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yusuke
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First reply posted First question asked Welcome!

I think there is a loss due to Coss(esr) when zvs.
Is there a way to find the loss?

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sushank
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25 solutions authored 100 sign-ins 50 replies posted

I assume you you are referring to Coss ESR, as you can see in the figure11 current is constant during Coss charging, here ploss would be I^2*ESR. but for this ESR information should be known. however ESR in this case does not remains constant and changes wrt temp, frequency, Vds max,

alternatively the best method is you can simulate in Ltspice your application and calculate it from there the loss during turn off or turn on across the FET even after ZVS implemented. 

thanks.

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sushank
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25 solutions authored 100 sign-ins 50 replies posted

Hi

average loss due to coss can be calculated as 0.5*Coss*Vds*Vds*fsw

fsw - switching freq

vds - drain to source voltage

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yusuke
Level 1
Level 1
First reply posted First question asked Welcome!

> 0.5*Coss*Vds*Vds*fsw

Isn't it a loss in hard switching?

https://www.infineon.com/dgdl/Infineon-ApplicationNote_MOSFET_CoolMOS_P7_600V-AN-v02_01-EN.pdf?fileI...

Figure 11 Simplified EOSS recycling mechanism in soft switching

 

Eoss is a not loss in soft switching

I would like to know the loss due to Esr during soft switching.

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sushank
Moderator
Moderator
Moderator
25 solutions authored 100 sign-ins 50 replies posted

I assume you you are referring to Coss ESR, as you can see in the figure11 current is constant during Coss charging, here ploss would be I^2*ESR. but for this ESR information should be known. however ESR in this case does not remains constant and changes wrt temp, frequency, Vds max,

alternatively the best method is you can simulate in Ltspice your application and calculate it from there the loss during turn off or turn on across the FET even after ZVS implemented. 

thanks.

0 Likes