Resources:
Build & demo video: Click here
Coil form tool Download STL file
PCB Gerber files Download gerbers
Schematic Download Schematic
Details:
Voltage input: 12~48VDC
Current input: up to 30A (@48VDC)
Peak power input: 1,400watts
The Circuit
This induction heater is based on the popular "Royer induction heater" schematic. I believe this is the original post/author? Click here
Changes made to the design include:
Higher rated MOSFETs
Bigger Zener diodes
RC filter on the Gates
Flyback Diode (D8)
Gate resistors to limit ringing (R8, R9)
In short, all of the changes help to improve the durability of the induction heater. It has been reported with the original design, often the MOSFET gate's would be damaged from flyback after extended use. To be fair, I haven't tested the circuit without my additions so I can't confirm or deny this. Gate resistors have to be added as ringing was quite a problem without them. The ringing would cause the MOSFETs to become quite hot & this can lead to premature failure. With the addition of a pair of 18R gate resistors. The ringing was reduced to an acceptable level.
Components:
2x Wakefield-Vette, 694-50 Heatsink Click here
2x IRFP4668PBF MOSFETs Click Here
10x WIMA, MKP1J034706B00KB00, 470nF, 630VAC Capacitor Click here
2x 2.2uF Ceramic 100v Capacitor Click here
2x FR307 Fast Diode Click here
2x 47R, 5w Metal Oxide resistor Click here
2x 470R, 5w Metal Oxide resistor Click here
2x 12v, 5w Zener Diode Click here
1x SB5H100 Schottky Diode Click here
2x 100uH, 15A inductor Click here (see below for details)
2x 10k, 1/2w resistor
1x 4.7k, 1/2w resistor
2x 18ohm 1/2w resistor
1x 5mm LED of your choice (power indicator LED)
The inductors
For the inductors, I opted to wind my own. Options for this size are somewhat limited & it was cheaper to make my own anyhow. If you don't wish to make your own, then alternatively you can buy them from banggood Click here
Toroid details:
Size: 42x22x17mm
Material: Iron Powder, HY2
Color Code: Yellow/White
For the wire, I used 1.25mm (16AWG) enamel insulated copper wire. Each toroid used approx 1.6m (63inch) of wire. This length of wire yields 30~32 turns around the toroid giving an approx inductance of 100uH.
Tinning the high current traces
Located on the underside of the PCB is several exposed traces that should be tinned with PLENTY of solder after all the components have been installed. These traces carry very high current that pulses through the work coil. Failure to adequately bolster these traces with copious amounts of solder will result in the solder melting off the PCB, which will result in the trace burning out, which in turn blows up one of the MOSFETs (not that I'd have done anything like that :P )
I'd recommend laying down some fairly heavy copper wire on top of the traces & solder it in place just to be on the safe side.
The Coil
This is the work coil. I made my coil from 3/8" copper tubing (the type used for aircon, fridges.etc) It's pretty inexpensive & easy to find at most hardware stores or aircon shops. The inside diameter of my coil is 70mm to accommodate almost anything I'd need to heat.
The coils consist of 6 & 1/2 turns. The amount of turns does play a role in determining the resonating frequency (and also power output/consumption). If you know what you are doing & are willing to experiment with different coils, then go for it. Otherwise, I'd suggest making a coil with 6~8 turns.
If you watched my build video, then you'll have seen me 3D print a form tool, used to wrap the copper around to form the coil into a spiral. Strictly speaking, It's not essential however, it does produce a nice uniform coil. You can download the STL file Here
Performance
With a 48V power input and a 140mm PC fan blowing air over the heatsinks & caps. Temperatures were quite acceptable at 80c (176f) for the MOSFETs, the capacitors were about the same. And the inductors never felt even slightly warm. I think for higher input voltages (above 48VDC) You'd have to start considering spacing the caps further apart for better cooling & depending on how far you push the envelope.... maybe water cooling the MOSFETs & work coil.
Will it melt Aluminum?
The original author demonstrates his induction heater melting an aluminum heatsink. I've attempted to melt alloy in my induction heater and it failed to do so. I'm not exactly sure why he was able to melt alloy and I was not but, I do wonder if he is tuning up his power input to achieve this? He seems to indicate this in his post. It's also possible different alloy's melt easier than others so perhaps this is something I'll explore later.
