Performance analysis and fault modelling of high resistance contact in brushless DC motor drive

Abstract

High resistance contact (HRC) is a typical stator fault commonly found in motors. This fault is the result of insulation aging, poor artistry, and damaged surfaces due to corrosion. Consequently, unbalance in the stator current can occur and leads to the deteriorated performance of the motor in terms of torque and speed. HRC fault is emulated by inserting an additional resistance in one of the phases of the stator winding. The voltage equations of the three-phase star-connected BLDC motor with resistance imbalance are established in the machine variables. Based on asymmetry in the impedance of the motor, mathematical equations are formulated to evaluate the harmonics responsible for the motor's faulty operation. The performance of the motor is studied by analyzing the variation in stator current, back emf profile, electromagnetic/motor torque, and angular speed. Further, the mathematical expressions of dependent machine variables are developed in terms of fault parameters. These expressions demonstrate the deviations of machine variables from their expected values with an increase in fault resistance. Experimental and simulation analysis on 24V 480 W BLDC motor has been done, and the results were obtained to validate the proposed work.