H-bridge problem - it switches off control

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Krzysztof Bieda

Joined Jan 5, 2016
46
Hello Everyone,
I have strange situation that my PMSM controller switches off when I put
high load.
I observe then 95A on fets.

I found that reverse shottky diodes influences it.
When I putted two SK54C in parralel then I did not observed that switching off.

I thought that I simply require more forward current on reverse diode, but when
I applied 40A (http://pl.farnell.com/vishay/vft4045bp-m3-4w/diode-schottky-45v-40a-ito-220ac/dp/2115198)
one then it even got worse.

I do not see it to be a software thing, because as I even checked I am far from top values for
control variables.

I think that it is something inside h-bridge that is causing it.
Maybe overheat, or wrong snubber circuit.
My circuit:
one.PNG
all.PNG

How do you see it?

Best regards,
Chris
 

ronv

Joined Nov 12, 2008
3,770
Hello Everyone,
I have strange situation that my PMSM controller switches off when I put
high load.
I observe then 95A on fets.

I found that reverse shottky diodes influences it.
When I putted two SK54C in parralel then I did not observed that switching off.

I thought that I simply require more forward current on reverse diode, but when
I applied 40A (http://pl.farnell.com/vishay/vft4045bp-m3-4w/diode-schottky-45v-40a-ito-220ac/dp/2115198)
one then it even got worse.

I do not see it to be a software thing, because as I even checked I am far from top values for
control variables.

I think that it is something inside h-bridge that is causing it.
Maybe overheat, or wrong snubber circuit.
My circuit:
View attachment 124244
View attachment 124245

How do you see it?

Best regards,
Chris
I don't see the need for any of the 4.7 nf capacitors. Not sure if that is your problem or not.
 
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