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I am interested in finding a design for the electronic/electrical components of an induction heater for a small shop using a 220V 60Hz input.

I do not need designs for the coils and cooling system, I can handle that.

There is an interesting web page describing a simple design for a small induction heater. In another question on this SE a reader complains about getting this design to work. From the discussion there it is evident that getting a good quality induction heater design is a non-trivial problem. The circuit on this page is advertised as being 300 watts.

I have the book "High-Frequency Induction Heating" by Frank Curtis (1944), but this book mostly focuses on coils and only has one sample circuit which is old has a lot of tubes. I also have the circuit in the Encyclopedia of Electronic Circuits vol III. The key component of that circuit is the MTM15N45 power FET, but it appears that component is still being made so this might be a viable circuit since it can be with a 220V line. This circuit is advertised as being 500 watts.

(Also, according to my initial calculations my types of applications would require a 20,000 watt system, so that would be 90 Amps at 220V. Basically I would have to divert the entire power of the house to the heater while it was in use. So, the Encyclopedia circuit may be too low power.)

Is there a better circuit than this, or a more detailed resource that would be appropriate?

Maybe this is too complex and I should just buy one?

enter image description here

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    \$\begingroup\$ "House" and "90A' typically does not go together, it is likely your utility connection is rated it to less than half of that. 20KW is a lot of power needing an industrial 3 Phase connection \$\endgroup\$ – crasic Feb 19 '16 at 2:48
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    \$\begingroup\$ I designed induction heaters for many years. Unless you are looking for the "enjoyment" of building, at the 20 KW level, you should consider purchasing. Surprisingly there are some VERY cheap units available from China. At the same time, at 20 KW you are likely to need 3 phase utility \$\endgroup\$ – Marla Feb 19 '16 at 2:51
  • \$\begingroup\$ The machine in the picture above is a 15kw unit and it is advertised as being single phase, 220 V, but it does have to be hardwired to the main supply line of the house. \$\endgroup\$ – Tyler Durden Feb 19 '16 at 3:15
  • \$\begingroup\$ @Marla Hello, what is your opinion of the Instructables project I linked below in my answer by MIT EE student bwang. His circuit looks sophisticated and welll-designed to me, but I am a complete novice. Do you see any problems or flaws in his design? Thanks for your valuable insights. \$\endgroup\$ – Tyler Durden Feb 19 '16 at 13:54
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    \$\begingroup\$ Probably not an ideally sized first project in induction heating.... \$\endgroup\$ – ChrisR Feb 19 '16 at 14:03
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At Instructables, I found a project design that looks pretty viable, although it would be a lot of work.

This design is for a system nominally rated around 10 kilowatts at 50 amps, so it would potentially be viable on a dryer circuit. Alternatively it could be amped up to 80 amps or more by connecting to the house mains on a dedicated, high-amperage line. By doing this 15kw is probably possible.

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    \$\begingroup\$ One problem with the Instructables project linked : No feedback to control (or limit) the frequency. With series tuned load, frequency needs to be above tank resonant. The changing properties of the heated load could cause tank frequency to change, and system would operate below tank resonant freq. At that point, the anti-parallel diode will begin dissipating a LOT of power - probably go PooF. \$\endgroup\$ – Marla Feb 19 '16 at 14:29
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because you need a high amperage and in DC power supplies there is none or high cost so first you step down the voltage (AC) from 110-220 to 12-15 with a modified transformer and in AC when you decrease the voltage the amperage increase automatically, for example 220v*40A=8800 watt & 12v*734A=8808 watt. now you have 12 volts and 734 amp DC but induction heater consist of high frequencies to do that you need an inverter or oscillator that's why AC to DC and back again DC to AC.

Note the induction heater generate an electromagnetic pulse that can harm your health and your home equipment/device and especially medical so use low voltage (below 12) to minimize the risks enter image description here

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