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Malcolm Mcculloch - One of the best experts on this subject based on the ideXlab platform.

  • prediction and measurement of the heat transfer coefficient in a direct oil cooled Electrical Machine with segmented stator
    IEEE Transactions on Industrial Electronics, 2018
    Co-Authors: Robert Camilleri, David A. Howey, Paul F Beard, Malcolm Mcculloch
    Abstract:

    The heat transfer coefficient (HTC) is a critical parameter that is required for accurate thermal modeling of Electrical Machines. This is often achieved from empirical correlations of ideal geometries or computational fluid dynamics (CFD) simulations. This paper presents a novel technique using double-sided thin film heat flux gauges for measuring the HTC from a direct oil-cooled Electrical Machine with segmented stator. While thin film gauges are often used in transient measurements of the HTC on gas turbine components, their application to Electrical Machines has been largely unexplored. This is the topic of this paper. Due to the large viscosity of the coolant, the transient technique was found to be inadequate and a steady-state adaptation for oil-cooled Machines was developed. This paper explores the challenges linked with this measurement technique when applied to oil-cooled Machines, and develops new nondimensional correlations of the Nusselt number with Reynolds number. These correlations are applicable to Machines with different geometries, flow, and coolant properties. The experimental results were compared to CFD simulations and existing pipe flow correlations. It is shown that these underpredict the HTC by approximately 60% at Re = 20. The discrepancy gradually decreases to around 10% at Re = 200.

  • Predicting the Temperature and Flow Distribution in a Direct Oil-Cooled Electrical Machine With Segmented Stator
    IEEE Transactions on Industrial Electronics, 2016
    Co-Authors: Robert Camilleri, David A. Howey, Malcolm Mcculloch
    Abstract:

    This paper presents a computationally efficient thermo-fluid model to predict the temperature and flow distribution in an oil-cooled Electrical Machine with a segmented stator. The Yokeless and Segmented Armature axial flux Machine was used as a case study in which a numerical model was set up and validated to within 6% of experimental results. The model was adapted to predict the temperature distribution of the segmented stator of a Machine, identifying the hotspot temperatures and their location. Changes to the flow geometry on the stator temperature distribution were investigated. It was shown how by carefully controlling the flow distribution in the stator, the temperature distribution is improved and the hot spot temperature is reduced by 13 K. This benefits the Machine by doubling the insulation lifetime or by increasing the current density by approximately 7%.

Robert Camilleri - One of the best experts on this subject based on the ideXlab platform.

  • prediction and measurement of the heat transfer coefficient in a direct oil cooled Electrical Machine with segmented stator
    IEEE Transactions on Industrial Electronics, 2018
    Co-Authors: Robert Camilleri, David A. Howey, Paul F Beard, Malcolm Mcculloch
    Abstract:

    The heat transfer coefficient (HTC) is a critical parameter that is required for accurate thermal modeling of Electrical Machines. This is often achieved from empirical correlations of ideal geometries or computational fluid dynamics (CFD) simulations. This paper presents a novel technique using double-sided thin film heat flux gauges for measuring the HTC from a direct oil-cooled Electrical Machine with segmented stator. While thin film gauges are often used in transient measurements of the HTC on gas turbine components, their application to Electrical Machines has been largely unexplored. This is the topic of this paper. Due to the large viscosity of the coolant, the transient technique was found to be inadequate and a steady-state adaptation for oil-cooled Machines was developed. This paper explores the challenges linked with this measurement technique when applied to oil-cooled Machines, and develops new nondimensional correlations of the Nusselt number with Reynolds number. These correlations are applicable to Machines with different geometries, flow, and coolant properties. The experimental results were compared to CFD simulations and existing pipe flow correlations. It is shown that these underpredict the HTC by approximately 60% at Re = 20. The discrepancy gradually decreases to around 10% at Re = 200.

  • Predicting the Temperature and Flow Distribution in a Direct Oil-Cooled Electrical Machine With Segmented Stator
    IEEE Transactions on Industrial Electronics, 2016
    Co-Authors: Robert Camilleri, David A. Howey, Malcolm Mcculloch
    Abstract:

    This paper presents a computationally efficient thermo-fluid model to predict the temperature and flow distribution in an oil-cooled Electrical Machine with a segmented stator. The Yokeless and Segmented Armature axial flux Machine was used as a case study in which a numerical model was set up and validated to within 6% of experimental results. The model was adapted to predict the temperature distribution of the segmented stator of a Machine, identifying the hotspot temperatures and their location. Changes to the flow geometry on the stator temperature distribution were investigated. It was shown how by carefully controlling the flow distribution in the stator, the temperature distribution is improved and the hot spot temperature is reduced by 13 K. This benefits the Machine by doubling the insulation lifetime or by increasing the current density by approximately 7%.

Tan-hoa Vuong - One of the best experts on this subject based on the ideXlab platform.

