A Hybrid Interior Rotor High-performance Line Start Permanent Magnet Synchronous Motor

This article describes the development of a line start permanent magnet synchronous motor with a rotor containing interior mounted magnets. The rotor is a hybrid of both circumferentially as well as radially magnetized magnets arranged so it produces consequent poles. Steady-state and transient performances of the line start permanent magnet synchronous motors have been analyzed by using time-stepping finite-element analysis. Simulation results show that the optimum performance of the rotor is achieved for a specific magnet volume, a substantial improvement on performances of all such rotors reported so far (based on the detailed study of all these rotor types). The hybrid rotor has improved the synchronous performance of the machine without degrading its starting characteristics when compared with an equivalent induction motor. Two experimental prototypes of the proposed design have been built in the laboratory, and their performances have been compared with the performance of a conventional line start permanent magnet synchronous motor having only circumferentially magnetized magnets in its rotor, as well as that of a standard induction motor of the same frame size and physical dimensions. The results indicate that the proposed hybrid interior rotor significantly improves machine performance.