Study On Starting Torque Of Line-Start Permanent Magnet Synchronous Motor

Textile machines are the essential and important production equipments for economic development and people's livelihood. In recent years, as motor technology continues to improve and energy-saving policies are issued, the low efficiency induction motors for textile will be gradually replaced by high efficiency and energy-saving permanent magnet synchronous motors. Due to light weight, easy maintenance and high power factor, line-start permanent magnet synchronous motors are widely used in the textile industry as the energy-efficient power equipments. In order to overcome the disadvantages such as heavy loads and high production costs, line-start permanent magnet synchronous motors should have high torque and high speed.For these reasons above, the paper designs a line-start permanent magnet synchronous motor (LS PMSM) with special-shaped rotor slots for textile. Because of this change in the structure, the motor parameters are changed in starting process, improving the motor starting torque performance. A 1.1kW, 4-pole LS PMSM is designed in this paper. First, the relationships between the torques and parameters are analyzed in the starting process, and parameters of the motor with special-shaped slots are calculated by using the equivalent magnetic circuit method. During the parameters calculation, the average calculation method on the special-shaped slots is proposed; magnetic flux leakage fields of slots are calculated by the finite element method, and the formulas of the upper leakage permeances per unit of two kinds of closed slots are obtained by the fitting method; the improved layer method is proposed to improve the accuracy of calculating slot leakage reactance. Then, a dynamic simulation on the motor is made by the Matlab software , and the Ansoft software is utilized to make two dimensional magnetic field finite element analysis on the torque, speed and other performance in motor starting process.By comparing simulation results with experimental data, these are proved that dynamic simulation program designed on special-shaped motor is correct; using the averaging method to calculate the special-shaped slots parameters is reasonable; the starting torque of the permanent magnet synchronous motor with special-shaped rotor slots is higher than that of traditional motor, that will bring benefits in improving efficiency and saving energy to textile motors.