Scorching_beam
Joined: 31 Oct 2009
Posts: 1
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 31 Oct 2009 10:56 Diodes Heating in Buck Converter |
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Dear guys
I have designed a Buck Converter of 24V/30A output.
There is a heating problem because of the clamping Diode.
When i switches on the converter, within a 10 minutes the Diode temperature raises upto 65 degree C, and it continues to raise.Due to the inductive kick of the Buck converter the power dissipation across the diode is Power dissipation=0.7V x 30A, which is much higher.I am using two MBR20100 diodes in parallel..The heat sink is extra large, and the temperature difference between one end of heat sink to the mean point (the point where the diode is connected to heat sink) is more then 6 degree C, which means the rate of generation of heat is much higher then the rate of absorption by the sink.
If any one has any idea either to change the MBR20100 diode, or some other suggestion ?
Regards
Scorching Beam
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FvM
Joined: 22 Jan 2008
Posts: 5161
Helped: 767
Location: Bochum, Germany
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31 Oct 2009 11:14 Re: Diodes Heating in Buck Converter |
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| Quote: |
| which means the rate of generation of heat is much higher then the rate of absorption by the sink. |
After reaching thermal equilibrium, the rates are identical of course.
There can be still a considerable temperature difference across the heatsink, depending on the design. The thermal
properties can be calculated easily, but the diode losses may be actually the largest amount to converter total losses.
Small improvements are possible by further oversizing the schottky diodes, but a synchronous buck design would be
needed to reduce the losses fundamentally.
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