Convective heat transfer prediction in disk-type electrical machines

Rasekh, Alireza; Sergeant, Peter; Vierendeels, Jan

doi:10.1016/j.applthermaleng.2015.08.093

Cited by 32 publications

(20 citation statements)

References 22 publications

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“…The key point in the thermal modelling is the introduction of analytical expressions for the convective heat transfer in disc type electrical machines which is developed in [7]. Here, the flow is characterised by the rotational Reynolds number…”

Section: B Thermal Modellingmentioning

confidence: 99%

“…The values of the coefficients can be found in [7]. As the analytical equations (6), (7) and (8) are used to express the convective heat flux at different boundaries in the machine, the thermal model can be simplified: 1) the model for the stator and the rotor can be separated; 2) due to thermal periodicity, only one segment of each is modelled.…”

Section: B Thermal Modellingmentioning

confidence: 99%

“…Therefore, this paper introduces a thermal modelling technique that reduces the full transient 3D-model, in which both Navier Stokes and thermal conduction equations are included, into a segment of the stator and the rotor where the conductive heat flux equations in the volumes are solved, and the convective heat fluxes at the boundaries are defined by means of analytical equations. These analytical equations are a function of two dimensionless numbers [7] and are based on computational fluid dynamics (CFD) analysis. In this CFD, gravity is included so that the whole machine has to be modelled.…”

Section: Introductionmentioning

confidence: 99%

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Coupled Electromagnetic and Thermal Analysis of an Axial Flux PM Machine

et al. 2015

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I. Introduction Due to their high torque density and an excellent efficiency, axial flux PM machines are favorable for vehicle propulsion and wind energy conversion. Although many effort was already done to simulate the electromagnetic properties of the machine using full 3D or multilayer-2D simulations, the work towards modelling of the thermal behavior is still very limited. As the disc-shaped rotors will operate as a fan during rotation, convective heat transfer in the air gap will have a major influence on the thermal design of the machine. Rather than performing full 3D combined fluid and thermal analysis, empiric analytical expressions based on CFD are used in this work to define the convective heat coefficient in different parts of the machine. The final thermal simulations are carried out for the stator and rotor individually, where only a segment needs to be modelled due to thermal periodicity. As a result, the use of this coupled modelling technique results in a significant decrease of the overall simulation time. The coupled electromagnetic and thermal modelling techniques are illustrated on a 4kW axial flux PM machine having the yokeless and segmented armature (YASA) topology. Finally, both the electromagnetic and thermal simulation results were validated on a preliminary prototype. II. Coupled Electromagnetic and Thermal Modelling In the first step of the analysis, the electromagnetic behavior of the machine is modelled. The results from the electromagnetic field computations are used to calculate the corresponding losses in post-processing. In a second step, these losses are used as the heat sources for the thermal simulations. As the axial flux PM machine has an inherent 3D structure, multilayer-2D simulations [1] are used to obtain the electromagnetic properties such as flux-linkage, back-emf and (cogging) torque. In postprocessing, the magnetic flux density pattern of the different layers in the core is used to calculated the core losses. The solutions for the air gap magnetic flux density pattern of each layer are combined and used for a time harmonic calculation of the eddy current losses in the permanent magnets [1]. Together with the Joule losses in the machine winding, the iron losses in the stator cores and eddy current losses in the PM's are used as the source terms in the thermal simulations. As the thermal process is particularly slow with respect to the electromagnetic one, the time average values of the losses are chosen as a source in the thermal model. Instead of using full 3D combined fluid and thermal analysis, empirical equations derived in [2] are used to model the convective heat transfer from each of the surfaces near the air gap region. Next to an empirical formula for the convective heat coefficients of each surface, an expression for the reference temperatures is also derived using dimensionless numbers. The reference temperature is the bulk fluid temperature of the domain near each surface which can be expressed as a function of the average stator, rotor and ambient temper...

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Section: B Thermal Modellingmentioning

confidence: 99%

Section: B Thermal Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coupled Electromagnetic and Thermal Analysis of an Axial Flux PM Machine

et al. 2015

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“…The smaller the equipment exergy destruction rate is, the less exergy dissipation and the better heat transfer performance are. The heat transfer performance of the motor can be estimated according to the exergy destruction . And the exergy destruction of the nodes in the model is calculated from

{\overset{•}{\overset{X}{true}}}_{i} = T_{in} {\overset{•}{δ}}_{i}

where

{\overset{•}{\overset{X}{true}}}_{i}

is the exergy destruction at node i and T in is an ambient temperature.…”

Section: Analysis Of Heat Transfer Characteristic By Second Laws Of Tmentioning

confidence: 99%

“…The heat transfer performance of the motor can be estimated according to the exergy destruction. 22,23 And the exergy destruction of the nodes in the model is calculated from…”

Section: The Calculation Of the Exergy Destruction Ratementioning

confidence: 99%

Heat transfer characteristic research based on thermal network method in submersible motor

Yang

2017

Int Trans Electr Energ Syst

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Summary A novel thermal network method is introduced to investigate the heat transfer characteristic of submersible motor in the paper. According to the special structure of motor and the related theories, the thermal network model is established. The equivalent thermal resistance in the model is calculated with improved empirical formula. And to improve the accuracy of the calculation, considering the influence of the manufacturing process on the temperature rise of the motor, the thermal‐contact resistance is introduced for the equivalent thermal resistance of different materials. The influence of oil flow in the inside and outside of the motor to the motor temperature rise is also fully considered, so Gauss‐Seidel method is used to realize temperature field and fluid field coupling. Each node temperature is solved by energy balance equation, and the second law of thermodynamics is introduced to analyze motor heat characteristic, so that it can improve motor performance by analyzing the entropy generation and the exergy destruction rate of motor. Finally, compared with the prototype temperature test, it shows that the calculated results are close to the test data. This method provides a certain basis for the motor heat transfer characteristic analysis.

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Thermal Analysis of a Canned SRM

Wang

Cheng

et al. 2018

Analysis and Mathematical Models of Canned Electrical Machine Drives

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Convective heat transfer prediction in disk-type electrical machines

Cited by 32 publications

References 22 publications

Coupled Electromagnetic and Thermal Analysis of an Axial Flux PM Machine

Coupled Electromagnetic and Thermal Analysis of an Axial Flux PM Machine

Heat transfer characteristic research based on thermal network method in submersible motor

Thermal Analysis of a Canned SRM

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