Co-simulations of induction machines coupled with a radial ball bearing for mechanical defects analysis

In this paper, two co-simulations are introduced to study the behaviour of a 2-D finite-element model and a magnetic equivalent model of an induction machine, both coupled with a mechanical radial ball bearing model. This comprehensive approach allows for the generation of synthetic vibration and current signals of a ball bearing mounted on a shaft, taking into account the entire machinery. The study investigates the misalignment effect caused by an inner ring defect in a ball bearing, analysing its impact on the current of the IM models. Likewise, the effects of eccentricity in the induction machine models on rotor vibration are studied through their coupling with the mechanical ball bearing model. This multiphysics co-simulation provides a novel numerical application to generate data relative to mechanical defects in induction machines. By using this coupled method, an inner ring defect of 1 mm depth and 3 mm length in the bearing model is accurately identified in the frequency spectrum of the stator current, whereas eccentricity faults for levels ranging between 5% and 40% are detected in the vibration spectrum of the ball bearing. The findings are accurately supported by related theory, and further validated through experimental verification for the case of the inner ring fault.