KerimF
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Yes you are right, I'm obviously not as good as my PC in multitasking (doing two thing at the same time).
Ignore my post, it applies only to the four Nmosfet version.
Alex
Added: I suppose that behind R10 and R9 there is a rail-to-rail output.
During gate voltage transistion, you'll get a "shootthrough" current peak of about 10 - 15 A at 12 V supply. If the transition is fast enough, this won't damage the transistors but cause excessive losses.so, the circuit in post #7 with 12 VDC supply and without 1k resistors in parallel with 10k resistors will work fine without blowing my transistors?
so, the circuit in post #7 with 12 VDC supply and without 1k resistors in parallel with 10k resistors will work fine without blowing my transistors?
so, the circuit in post #7 with 12 VDC supply and without 1k resistors in parallel with 10k resistors will work fine without blowing my transistors?
What do you mean?
It doesn't matter if the transistors are driven will a 3 or 5 or 12v voltage.
Alex
Please let us remember always that the hardware AND software should run in harmony for the controller to give what we expect.
For example, which is the dead time you have decided on?
I mean the time when both Q5 and Q6 are open (post #17) hence Q1 and Q3 (P-MOS) are off.
As you know, a MOSFET has a relatively high input capacitance, mainly the power ones.
When Q5 or Q6 is turned on (becomes saturated, its collector close to ground), the driven Cgs will be discharged rather quickly.
But when Q5 or Q6 is off, Cgs will have to charge via a 10K resistor (R5 or R6) and the PMOS will not turn off very fast.
So if there is no dead time at each transition, each leg will act as a short circuit between 12V and ground for a very short time.
The effect of this malfunction (caused by the software which is not compatible with the circuit) will be noticed more when the frequency is increased.
You are fortunate that your bridge didn't give a smoke yet
Kerim
indeed it did give smoke but i was fast . now i put a 50 usecs dead time between turning on the outputs, but it still heats up not like before although but if i increase the dead time more than this i wont be able to get the desired frequency output. and when i think of heating in a low frequency i can't imagine how would it be with an 8 ampere load.
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