3.3 kW 10-Layer Conical Helical Planar Transformer

High-Frequency LLC Resonant Converter Magnetics (420V : 420V, 100 kHz)

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📌 Project Overview

This repository contains the simulation source files and 10-layer PCB layout for a high-power-density 3.3 kW Planar Transformer optimized for electric vehicle On-Board Chargers (OBC) and LLC resonant converters operating at 100 kHz.

The design combines a gapped Ferroxcube E38/8/25 3C97 ferrite core with a 10-layer 2 oz heavy copper PCB implementing a progressive 2D Conical Helical Stepped Winding.

       +-------------------------------------------------------------+
       |                  AIR FLOW (2.0 m3/min)                      |
       |  =======> Panasonic ASEN10211 Axial Fan (2700 RPM)  =======>|
       +-------------------------------------------------------------+
                                     |
                                     v
       +-------------------------------------------------------------+
       |   +-----------------------------------------------------+   |
       |   |      Radian INH40001-15 Heatsink #1 (Left PCB Edge) |   |
       |   +-----------------------------------------------------+   |
       |   |                                                     |   |
       |   |        +-----------------------------------+        |   |
       |   |        |   Ferroxcube E38 3C97 Core Body   |        |   |
       |   |        |    Hotspot Location: T = 70°C     |        |   |
       |   |        +-----------------------------------+        |   |
       |   |                                                     |   |
       |   |   +-------------------------------------------------+   |
       |   |   | Radian INH40001-15 Heatsink #2 (Right PCB Edge) |   |
       |   +---+-------------------------------------------------+---+

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📁 Repository Simulation & Design Files

| File Name | Module / Software | Description | | :

Note

Open-Circuit (No-Load) Simulation Note:
The included aluminium.aedt project contains the master 3D electromagnetic CAD geometry and material definitions. To reproduce Open-Circuit (No-Load) test data yourself, open aluminium.aedt in ANSYS Maxwell 3D, set the Secondary excitation to $0\text{ A}$ (Open Circuit), and execute the Eddy Current solver to observe open-circuit magnetizing flux linkage and magnetizing inductance ($L_m = 477.0,\mu\text{H}$).

--- | :--- | :--- | | 🔹 aluminium.aedt | ANSYS Maxwell 3D | 3D Electromagnetic Model: Gapped E38/8/25 core, 10-layer conical helical windings ($L_{11} = 477,\mu\text{H}$, $k = 0.998$, $L_\sigma = 1.00,\mu\text{H}$, $\eta = 99.70%$). | | 🔹 silicon.aedt | ANSYS Icepak 3D | 3D CFD Thermal Model: Forced air cooling with Panasonic ASEN10211 Fan ($2700\text{ RPM}$) + Dual Radian INH40001-15 Heatsinks ($70.0^\circ\text{C}$ peak hotspot). | | 🔹 planar_transformer_10L_thermal_efficient.kicad_pcb | KiCad 7.0 / 8.0 | 10-Layer Production PCB Layout: 2 oz copper layers, $2.00\text{ mm}$ trace ribbons, 2D conical stepped via interconnects. |

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⚡ Certified Performance Summary

• Power Rating: 3.3 kW ($420\text{ V} : 420\text{ V}$, $8.25\text{ A}$ RMS, $100\text{ kHz}$)
• Magnetizing Inductance ($L_m$): $477.0,\mu\text{H}$ ($N = 5$, $A_L = 630\text{ nH/turn}^2$)
• Coupling Coefficient ($k$): $0.9979 \approx 0.998$
• Integrated ZVS Tank Inductance ($L_\sigma$): $1.00,\mu\text{H}$ ($390\text{ nH}$ / winding)
• Full-Load Efficiency ($\eta$): 99.70% ($9.99\text{ W}$ total dissipation)
• Peak Hotspot Temperature ($T_{max}$): 70.0°C ($\Delta T = 45.0^\circ\text{C}$, $+100^\circ\text{C}$ FR-4 margin)

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🚀 Key Engineering Novelties

1. 2D Conical Helical Stepped Winding: Stepping turn radii inward ($12.8\text{ mm} \rightarrow 6.4\text{ mm}$) reduces vertical copper overlap area by $> 60%$, suppressing intra-winding parasitic capacitance ($C_p$) and eliminating switching ringing.
2. Integrated LLC Resonant Tank Inductor ($L_r = 1.00,\mu\text{H}$): Tuned leakage flux path eliminates the need for a discrete series inductor.
3. 10-Layer Heavy Copper Heat Spreader Matrix: $10 \times 2\text{ oz}$ copper planes ($k_{xy} = 170.8\text{ W/m}\cdot\text{K}$) conduct heat out of the core window to outer edge heatsinks, dropping peak hotspot temp from $140^\circ\text{C} \rightarrow \mathbf{70.0^\circ\text{C}}$.

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✒️ Citation & Zenodo Archive

If you use this model or dataset in your research, please cite:

@misc{satika2026planar,
  author       = {Sunidhi Satika},
  title        = {3.3 kW 10-Layer Conical Helical Planar Transformer Design & FEA Dataset},
  year         = {2026},
  publisher    = {Zenodo},
  doi          = {10.5281/zenodo.22043332},
  url          = {https://doi.org/10.5281/zenodo.22043332}
}

Author Information

• Author: Sunidhi Satika
• Department: Department of Electrical Engineering
• Institution: Indian Institute of Technology Bhubaneswar (IIT Bhubaneswar)