A Post-Assembly Magnetization Method for a Line-Start Permanent-Magnet Motor

A surface-mounted permanent-magnet (PM) synchronous motor with a novel structure is presented. It has the merits of line-start, and its PMs can be magnetized postassembly. It has additional copper bars at the two sides of PMs to serve as the rotor cage of an induction motor to allow it to produce self-starting torque. After the motor is assembled with the PMs before magnetization, the copper bars are then used ingeniously as the excitation coils to magnetize the PMs. No special magnetizing fixtures are therefore needed. A time-stepping finite-element method, which can simulate the dynamic magnetizing process, is used to compare the performance of different designs and determine also the parameters of the magnetizing circuit. The performance of the proposed motor is verified by numerical computation.