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Diode ON Resistance

0 votes
33 views
Hello,

I haven't been able to identify a method to determine the value that is used for the Diode On resistance in the "Dual Active Bridge Converter" Demo model (check the attachment). Please, could you provide information on how to obtain this value ?

 

Thanks,
asked Jan 8 by carlosivanrp (12 points)

1 Answer

0 votes

Hello,

Have you looked at the model initialization code included within? There we mention the primary and secondary side MOSFETs used in the simulation, both from Wolfspeed, as well as their nominal (data sheet) values for diode on-resistance. Does that help? And just in case you can't actually find the model initialization commands, I attached the Note from the model description with these instructions below.

Best regards,

Kris

answered Jan 14 by Kris Eberle (665 points)
Thanks Kris.

I can see that the ron_body_diode parameter has been defined as 5 miliohms in both cases (C3M0030090K and C3M0065090D MOSFETs). However, according to figure 9 of the corresponding datasheets and my calculations, the slope resistance @ VGS = 0 (dynamic resistance @ VGS = 0) of the body diode is not equal to 5 miliohms but is approximately 33.5 miliohms for the C3M0030090K and 68.8 miliohms C3M0065090D. I use the criteria that the ron_body_diode parameter is the dynamic resistance of this diode, i.e. the slope of the curves of Figure 9 @ VGS = 0. Please, could you help me to clarify this?

Thanks,
Hello,

For C3M0065090D, since it is rated as 36A @ 25C then we measure Ron (the slope) at 36A from that figure. You might choose a value closer to 10 ohms, but I don't think it is as high as the 30's. Anyway, you are welcome to change the value in the model. Let me know if this helps.

Regards,

Kris
Hello, thanks.

I am using Ohm's law to calculate the slope (1/Ron) from figures 9s of both datasheets C3M0030090K and C3M0065090D. Now I have changed to 33.5 miliohms and 68.8 miliohms the Ron body diode and the efficiency is not degraded as expected. I realized that the current is flowing through the MOSFET channel and there is no current flowing through the body diode. I expect that the MOSFET and the body diode share the drain current. Is that ok?

Thanks.
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