Numerical and Experimental Investigation of Heat Flow in Permanent Magnet Brushless DC Hub Motor

Fasil, Muhammed; Plesner, Daniel; Walther, Jens Honoré; Mijatović, Nenad; Holbøll, Joachim; Jensen, Bogi Bech

doi:10.4271/2014-01-2900

Cited by 5 publications

(1 citation statement)

References 10 publications

(19 reference statements)

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“…These advanced cooling methods are not suitable for small outrunner motors such as PM brushless DC wheel hub motors (PMBLDC). Outrunner motor construction and application limits the use of complex cooling methods due to the restricted packaging space, so such motors mainly rely upon aerodynamic cooling [17]. The wheel hub motor cooling strategies are mostly focused on ensuring adequate heat dissipation from the electric coils to the ambient air by developing low thermal resistance paths.…”

Section: Introductionmentioning

confidence: 99%

A CFD-Based Numerical Evaluation, Assessment and Optimization of Conjugate Heat Transfer for Aerodynamic Cooling of a Wheel-Hub-Motors in Micro-Mobility Vehicles

Divakaran¹,

Gkanas²,

Shepherd³

et al. 2023

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Micro-mobility vehicles such as electric scooters and bikes are increasingly used for urban transportation; their designs usually trade off performance and range. Addressing thermal and cooling issues in such vehicles could enhance performance, reliability, life, and range. Limited packaging space within the wheels precludes the use of complex cooling systems that would also increase the cost and complexity of these mass-produced wheel motors. The present study begins by evaluating the external aerodynamics of the scooter to characterise the airflow conditions near the rotating wheel; then, a steady-state conjugate heat transfer model of a commercially available wheel hub motor (500W) is created using commercial computational fluid dynamics (CFD) software, StarCCM+. The CAD model of the motor used for this analysis has an external rotor permanent magnet (PM) brushless DC topology. Both internal and external fluid domains are considered to evaluate the combined flow dynamics and conjugate heat transfer from the windings (heat source) to the ambient air. At the maximum speed (482rpm) of the motor, for a total power loss of 180W (η=64%), a maximum temperature of 295°C is observed in the windings. Evaluating the thermal path shows that approximately 58.1% of the total heat generated in the winding is dissipated radially via convection through the air gap, and only 3.66% through the shaft via conduction. The thermal resistance for the shaft is in the range of 22-60 K/W and the rotor components is in the range of 0-2 K/W for the operational speed range of 0-1000rpm. Taguchi’s Design of Experiment (DOE) with Design manager study has been conducted to optimize the performance of design parameters (Fins and air-vents/<i>holes</i>) in cooling the motor. Air vents and external fins on rotor–lid (rotor <i>cover</i>) has a greater effect on cooling the motor than other design parameters.</div></div>

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Section: Introductionmentioning

confidence: 99%

A CFD-Based Numerical Evaluation, Assessment and Optimization of Conjugate Heat Transfer for Aerodynamic Cooling of a Wheel-Hub-Motors in Micro-Mobility Vehicles

Divakaran¹,

Gkanas²,

Shepherd³

et al. 2023

SAE Technical Paper Series

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CFD Based Aerodynamics Conjugate Heat Transfer and Airgap Fluid Flow Thermal Analysis to a Wheel Hub Motor for Electric Scooters

Divakaran

Abo-Serie

Gkanas

et al. 2023

Springer Proceedings in Energy

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The geometry of commercially available wheel hub motors inherently restricts packaging space and may prevent the introduction of more sophisticated, efficient, and expensive cooling systems. Due to the limited available space in the wheels, commercial hub motors often rely on aerodynamic passive cooling. The small air-gap (0.5–1 mm) between the coils and the magnets results in heat transfer to the magnets and consequently increases their temperature. As a result, the perfeormance of the permanent magnets (PMs) will be limited and also will heavily affect their lifetime; thus, advanced cooling strategies must be introduced. In the current study, a three-dimensional (3D) thermal model was developed for a commercially available 500 W scooter hub motor under a constant heat load of 180 W using Computational Fluid Dynamics (CFD) (= 64%).The spatial distribution of the temperature for the motor parts are evaluated considering both the internal and external fluid flow dynamics. Further, analysis of airflow in the the gap is performed and the results from the CFD is compared with the published correlations. The flow in such small motor was found to be laminar with Taylor number below 40. Results also showed that enhancement of the cooling is necessary to avoid damage of the winding vernish and to reduce the magnets temperature particularly when the motor works at high torque with low efficiency.

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Experimentally validated numerical model of thermal and flow processes within the permanent magnet brushless direct current motor

Melka

Smołka

Hetmańczyk

et al. 2018

International Journal of Thermal Sciences

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Numerical and Experimental Investigation of Heat Flow in Permanent Magnet Brushless DC Hub Motor

Cited by 5 publications

References 10 publications

A CFD-Based Numerical Evaluation, Assessment and Optimization of Conjugate Heat Transfer for Aerodynamic Cooling of a Wheel-Hub-Motors in Micro-Mobility Vehicles

A CFD-Based Numerical Evaluation, Assessment and Optimization of Conjugate Heat Transfer for Aerodynamic Cooling of a Wheel-Hub-Motors in Micro-Mobility Vehicles

CFD Based Aerodynamics Conjugate Heat Transfer and Airgap Fluid Flow Thermal Analysis to a Wheel Hub Motor for Electric Scooters

Experimentally validated numerical model of thermal and flow processes within the permanent magnet brushless direct current motor

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