Stator current envelope extraction for analysis of broken rotor bar in induction motors

This paper introduces an alternative tool for stator current envelope extraction in induction motors (IMs) aiming for identifying broken rotor bar (BRB). A new time-domain signal processing algorithm using second order generalized integrator-adaptive notch filter (SOGI-ANF) is introduced for online extraction of both steady state and transient envelopes. The adaptive nature and the structural simplicity of the SOGI-ANF as well as its low cost and low computation burden characteristics make it highly suitable for hardware implementation using embedded devices. The superiority of the SOGI-ANF over traditional Hilbert transform-based methods is its adaptive nature which allows accurate tracking of envelope variations. The analytical basis of the proposed method and its experimental verification using a STM32F4 discovery board are investigated. Finite element method (FEM) and experimental setup in the laboratory are also employed to demonstrate the adaptivity and performance of the SOGI-ANF in extracting the steady state and transient phase current envelopes.