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Induction Heater will 1.5v 1000a work or does voltage need to be higher?

gary350

Well-Known Member
Will an induction heater work with 1.5 volts or does it need higher voltage?

I bought four 1GBTs several years ago for H circuit but the project went away now I have a new project. I need information what works best and a target to work for before I start.

Black smith is interested in this project he heats 1/2" diameter solid steel rods red hot to bend into desired shapes. I have several EI transformer lamination that I saved for 1500w, 3000w, 5000w transformer. I hope I can run this circuit on 120vac with output of 1v at 1500a or 1.5v at 1000a.

I can wind and build my own transformer, no problem, I worked in a transformer factory once I have formulas and know how to do it for 100% duty cycle.

I wish I could see the inside of an industrial induction heater, I would like to see how mosfets are mounted and how they are cooled.

Looking at pictures I see the main coil is water cooled copper tubing attached with brass fittings. I assume brass fittings connect to the water cooled heat sinks with 2 mosfets on each heat sink.

Are industrial units water cooled?

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MaxHeadRoom78

Well-Known Member
All the HF induction heaters I have serviced have had the coil water cooled.
There is a very high current/low voltage at the coil level.
Mosfets and in some cases in large industrial ones, the capacitors are water cooled.
Max.
 

rjenkinsgb

Active Member
All the HF induction heaters I have serviced
Remember the "HF" part - transformer laminations designed for mains use will almost certainly be useless at the frequencies needed, the losses will be impractical.

You will need powdered iron or ferrite transformer cores for the power transformer.

The frequency has to be high enough so the output coil is acting as a good inductor, to transfer power to the part being heated, and not just be a chunk of copper pipe.
 

MaxHeadRoom78

Well-Known Member
Remember the "HF" part - transformer laminations designed for mains use will almost certainly be useless at the frequencies needed, the losses will be impractical.

You will need powdered iron or ferrite transformer cores for the power transformer.

The frequency has to be high enough so the output coil is acting as a good inductor, to transfer power to the part being heated, and not just be a chunk of copper pipe.
The ones I am familiar and small ones built, the mains transformer is just for the low voltage DC supply, the only other inductor(s) is the HF coil, there is no other transformer, although some do have a HF transformation by way of two HF coils, one wound over the other, the conductors are the same copper tube as the coil, there is no inductive material used.
For DIY types, Google Royer HF Heating.
Max.
 

gary350

Well-Known Member
What about DC voltage?

I know 1 or 2 volts works great for a spot welder. I increased voltage on my small induction heater from 12v to 20v it did not seem to make much difference. How low can voltage go?
 

MaxHeadRoom78

Well-Known Member
If you go too low, it goes below the operating point of the Mosfets or whatever switching devices are being used and they are never going to turn on.
Max.
 

gary350

Well-Known Member
If you go too low, it goes below the operating point of the Mosfets or whatever switching devices are being used and they are never going to turn on.
Max.
Maybe datasheet will have that information on IGBT. I am hoping I can use my 20v transformer to do some testing.
 

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