Questions about the maximum switching frequency of the SIC module

yxj34825

I am using a SiC module CAB016M12FM3, with the driver board CGD1700HB2M-UNA, after calculating the maximum frequency of the module is 446KHZ, but we actually emit 600KHZ, does this have any effect? Or is it possible?

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AustinC

Hi yxj34825,

Exceeding the maximum switching frequency of the gate driver will draw excessive power from the isolated power supplies and possibly lead to premature failure of the supplies or the driver board may not operate at all.

Are you utilizing a soft-switched topology? If you're achieving zero voltage switching (ZVS) in your system, then the total gate charge (QG) will be lower than what is stated on the datasheet by roughly the gate-to-drain charge (QGD), which would result in a theoretical maximum switching frequency >600 kHz with this module & gate driver pairing. It is likely that for a more robust design, an isolated power supply capable of >2 W would be selected to comfortably hit this frequency with margin. You will also want to ensure that the other components in the system (gate resistors, the gate driver IC) can support the much higher power loss.

Best Regards,

Austin C.

yxj34825

Hello, thank you for your reply. We haven't achieved soft switching yet; it's always hard turn-on and turn-off. Is there any good way to calculate Qg? For instance, the data sheet shows Qg measured at 800V and 160A. In our actual situation, it's approximately 1000V and 20A. How can we calculate Qg under these conditions? Thank you for your reply.