Disclaimer!

• I assume no liability whatsoever for this design!

• I do not provide any personal advice on circuit designs for driving this coil!

• Any deviations—whether in material, size, frequency, etc.—are not guaranteed!

• PRs or issues are not supported in this repository!

Foreword

Induction heaters (Induction heating - Wikipedia) are used in many different areas. The power can range from a few watts to several 1000 watts. The best-known applications are, for example, hobs or for hardening metal.

Induction heating with different concepts/designs is now also used in 3D printing. The basic principle is always the same, heat is generated by eddy currents in the material. Depending on the design, the magnetic field can spread very widely, which is not always desirable, or a large part of it cannot be used! Some sensors are also sensitive to magnetic fields and then have to be shielded at great expense.

This repo includes two different designs (rounded and square) of a ferrite coil that can be used as an induction heater (example 3D printer). Unlike other designs, the coil is shielded and the magnetic field has its greatest effect in only one direction. The design has been tested in practice myself.

This design is under CERN-OHL-P license. (https://cern-ohl.web.cern.ch/)

Design Benefits

• Magnetic field open/pronounced only in one direction.

• Shielding provided by the internal winding, which also protects it.

• Compact design (15x15x10 mm).

3C95/FTP97(PC97) Ferrite material (see datasheets folder).

• This material offers relatively constant permeability over a wide temperature range (up to 225°C), which means that the inductance changes only slightly.

• Compared to other materials (e.g. N87), core losses up to a ferrite temperature of 100°C are relatively low.

• The optimal operating frequency is between 100-500 kHz.

Winding with sheathed HF litz wire (max 100x0.1 mm) *

• Improved switching efficiency due to lower switching losses

• Easy to shape and process.

• Available in different cross-sections

Note!

Only HF litz wires are recommended for winding, as it offers a much better current-carrying capacity at high frequencies (skin effect - Wikipedia).

Solid copper wire leads to increased losses and heat in the coil!

The maximum flux density (Bsat) of the ferrite material must not be exceeded!

*individually insulated stranded wire

Manufacturers of litz wires

Litz Wire, HF-Litz, High Frequency Litz Wire, Litz Wire for High Efficiency | ELEKTRISOLA

RUPALIT® HF Litz Wires · PackLitzWire

High Frequency Litz Wires - Karl Schupp AG

Efficiency

The efficiency of the overall system (80-95%) depends on the following factors:

• How well can eddy currents be generated in the material to be heated?

• Working frequency (depending on material)

• Resonant circuit design (control)

• Coupling factor (depending on distance, material and frequency)

Application example 3D printing