How do I make my induction heater get 200 degrees hotter?

[tcmtech]

I didn't know I was playing with a micky mouse toy but you did. You knew about IGBTs the whole time and kept it a secret. I had FUN that was the original purpose of this project.

Glad you didn't take it personally! I wasn't aware you didn't know about IGBT's especially the industrial application ones.

For rough experimenting they are my #1 go to switching device. Gate controlled like a mosfet but with a robust power handling capacity of a power transistor. That and by most electronics hobbyists standards they are relatively cheap and easy to find in ridiculously huge power handling capacities making them darn near indestructible.

Personally I prefer these for general abusive experimenting. 1200 volt 600 amp and cheap. **broken link removed**

Granted they cant do MHZ switching frequencies but they usually handle running anything under 100 KHz range like a breeze.

 

[gary350]

I need 2 of those CM600MA-24H IGBTs.

Do they need a heat sink or some type of water cooling?

How can I drove 2 of those at 60 KHz to 100 KHz?

I can use my Lincoln Arc Welder as the power supply. I will need 4 high power diodes.

 

[Mosaic]

Gary:

You make me feel that I am wasting my time .

Here is the schematic you need:
https://www.mindchallenger.com/inductionheater/inductionschematic.gif
note it tells u the heatsink required etc.

based on two of these:
https://www.newark.com/fairchild-semiconductor/fdh44n50/n-channel-mosfet-500v-44a-to-247/dp/58K1460

The whole DIY site is here: It is a 3KW unit.
https://www.mindchallenger.com/inductionheater/

Stop guessing and read dude.

 

[tcmtech]

I need 2 of those CM600MA-24H IGBTs.

Do they need a heat sink or some type of cooling?

How can I drove 2 of those at 60 KHz to 100 KHz?

I can use my Lincoln Arc Welder as the power supply. I will need 4 high power diodes.

Just like any other semiconductor device they need a heatsink that is adequate for the power they are dissipating.

I Recommend using IRF21xx type driver IC's. IRF2110 work well for driving two large IGBT's, mosfets or darlington transistors either in totem pole or push pull configurations.

Your arc welder is a constant current source not a constant voltage source making it a very poor choice for power supply for this type of application.
I would recomend finding a good used buck/boost transformer and using that for base of your main power source. The most common configurations come with 115/230, 277 or 230/460 VAC inputs and either 8/16, 12/24, 16/32 or 24/48 VAC dual secondary outputs making them easy to work with.
Best part is they can be found in ratings into the multi KVA sizes fairly cheap and can take severe short term overloading without problems.

 

[gary350]

I checked my arc welder with my meter this is what I get.

75v 40a
75v 60a
75v 75a
75v 90a
75v 100a
75v 115a
75v 130a
75v 145a
73v 160a
71v 180a
69v 200a
67v 225a

The selector switch opens and closes the air gap in the EI transformer core. Wide air gap only allows the core to transfer low power from primany to secondary coil turns ratio stays the same. As the gap closes current comes up voltage stays the same. I think only reason voltage drops at the last 4 settings 160a to 225a is gap is closed enough to load the transformer even with no load attached to the secondary coil.

I like the idea using a 1200v 600a IGBT because it wont be possible to kill the IGBT with a 225a short circuit.

 

[tcmtech]

Yes and as you load up each range you will have a steadily dropping output voltage despite the amps staying close the what ever range you have it set on.

Thats why they are called constant current sources but granted yes you could not burn things out from over current or short circuit issues and it doubtful you could overvoltage one to the point of destruction either.

About your only source of failure would be to destroy the gate by over voltage or cook one to death.

 

[gary350]

I decided to put my dead circuit back together, replaced the mosfets and replaced the 7812 with 12 VDC of AA batteries. The gate has 12.56 VDC with the circuit ON voltage does not drop or fluxuate it holds at 12.56 VDC all the time even with both loads.

With the original LC coil 7/8" inside diameter, 1.250" long, 8 turns, current is 6a with no load, 26a with the 1/4" steel rod, and 33a with the 3/8" rod. Current is down 4a and the rod no longer gets red hot is 12 seconds, it took 30 seconds.

With a new LC coil 1.125" inside diameter, 1.250" long, 8 turns, current is 4.5a with no load, 15a with the 1/4" rod, 21a with the 3/8" rod. After 2 minutes the rod was just starting to get red hot.

Looks like I am going backwards not forward.

 

[tcmtech]

Also to note on the larger commercial induction heater system its common to run the main power and switching systems at that higher voltage DC voltages that rectified mains power gives and use impedance matching transformers and LC circuits to drop the high voltage down to a lower isolated output that drives the actual induction heating coils similar to how the old tube amplifier system used impedance matching transformers to run a low impedance speaker off of a amplifier circuit that ran in the hundreds of volts but milliamps current capacities.

Just something to consider when going above the few hundred watt induction coil power range.

