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Stator inter-turn faults are among the most important electric motor failures as they progress fast and lead to catastrophic motor breakdowns. Inter-turn faults are caused due to the windings' insulation degradation. The main stress which deteriorates the insulation is the thermal one. Proper understanding of how this stress influences the electrical properties of insulation over time may lead to...
Gallium Nitride (GaN) based devices on Silicon (Si) substrates (GaN-on-Si) promise unmatched performance at low cost. Despite this theoretical promise, the lattice and thermal conductivity mismatch between the GaN and Si has obstructed the realization of reliable electrically graded high voltage devices. Recently, a small number of manufacturers have claimed the successful development of such devices...
Machines in electric vehicles are driven by switching power electronic devices and undergo variable load cycling. In transient conditions high currents and temperatures develop, forcing the electric motor and particularly the insulation materials to undergo severe multi-stress. Insulation degradation will progressively lead to short-circuits which are harmful for the traction motor, vehicle safety...
This paper presents a novel protection technique for the detection of inter-turn faults in synchronous machines. It is based on the calculation of voltage in the stator windings from the usual phases and neutral voltage, typically available in all generator protection relays. The existing turn-to-turn protection mechanisms require additional voltage transformers. The main contribution of this technique...
Major recent developments in growth expertise related to the cubic polytype of Silicon Carbide, the 3C-SiC, coupled with its remarkable physical properties and the low fabrication cost, suggest that within the next five years, 3C-SiC devices can become a commercial reality. It is therefore important to develop Finite Element Method (FEM) techniques and models for accurate device simulation. Furthermore,...
Although induction motors are robust devices, faults may appear and so reliable and stable operation is required. More aspects need to be addressed nowadays in terms of condition monitoring. It is necessary to extract as much information as possible related to the overall motor condition and health. Also, different levels of diagnosis are required, as well necessity of detecting the fault level severity...
Thermal management of Axial Flux Permanent Magnet (AFPM) machines is essential because it determines the machine's continuous power output and reliability. Also, thermal management is required to avoid catastrophic failure due to degradation. To help meet this challenge, a secondary cooling method can be integrated into the rotor, which can yield improved machine performance and reliability. Thermal...
The reliable diagnostic of non-adjacent rotor bar breakages in induction motors based on the analysis of currents is still an unsolved industrial problem. The traditional MCSA has not proven to be robust enough for assessing the rotor condition under this situation; this is due to the fact that the joint effect of breakages located at certain relative positions can be subtractive rather than additive,...
Inter-turn stator short circuits can develop quickly leading to serious damage of an electric machine. However, degradation mechanisms of winding insulation are not yet fully understood. The main contribution of this article is analysis of the impact of thermal ageing on the electrical properties of winding insulation. The insulation samples have been aged thermally at 200–275 °C and for 100–1600...
The electric motor is the electric vehicle's heart. It is crucial that any occurring faults are detected promptly so that a catastrophic failure is avoided. At the same time, a deep knowledge of the degradation mechanisms is required to allow maximum performance at minimum cost. This paper focuses on this balance. Statistical results from measurements of unaged and accelerated aged winding insulation...
It has been noted that, in the induction motor the mechanical load oscillations can produce stator current spectrum harmonics, similar to the ones of the broken bar fault. As a consequence, these two different conditions have to be reliably distinguished. This paper proposes a new method aiming to this direction. More specifically, it is proposed to monitor the inherent eccentricity harmonics and...
It has been reported that the only-static and only-dynamic eccentricity cannot be reliably detected in induction motors which produce Principal Slot Harmonics (PSH) with the use of the traditional MCSA method. Most work was focused in the detection of dynamic and mixed, rather than static eccentricity. In this paper, the detection of the only-static eccentricity fault in Δ-connected induction motors...
The diagnosis of faults in induction motors is a crucial scientific subject since it affects the industrial production functionality and reliability. Lately, a new scientific area is born: the electrical machines prognostics. So, aiming to this direction the complete knowledge of all abnormal parameters during the induction motor operation should be identified. In this paper, a methodology is described...
In this work the influence of semi-magnetic stator wedges on the electromagnetic characteristics and the behavior of the induction motor is investigated. The study will be carried out using FEM analysis. The spatial and time-dependant electromagnetic variables of the motors will be studied. The analysis will reveal that the application of wedges decreases the higher harmonic content of the electromagnetic...
This paper consists a study of the influence of specific design parameters on the double-cage induction motor behavior. The study is carried out using FEM analysis. Three double rotor bar induction motors have been simulated and their electromagnetic characteristics are compared to each other. The differences in the three motors' design are: the first one has a single rotor cage and the other two...
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