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I suspect that a nice blower can keep them cool. Those heatsinks are tiny, but they do have effective surface area which should let me remove the heat from those fins pretty quickly.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701
Here's my latest "ZVS" driver module. It uses 2xIRF 540 (85W only, 100V 0.055Ohm 22A). Do you like the heatsinks?They are small, and the mosfets do fine. Why?
IRFP460, according to IR datasheet has 280W 500V 0.27Ohm 20A . 280W and 500V sound great, but the resistance between D and S is bigger, resulting in more heat.
The only stressed component is the inductor, I need to replace it with another one with ticker wire to stand the current. Yes the inductor is not on a toroidal.
You'll also notice a third heatsink, is (unneeded) for the L7812 that is connected to the two mosfet gates via 1/4W 460Ohm resistors. No need for 3W or more.
This board runs at 15V 20A, it powers a 5+5 primary on the ferrite core pictured, that has a 12 turns secondary for powering a second flyback transformer, via the initial windinding. That also works.
Registered Member #1938
Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701
Thanks Patrick, but I'm careful. For high power devices, or for higher voltages, I don't do what you've seen in the last pic. A good moment to remember and post a warning about the dangerous currents put out by a ZVS driven flyback.
The IRFP250 has a .07 ohm resistance between the D and S, so it won't dissipating nearly as much heat as a the 460, and a little more heat than the 540. Does 35W of heat dissipation sound right to you guys for a typical setup with an IRFP250?
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Primary woes
