How long is the switching time now? I can't see any leakage inductance spikes so I'm guessing it's a bit slow - which will make all energy stored in the leakage inductance of the transformer be dissipated in the transistors.
100kHz. There is no spikes becouse of snubbers. Without them I have ~1MHz 600-700V overvoltage. Temperature is 60 'C on radiator with 175V/2A load for 1 hour. I can achieve 7A, but with too hot transistors.
What I meant to ask was how long the switching lasts, that is, how long is the time when voltage is rising/falling when transistors turn on/off.
What snubbers do you have right now?
What snubbers do you have right now?
That sounds a bit slow.
How long is the on time per transistor?
Is 100kHz transformer frequency (200kHz output ripple frequency) or output ripple frequency (50kHz transformer frequency)?
How long is the on time per transistor?
Is 100kHz transformer frequency (200kHz output ripple frequency) or output ripple frequency (50kHz transformer frequency)?
So the on time is about 5µs then?
With 600ns total switching time for a 5µs on time you might have upp to 10% of output power in switching loss. I believe you'll have to speed up the drive to the fets if you want lower losses.
With 600ns total switching time for a 5µs on time you might have upp to 10% of output power in switching loss. I believe you'll have to speed up the drive to the fets if you want lower losses.
But faster switching requires a better PCB and overall layout, low inductances, damping of parasitic resonances, ground plane, etc... It's always the same compromise.
Of course 🙂
Another way would be to lower the frequency and/or trying to get higher duty cycle. But maybe there is a good design reason for the ~50% duty cycle, I don't know the application, required holdup, input voltage tolerance and so on.
Another way would be to lower the frequency and/or trying to get higher duty cycle. But maybe there is a good design reason for the ~50% duty cycle, I don't know the application, required holdup, input voltage tolerance and so on.
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