WARNING!
This induction heater produces hundreds of volts across its output. DO NOT touch the circuit OR workcoil while powered on! Or you risk being electrocuted! Once the power is switched off, the capacitor bank instantly discharges and the circuit is safe to work on.
Downloads:
Specifications:
PCB Size: 86 x 284mm
Input voltage: 40~65VDC
Max input current: 50A
Max power consumption: 3,250watts
Assembling the PCB
You’ll find all the components & their specifications listed below. You can download a detailed schematic to identify what component goes where on the PCB.
PCB Components:
C1~14 – 330nF 600VAC Capacitors
C15, C16 – 2.2uF 100V Ceramic Capacitors
D1, D2 - 12V 5W Zener Diode
D3, D4 – FR307 Fast Diode
D5 – 5mm LED
D6 - SB5H100 200A 100V Schottky Diode
L1, L2 – 60uH 25A Custom made inductors (watch video)
R1, R3 – 150R 5W Metal Oxide Resistor
R2, R4 – 1K 5W Metal Oxide Resistor
R5, R6 – 10K 1/2W Metal Oxide Resistor
R7 – 4.7K 1/2W Metal Oxide Resistor
R8, R9, R10, R11 – 18R 1/2W Metal Oxide Resistor
Q1, Q2, Q3, Q4 - IRFP4668PBF MOSFET
Bolstering the PCB traces
The traces on the PCB that are exposed on the underside need to be bolstered by either cutting out copper busbars from a sheet of copper (1.5mm or thicker) Or by using 14AWG, 2.5mm core electrical cable, soldered to the PCB traces. I used the latter method in the build video, and although it’s not very aesthetically pleasing. It’s proven to work without any issues
Workcoil Design
The workcoil is the business end of all induction heaters. When it comes to designing a workcoil several design elements should be taken into account. This is an area where I’d admit, I’m still learning myself, so I don’t consider my advice on this topic to be all that helpful. But, a good starting point is to have a workcoil with 6 turns of 3/8” copper tubing to make the workcoil.
The internal diameter should be around 10~20mm larger than the piece of metal you’re intending to heat.
Using a workcoil that has a much larger diameter than the piece of metal you’re heating, will reduce performance & lead to longer heat times.
The air gap between turns has a significant role in determining the input current consumption and power output. Increasing the air gap also increases input current consumption. And the opposite is also true, smaller airgap = lower input current consumption. Calculating the correct air gap on paper before you construct your workcoil is very doable however, it's also possible to use a trial & error method. Start by keeping the windings tight (around 2mm air gap), operate the induction heater, and monitor the current consumption, if you wish to increase the current, then gently spread the winding further apart to increase the airgap. You can repeat this process until you achieve your ideal power input/output. (Don't forget to have the induction heater OFF while making alterations to the workcoil)
A company called ‘Ambrell’ published a 28-page guide around workcoil design. You can request a free copy of their guide by using this link Click Here (They do ask for your name & email, but it’s 100% free)
Cooling
During normal operation, the MOSFET heatsinks & capacitors will get hot! You will need to use a fan to blow air over the components to keep the temperatures at acceptable levels.
For runtime more than 30 secs or so, the workcoil will get very hot. I’d highly recommend cooling the workcoil by continually pumping water through it.
Printed Circuit Board
Order your own custom printed circuit board using the files below:
Inductors
I made my own custom inductors for this project. I used a total of 4x T157-26 Inductor Toroid Rings. Each inductor has 2 toroid rings stacked on top of one another. I have found this to be the most cost-effective solution for this project. A total of 16 turns of 2mm (12AWG) magnet wire is wrapped around the toroids to produce an inductor with approximately 60uH of inductance.
You can customize the inductance by adding or subtracting turns around the toroids. If you’re heating smaller pieces of metal, to maximize power output from the induction heater into the piece of metal you’re heating, you may want to consider lowering the inductance to around 30~40uH. Similarly, the inverse is true. If you’re heating large pieces of metal & your induction heater is drawing more current than the maximum allowed (50A) Then increasing the inductance to 60~200uH will bring the input current down to a safe level.
If you’re using 2x T157-26 stacked together, below is a cheat sheet to quickly customize the inductance.
Number of turns for inductance:
36uH = 13 Turns
60uH = 16 Turns
100uH = 21 Turns
150uH = 26 Turns
200uH = 30 Turns
Alternatively, you can use this calculator to help you customize the inductance
Components:
4x T157-26 Inductor Toroid Ring
· Size: 40x24x15mm
· Material: Iron Powder
· Magnetic Permeability: 75
4x Wakefield-Vette 694-5 MOSFET Heatsink
· Size: L:50 W:22 H: 35mm
· To fit: TO-247 package
14x WIMA MKP1O133306F00KSSD 330nF 600VAC Capacitors
· Size: L: 31.5 W: 15 H: 26mm
· Lead Spacing: 27.5mm
· Voltage: 600VAC, 1000VDC
· Capacitance: 330nF
2x TDK FG20X7R2A225KRT06 2.2uF 100V Ceramic Capacitors
· Size: L:7 W: 5.5 H: 4mm
· Lead Spacing: 5mm
· Voltage: 100VDC
· Capacitance: 2.2uF
2x ON Semiconductor 1N5349BRLG 12V 5W Zener Diode
· Package: 017AA-2
· Power: 5W
· Zener Voltage: 12V
· Package: DO-201AD
· Voltage: 1000V
· Current: 3A
· Type: Fast recovery 500ns
1x 5mm LED
· Forward Current: 20ma
· Regular Through hole 5mm LED
· Color of your choosing
1x Vishay SB5H100-E3/54 Schottky Diode
· Package: DO-201AD
· Voltage: 100V
· Surge current: 200A
2x 150R 5W Metal Oxide Resistor
· Size: L: 17.5 D: 6.5mm
· Power: 5W
· Size: L: 17.5 D: 6.5mm
· Power: 5W
2x 10K 1/2W Metal Oxide Resistor
· Size: L: 6.5 D: 2.5mm
· Power: 1/2W
1x 4.7K 1/2W Metal Oxide Resistor
· Size: L: 6.5 D: 2.5mm
· Power: 1/2W
4x 18R 1/2W Metal Oxide Resistor
· Size: L: 6.5 D: 2.5mm
· Power: 1/2W
· Package: TO-247-3
· N-Channel MOSFET
· Vds: 200V
· Id: 130A
· Rds On Resistance: 9.7mOhms
Other Components & hardware:
· 3.2meters (11ft) of 2.0mm (12AWG) Magnet Wire (aka ‘enamel copper wire’) for winding the inductors
· 2~3 meters of 3/8” Copper Tubing to make workcoil
· 2mm (14 Gauge) thick Copper sheet to cut into PCB busbars OR 2.5mm core electrical cable to solder to PCB traces
What is the inductance value of the work coil used?
