line-Start Permanent-Magnet Synchronous Motor Using Composite Solid Rotor

Abstract

This paper presents a composite solid rotor designed to improve starting performance of the line-start permanent-magnet synchronous motor (LSPMSM). The rotor is mainly constituted by the solid steel which can inherently generate high starting torque. Moreover, the axial slots milled on the rotor surface deepen the flux penetration into core and a brass made cage attached to the rotor enlarges the eddy current density. With above promotions, the induction torque increases, and hence drives the motor to startup and synchronize under heavy load conditions. The enhanced starting capability by applying the proposed rotor for an LSPMSM is validated by the 2-D time-stepping finite-element method (FEM). To guarantee a well match with the 3-D construction where end effects occur, an equivalent circuit is built in the 2-D method to represent the uneven ring fractions. Simultaneously, considering the non-axial currents in core ends, conductivity of the solid-rotor segments in 2-D field is corrected by a multistep optimum-seeking technique. Calculation precision of the 2-D FEM covering end effects is certificated by the corresponding 3-D FEM with good results agreement.