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Registered Member #61452
Joined: Mon Jan 30 2017, 01:05AM
Location:
Posts: 3
Hi,
I made a ZVS Induction Heater. How can i have a medium power (like 500w) but with a tiny induction coil. The small piece I want heat have 5mm x 2 mm, How can i concentrate all the induction inside this space?
If i put a small coil, the frequency will be too high. May i user a coil like this: Induction coil
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Welcome to the 4hv.org forum.
>> If i put a small coil, the frequency will be too high.
That could be mitigated by putting more turns on the small work coil. It doesn't need to be single-layer. It doesn't need to be made from tubing, with coolant flow inside the conductor.
You can also bring the frequency down by increasing the tank capacitance. Then tank impedance will be lower, and current higher. Might require different coupling to your ZVS driver.
Registered Member #61452
Joined: Mon Jan 30 2017, 01:05AM
Location:
Posts: 3
Thank you klugesmith. If i do many turns, the second layer will not receive the induction of the first layer, and the third layer will no receive the induction of layer 1 and 2...?
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
No. To find the magnetic flux density in the middle, you simply add the flux density due to each layer.
The flux due to each layer also, more or less, threads all the other layers. So total inductance, assuming the layers are connected together in series, still tends to go up with the square of the total turns count. Are you familiar with air-core coil formulas and online calculators?
Here's a 25-tesla resistive electromagnet with 5 layers of Florida Bitter solenoid windings and 27 or 28 megawatts of DC power.
The same lab recently commissioned a 45-tesla hybrid electromagnet. A 33.5 tesla resistive magnet (apparently with three layers) is surrounded by an 11.5-tesla superconducting magnet.
Registered Member #1321
Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843
You can probably get some ferrite inexpensively on ebay, e.g., a ferrite rod, and then do an experiment to see how it works for your application.
Or you can get a big "U" core and two "I" pieces from TSC international and create something more sophisticated.
I'm wondering things like: What metal are you trying to heat, what temperature are you trying to reach, is there anything critically important about the process, and is this for mass production or just one or two pieces?
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Induction header - Magnetic Field Concentration
