1000 Watt ZVS Induction Heater Work Coil Inductance Study

[@allpraisebob]

You can find the inductance in a resonant tank circuit if you know the capacitance and frequency of oscillation using the formula: L = 1 / (39.4784 * C * (f^2)) where C is in Farads, F is in Hz and L is in Henries (the weird number in the denominator is 2pi^2).

[@frenchcreekvalley]

I will answer your questions, one at a time: Question: The diameter of the induction coil should be 6 mm--- I assume that you are asking about the outside diameter of the tubing that we use to make the coils. Yes, the coils that come with these 1000 watt induction heaters do have 6mm OD tubing. In the USA we use inches. A very common size is 1/4", or 0.250 inch diameter which equates to about 6.3mm. ------------ Question: the inner diameter should be 40mm, is it correct?- Here we are talking about the inner diameter of the work coil. 40mm equates to about 1.5 inches. Yes, this is correct for one of the work coils that came with these 1000 watt induction heaters. But the work coils that came with other heaters were ID's (Inside Diameters) of about 45mm and 50 mm. ------------- Question: Keep these values constant. I do not understand this question. So far, I always use the 1/4 inch diameter tubing, but, as you can see in the video, I have coils with several different inside diameters. ------------------------------ Question: Places in this video are missing. It will be for the new video. I do not understand this question. Please tell me what seems to be missing. ----------------------- Question: You must connect the ammeter to the circuit. Induction coil trials; No, I connect the ammeter in series with the DC power supply, I realize that my readings will be slightly inaccurate because I also see the heat loss of the circuit, but I don't see that as a major issue. ------------------------ Question: Must be the same types of metal. Only the pipe thickness inside the coil should be different. Will the ammeter and current values ​​be different? Yes, the actual current will vary as the length of the coils and connections varies, but since it is all copper metal, I believe it to be of little significance. The effect of inductance changes will have a much larger effect. -------------------------------------------------- If I missed any of your concerns, please feel free to ask again.

[@أبوعلي-ح2ي8ل]

كيف اصل الى الحد الاقصى من الحرارة هل يجب ان يكون الأنبوب او السلك فرغ ام انهوا محشو بل نحاس

[@frenchcreekvalley]

The work coil is a hollow copper tube. To get the maximum temperature, I make work coils that closely fit the size of the work piece.

[@أبوعلي-ح2ي8ل]

شكرا على هاذه المعلومات القيمة ولاكن عندي سؤال لقد صنعة دارة بنفسي بتنسيق مع شخص اخر استعمال فيها ٨ قطع نوع Rfip260m وا ٨ مكثف نوع ٠.٣٣ميكرو فأراد ١٢٠٠ فلت ولاكن لم استطع صهر الحديد

[@eventhatsme]

I bought the same ZVS without the induction coil. Now I regret as it seems difficult to only order the coil seperately. I was hoping I could use it to melt small aluminium pieces in a Ø40mm ferrite container. Can you elaborate why you want a specific frequency for the coil + capacitor? Should this match the ZVS circuit frequency to get the maximum power transfer or is it dependent on the object you want to heat?

[@frenchcreekvalley]

My main concern about frequency is to keep it low enough so the Mosfets can turn on quickly enough to minimize their heating up and possibly being destroyed. My testing suggests that about 130 kHz is the maximum frequency for safe operation of the Mosfets. But I usually run the systems at frequencies between about 90kHz and about 40kHz. I know what workcoil/capacitor combinations it takes to get these frequencies so I make my coils and plan my work accordingly. That's what this video and the links are about. Some people seem to worry a lot about "Skin effect" as it relates to frequency and heating rates. With these relatively low power induction heaters, there isn't a lot you can do to take advantage of those effects, nor, in my opinion, is there the need to worry about it. I hope this answers your question. If not feel free to ask another one.

[@eventhatsme]

Excellent! This makes it more understandable. Did you have good agreement between calculated inductor values and those measured with the LC meter?

