Broken rotor bar fault detection — A virtual current approach combined with a robust linear parameter-varying observer

Abstract

This work presents a method for detecting broken rotor bar (BRB) faults in induction motors (IM). The method is based on the Virtual Rotor Current (VRC) estimation, an approach that considers an additional virtual winding in the rotor modeling, concentrating any unbalance on the rotor circuit. Using Linear Parameter Varying (LPV) $H_{\infty }$ robust observer, the VRC is estimated, providing relevant information about the fault condition. The main contribution of the paper is the innovative estimation of the VRC and its analysis to extract information about the IM condition. The paper presents the IM fault modeling, the $H_{\infty }$ LPV observer development, and the fault index definition. The method is validated using simulated and experimental data for steady-state line-connected IMs, both for incipient and severe fault conditions under different load configurations and voltage unbalance, demonstrating its ability to detect faults in a wide operational range, including low load levels.