Modeling and simulation of line start permanent magnet synchronous motors with asymmetrical stator windings

Line start permanent magnet synchronous motors (LSPMSMs) are now being widely used in the industry because of their attractive features such as, high efficiency, high power factor as well as high power density. Accurate modeling of LSPMSMs is the first step in recognizing abnormalities in such motors. This paper presents a step towards an accurate mathematical modelling of LSPMS motor under asymmetrical stator windings condition. The developed mathematical model has been implemented using MATLAB/SIMULINK. A 4hp, 4-pole, 380V LSPMS motor is used in the simulation of the developed model to investigate the performance of the motor under different loading levels and stator winding asymmetric conditions. Simulation results show that under asymmetrical stator winding oscillation are clear in the electromagnetic torque. In addition, due to this asymmetry in stator windings, the torque experience high oscillations at steady state when compared to the transient period.

I. Introduction

High efficiency motors are being gradually exerted in many industrial applications of developed countries because of their positive impacts on the environment (reducing energy consumption and CO2 emission). The efficiency improvement of induction motors, which are the majority of the motors used in industry, was tried through an optimal design of induction motors [1]. However, it is difficult to improve the induction motors efficiency significantly due to its inherent limitations. In industrial applications, especially in oil and gas plants, induction motors are being gradually replaced by high efficiency permanent magnet motors, called line start permanent magnet synchronous motors (LSPMSMs). LSPMSMs have significant advantages over induction motors, namely: higher efficiency, higher power factor, higher torque and power density [2], [3].