 

[gary350]

I have my original circuit back together for the exception of the 7812 voltage regulator which was replaced by 8 AA batteries to get +12.56 VDC. Maximum power has dropped from 36a to 32 amps. The 3/8" steel rod no longer heats red hot in 12 seconds, it now takes 29 seconds. How much power goes through the gates and ADDS to the total power of the LC coil? I am trying to understand why power and performance has dropped?

 

[tcmtech]

At this point I suggest reading and studying everything in Mosaics last link in post 43 in detail.

It's probably the most thoroughly explained DIY induction heater builds I have ever seen!

Darn near makes me want to build one.

 

[jjw]

I have my original circuit back together for the exception of the 7812 voltage regulator which was replaced by 8 AA batteries to get +12.56 VDC. Maximum power has dropped from 36a to 32 amps. The 3/8" steel rod no longer heats red hot in 12 seconds, it now takes 29 seconds. How much power goes through the gates and ADDS to the total power of the LC coil? I am trying to understand why power and performance has dropped?

No power goes through the gates to the coil.
The 220 ohm gate resistors consume about 0.3W each.
Are the new FETs of the same type as in the original circuit?

 

[gary350]

No power goes through the gates to the coil.
The 220 ohm gate resistors consume about 0.3W each.
Are the new FETs of the same type as in the original circuit?

New mosfets are the same mosfets as before.

 

[Timothy_Egoroff]

Hello, again. this article will teach you how to make a 30kva (24KW) induction heater, this is a step by step instructive article, follow each step exactly to build it: https://www.instructables.com/id/30-kVA-Induction-Heater/

ps, i found the IXFX230N20T mosfets to be the most powerful and reliable for my induction heater.

 

[unclejed613]

welcome to ETO. you might want to start a new thread on this subject, some of the posters in this thread aren't here any more.

wow, this is an old thread you dug up...

 

[gary350]

Gary:

The whole DIY site is here: It is a 3KW unit.
https://www.mindchallenger.com/inductionheater/

Stop guessing and read dude.

I remember this read this long time ago. This guy must have a 100a breaker in his home circuit box he using 120vac changing it to 170vdc then doubling it to 340vdc. This could be dangerious sliging steel rods in the work coil all day. Work coil needs to be insulated with 2000 degree furnace cement. I can not zoom in on this circuit to read part values and some have no values. I build a work coil with copper tubing for this circuit several years ago.

 

[unclejed613]

other than skin effect, the primary reason for using tubing, is you can feed water through it for cooling. most commercial equipment does that. because it's live circuitry, the water has to be distilled water.

 

[gary350]

This post ended 4 years ago same time we moved away from Arizona and moved back to Tennessee. We found a temperary place to live, moved 2 more times before finding the house we live in now. House in Az sold about Aug or Sept 2015. No wonder there was no activity on this post for 4 years. I'm not sure I was even on the computer for probably 2 years.

I read this entire thread today. Most of this I don't remember. I need to get serious about building this circuit https://www.mindchallenger.com/inductionheater/inductionschematic.gif

I worked on my workshop yesterday every time it rains with 50 mph wind it rains inside the work shop too. Metal roof is worthless in high wind it blows water in all the cracks and up the ridges. Yesterday I put silicone on all the cracks and longer screws with new rubber seals where old screws were. I put spray foam in the end of all ridges.

Shop needs AC it is 160 degrees inside during 100 degree summer heat the dark mud brown paint color makes the metal get hot as an oven. Yesterday it was 70 degrees outside and 110 inside the shop. Shop needs to be insulated with wall covering on 4 walls and ceiling. If I don't get the shop insulated and AC installed I won't be doing anything in there until November.

Our first camping trip is in 3 weeks and we have camping trips planned all summer.

I am looking over this circuit some part numbers are hard to read. I already made a work coil few years ago, I need to build a better coil for this circuit. I think heat sinks need to be water cooled. I will change transformer I have to 10.6vac = 15DC 140amps. I have 250 amp diodes they need heat sinks too..

 

[Timothy_Egoroff]

Hi Gary, i read your message, it is eye opening! i suggest (if you have the money) for insulating your shop paint the outside or inside of your shop with a paint product called C-Coat or us a paint additive called thermacels, (same stuff used on the space shittle for re-entry) it is a super insulator and outperforms most if not all insulation methods, if you decide to use an airconditioner this will save you a fortune on power as well, here is a link to the thermally insulating paint additive if you are interested:
information about the 'thermaCels' additive: https://hytechsales.com/insulating_paint_additives.html
where to buy easily: (amazon) https://www.amazon.com/ThermaCels-I...on-Package/dp/B01AC7XA8E?th=1#customerReviews

also there are a multitude of other uses for this stuff, i have it mixed (30%) with a high temp (3000 degree F) furnace cement which covers the work coil for my I.H. (it prevents heat from being transmitted into the work coil from the heated part).

 

[gary350]

I have almost everything to make this circuit but I have no use for this so I'm not motivate to build it.