  • Study and improvement in the radio communication quality for rotating Electrical Machine
    Electrical Engineering, 2019
    Co-Authors: Sonia Ben Brahim, Jacques David, Ridha Bouallegue, Tan-hoa Vuong
    Abstract:

    The wireless communication for rotating Electrical Machines is beneficial for diagnosis purposes as well as real-time monitoring. The electromagnetic waves propagation characteristics inside Electrical Machine is rather delicate. So it will be interesting to find a dynamic tool adapted to our problem. The idea is to validate these propagation concepts with real signatures. The tool must then analyze the signatures of the received signal strength indication. These experiments have shown that the antenna rotation is a disturbance-causing factor of the signal transmission. Thus, in this paper, our aim is to analyze the electromagnetic wave propagation characteristics in rotating environments in order to obtain the optimum parameters and providing a strong theoretical support for radio monitoring system performance improvement. Therefore, our work will process the important parameter which is the path loss variation in rotating environments.

  • A Wireless On-line Temperature Monitoring System for Rotating Electrical Machine
    Wireless Personal Communications, 2017
    Co-Authors: Sonia Ben Brahim, Tan-hoa Vuong, Jacques David, Ridha Bouallegue, Maria David
    Abstract:

    Wireless communication can be a useful method to monitor the Electrical Machine as it provides the main characteristics of online signal processing. Our contribution in this current paper consists in studying a new system to monitor the rotating Electrical Machines based on wireless communication. The main objective of this system is to detect the temperature value of the squirrel cage induction Machine’s rotor, using the IEEE 802.11 protocol. However, the application of wireless communication inside the rotating Electrical Machines is not self-evident due to the fact that the electromagnetic compatibility problems between devices isn’t obviously guaranteed. So, in order to obtain a good reliability for wireless communication, the study of the electromagnetic field inside rotating Electrical Machine is essential. As a first step in this paper, we are going to focus mainly on the flux effect of the rotating Electrical Machine through the finite element method which offers so much information on the phenomena characterizing the Electrical Machine operation. This method proves that the high frequency domain transmitter won’t be disturbed by the low frequency existing flux inside the Machine. As a second step in this study, the proposed network system design is presented. Then, the communication protocol, the hardware design based on the transmitting chip Roving Networks (RN-171) as well as the software design are illustrated. Finally, the experimental results of the proposed system are investigated to validate its feasibility.

  • SoftCOM - Wireless communication to monitor the rotating Electrical Machines
    2015 23rd International Conference on Software Telecommunications and Computer Networks (SoftCOM), 2015
    Co-Authors: S. Ben Brahim, Ridha Bouallegue, Jacques David, Tan-hoa Vuong
    Abstract:

    Electrical Machine monitoring is important to protect motor from unexpected problems. Today, using wireless communication for Electrical Machines is interesting for both real time monitoring and diagnosis purposes. In this paper, our contribution is to study a new technique to monitor the rotating Electrical Machines using wireless communication IEEE 802.11. The protocol IEEE 802.11 is recommended for this type of applications because it provides a faster connection and better security. Using the application of wireless communication to monitor the rotating Electrical Machines is not self-evident, as the ElectroMagnetic Compatibility (EMC) problem between devices isn't necessarily guaranteed. So, a study of the electromagnetic field to obtain a good reliability for wireless communication is crucial. This paper studies the effect of the rotating Electrical Machine flux. This study, based on Finite Element Method (FEM) offers much more information on the phenomena characterizing the operation of Electrical Machines. Finally, the experimental results of rotating component are built to validate the feasibility of the proposed system and to study electromagnetic wave propagation characteristics of both stationary and rotating transmitter inside and outside Electrical Machine.

B. Streibl - One of the best experts on this subject based on the ideXlab platform.

  • Measurements and simulations of the convective heat transfer coefficients on the end windings of an Electrical Machine
    IEEE Transactions on Industrial Electronics, 2012
    Co-Authors: Martin Hettegger, B. Streibl
    Abstract:

    —The prediction of the thermal behavior of an elec-trical Machine in the design process basically depends on the used boundary conditions such as the convective heat transfer coefficient. Due to the complicated shape of the end windings, the heat transfer coefficient has to be identified empirically by using thermopiles as heat flux sensors placed at certain positions on the end windings, because an analytical derivation is not feasible. This paper presents the results of the measured values of the heat transfer on the end windings of an Electrical Machine. The gained coefficients are compared to the results obtained by numerical simulations using commercial software for computational fluid dynamics. The simulation results are discussed according to the validity of the gained heat transfer coefficient. The configuration of the simulation has been tested on a cylindrical shape in a cross-flow.

Jean-philippe Lecointe - One of the best experts on this subject based on the ideXlab platform.

  • Rotor Design for Reducing the Switching Magnetic Noise of AC Electrical Machine Variable-Speed Drives
    IEEE Transactions on Industrial Electronics, 2011
    Co-Authors: Jean-françois Brudny, Jean-philippe Lecointe
    Abstract:

    This paper is focused on the analysis of the acoustic noise of the magnetic origin emitted by ac Electrical Machine variable-speed drives. First, the principle of noise generation is presented as well as the method for taking into account the effects of the current harmonics on noise generated by the pulsewidth modulation supply. The experimental results for noise and vibrations are then presented. Afterward, the elements of the per-phase equivalent circuit for higher harmonic orders are identified. They show that usual assumptions to characterize that circuit are not applicable for high-frequency harmonics. The originality of this paper concerns the rotor design: A practical procedure to diminish the acoustic noise due to the switching is defined from the per-phase equivalent circuit. It is also shown that this design makes it possible to increase the Machine efficiency.