I would like to build one however I have MacBook pro using Google Chrome and not sure where to find or buy PCB for 1.4Kw Induction Heater v1.1 to start. Also which app to open .gbr file to view in my Mac. I download GIMP don't work. (However I'm learning). Please let me soon. I'm from Colorado, thank you.
hi i have exactly the same issue as Nicholas DeSimone i can find no issues with my build followed exactly and it has blown 3 of the mosfets only q2 gets warm the only difference i can see is the power supply which is a huawei R4875G1 55v75a could that be the problem
Well done, i will try it, Can you give me advice in case I want to make the electrical circuit work for long periods without problems.
Great work and your ideas are special, thank you
Is there any other option 2.2uf,100v capacitor. Not available in online or offline.
hola buenas noches, arme el proyecto igual igual solo use los transistores IRFP260 despues esta todo igual y los problemas que me surgen es que cuando lo conecto se me caalientan todos los capacitores mas la bobina en si de 3/8 y cuando le ingreso un fierro para calentar ya no me calientan los capacitores si no uno de los 4 transistores, se me va a mas de 100 grados en menos de un minuto. AYUDAA POR FAVOOORRR...
Do you by chance have the BOM files and/or the other files that JLPCB is asking for for the to assemble this project?
Muchas gracias por su generosidad compartiendo todos los detalles de este proyecto magnífico.
Have you melted any metal yet, and could you do a video about melting bronze and/or other metals?
Hello! I don't understand the circuit, the diodes under the value "3d,4d" are connected, with only one contact, and where to attach the 2nd contact? And could you redraw the diagram a little to make it clearer? Thanks in advance
Hey I followed your build for a project I’m working on. I’m running into a problem where the power supply I’m using starts current limiting at around 6 volts and I can’t go any higher and it doesn’t seem to be getting any heat in the workpiece. When I run it it seems like one of the mosfets gets really hot while the other ones just get warm. I’ve done it on multiple boards and experienced the same issue. The only difference between my build and yours is that i’m using insulated wire instead of copper tubing because of certain limitations.
How can I buy complete set for ready to use it ?
A great Job! Can you trying this induction heater for cooker using pancake coil?
It's a wonderful job to share with you
May God increase your knowledge even more. Amen
If you are willing, I want to ask you one question
Can you buy component parts and send them to me via DHL as I intend to try this project?
Dear Father of Knowledge, If you are willing to send the goods, I am willing to send you the purchase money first.
Thank you in advance for your cooperation
munaaymen@gmail.com
from ethiopia
Hi can anyone tell me what would be the minimum wattage soldering iron to bolster the traces on the pcb board ? And what gauge solder would be adequate ? Thanks Amon or anyone else
Bob lee
Hi, I'm loving this design and video ! But it also raised some questions for me: 1) Did you ever contemplate using an inverter stick welding machine (MMA/SMAW) as your PSU for this? It seems to me that would provide exactly the kind of input you want to come into your PCB. 2) Do you know what temperatures you reached with steel? the video where you're hammering steel appears to be below forging temp (my intended application) but it could be that the camera was playing tricks...
hello, my 18R 0,25W resistors start burning if i use more than 34V input voltage? how can this happen? For usual the gate charge current should be so low that they dont get warm at all. please help. My cuircuit is the identical as yours but the work coil is a 10mm cooper wire with 6 turns.
Why did you add more capacitors, for the same total capacitance? Workload distribution?
hi i was wondering if i could replace the 2.2uF ceramic caps with these non polarized (crossover) capacitors as they are much MUCH easier to obtain and don't have a horrendous shipping cost attached to it (no australian retailers/electronic component vendors that i know of stock these parts in australia) the other caps are speced at the same voltage and capacitance my only concern is to do with the different type as i am not sure what effect it would have on the circuit.
here is a link to the caps in question
https://www.jaycar.com.au/2-2uf-100v-electrolytic-crossover-capacitor/p/RY6902?gclid=Cj0KCQiAnuGNBhCPARIsACbnLzpnBfZGOl3D4YQhxApA6-ZMy0jrrieKZfQnULqNt8sq0HMgdt9LI70aAsCpEALw_wcB
kind regards jesse
thank you sir . Can I use IRFP4227 instead of IRFP4668? thank you very much