The study of a periodic signal energy flow between adjacent frequency bandwidths in a diagnostic system of an induction motor

The paper presents results of a research study on the nature of energy flow of an axial flux signal of an induction motor between two adjacent frequency bandwidths in steady-state and depending on the machine load. Existing periodic energy flows of this diagnostic hamper both fault or damage detection and identification. To ensure a sufficient resolution of diagnostic systems it is required to separate flow effects from fault symptoms. Also, separating the effects requires the application of advanced time-and-frequency domain methods. In this paper the authors present the application of narrowband wavelet filters that are based on the family of orthogonal Legendre polynomials. The authors developed wavelet orthonormal basis based on recursive formula generating higher order Legendre polynomials. For the scaling function that was designed based on the scaled polynomial, a synthesis of the fundamental wavelet followed by a synthesis of the orthonormal fundamental wavelet set was carried out. The analysis results confirmed that it is possible to ensure a sufficient level of selectivity of a diagnostic system.