Electromechanical modeling of a motor–gearbox system for local gear tooth faults detection

Many of today's industrial applications are powered by electromechanical drives. Wind turbines, fuel based and hydroelectric generators or electric drivetrains are examples of these applications. Developing accurate models of these systems has attracted a significant interest in recent years, because it can help enormously to enhance their reliability and develop efficient maintenance strategies to avoid prominent failure modes. In this paper, motor–gearbox systems are investigated in their both mechanical and electrical aspects. An electrical model of an induction machine is coupled with a lumped parameter model of a two-stage gear system to build an integrated model of these systems. The coupling between these sub-models is realized in a way that allows to consider transient regimes. Furthermore, an improved potential energy method is used to determine the mesh stiffness of gear pairs considering actual gear shapes and an original method is proposed to refine stiffness curves based on the correlation measure with experimental measurements. The developed model is validated under varying operating conditions using vibration and electrical measurements and simulation results were in good agreement with experiment. Moreover, the model was investigated for the detection of gear tooth faults using both vibration and motor current signature analysis in time and frequency domains, the model response under faulty condition was satisfactory compared with the observed response.