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Accurate Equivalent Modeling and Thermal Analtsis of Stator Slot of Flat Wire Motor

  • Electric, Fuel Cell, and Hybrid Vehicle, Electrical and Electronics
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Abstract

This paper presents a new method for the layered equivalent modeling of slot winding in the stator of a flat wire motor to accurately study the thermal performance under steady-state conditions. The conventional equivalent model for flat wire winding involves treating the slot winding as a single copper rod for temperature analysis. This method is not applicable to flat wire motors under high-power density operating conditions. As the power density of the motor increases, the flat wire winding is more affected by skin effect and proximity effect, resulting in a sharp increase in AC loss and uneven distribution of losses in the slot winding. The conductor losses are highest near the slot opening, a characteristic that conventional model is unable to reflect. The proposed layered modeling method fully takes into account the characteristics of flat wire winding. This method involves adding interlayer insulation to divide the overall modeled conductor into layers and fully considers the thermal parameters, heat transfer characteristics, and distribution of materials within the slot to establish a new equivalent model for flat wire winding. Finally, the comparison of the results with the actual model and experimental tests demonstrates that this method effectively improves the calculation accuracy by 2.2% of the flat wire winding equivalent model.

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Data Availability

The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request.

Abbreviations

k h :

Hysteresis loss coefficient

k c :

Eddy current loss coefficient

B m :

Magnetic field amplitude

B(t) :

Magnetic field waveform

\(H_{x}\) :

Magnetic field strength in the x direction (A/m)

\(J_{z}\) :

Conductor current density (A/m2)

\(\mu\) :

Conductor permeability (H/m)

\(\sigma\) :

Conductivity of conductor (S/m)

\(\omega\) :

Electric angular velocity (rad/s)

\(H_{1}\) :

Modulus of magnetic field strength (A/m)

\(H2\) :

Modulus of magnetic field strength \(H2\) (A/m)

\(\varphi_{1}\) :

Phase of the magnetic field strength \(H_{1}\) (rad)

\(\varphi_{2}\) :

Phase of the magnetic field strength \(H2\) (rad)

P cu :

Total copper losses of winding (W)

P AC :

AC loss (W)

P DC :

DC loss (W)

L a :

Effective length of the conductor (m)

B :

Flux density of sinusoidal external magnetic field (T)

σ:

Electrical conductivity (S/m)

ω:

Angular frequency (rad/s)

h :

Conductor height (m)

w r :

Conductor width (m)

λ i :

Thermal conductivity of each insulating material (W/(m·K))

δ i :

Equivalent thickness (m)

A in :

Area of the insulating paint (m2)

H w :

Conductor height (m)

B w :

Conductor width (m)

H c :

Height of the flat copper wire (m)

B c :

Width of the flat copper wire (m)

N :

The number of conductors per slot

\(Aim\) :

Area of impregnated paint (m2)

\(\Delta m\) :

Quality difference between unimpregnated and impregnated motors (kg)

\(Z\) :

The number of stator slots

\(Lah\) :

Average length of the half-turn coil (m)

\(As\) :

Area of slot insulation (m2)

\(Ls\) :

Length of slot wall (m)

\(ws1\) :

Thickness of slot insulation (m)

\(Acu\) :

Area of flat copper wire (m2)

\(\lambda ei\) :

Thermal conductivity of the equivalent insulating material (W/(m·K))

\(Ar\) :

Equivalent insulation area (m2)

\(\lambda es\) :

Thermal conductivity of the adjusted slot insulation (W/(m·K))

\(ws2\) :

Thickness of the slot insulation after adjustment (m)

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Authors and Affiliations

  1. School of Mechanical and Automotive Engineering, Shanghai University of Engineering Science, Shanghai, 201620, China

    Yecui Yan, Lin Chen, Hongjuan Ren & Cong Li

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  1. Yecui Yan
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  2. Lin Chen
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  3. Hongjuan Ren
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  4. Cong Li
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Correspondence to Yecui Yan.

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Yan, Y., Chen, L., Ren, H. et al. Accurate Equivalent Modeling and Thermal Analtsis of Stator Slot of Flat Wire Motor. Int.J Automot. Technol. (2024). https://doi.org/10.1007/s12239-024-00046-2

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  • DOI: https://doi.org/10.1007/s12239-024-00046-2

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