Induction heater by MOSFET IRFN 260

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
Dear sir. . my subject on induction heater of IRFN 260p MOSFET using .
When I started testing it was conduction fully at 21amp ac on 12v ac input to rectifier .later reduced to 6 ampire suddenly jump to 14 ampire ie. Saturated no heating in metal occurs only MOSFET is heating up again after swithing on Witham intervel same problem repeats where IAM wrong the circuit is in my dp
 

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
good evening ,

dear sir I've attached the made circuit as per the drawing . the main observation is vcc ac ampire only i checked ie before bridge rect. first time when heated with ms material strrip like knife at 20 ampire heating stopped even after removing the strip amps remained same .it reduced after switching off with intervel now this is happening at 6 amps itself current gradually raising to 16 amps & above .12 v vcc . .25A capacity full wave bridge rect.please guide me also what is full load current of circuit . even i connected to 24 v vcc not working only mosfet temp raised in low
readings

no load plain coil at 12 v vcc 25 a capacity .........1.76a
sudden raise at 18 amp something like saturated no change in amps ]
please suggest me the path to come over .
sorry for the grammar mistakes .
thankyou
gdnaiuduPHOTO_20191007_200739.jpg PHOTO_20191007_200806.jpg
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
Are some of those coil turns touching?
If you use copper tube, you can water cool it.
Max.
 

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
Are some of those coil turns touching?
If you use copper tube, you can water cool it.
Max.
no sir , gap between each turn is less than 1mm no short circuit sir .

Are some of those coil turns touching?
If you use copper tube, you can water cool it.
Max.
dear sir, one more doubt i have i didn't do water weather it might the issue of problem sir

Show us your circuit diagram...[/
Can you post a pic of your actual constructed circuit layout?
Goodmorning sir , attaching the constructed setup sir.
 

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Dodgydave

Joined Jun 22, 2012
8,389
I still say the Mosfets are both on at the same time, you need to cross couple the Gates to each Drain, to make a Multivibrator oscillator to make sure only one transistor is on at once...


royer-oscillator-flyback_schem.png
 

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
Good afternoon sir , thanku for feed back I am not clear as u told each gates are crossed via diodes to other drain . On MOSFETs also heating happens say 6amp arround after it sundden raise to 13amp no heating on material takes place . One more thing even if heat material removed current remains unaltered sir thank you
 

shortbus

Joined Sep 30, 2009
6,979
I still say the Mosfets are both on at the same time, you need to cross couple the Gates to each Drain, to make a Multivibrator oscillator to make sure only one transistor is on at once...
That is why what is being talked about isn't a true Royer, but a modification called a Mazzilli. It counts on one of the mosfets turning on before the other at startup. Your schematic may be for a Royer(I don't know didn't research them) but the TS is for a Mazzilli, what they call a ZVS zero voltage switch, a resonate oscillator. Your schematic is not what all of the ZVS induction heater modules use.
 

shortbus

Joined Sep 30, 2009
6,979
@ D Ramesh I have some questions and a link that may help you get this working.

What are you using to power this? If using a switching power supply, you should have a on-off switch between the power supply and the ZVS. Switchers don't start up at full Voltage but the ZVS needs full voltage on it when first turned on. If not it will latch on with only one mosfet turned on and not oscillate. You also need a power supply capable of having enough current/amps to run the ZVS, if it doesn't have enough power available the voltage from it will drop and it will stop oscillating and latch up. Most people use either batteries or a unregulated linear DC power supply and not a switcher because of the need for voltage remaining stable over amps.

Also when heating steel you need to understand as it gets hot there is something called the Currie point with steel and the magnetic connection drops it becomes non magnetic at that temperature. Also before that point is reached the amperage of the circuit starts to drop from the value that is used when the metal is first put in the work coil.

I only know this because I to have started working with one of these and researched a lot . Read many sites and watched a lot of Youtube to try and understand how and why they work. But unlike you I bought one from Ebay, because I couldn't buy the components for the price of one already made.

Here is the best link to these I have found. I bought the one he talks about last, the one used with 12VDC and above.

https://spaco.org/Blacksmithing/ZVSInductionHeater/1000WattZVSInductionHeaterNotes.htm He has some really good Youtube videos on them too.
 

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
Dear sir thanks alot for Ur precios time for me , please guide me circuitof zvs oscilator for working. My application on induction heater on melting metal is my idea.so reffer. an suitable circuit. Getting knowledge by expert seniors;like u sir is gods blessing to me.thanl you.
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
One thing to keep in mind with these designs like this is to use the right type of capacitor.
WIMA MKP4 etc.
Max.
 

shortbus

Joined Sep 30, 2009
6,979
application on induction heater on melting metal is my idea.
One of this size powered by 12V is not the way to go for melting metal, unless it might be very small amounts. 12V is not enough for doing this, go to the link I gave you and read, then when you think you understand read again. He is doing very small amounts of metal melting in some of the videos. But you will need water cooled coils when melting by that I mean with a pump and a radiator of some sort to keep the heat down. The heat isn't so much made electrically in the coils but from conduction/convection from the crucible transferring into the coils.

What metal are you trying to melt? How much at a time?
 

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
One of this size powered by 12V is not the way to go for melting metal, unless it might be very small amounts. 12V is not enough for doing this, go to the link I gave you and read, then when you think you understand read again. He is doing very small amounts of metal melting in some of the videos. But you will need water cooled coils when melting by that I mean with a pump and a radiator of some sort to keep the heat down. The heat isn't so much made electrically in the coils but from conduction/convection from the crucible transferring into the coils.

What metal are you trying to melt? How much at a time?
Good morning sir , gold refined from e-waste after passing through chemical process .raw ,aterial will be like fines form
 

Thread Starter

D Ramesh

Joined Oct 6, 2019
13
One of this size powered by 12V is not the way to go for melting metal, unless it might be very small amounts. 12V is not enough for doing this, go to the link I gave you and read, then when you think you understand read again. He is doing very small amounts of metal melting in some of the videos. But you will need water cooled coils when melting by that I mean with a pump and a radiator of some sort to keep the heat down. The heat isn't so much made electrically in the coils but from conduction/convection from the crucible transferring into the coils.

What metal are you trying to melt? How much at a time?
One more thing sir the transformer involved in this circuit is 12v 70 ampire as u told the current gradually increases but my case no latched on 6 amp it self
 
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