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Condition monitoring of electric machines is a procedure of increasing importance, as fault tolerant systems are becoming mandatory in many applications. Early diagnosis of faults is a basic pillar in order to achieve full tolerance by the maintenance of faulty parts in electrical machines. As far as electrical drives are concerned, the share of mechanical faults (imbalances, gears and bearings) is...
Rotor fault diagnosis techniques developed for induction machines (IMs) are classically based on current spectral analysis (CSA). For the case of rotor asymmetry in Wound-Rotor Induction Machine (WRIM), the magnitude of the negative sequence component at -sf of the rotor current space-vector is commonly monitored in order to quantify its contribution. Nevertheless, CSA still has some limitations....
Fault detection in induction machines is commonly realized through motor current signature analysis. In case of Wound-Rotor Induction Machine rotor faults, the amplitude of the inverse sequence harmonic component -sf of the rotor current space-vector is monitored in order to sense its variation. However, motor current signature analysis is limited by some drawbacks. In fact, under transient operating...
This paper introduces a diagnostic technique for the detection of mixed Stator-Rotor electrical faults in Doubly Fed Induction Machine (DFIM) for wind power systems. Operating in aggressive environments, the detection of anomalies at an incipient stage is crucial to decide about the operating continuity of the machines. In this paper the behavior of DFIM is investigated under the assumption that the...
This paper investigates a new approach for the diagnosis of Rotor asymmetry in Wound-Rotor Induction Machines (WRIM). The method is assessed in a Wind Energy Conversion System, where the rotor side of the WRIM is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. The control system affects electric quantities and their signature...
This paper focuses on the diagnosis of induction motors in variable speed drives where the control variables are used for fault detection. After an overview of typical failure mechanisms and their causes, recent advances in the field are presented and discussed. To this aim some recent investigations, along with important and fundamental papers, are reviewed and reported in a comprehensive list of...
Multiphase permanent-magnet generators are an attractive alternative for a variety of emerging applications owing to their reliability and dynamic performance such as hybrid traction systems. In this context, diagnosing the status of the rotor magnets is crucial for improving the reliability of the generators. The effect of the closed-loop control system cannot be neglected when the fault detection...
Design of modern Wind Energy Conversion Systems (WECSs) must take into account two crucial aspects: efficient control strategies and reliable monitoring and diagnosis techniques. Wind turbine generators based on Wound Rotor Induction Machine (WRIM) is actually the preferred technology mainly because of the lower rating of the power converter connected to the rotor side. With the association of a back-to...
Design of modern wind farms, and more specifically for smart grids, must take into account two crucial aspects: efficient control strategies and reliable monitoring and diagnosis systems. Wind turbine generators based on Wound Rotor Induction Machine (WRIM) is actually the preferred technology considering the above purposes. With the association of a back-to back converter on the rotor side a Stator-Flux-Oriented-Control...
This paper investigates the detectability of mechanical unbalance in double cage induction motor load using motor vibration signature analysis technique. Rotor imbalances induce specific harmonic components in electrical, electromagnetical, and mechanical quantities. Harmonic components characteristic of this category of rotor faults, issued from vibration signals analysis, are closely related to...
High-resistance connections in electric drives can cause localized overheating and motor supply voltage unbalance, which degrade the performance, efficiency, and reliability of the system. An enhanced field oriented control scheme for induction machines that is capable of detecting resistive unbalance due to high resistance connections, and regulating the inverse sequence current is proposed as the...
This paper presents a new diagnosis approach for quantitative rotor faults evaluation in three-phase wound rotor induction machines. In the considered application, the rotor windings are supplied by a static converter for the control of active and reactive power flows exchanged between the machine and the electrical grid. Under speed or fault-varying conditions, the typical rotor fault frequency components,...
High-resistance connections in electrical machines cause unbalances in the stator resistances, reduce the efficiency and increase the fire hazard. In this paper the problem of detection of high-resistance connections is investigated for multiphase induction machines with an odd number of phases. The main contribution of the paper is a control scheme that can determine the stator resistance unbalance...
This paper investigates the detectability of rotor broken bars in indirect rotor flux oriented control (IRFOC) for variable speed double cage induction motor drives, using vibration signature analysis techniques. The Impact of the closed loop control system cannot be neglected when the detection of rotor asymmetries in the machine is based on the signature analysis of electrical or mechanical variables...
Multiphase Permanent-Magnet Generators are an attractive alternative to induction machines for a variety of applications owing to their reliability and dynamic performance, suited for emerging applications such as automotive or traction systems. In this context, diagnosing the status of the rotor magnets is crucial for improving the reliability of the generators. This paper is focused on the demagnetization...
The paper introduces diagnostic technique for the detection of intermittent stator High-Resistance connection in Wound Rotor Induction Machines. In this context, traditional Fourier Analysis (FA) fails to quantify the extend of fault propagation over time. To overcome this limitation a wavelet based analysis of rotor currents is here proposed in order to detect stator faults. This technique allows...
The paper investigates the diagnosis of rotor broken bars in field oriented controlled (FOC) double cage induction motor drives, using current and vibration signature analysis techniques. The Impact of the closed loop control system cannot be neglected when the detection of asymmetries in the machine are based on the signature analysis of electrical variables. The proposed diagnosis approach is based...
The diagnosis of rotor broken bars in induction machines (IMs) is commonly carried out by means of Motor Current Signature Analysis, i.e., by classical spectrum analysis of the input currents. Specifically in case of broken bars, the amplitude of the left and right sideband components of a phase current is monitored in order to sense their signature. However Motor Current Signature Analysis, based...
Advanced monitoring techniques leading to fault diagnosis and prediction of induction machine faults, operating under non-stationary conditions have gained strength because of its considerable influence on the operational continuation of many industrial processes. In case of rotor broken bars, fault detection based on sideband components issued from currents, flux, instantaneous control or power signals...
Fault-tolerant control strategies for quad-inverter based multiphase-multilevel converters are proposed and experimentally verified in this paper. Explicitly, the conversion scheme consists of four standard 2-level three-phase voltage source inverters (VSIs), able to supply a dual three-phase induction motor in open-end stator winding configuration (asymmetric six-phase machine), quadrupling the utility...
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