Effects of magnetic slot wedges on electromagnetic parameters and performance of MW-class high-voltage flame-proof motors
Jinhui Liu, Yujin Peng, Hongrui Deng, Xiaobo Sun, Minghui WangBackground
With the continuous upgrading of global energy efficiency standards, high-efficiency high-voltage motors have become dominant in the market. However, the open slots of stator cores in such motors lead to uneven air-gap permeability, reducing motor efficiency and causing electromagnetic vibration, which affects operational reliability.
Objective
This study aims to investigate the impact of replacing conventional insulating slot wedges with magnetic slot wedges on the electromagnetic performance, losses, and vibration characteristics of a 1.4 MW high-voltage flameproof asynchronous motor, providing a basis for the proper selection and application of slot wedges.
Methods
A two-dimensional transient magnetic field finite element model was established, and a field-circuit coupling method was applied. Comparative analyses were conducted on magnetic flux density, magnetic field distribution, speed and torque response, current response, and air-gap magnetic field harmonics for both conventional and magnetic slot wedges. The influence of magnetic slot wedges on motor parameters such as air-gap coefficient, tooth harmonics, stator slot leakage reactance, maximum torque, no-load current, starting performance, and various losses was quantitatively evaluated.
Results
The results indicate that magnetic slot wedges effectively improve the distribution of air-gap magnetic flux density, reduce harmonic content and amplitude, decrease no-load current and additional losses, and enhance motor power factor and efficiency. However, increasing the magnetic permeability of the slot wedges reduces the maximum torque and starting torque of the motor.
Conclusions
Magnetic slot wedges can significantly optimize the electromagnetic performance and reduce losses in megawatt-level high-voltage flameproof motors. Nevertheless, their negative impact on torque characteristics must be considered. Comprehensive evaluation of electromagnetic parameters and performance is essential for the appropriate application of magnetic slot wedges.