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Power loss calculation question

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Stenberg

New Member
Hi!
I have gotten a little stuck, and need to find an answer before being able to continuing with calculations.

A have a AC/DC converter Totem-pole, a picture is uploaded below.
I have calculated power losses for a diode and for a transistor.

My question is, since the transistors are placed in a half-bridge, and conducting one at a time, are the calculated power loss for one transistor the power loss for one or both transistors in the half-bridge?

I have added the calculations below, please take a look.

Thanks for your help!

//Stenberg
 

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MrAl

Well-Known Member
Most Helpful Member
Hello,

Cant read your writing as it is too light. Dont you check before posting?

A transistor draws current when it is on but not much when off, so the power dissipation is mostly when on.
There are also switching losses that would have to be added if there is significant switching times.
 

MrAl

Well-Known Member
Most Helpful Member
Hello,

Are you aware that for the switching times the voltage is falling when the current is rising, or the voltage is rising when the current is falling, so there is a factor of 1/6 involved for that portion of the cycle as an approximation.

Also, one of the schematics does not look right with an inductor running into the gate of one of the MOSFETs.
 
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