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Connection of an LC filter to the output of voltage source inverter (VSI) in squirrel cage induction motor (SQIM) drive converts the pulse-width modulated (PWM) voltages into smooth sinusoidal voltages. However, this connection may lead to closed-loop instability in the rotor flux-oriented (RFO) vector-controlled (VC) SQIM system. The closed-loop stability of the combined SQIM + LC filter (SQLC) system is complex and has not been analyzed properly in the literature. In this paper, a detailed closed-loop stability analysis of the SQLC system has been presented based on stability region (SR) and accordingly the PI gains of VC has been designed. The SR method is adopted to derive the common stability regions for the SQIM system and SQLC system. Thereby, the paper proves that connecting an LC filter in-between the VSI and the SQIM system does not always destabilize the closed-loop system. Further, for an SQLC system, the complete range of current controller gains is obtained at various operating points. The frequency-domain specifications have been used to select a proper stabilizing set and the effect of parametric variation of LC filter on the stabilizing set has also been discussed. The experimental results are provided to validate the analysis. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new method for an online electric parameters identification of an induction motor (IM). This method is carried out in the IM standstill configuration and uses adaptive linear neuron (ADALINE) networks. In order to simplify the identification process, the IM model is approximated by two first-order subsystems: one is valid at low frequencies (LFs), called the slow system and the other is valid at high frequencies (HFs), called the fast system. By means of two ADALINE networks, the parameters of the slow system and the fast system are identified in LFs and HFs, respectively, and thus, the required IM parameters are derived. Finally, experimental results are presented in order to validate the proposed method and to check the accuracy of the obtained parameters. The originality of this paper is the building of a model representation that is suitable for implementation with ADALINE networks. This leads to a simple implementation and ease of parameters identification. [ABSTRACT FROM AUTHOR]

This paper investigates the opportunity for energy saving in a three-phase induction motor (IM) driving pump load and proposes an improved loss model control (LMC). Compared with other power-loss reduction algorithms for IM, the presented one has the advantages of fast and smooth flux adaptation, high accuracy, and versatile implementation. The performance of LMC depends mainly on the accuracy of modeling the motor drive and losses. In this paper, the derived loss model considers the surplus power loss caused by inverter voltage harmonics using closed-form equations and also includes the magnetic saturation. An artificial neural network controller is synthesized and trained offline to determine the optimal flux level that achieves maximum drive efficiency. The drive's voltage and speed control loops are connected via the actual stator frequency, making the scheme comparatively reliable. Simulation and experimental studies are performed on 5.5-kW test motor using the proposed control method. The test results are provided and compared with the fixed flux operation to validate the effectiveness. [ABSTRACT FROM PUBLISHER]

In the last decade, the use of PWM voltage-source inverters to control three-phase squirrel-cage induction motors has increased significantly. Consequently, high-frequency current activity in the bearings of inverter-fed motors and/or of devices mechanically coupled to their shaft is presently a common issue, ultimately shortening the bearings lifetime. In fact, bearing failures occurrence in inverter-fed motors increased dramatically in the last few years. Recently, the effectiveness of insulation-based bearing current mitigation techniques (e.g., bearings with insulated rings or ceramic spheres) and/or motor shaft grounding with an electric contact brush has been fairly investigated. However, there are some alternative high-frequency common-mode bearing current mitigation techniques requiring further investigation. In this paper, a stator slot-embedded partial electrostatic shield to reduce the capacitive coupling between the stator windings and the rotor in inverter-fed motors is proposed, analyzed, and implemented, being experimentally demonstrated its practicability and effectiveness in attenuating the common-mode voltage between the rotor shaft and the frame/ground, contributing to the reduction of high-frequency common-mode bearing current activity. [ABSTRACT FROM PUBLISHER]