What would it take to make this induction heater more powerful?
In truth, the components used could probably handle 60V (just monitor the peak voltage across the caps & make sure to stay within their max voltage rating). However, at higher power levels, you certainly need to bolster the high current traces on the PCB to prevent failure. Keeping the caps & MOSFETs within temperate limits could also be a challenge. Perhaps water-cooling would be a viable solution? In any case, it's certainly possible for this circuit to handle higher voltage than 48VDC if appropriate measures are implemented.
Man, I made the same schematic, made a new PCB, get it ordered. But, it does not work (does not oscillate). I tried Ltspice to simulate the circuit, got a flat line. I have no idea what went wrong and what's causing the issue, can anyone assist?
An aluminum rod that doesn't fill the coil throat doesn't have good heating prospects; either use another
material like a graphite crucible (the graphite heats, so anything inside it, does too), or a smaller-diameter
coil. There's also a 'skin effect' so that at 10 kHz, only about a millimeter of the aluminum conducts; what's the frequency here, 30 kHz? Much less than a millimeter...
I too ordered five PCBs and built one, A 1400 W that works. I have annealed lots of brass reloading rifle casing with it, Working awesome starting to build my second one.
Hey! From Canada. Ordered 5 pcbs, parts, assembled one and it works. can't believe it. i am such a noob. Powering with 12v, one mosfet gets hot. i powered the circuit once for .5 seconds without the induction coil. Bad?. i have 4 more to build. haha. thank you so mucho. I need to heat up 16mm steel rods to bend them 180 in a short radius. Edit: I made the exact same coil he makes and now the circuit is perfect, no overheating on one side. I have 2 perfect boards now, lets do the 3 others. 7 turns (8 loops when you count them with your finger).
i have the same mosfet but not that 1400watt of power.
what components should i change? or i need to change the circuit??
I will have to experiment. Thank you.
Hi, I know it is an old post, I'm building this circuit to anneal brass and I'm wondering how to find/tune the right resonating frequency for what I need, around 120 Khz.
I build one of the 1400 watt and it works good, i was wondering how i could build a induction coil with copper tubing 5/8 on side diameter, How many reps should i make.
What's the size of the PCB and how many layer is it.
Has someone ordered this pcb with the gerber files from JLCPCB without modification? I just want to know if I can straight up use the gerber files provided for ordering myself a pcb made by jlc, or if I need modifications of some sort to be done.
Shouldn't we use AC supply instead of DC for the induction heater and why?
Does anyone have spare PCB to sell in Europe?
That metal rod you heated up red hot in the video, what safety considerations have you incorporated in this project should you drop the rod onto the coil and shorted it out?
Hi
This question might be very stupid but I really want to know...
What is the function of L1 & L2？
HOW TO BUY PCB
Where can I buy the pcb?
What about the considerations to re-design the workcoil to be a pancake type?!
Please send me the PCB drawing by email because I am in a country where I don't have access to buy it, so I have to make it myself.
لطفآ نقشه pcbرا از طریق ايميل برایم بفرستید چون من در کشوری هستم که دسترسی به خرید آماده ندارم باید خودم بسازم.Please send me the PCB drawing by email because I am in a country where I don't have access to buy it, so I have to make it myself.
I've built a annealing coil approximately 19mm ID, two layers of 3.25 turns, 6.35mm (1/4") OD Copper Tubing for a total of 6.5 turns. My LCR meter measures the coil at around 3uh of inductance. I've measured other inductors and the meter seems reasonably accurate. I've built the ZVS Circuit as designed with PCB's from JLPCB (I have a few extras...). My Power supply is a 48Vdc 25A MEISHILE from Amazon and it's set for 48Vdc. As soon as I turn it on, without a case in the coil, it crowbars the power supply off within 10 seconds and has blown 20a fuses on the DC side. The coil is getting very warm, but not warm enough to burn skin. I'm wondering what the coil inductance should be?? 3uh seems a little high, I was shooting for less than 1 because 3uh calulates to 42Khz frequency. Any ideas? Thanks!