Sensorless Speed Estimation for the Diagnosis of Induction Motors via MCSA. Review and Commercial Devices Analysis

Abstract

Sensorless speed estimation has been extensively studied for its use in control schemes. Nevertheless, it is also a key step when applying Motor Current Signature Analysis to induction motor diagnosis: accurate speed estimation is vital to locate fault harmonics, and prevent false positives and false negatives, as shown at the beginning of the paper through a real industrial case. Unfortunately, existing sensorless speed estimation techniques either do not provide enough precision for this purpose or have limited applicability. Currently, this is preventing Industry 4.0 from having a precise and automatic system to monitor the motor condition. Despite its importance, there is no research published reviewing this topic. To fill this gap, this paper investigates, from both theoretical background and an industrial application perspective, the reasons behind these problems. Therefore, the families of sensorless speed estimation techniques, mainly conceived for sensorless control, are here reviewed and thoroughly analyzed from the perspective of their use for diagnosis. Moreover, the algorithms implemented in the two leading commercial diagnostic devices are analyzed using real examples from a database of industrial measurements belonging to 79 induction motors. The analysis and discussion through the paper are synthesized to summarize the lacks and weaknesses of the industry application of these methods, which helps to highlight the open problems, challenges and research prospects, showing the direction in which research efforts have to be made to solve this important problem.

The Use of Digital Twins in Finite Element for the Study of Induction Motors Faults

“…The currents in the frequency domain of the same phase, from the simulation of healthy TIM and with rotor failure, are shown in Figure 4. It is verified that, as described in [10,15,18,22,23,29,33,38,[46][47][48], the left sideband amplitude of the main frequency component of the faulty model was higher compared to the healthy one. Considering that the slip of the motor in question for such operating conditions is 4.28%, the increase in amplitude occurred in the region of the rotor fault frequency.…”

“…Thus, it was possible to verify the typical broken-bar faults signature in the stator current signal, which have already been previously reported by many papers in technical literature [10,15,18,22,23,29,33,38,[46][47][48].…”

“…It is worth noting that each fault diagnosis strategy has its advantages and limitations, some of which are considered invasive, as it is necessary to stop the machine operation for the installation of sensors. Due to this inconvenience, non-invasive fault diagnosis techniques, such as the motor current signature analysis (MCSA), have been highlighted in the technical literature [ 18 , 19 , 20 , 21 , 22 , 23 ], according to the notes in the next section.…”

“…The research [ 23 ] brings forward a study of the use of transient current to analyze the beginning of short-circuits between the induction motor stator windings turns. The proposed methodology extracts the second component of motor starting current signals transient envelope by principal component analysis.…”

“…Thus, most mechanical and electrical faults that can arise in an induction motor are detectable by current analysis [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. For these reasons, the current signature has become a practical parameter for detecting squirrel cage motor faults.…”