This study investigates partial demagnetization faults arising from stator interturn faults in a surface-mounted permanent-magnet-type brushless direct current motor. Because of rotor demagnetization, the fault severity increases significantly owing to an increase in the stator phase current and temperature. The effect of such a fault is reflected in machine parameters such as the motor back-EMF and radial magnetic flux, which are used to analyse the characteristics of faults. A mathematical model of a machine under possible fault conditions is developed using the finite element method and advanced hybrid model approaches. Experimental investigations are conducted to validate the proposed methodology. Subsequently, the machine parameters used for fault diagnosis are employed to develop an online expert-based system that can detect, classify and estimate the percent increase in the values of the parameters to determine the fault severity of the machine under fault conditions. It is discovered that the proposed approach is suitable for industrial and commercial applications in electric vehicles, where the machine's state-of-health estimation is crucial for avoiding major faults that may result in its failure.
INTRODUCTIONPermanent magnet (PM) synchronous machines, such as brushless direct current (BLDC) motors, are widely deployed in commercial and e-mobility applications, including electric vehicles (EVs). PM synchronous machines comprise high-flux density PMs that are placed either on the surface or interior of the machine rotor. Among the many available PM machines, BLDC motors are preferred because of their simple compact structure, which is characterized by a high torque-to-weight ratio, an efficient power/torque density, and a highly dynamic performance [1,2]. The placement of rotor PMs in the machine depends on the motor type, i.e., surface-mounted permanent magnet (SPM)-type or interior permanent magnet (IPM)-type BLDC motors [3,4]. When the rotor PMs are directly exposed to the air gap and stator teeth, the SPM-type BLDC motor is more susceptible to physical and thermal variations in the machine during operation. Consequently, this results in rotorThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.