Speed Estimation of Six-Phase Induction Motors, Using the Rotor Slot Harmonics

Abstract

Multiphase machines have recently been promoted as a viable alternative to traditional three-phase machines. Most experts are looking for strategies to estimate the rotation speed of such complex systems, since speed data are required for high-performance control purposes. Traditionally, electromechanical sensors were used to detect the rotor speed of electric motors. These devices are extremely accurate, but they are also delicate and costly to deploy. New speed estimating algorithms must be created for these situations. This paper looks at how to estimate rotor speed in symmetrical six-phase induction motors (IMs) using a novel strategy for rotor speed estimation based on the Short Time Fourier Transform (STFT) method. The technique is based on tracking the frequencies of the rotor slot harmonics (RSH) seen in most squirrel-cage IM stator currents, thus assuring a broad range of applications. To monitor the RSH, the STFT employs a sliding window to perform the discrete Fourier transform technique, making it more suitable for online use with noisy and nonstationary signals. Experimental tests demonstrate the effectiveness of the suggested approach.

Review of speed estimation algorithms for three- phase induction motor

“…There are two computation procedure suggested for the speed sensor-less estimation. The first one is rotor speed computation procedure [ 54 , 65 , 69 ]. It depends mainly on motor model equations.…”

“…Because of the reluctance modulation caused by the existence of rotor slots, the techniques in this category are dependent upon the concept that the speed of rotor is calculated from the ripple created in the voltages and currents of stator [ 54 , 55 , 77 , 58 ]. When modeling the induction machine, the air gap length variable can be used to account for the rotor slot's presence.…”

“…Band-pass filters are used to pre-filter the stator currents and voltages, and the center frequency may be tuned to the harmonics of the rotor slots [107] . High performance speed estimation is effective in getting rid of usual sensor failures, through the rotor slot harmonic (RSH) based method that featured for parameter mismatch robustness [ 51 , 53 , 54 , 58 , 58 ].…”

“…Due to the ripple in the voltages and currents of stator caused by the modulation of reluctance brought on by existence of rotor slots is used to calculate the rotor speed. The third technique depends on high frequency signal (voltage or current) injection at machine terminals [ 45 , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] ]. A test signal is introduced into the motor windings, and the response is then observed.…”

Rotor speed estimation for half-broken bar detection in induction motors using Kalman filtering

“…These variables have been used individually or in combination to analyze information and to detect anomalies when the fault has progressed to an advanced stage [14]. Recent studies have demonstrated the effectiveness of speed measurements for detecting IM faults at an early stage of its evolution [15][16][17]. Speed monitoring provides a signal with no oscillating principal component, which improves signature analysis as it is not affected by spectral leakage.…”