[@frenchcreekvalley]

@@eventhatsme I think I talk about this somewhere, but the calculated values are generally within about 25% of the value that I get on the LC meter. I mght add that, so far, the LC meter is quite repeatable for a given coil from day to day and time to time, as long as I remember to zero it each time I turn it on, before taking a reading. Also note that you cannot accurately calculate the actual resonant frequency of the oscillator's tank circuit from the either of those values since there are other capacitances and inductances on the board.

[@eventhatsme]

@@frenchcreekvalley Is there a way to measure the frequency during operation with a scope or will there be high voltage troughout the circuit? (I forgot I have a current clamp)

[@frenchcreekvalley]

@@eventhatsme I can and used to use a scope and connect to a Mosfet gate to measure frequency. If you look at some of my recent videos, you will see that I added a frequency counter. For a given capacitor/coil combination with no workpiece in the coil, the frequency is pretty stable, but I can see the effect of putting work in the coil that way. At one point I bought a little digital o'scope (DSO112) that even gives a numerical readout of frequency.

[@darrencorbett9883]

Thanks for this info, regards from Australia 👍

[@hoangkhuong9]

Thanks for your shared, so with 1000 watt zvs induction heater as your design. how calculate for flat work coil building from 6mm dia. copper tube?

[@frenchcreekvalley]

You can calculate the resonant frequency using the formula on this page: www.1728.org/resfreq.htm I have much more work coil information here: spaco.org/Blacksmithing/ZVSInductionHeater/WorkCoilsForZVSInductionHeater.htm Click on the "work Coil Data, Observed" link and open the spreadsheet. I recently added information for a "pancake" or "flat" coil. So far in my testing, I find that the actual operating frequency is about 10 percent to 20 percent lower than the value predicted by the formula. But when I calculate the tank circuit frequency, I am only inputting the L of the work coil and the C of the capacitors on the board. There are several other sources of L and C on the board itself and that makes up for the difference.

[@hoangkhuong9]

@@frenchcreekvalley Thanks so much for your soon reply. i will check now

[@hoangkhuong9]

@@frenchcreekvalley Sir, please help me to shared links for test pancake zvs induction heater. i cant find @ your channel. Thanks

[@frenchcreekvalley]

@@hoangkhuong9 The "Pancake" Coil video is here: kzbin.info/www/bejne/n32lhKaAo5ytY6s

[@frenchcreekvalley]

The copper work coils are covered with fiberglass sleeving. Here is one source for that sleeving: www.ebay.com/itm/1meter-Manhattan-F240-2AWG-6-68mm-240-C-Fiberglass-high-temperature-sleeving-/161643155584?hash=item25a2aed080

[@yeroon4203]

Interesting stuff! How do you think these circuits would cope with a standard coil from a cooktop which has an inductance of around 40 uH?

[@frenchcreekvalley]

I don't have any experience with those cooktop but I have seen a few forum posts from folks who have played with them. Most guys have found them to be pretty complex internally and tough to hack. My main concern would be how they keep those coils cooled and how you could cool it. This 1000 watt ZVS induction heater runs at about 100 kHZ with it's normal work coil. That would drop to about 18 kHz with a 40 uH work coil. I think that would be okay with the rest of the circuit.

[@yeroon4203]

@@frenchcreekvalley Thanks for your quick reply. The cooktops are generally able to output up to 2000W per coil, but that's at 110 or 220 volts, so a lot less current flowing than 12 to 48 volts. I'll see if I can get my hands on the components and do some testing.

[@frenchcreekvalley]

@@yeroon4203 You might want to visit this guy's tear-down of one: highvoltageforum.net/index.php?topic=104.msg551#msg551 He's the moderator of that site. From Denmark. You may already know this, but in Europe, they are often called "HOBs" (Heater Or Burner, I think) So-- "induction HOB" over there.

[@ianblank]

Thank you, this helped me a lot

[@howardiko7156]

Hey this is great. Ham guys study this stuff. What if you layer the coil? Is more inductance the goal/lower frequency?

