Transient-torque analysis for line-starting permanent-magnet synchronous motors

Abstract

Using the analysis method for resolving the starting torque of line-starting permanent magnet (PM) synchronous machines with starting cage, the electromagnetic torque can be separated into two components, the driving ldquocage torquerdquo and the braking ldquomagnet torquerdquo. The correct saturation of the iron must be considered, when calculating the separate torque components. The sum of the two torque components exhibits a good agreement with the originally calculated starting torque with the Finite Element time stepping technique. This novel method also helps to have a better knowledge of the synchronization mechanism. Results are given for a two-pole prototype motor with PN=5 kW, nN=3000 min-1, VN=200 V, Y-connection.