The Influence of Second Air-Gap Length on the Performance of 10 kV, 1000 kW Permanent Magnet Synchronous Motor

Background: The influence of the second air-gap length on the performance of permanent magnet synchronous motor is usually ignored. A comparative analysis is made of line-start high-voltage permanent magnet synchronous motor in this paper. Objective: The purpose of this paper is to analyze the influence of the second air-gap length on the motor performance. Methods: A 10kV 1000kW permanent magnet synchronous motor is taken as an example and the model is established based on the finite element calculation method when the second air-gap length is different. The influence of the second air-gap length on the phasor diagram, no-load back electrodynamic force, starting performance and steady-state operation performance are studied. Based on the finite element calculation method, the torque angle, current, power factor, external power factor and d/q-axis current of the motor are analyzed, and the change of the motor phasor diagram is obtained. The influence of the second air-gap length on the no-load back electrodynamic force is studied. Results and Conclusion: The relationship between the no-load back electrodynamic force and the no-load air-gap fundamental magnetic field is determined, and the influence mechanism of the noload air-gap fundamental magnetic field on no-load back electrodynamic force is revealed. Furthermore, the influence of the no-load back electrodynamic force on the starting performance is studied. Finally, the influence of the second air-gap length on the 10kV 1000kW permanent magnet synchronous motor steady-state performance is obtained. Based on the above analysis, some references are given for the design of motor.