[@frenchcreekvalley]

I have compiled most of my work coil info here: spaco.org/Blacksmithing/ZVSInductionHeater/WorkCoilsForZVSInductionHeater.htm Click on the "Work Coil Data, Observed" spreadsheet to see (I hope) the answer to your question.

[@hebrewhammer1000]

Thank you for sharing! Very informative.

[@billfletcher5166]

I thought when you stretch out the coil the inductance will go down not up. At least in RF it works that way.

[@francoismaltais7798]

I second that. If the readings are good, it as something to do with the composition of the braid, or a modification of the shape. Also i can see half a turn more on many coils.

[@katana1960]

Another question; Where did you buy the fiberglass/ceramic sleeving? I'm putting my machine together and am try to copy your design as closely as possible. Is the sleeving for heat protection or to stop arcing from the coil? Thanks

[@frenchcreekvalley]

A good question. My first priority was to eliminate arcing. But I have since found that the insulation also reflects quite a bit of heat back into the work. This also keeps the water temperature down. I see it as a "win, win, win" solution. Here is where I have been buying the sleeving: www.ebay.com/itm/1meter-Manhattan-F240-2AWG-6-68mm-240-C-Fiberglass-high-temperature-sleeving/161643155584?hash=item25a2aed080:g:r0UAAOSw-7RVCqnZ&frcectupt=true The cost is USD $5.00 per meter, but if you order more, it will come in one piece, which it an advantage to me. For example, I ordered 3 meters and the price was USD $15.00 plus shipping.

[@Ttalos]

McMaster Carr is a great source

[@billyproctor9714]

Thank for the info, Billy, Ladysmith

[@TheFlyre]

hey brother what the best way to get hold of you?

[@frenchcreekvalley]

[e-mail]

[@maxitaibo7461]

Que son?caños de cobre con aislante de fibra de vidrio

[@frenchcreekvalley]

The copper pipes with fiberglass insulation are "copper refrigeration tubing". The size of the tubing that I usually use is 1/4" outside diameter.

[@viktorkaradzhov981]

Hi, l want to ask you which coil generated most strong frequencies, l mean how many windings of copper pipe will generate more strong frequencies?

[@frenchcreekvalley]

Hello Claudio. You have asked a very complex question. The frequency varies with the number of turns in the coil, but the amount of POWER that is transferred from the coil to the work piece depends upon many other factors. For the type of induction heating circuit that I am using, (the "ZVS" or "Zero Voltage Switching" circuit), I need at least 4 or 5 turns on the work coil to keep the frequency DOWN to a range that prevents overheating and burnout of components. I can give you a better answer if you can tell me what you want to accomplish. You can also visit this web page for more work coil design information that relates specifically to these ZVS induction heaters: spaco.org/Blacksmithing/ZVSInductionHeater/WorkCoilsForZVSInductionHeater.htm

[@viktorkaradzhov981]

It very complicated, but l wil try to explain to you The secret services make remote electronic torture till dead on so many people, l am one of them, from 9 years the secret services irradiating me with ultrasound, infrasound and microwave weapons! In the community on Facebook and Twitter people talk, that frequencies produce from ZVS Driver will block the equipment with which the operative officers work with, give him a blue fog on screen on device (please look this video kzbin.info/www/bejne/Zp3HhJSfjpJ1jaM) I tried to achieve most intents frequency to block him for good, most extreme frequency You been trying so many coils, which generate most extreme frequency? Specifically l want to ask you about this coil which the spiral is flat, look like this 🍥 This is last hope for many of us

[@frenchcreekvalley]

@@viktorkaradzhov981 I am sorry, but I do not think these induction heaters radiate with very much power. to the air around them. The flat spiral coil operates at about 19 kHz to 27 kHz.. The smallest coil that I have made operates at about 133 kHz.

[@elderjameso]

as bobinas de cobre são revestidas com papel.

[@geofflotton5292]

Basic inductor design.