A Modeling Approach for Gearbox Monitoring Using Stator Current Signature in Induction Machines

The gearbox monitoring using motor current signature analysis has been rarely proposed while gearboxes are widely used in the industrial applications and they are subjected to progressive deterioration. In this paper, a simple dynamic model of a single stage gearbox is used to show accurately the effect of the rotating input, output and mesh frequency components in the stator current signature for induction machine-based electromechanical systems. With this model, the influence of the transmission error and of the eccentricities of pinion and wheel is shown in the stator current spectrum and it gives an accurate location of the gearbox input and output rotating frequencies. In the same way, the influence of the pinion-wheel teeth contact stiffness variation, which is at the origin of the mesh frequency components in the stator current signature, is demonstrated even for a healthy gearbox. In order to validate the proposed model, a test-bed based on a wound-rotor 4kW three-phase induction machine connected to a gearbox has been used.