MOSFET Burning Problem in UPS

[masterleous]

ups fet

check this out

Very good discussion to drive MOSFET through NPN and PNP Push Pull Technique

Thanks

 

[zahidj]

mosfet failures in ups

try using a timer in charging circuit ,i.e charging start after few minutes
i think fets only burn when power is restored.

 

[wandler]

ups mosfet

I had this same problem on a Plasma power supply I built and contacted IR for a solution. Since I couldn't get higher VDS breakdown voltage they told me to put a zener in series with a diode from Drain to Gate. So if the power supply voltage spiked under transient or no load situations the high VDS would turn the FET on very rapidly and bleed through the device. Trying to control Vgs didn't work for my circuit, nor did snubber circuits on the output.

 

[ifithegr8]

what causes mosfet burn

The MOSFETs used here are IRF3205.This UPS has disadvantage that the MOSFETs used here are burning so frequently, (The other UPS of same Model design have same problem).


see brother i am manufacturing UPS Square wave.Problem you are telling that one side FET burns and it happens on CHG.

On my word make following changes and do let me know

Use IRFP150N

use PIN 1 that is Gate as input 4rm the clck.
join Pin 1 to the pin 3 that is source via 4.7kOhm Pin 2 goes to transformer
pin 3 is connected to -ive of bat

make two stages for tho inputs of transformer

Do let me know
afnan_decent@hotmail.com

 

[Mithun_K_Das]

I felt this same problem with IRFZ44N. I tried hard to solve the problem, finally I changed the zener diode 12V replacing by 6.2V. as the gate voltage is no required too high, so it was sufficient. It was on my design. you can try this too. and also change the MOSFET. replace with more VA(low voltage high current) as IRF540. You didn't write anything about the VA of the UPS. If the capacity is more than the MOSFET can drive then it will burn out easily. and a delay should be kept between inverter mode to main mode. or a high current flows after the inverter mode changes to main mode. this is a serious problem. if there is no time delay for charging between the inverter mode and main mode then its the main problem for your UPS. in this case you the MOSFET capacity should be at least 2times than the inverter capacity. if you cant add more FETs then find out the gate voltage of the both channels. if the gate voltage are not same then the FETs are burning in inverter mode, and if its ok then FETs are burning at changeover mode+charging mode. in this case, add a diode(6A) with each fet (S to D). this will help the internal diode to take more current. any way another case may happen, check the ups carefully. is the burning process is happening just at the changing time??? or within some ms??? then the problem is the oscillator is not beibg stopped while the UPS goes main mode. if so then the MOSFET have to carry a huge current, charging current + back up current. if this happen, then nothing can help you without changing the UPS.

I think all these will help you.
Thanks
Mithun

 

[richmon74]

I think you should upgrade your MOSFET to higher curent ratings and observe