This work presents a method for the robust detection, classification and possible compensation of harmonics in electric drives during real-time operation, with the aim of providing a framework for monitoring and diagnostic without the need of additional hardware. The detection is performed with a sparse fast Fourier transform algorithm, for its lower computational effort when the signals are sparse (which, by definition, contain few meaningful spectral lines). The classification is performed on the results of the signal frequency analysis by means of the Mahalanobis distance concept, improving the robustness and noise rejection properties of the method. The compensation part relies on a family of regulators in parallel, each operating in the rotating reference frame of the harmonic to be cancelled. The theoretical background is followed by a discussion on the implementation and the interaction of the three blocks for a successful real-time operation. The system was tested in laboratory and proved to fulfil the requirements, by running in parallel to a vector control for synchronous machines. It was also found that the method is a useful tool to determine the presence of unknown harmonics in an electric drive system, thus potentially providing early warnings of unexpected failures.
A comparative analysis of various techniques for pulse width modulation (PWM) of asymmetrical six-phase permanent magnet synchronous machine (PMSM) is presented in this paper. An asymmetric six-phase PMSM consists of two sets of three-phase winding groups spatially displaced by 30 0 . A current control architecture based on a vector space decomposition (VSD) approach has been utilized for control of PM machine, having individual current controller in each harmonic plane. The output voltage references from current controllers is then used for PWM generation. Various PWM methods from literature, which have been proposed for two-level converter-fed six-phase machines, are then reviewed and most promising 12 and 24 sector SVPWM methods are implemented in the above control architecture. Most common industrial adaptation of six-phase drives consists of two independent three-phase drive units configured to supply two three-phase winding sets. In such situation, it can happen that these drives can have their own independent three-phase modulators synchronized to its own clock. Problems can arise due to independent operation of these two sets of drives while controlling a six-phase machine due to lack of synchronization between these two modulators as well as non-synchronous sampling of machine currents. The main objective of this paper is to compare the performance of above PWM modulators with respect to different situations considering synchronization between reference signals to modulators as well as synchronization between sampling of phase current of two drives.
This paper discusses the use of the Mahalanobis distance as a solution for a robust and automatic segregation of harmonics in the signals measured in electric drives, as for example the phase currents or the mechanical speed. The Mahalanobis distance is used during real-time operation to clean the results of an on-line frequency analysis, reducing the uncertainties related to frequency resolution, spectral leakage and background noise. At the same time, it is a powerful tool to classify the known harmonics from the unknown ones, thus providing the drive with valuable information that can be used for further decisional control actions. The overall theoretical background is reviewed as well as its implementation in an operational drive system. Experimental results are provided, proving the validity of the concept.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.