Instructables

This is an amazing induction heater and now you can build your own for fun or as a powerful tool. I have put together an extensive tutorial at http://inductionheatertutorial.com with schematics for building a 3 and 12kw unit. You'll be able to instantly melt steel aluminum and copper. You can use this for brazing, melting and forging metals. You can use this for casting, too. The tutorial covers theory, components and assembly of some of critical components. The tutorial is large. I will go over the main steps here to give you an idea of what goes into a project like this and how to design it so you don't blow any mosfets or IGBTs.

If you wish, you can refer to the link above. This Instructable presumes you have a good understanding of electronics and induction heaters. Let's begin.

 
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Step 1: Components

Picture of Components

The basic components are the inverter, driver, coupling transformer and RLC tank circuit. I'll show you the schematics in a little bit. Let's start with the inverter. This is an electrical device that changes the direction of DC current to AC current. For a high-power unit this must be robust. Above you can see the shielding that is used to protect the mosfet gate drive from any stray EMF. Stray EMF causes noise, which results in high-frequency switching. This leads to overheating and failure of the mosfet.

The high-current traces on the circuit board are underneath. Many layers of copper are used to allow them to carry over 50A of current. You do not want them overheating. Also note the large aluminum water-cooled heat sinks on each side. This is needed to remove the heat generated by the mosfets. I originally used fan-cooling, but to deal with this power I have small pond pumps moving plain water through the aluminum heat sinks. As long as the water is clean there should be no conduction. I also have thin mica pads underneath the mosfets to ensure there is no conduction through the sinks.

trinijay28 days ago

I have been looking for some more information about your driver, it seems strait forward expect the program, sketch you make for your arduino. I found some old forums you've posted on but nothing useful to me. PM me or email me if you don't want to make it public,

I'm looking at yours as an footstep to use for the 30Kva induction driver. I know some modifications are needed but starting with the knowledge of your driver is a great asset

For credibility this is my website, http://skydom.weebly.com/creators--partners.html and I'm making this on behalf of a makerspace i am with.


the sketch for the arduino programming is all I really need

bpark10003 months ago

How do you prevent the cooling water electrolyzing and corroding the tubing? When I built a 4KW heater, I ran the water through the secondary of the transformer (one turn sheet brass 4" wide 3" diameter), then through the work coil. So there was no voltage applied to the water, other then a small resistive component.

imsmooth (author)  bpark10003 months ago
There are no dissimilar metals
Only copper

The aluminum heat sink has its own cooling system
My question is not about 1 or 2 volt galvanic potentials, it is about applying many volts to the water (copper sections of the cooling system are at different potentials, and have the same water flowing through them, correct?)

If you feed water through the work coil (in one side, out the other side, returning to the same reservoir), the voltage on the secondary of the output transformer is applied to the water (unless you do as I did and run the water also through the transformer secondary).

High-power lasers had this and the water was carefully deionized, but it corrodes anyway.
WillowFox3 months ago

With my nonexistent knowledge of electricity theories and all, I can finally do my induction heather for forging, really tired of the fossil fuels. We all like the old touch of a steel rod getting heathed on a furnace, but this is way more practical, space saving, kinda enviromentally friendly, only using home voltages. Thanks for the tutorial man.

pollux643 months ago

Wow, this is some heavy electronics. I'll put it in the todo list since I have other business now, but my compliments on your design. Nice to see so many DIY initiatives.

Nevala3 months ago

Very cool instructable, but please be careful dropping the molten metal out on your concrete floor. Any water content in the concrete can rapidly (read: explosively) turn to steam and fail catastrophically.
I would recommend getting some inexpensive firebrick for collecting the metal ejection.

KROKKENOSTER3 months ago

Wow this give a person the insight on how the inverter welding machines work! They are light and give excellent resuls

KROKKENOSTER3 months ago

Wow this give a person the insight on how the inverter welding machines work! They are light and give excellent resuls

Jackn73 months ago

I'm guessing by the look of it that the Working Coil is water cooled too, is there anything that needs to be taken into consideration between a dry coil and one filled with water as far as design.

Do you have to use distilled water or anything?

imsmooth (author)  Jackn73 months ago

I just addressed this in the instructable. I just use plain tap water. Make sure it is clean, meaning does not have a high mineral content which could make it conductive. I one pump to run water through the mosfets. Each mosfet has a mica pad isolating it from the cooling sink. I use another pump to run water through the capacitor and work coil. This is a large multi-gallon bucket of ice water. You can run this water through a radiator if you wish to disperse the large amount of heat the work coil generates.

Jackn7 imsmooth3 months ago

Thanks for taking the time to answer. :)

Yeah I was thinking about possible conductivity issues, or changes in inductance, that sort of thing.

Separate cooling for the Mosfets and the working coil makes sense too.

Cheers!

Wroger-Wroger3 months ago

I thought about saying some thing utterly stupid, like:

"Can I run this on 2 AA batteries?".

But honestly - I have 240V AC 10A domestic outlets, and a smaller version (with all of it's limitations) would be appreciated.

So the limit of the outlet is 2400W.

Can you toss up a set of plans that run at 2400W?

transistor23 months ago

how much does this cost to make

imsmooth (author)  transistor23 months ago

3kw is about $300

12kw is about $1000

fzumrk3 months ago

That thing is scary! Awesome job.

hzxasdf3 months ago

制作步骤再详细一些

fgeneral3 months ago

nice pro