Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Woudl you need copper heatsinking for a 750W offline PSU?

Status
Not open for further replies.
C

cupoftea

Advanced Member level 5
Joined
Jun 13, 2021
Messages
2,609
Helped
54
Reputation
108
Reaction score
115
Trophy points
63
Activity points
13,682
Hi,
Supposing you had to do an offline SMPS (220VAC) for 24Vout at 750W.
The enclosure dimension should be no more than 275mm x 142mm by 40mm high.
You can have 2 cooling fans, each 12V, 0.18A, and obviously the associated cooling vents in the enclosure. The enclosure can be made of metal.
Ambient temperature withstand just like any usual Meanwell type offline PSU.

Would you use heatsinks made just of aluminium?, or would you need also to screw fairly large pieces of copper to the heatsinks, in order to provide sufficient cooling?....eg dont just screw the FETs/Diodes to the aluminium heatsink, but screw them to a decent chunk of copper, which itself then gets screwed to the aluminium heatsink? Also, have say a decent chunk of copper screwed to the top of the PFC FET diode heatsink, for that extra cooling..

So, would you need these extra copper heatsink pieces, or not?
 

Sort by date Sort by votes
Depends on the efficiency. If the efficiency is assumed as %90, Power Dissipation over Transistor(s) will be at least 75W. So well ventilated heatsink will obviously be necessary.
 
Upvote 0 Downvote
What do you exactly mean with extra cooling? Copper has higher thermal conductivity (384 versus 229 W/K*m), but using an extra piece of copper between power device and heatsink doesn't necessarily reduce the total thermal resistance. In case of a reasonably shaped heatsink it may even increase it.
 
Upvote 0 Downvote
Thanks, we have been offered to buy a 750W PSU....and we took it apart, and noticed these copper pieces which have been screwed to the aluminium heatsinks, and wondered if this is common practice?
 

Upvote 0 Downvote
What a slab of copper under a power device can do is reduce the thermal gradient immediately beneath and around the device, if the heatsink surface beneath the device is really too thin.
A properly dimensioned extruded heatsink will not suffer from that problem.

Its really a band aid solution, but it does work if the heatsink is for example, just a large flat plate of thin material.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top