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Thermofluidic analysis of interior permanent magnet synchronous motors with internal air circulation by protrusion-shaped flow inducers for effective thermal management

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Abstract

A three-dimensional thermofluidic model was developed for simulating fluid flow and heat transfer in interior permanent magnet synchronous motors (IPMSMs) with internal air circulation for effective thermal management. Protrusion-shaped flow inducers were introduced to facilitate the internal air circulation through rotor ventilation holes, increasing convection and preventing temperature rises in primary motor components. The numerical model agreed well with the experimental data. Subsequently, various geometrical design variables of the protrusion were selected to determine the thermofluidic characteristics of the electric motor associated with local temperature distributions for critical motor components. The protrusion increased the mass flow into the ventilation holes; accordingly, the maximal rotor temperature was inversely proportional to the protrusion design. Additionally, a thin airgap between the stator and rotor affected the radial heat transfer rate by forming additional thermal resistance layers. This flow was modeled using the Taylor-Couette paradigm, with the relative error under 1 %.

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Abbreviations

\(\overrightarrow {\rm{a}} \) :

Acceleration

A v :

Cross section area of ventilation hole

C :

Specific heat

C μ :

Function of the mean strain and rotation rates

D h :

Diameter of ventilation hole

f :

Friction factor

\(\overrightarrow F \) :

Body force

g :

Gravitational acceleration

ġ :

Heat generation rate per unit volume

G b :

Generation of turbulence kinetic energy due to buoyancy

G k :

Generation of turbulence kinetic energy due to the mean velocity gradients

h amb :

Natural convection coefficient of the ambient flow

H :

Height of protrusion

k :

Turbulence kinetic energy

ṁ :

Mass flow rate

Nu :

Nusselt number

Pr:

Prandtl number

P :

Pressure

P vβnt :

Radial path with ventilation hole

P soiid :

Radial path without ventilation hole

\(\dot Q\) :

Heat transfer rate

\(\overrightarrow r \) :

Radius vector

r :

Radial coordinate

R :

Total thermal resistance

R i :

External radius

R o :

Internal radius

Re :

Reynolds number

S:

Modulus of the mean strain rate tensor

S ij :

Mean strain rate tensor

S k :

User-defined source term for turbulent kinetic energy

S ε :

User-defined source term for dissipation rate of turbulent kinetic energy

t :

Time

T :

Temperature

T s :

Surface temperature

T ∞ :

Ambient temperature

u r :

Cylindrical velocity component in r -direction

u θ :

Cylindrical velocity component in θ -direction

u z :

Cylindrical velocity component in z -direction

u′¸ :

Circumferential velocity component

U *:

Modulus of the mean strain and rotation rate tensor

v :

Kinematic viscosity

\({\overrightarrow U ^\prime }\) :

Velocity to the rotating reference frame

\({\overrightarrow U _{\rm{t}}}\) :

Translational frame velocity

ü g :

Component of the flow velocity parallel to the gravitational vector

ü’ g :

Component of the flow velocity perpendicular to the gravitational vector

ü s :

Mean air velocity

Y m :

Contribution of the fluctuating dilatation

z :

Cartesian coordinate (usually up)

\(\overrightarrow \alpha \) :

Angular acceleration

δ:

Airgap thickness

ε :

Rate of dissipation of turbulence kinetic energy

ϕ :

Angle

γ :

Angle of protrusion

η :

Strain tensors rate per seconds

κ :

Curvature of protrusion

λ :

Thermal conductivity

λ eff :

Effective thermal conductivity

μ :

Viscosity

μ t :

Turbulence eddy viscosity

θ :

Angular coordinate

ρ :

Density

ω :

Angular velocity

σ k :

Turbulent Prandtl number for turbulent kinetic energy

σ ε :

Turbulent Prandtl number for dissipation rate of turbulent kinetic energy

\(\overrightarrow \omega \) :

Angular velocity vector

ω :

Angular velocity

Ωij :

Mean rotation rate tensor

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Acknowledgments

This work was supported by the Korea Evaluation Institute of Industrial Technology [grant numbers 201900000001139 and 201900000002587].

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Authors and Affiliations

  1. Graduate School, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea

    Jonghyo Lee & Namkwon Lee

  2. Division of Mechanical Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Korea

    Sukkee Um

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  1. Jonghyo Lee
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Corresponding author

Correspondence to Sukkee Um.

Additional information

Recommended by Editor Yong Tae Kang

Jonghyo Lee obtained his B.S. degree in Mechanical Engineering from Chonnam National University, Gwangju, S. Korea. Currently, he is studying as a Ph.D. student at Hanyang University, Seoul, S. Korea. His research interest includes heat transfer in advanced electric driving systems.

Namkwon Lee obtained his B.S. degree in Mechanical Engineering from Dong-A University, Busan, S. Korea. Currently, he is studying as a Ph.D. student at Hanyang University, Seoul, S. Korea. His research interests include heat transfer in advanced refrigeration systems and heat exchanger designs.

Sukkee Um obtained his B.S. and M.S. degrees from Hanyang University, Seoul, S. Korea and Ph.D. degree from the Pennsylvania State University, University Park, USA. He joined the Division of Mechanical Engineering of Hanyang University as an Assistant Professor in 2007. His teaching and research interests include heat and mass transfer, polymer electrolyte fuel cells, hydrogen production, and micro/nano transport phenomena using digital twin technologies.

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Lee, J., Lee, N. & Um, S. Thermofluidic analysis of interior permanent magnet synchronous motors with internal air circulation by protrusion-shaped flow inducers for effective thermal management. J Mech Sci Technol 34, 3415–3426 (2020). https://doi.org/10.1007/s12206-020-0734-y

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  • DOI: https://doi.org/10.1007/s12206-020-0734-y

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