Quote:
Originally Posted by MPaulHolmes
Hey Joe! Yes, the gate resistors were 30, but I changed them to 20 in the last 3 (yours, Bens, Adrians).
|
oh, that changes things slightly!
Heat generation at full frequency: 334W
Heat generation at half frequency: 217W
change: 35% reduction
Predicted temps should now be:
mosfet: 58
heatsink: 51
So, I guess the prediction is still too low, but it's a hair closer.
The numbers at the bottom of my post for reduction in heat generation were assuming 30 ohm gate resistors. They've dropped a little:
15 Ohm Rgate - 16% less heat generation
10 Ohm Rgate - 33% less heat generation
5 Ohm Rgate - 51% less heat generation
I'd like to put my scope on there and check out the voltage spikes...
Quote:
Originally Posted by MPaulHolmes
I don't have any info on the number of hours for the mosfets/diodes at a given temp.
|
I asked about that - apparently, thermal cycles play a bigger role than actual temperature. I guess actual life is hard to estimate.