The Heart of an Induction Heater

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Heart of an Induction Heater
Hello everyone! I started this morning out with a beautiful walk along the gulf coast for the American Heart Association. I wanted to share two things with you today, a couple photos from the event and one more thing (keep reading).
Gulf Coast Heart Walk American Heart Association American Heart Association Heart Walk American Heart Association

Generosity Begets Generosity

All the giving got me thinking, after all, you know what they say about giving. Generosity Begets Generosity. Generosity is a gift that keeps on giving—so many of the gifts we receive in life turn us into givers.
I wanted to show my appreciation to the Patrons who continue to believe in this project even when life slows its progress way more than I’d like! I was reminded today that I actually did not start this project for myself. I am not a blacksmith, I have no immediate need for an induction heater, but I am a creator. Each and every human has this incredible capacity to imagine and to change things. I wanted to bring a tool within the reach of others that remained out of reach for most. Not a wimpy, “doesn’t deliver on what the box said kind of tool”, but one of a caliber that is not matched in the consumer market at all today.

The Heart of an Induction Heater

I would like to offer the “heart of an induction heater” to all of my existing Patrons (as of today September 22, 2018).
U-I Core Set
E/I Core from two U/I cores
U-I Core Set
At about twice the size of a human heart and just about as difficult to source, the matching transformer is by far the most critical, specialized component of the induction heater. Coolant flows around its core in two directions keeping it cool as huge amounts of energy flow through it, making it possible to pump power from your wall outlet into your workpiece. Without it, the IH is just an inverter with some other not really all that exciting electronics. It would be akin to a truck without a transmission. You can’t just connect the crankshaft to the wheels and expect anything good!
I’m including two massive U & I core sets. The same ones that make up the large E/I matching transformer in the newest revision.
Material: 3C85
  • Single U-I core set AL: ~8400
  • Single U-I core set µe: ~2000
  • Single U-Core Dimensions: 93mm x 76mm x  30mm thick
  • Single I-Core Dimensions: 93mm x 28mm x 30mm thick
  • Overall Dimensions: U-I Set: 104mm x 93mm
  • Opening Dimensions: 47mm x 36mm
3C85 Material Technical Data:
  • Optimal frequency: < 200kHz
  • Permeability ui:           2000 +/- 20%
  • Induction at 100kHz, 250 A/m, Bs:   > 400mT
Heart of an Induction Heater

But Wait There’s More

Since driving your IGBT properly is a big deal and kind of important for the whole setup, I’m also including a new driver PCB with two Powerex VLA504-01 Hybrid IC Gate Drivers and two Powerex VLA106-15242 DC to DC Converters. Just those four components are about a $70 value alone if you buy them from Digi-Key. The remaining components on the board are just a few dollars worth of passives. an entire Hybrid Driver kit! The full schematics and bill of materials for the Hybrid Driver board can be found here:
For more info on the driver board be sure to read this:
As well as this post:
Recap, what I’m giving my Patrons:
  • 2 x 93mm x 76mm x  30mm 3C85 Ferrite U Cores
  • 2 x 93mm x 28mm x 30mm 3C85 Ferrite I Cores
  • 1 x New Hybrid Driver Kit including all parts in the BOM above and a PCB

That is a $106.85 value. Thank you for your support!

If you would like to purchase an additional driver kit or U/I core set I’ve included info on that in the FAQs below.

Send Me Free Stuff!

If you are currently a Patron as of the date of this post and would like me to send you this thank you gift, just drop me a private message on Patron saying hello and include your shipping address. The only thing I would ask is that you only request this gift if you are going to use it. We’ll go on the honor system here. 🙂
I look forward to working on this project more and hearing your feedback as well, as you either work on your own or use an IH I’ve built for you in the future.
Q: Is it possible to drive a tank circuit in an Induction Heater with one IGBT?
A: Yes.  This is actually how my brothers old IH is set up now. Here is a quick schematic. The capacitors were all off eBay for cheap.
Single IGBT Inverter
Matching transformer and coupling caps
Single IGBT Inverter
Filter Cap & Coupling Caps
Single IGBT Inverter
Single IGBT driver and brick
Single IGBT Inverter Schematic
Single IGBT inverter schematic
Q: Can you share more details on the matching transformer?
A: Of course but I need some more space to do it properly. I’m working on a post about just that. In the meantime here is a photo and a short explanation to give you something to start with.
  • The Matching transformer is wound with 1/4″OD inch copper tubing.
  • All windings are wrapped in x2 overlapping Scotch Professional Grade Vinyl Electrical Tape Super 88. Meaning as you spiral down the length of the copper tube the electrical tape covers 50% of the layer before it resulting in a 50%+50% overlap (no gaps) and a 200% layer thickness overall (better electrical and mechanical isolation).
  • The primary winding (connected to the inverter) is composed of 13-14 turns. It has terminals made of copper soldered near the ends to accommodate a high current connection while leaving the ends of the tube free to hook up to the cooling system.
  • The secondary winding (connected to the tank cap and work coil) is a single turn composed of 4 individual 1/4″ copper tubes connected on each end with a 1/2″ manifold. One side of the manifold connects to one side of the tank capacitor, the other connects to one side of the work coil via a copper plate. The other side of the work coil connects back to the other side of the tank capacitor via another copper plate in close proximity to the first plate. This whole set up ensure the flux is fully enclosed in the system. Were it not you would heat up surrounding metal and loose usable power. (An issue in the first model with the toroidal matching transformer and large tank setup.)
Matching Transformer
Q: If I’m not currently a Patron or I would like an additional hybrid driver kit could I just purchase one?
A: Yes. I’m not set up to do this formally yet but I can accept Paypal, just drop me a message. For this small batch I made, I’m selling them for $54.95 flat (free shipping to the 48 states, at cost everywhere else). That’s half the cost of buying all the parts yourself or a similar evaluation board (the BG2B). I’ll be able to get this even lower in the future on larger orders for inclusion in the full IH kit. Done! –> I’m also still working on a bulk order for the passives to get the entire driver kit complete. The price difference with and without the passives will likely be less than a couple bucks, keep that in mind if ordering those parts would be an issue for you.
Here is the full excel pricing sheet with individual component pricing info from Digi-Key current as the date of this post.
Q: If I’m not currently a Patron or I would like an additional set of ferrite U/I cores could I just purchase one?
A: Yes. These are quite heavy and require careful packing since they are a fragile ceramic. I’m selling them for $25.95 a set (1 x U core and 1 x I core) flat (free shipping to the 48 states, at cost everywhere else).
Q: What shipping method are you using for the free shipping option?
A: Whichever is the lowest cost at the time of shipping to your location. Usually either USPS first class, priority, or FedEx ground. If you would like to choose a specific method I can do that and just pass on the exact cost to you, no markup.
Q: What about the other parts of the system like the main board, AC rectification & filtering, liquid cooling setup, etc. Can I get one of those?
A: Although I do have fairly complete designs worked out on the rest of the system I don’t have a stock on the parts. I am going to start making posts on the individual components starting with the matching transformer to give you what you need to duplicate each part. The main board schematic and board design are on GitHub although I will be making some changes to it on the next go around.
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