Detection and Identification of Stator Inter-turn Faults and Demagnetization effects in Hybrid Analytical-Numerical model of a BLDC Motor using Electromagnetic Signatures

Abstract

During the continuous and loaded operations of Brushless Direct Current (BLDC) motors in heavy industrial applications, they are vulnerable to faults. Among various available faults, BLDC motors are more subjected to Stator Interturn Fault (SITF) in the stator and demagnetization of Permanent Magnets (PMs) in the rotor of the machine. The breakdown of winding insulation causes SITF leading the heavy flow of inrush currents damaging the stator windings. Consequently, the effect of high currents is reflected on the PMs which adversely affect its magnetizing characteristics. The cumulative effect stimulates the demagnetization effect in the machine. This paper shall aim in developing a hybrid fault model of a BLDC motor adopting the conventional analytical and numerical approaches. This novel fault modeling method viz. Hybrid Electrical Equivalent Circuit (EEC)-Numerical based approach shall be used to diagnose the SITF and demagnetization fault in the BLDC motor. The performance of the machine is investigated under healthy, SITF, demagnetization and combined fault effect of both SITF and demagnetization faults together. The adverse change in motor characteristic performance is investigated through the significant change in machine quantities like phase currents, back-EMF, electromagnetic torque, mechanical speed and magnetic flux density & flux lines. Moreover, the operation of the machine under both the SITF and demagnetization fault simultaneously shall draw an inference through the significant detectable changes to distinguish between the two types of respective faults.