MOSFETS keeps exploding i dont now why ...

[billu8660]

hi,
i am building this as part of my final year project, the irfp460 on this keeps exploding, it seems to work fine with lower dc voltages 40vdc....but when i apply 310vdc kabooooomm :"::

 

[wally7856]

Your schematic needs to be much larger

 

[MicrosiM]

It seems to me the same old classic circuit, but as wally said, its to small !!

Please provide full information's about the project

 

[billu8660]

sorry for the mistake fellows -)

 

[DjLeco]

Use this modifications , and will work.

Capacitors must be MKP good quality.

Seried condensator with primary, must me tested value between 1 and 3uF, depends on freq, good quality capacitor , at least 400Vdc.

Seried coil in secondary, must not saturate under 20 Amps.

I recommend T130-2 material, with 20-25 turns, Cu-Em, min 1,5mm diam.

Use MINIMUM 500VDS mosfets, like IRFP460.

Good luck!

 

[billu8660]

@ dj leco......thanks man i'll try and update you a.s.a.p

 

[billu8660]

@djleco...... frequency is 50khz.....whats this MKP stuff i live in Pakistan only china stuff here......can i use MOSFETS IRFPG50 as well?
i am using ETD49 trafo....pri turns 38 0.75mm wire dia.....sec turns 6 0.75mm x 7, these are calculated by a program taken from this forum....are these figs OK?

Again thanks a lot man

 

[DjLeco]

For RT CT values on schematic (10K+1nF), freq is around 65-70 Khz.

IRFPG50, is too weak for your application, 2 ohms RDS on, is bad.

 

[billu8660]

@djleco.....i have modified the ckt of sg3525 to make freq 50khz.....ok i will not use irfpg50.....can u please tell me about the etd49's calculation?

 

[DjLeco]

Please ask Mr. Microsim, he knows exactly how to calculate for ETD49.

I use ONLY ETD59 in mines projects, and I always experimentate, I'm too poor at mathematics and formulas...

 

[billu8660]

@ microsim hi, i need 35olts @ 20amps from etd49 with 50khz freq, 310v input, what will be the pri sec turns and wire dia?

thanks

 

[MicrosiM]

@ microsim hi, i need 35olts @ 20amps from etd49 with 50khz freq, 310v input, what will be the pri sec turns and wire dia?

thanks

In full bridge, for 310V at the primary of the transformer, you will need 67 turns for PRIMARY

and 7.5 or 8 Turns for secondary side (35VDC)

I am not sure if this circuit will fit your application, i think this voltage can be obtained using other method

see attached

 

[billu8660]

@microsim......67 turns of what wire dia and strands,similarly 8 turns dia and strands?........ and please upload large and clear schematic sir ........i need this 35v 15 or 20 amp stage for LM723 linear stage....see image attached

 

[gloriel]

halfbridge topology maybe fit with your application.

 

[billu8660]

@ djleco
hi there man,
i have found these for 1uF mylar caps here in Karachi electronics shop, will they work or not please let me know.....

 

[DjLeco]

Looks OK, try it!

U can try to find at Mouser or Farnell or Digikey, those ones:

http://www.farnell.com/datasheets/222017.pdf

very good ones (I use)

http://www.farnell.com/datasheets/1306065.pdf

or (not tested)

http://www.farnell.com/datasheets/1504335.pdf

http://www.farnell.com/datasheets/1449999.pdf

 

[billu8660]

@DJleco

bro it worked 2 to 3 times when i turned it on and off..... 300Vdc to 33.2Vdc ........but then on the fourth time one of the high side MOSFET explodes ..

can i replace IRFP460 with IRFPG50 may be that will work?.....i will not drain 15 amp of current from the secondary side ..... its just a final year project ....i can show this without heavy load.....will IRFPG50 work?

in addition what could have gone wrong this time any guess?????

if even using IRFPG50 wont work i will definitely kill myself

 

[MicrosiM]

@DJleco

bro it worked 2 to 3 times when i turned it on and off..... 300Vdc to 33.2Vdc ........but then on the fourth time one of the high side MOSFET explodes ..

can i replace IRFP460 with IRFPG50 may be that will work?.....i will not drain 15 amp of current from the secondary side ..... its just a final year project ....i can show this without heavy load.....will IRFPG50 work?

in addition what could have gone wrong this time any guess?????

if even using IRFPG50 wont work i will definitely kill myself

It will be a good idea if you show some pictures of the PCB and the final schematics

 

[billu8660]

@microsim
sir,
i made it on veroboards with long wires hanging here and there ... mean from IR2110 to MOSFETS gates etc.......a complete mess

vero 1 for offline 200 to 310Vdc
vero 2 for SG3525 and IR2110
vero 3 MOSFETS ..ETD49 bridge caps inductor....

sir i will replace IRFP460 with IRFPG50 tomorrow ....and will tell you the result....

 

[MicrosiM]

@microsim
sir,
i made it on veroboards with long wires hanging here and there ... mean from IR2110 to MOSFETS gates etc.......a complete mess

vero 1 for offline 200 to 310Vdc
vero 2 for SG3525 and IR2110
vero 3 MOSFETS ..ETD49 bridge caps inductor....

sir i will replace IRFP460 with IRFPG50 tomorrow ....and will tell you the result....

hmmm

using long wires as you have just described will make it impossible for you to success with this SMPS, you MUST use one PCB for MOSFETS + IR with shortest tracks


regards