In my final year project, i have to simulate full bridge inverter using PSpice. In this project, two comparators uA741 were used to give supply for the N-channel Mosfet. But the problem is, when i try to simulate my work mosfet can't turn ON because the value of Vgs for the mosfet is less than 12V. Can somebody help me what should i do to make sure this mosfet can operate properly.
The inputs on the 741 opamps are not biased so they will not work. Their output high voltage is +3.5V but your lower Mosfets need a gate voltage of +10V and the upper Mosfets need a gate voltage of +180V to turn on.
Is there some reason you're using +/-5V for your op-amps? Is there any reason you're using all N-FET's for your bridge circuit? If your high side FET's were P-FET's then the bridge might work, but you would need to deive the gates to very near the 170V to trun them off. You would need an extra transistor on each input side to translate the voltage.
i dont have any idea why i put -/+5V for my op-amp because i really new with this part and i just lookin the source from internet and try that value...so bad right? and actually i want to use all N-channel mosfet because i'm already buy the n-channel for my project and IR2181 as it driver. I want to try your suggestion but I don't really understand about an extra transistor on each input side. using the same transistor? Can you post to me your drawing? Sorry and thanks a lot for reply me
The lousy old 741 opamps are much too slow. While they are slowly ramping the gates of the Mosfets then the Mosfets will be quickly heating and might burn out.
Use real comparators if you want which switch much faster.
thanks a lot for your advice. I'm really sure it will help me for my simulation stage...I'll try to use real comparators as you said. Thanks again and i really appreciate it...