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Originally Posted by Gdeaver
Don't forget switching losses from the fet turning on and off. The fet is in the linear region during each cycle for a small period of time. Fets do not turn of instantly.
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Yes. What would be your quantitative estimate of the overall effect (watts averaged over 67μs) of this switching (one rise and one fall every 67μs) for the FDP8441 when the current is 30 amps?
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Also, the black jags are switching both h legs on and off constantly. Black jag fets always see some current. Jags do not have diodes or TVS devices to protect the intrinsic diode of the fet from inductive kick back when they turn off.
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According to
this post, for any given PWM command, in one leg of the H bridge the low-side FET pair is ON, and the high-side FET pair is OFF. In the other leg of the H bridge, the high and low FET pairs are alternately ON and OFF. Protection from inductive current is provided by shorting the motor through the low-side FETs during the OFF portion of the PWM cycle.
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The Victors are low side switchers.
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Not saying you're wrong, but what's your source for this info?