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.
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!
I would like to build a case annealer.
Having trouble finding info needed in one place. This really screws with my dyslexia.
Any help is appreciated.
This is a powerfull project am thinking can we use it for cooking in developing countries using solar powe where most people are using biomass especialy wood degrading environment
Hi all,
I see a lot of induction heating projects having input voltages of 12 till 48 volt and it made me wondering. What would happen if you rectify 230AC and rectify this to be used as an input? If this is possible could you then still control output bij PWM?
Maybe stupid question but for anyone willing to answer I would like to thank you in advance.
kind regards,
Mitchell
I understand the circuit overall but I can't figure out why the flyback diode (D8) is used for. Wouldn't it just never activate? Since it is always connected directly to Vcc and GND in reverse.
And is the the RC filter used to limit ringing on the transistor gate? Or is it needed for something else? Thanks.
Has anyone figured out what resistors should be used for R8 and R9? I understand that they are 18 Ohm but how many watts?
Can I buy ready one to try it?
These are the mosfets I was able to get, I dont know if they are the correct ones needed.
Can someone tell me if they have experienced the following issue with the board.
I just hooked up everything for the first time, finally got all my parts in and built the board. When the 48V hits the board for the first time the LED lights up then it starts to dim and eventually turns off, then when 48V is applied over and over again the board seems non functioning. I am running a brass annealer so the circuit sends the voltage to the board for the specified time, then it turns off the circuit, then it starts all over again.
First time the machine boots up the led lights up, each consecutive time after that nothing is happening with the board. Not sure what's going on with the board but I tested and I am getting my 48V going to the board.
Hey! What do you say about putting double mosfets with each gate resistor.
Hi, I have a question. My goal is to build something I can use when working on my car. Think something like Storm Heater. If I use a 6 mm OD copper tubing to make the coil, should I downrate your project or cold it be used as it is nonetheless? Would it be mandatory to provide water recirculating cooling to the coil?
Last question, I would mount the coil on some insulated handle, connecting it to your Board through an extension cable, would it be fine?
THX for your amazing Job!
Enrico from
Did you measure the coil? is it just uH?
Hello,
I have a project where I have to produce a certain quantity of heat with the lowest consumption possible. This quantity is quite low, got it @12V and 36 Amps with the appropriated workcoils on a chinese induction circuit. I want to use your circuit because of its durability. Do you think I could get lower amps @48V to reach the same wattage? for example 48V and 9 amp? By designing the workcoil properly?
My main concern being heat dissipation this could make my life more easier 😁
Hey. I had an incident with blowing my mosfets because one of the traces blew apart. Fixed the trace, switched to new mosfets and powered it back on to see no heating at all and then later figured another mosfet burnt... Any ideas? No traces failed this time. I am using the v1.1 heater with 48vdc @ 30 A. This project is taking me a little too long.
I'm having a couple of issues with my version of this circuit. I've had to substitute IXFQ140N mosfets, as the IRFP mosfets weren't available. I believe these should be very comparable.
First, the gate resistors are getting very hot. I turned one of mine brown in perhaps 5 seconds when I first fired up my circuits. Would lowering R8/R9 to 10 ohms perhaps help that, or does it indicate some other issue? I'm going to triple check everything to make sure I don't have anything different from the provided schematic, but I believe everything is exactly the same except for the mosfets.
Second, this circuit is latching my SSR closed, such that my Arduino can not turn it off. Still trying to figure out why. Has anyone else had such an issue? Might be the cheap SSR but I did not have this issue with the cheap Amazon ZVS circuit running the same power level.
I'm considering simplifying the circuit back to the basic ZVS style, just using the more robust components, and then slowly adding back the extra features (RC circuit, flyback diode, gate resistors) to see which area may be causing me issues.