How to make full bridge work???

[binary2007]

Hi everyone.

I have one big problem concerning full bridge driving DC motor. The voltage used in my application is 80V and motor has a power of 2kW but it is used just about 50% of that power. Every bridge I tried to construct using manuals and how tos failed. Once I burned 3 FETs, other time it did not move... Anyway, is there any place where I can see how similar full bridges are done or someone who did something similar? I use PIC MCU with one channel PWM. The direction of rotation is determined by two additional pins that have complement values in working mode. I use FET drivers so any line from MCU is not directly connected to the bridge.

Thanks in advance!

 

[VVV]

It sounds like the problem may be that you do not have enough dead-time.
There should be a small delay between where you turn off one set of MOSFETs to where you turn on the others.
I don't know what drivers you have, but start with a large dead-time, something in the order of 1-2us.

If you post your schematic, maybe we will spot the problem.

 

[anilshrirao]

hi!
As per as I know the problem is not with the brifge connection. As I don't know how u connected the mosfet in bridge but if as u said they burnt then it means they are driving much current than the rating. So u calculate your circuit required current. connect two are more mos in parallel to withstand that current and carefully ceck the grounding. i hope it help u....