Current Control Sample Time of CRD07500AA12N-FMC

milovanmajstorovic

Hello,

I have a question regarding the CRD07500AA12N-FMC design. On the page of this reference design, it's noted that the switching frequency of the module is up to 100 kHz. Given the fact that this reference design utilizes AMC1303M0520DWVR delta-sigma modulators for the current measurements, and TMDSCNCD280039C MCU, can you tell me if 100 kHz switching frequency is obtainable in the current control closed-loop mode, i.e. can this delta-sigma modulators-MCU combination produce current measurements information every 1/100 kHz = 10 us? Have any current closed-loop tests done with this reference design?

Best regards,

Milovan Majstorovic

Forum_Moderator

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ChrisN

Hello Milovan,

Thank you for your question. The 100 kHz switching frequency rating is based on the hardware thermals. The reference design has been tested in an open-loop configuration using the delta-sigma modulators for measuring the fundamental current, not cycle-by-cycle current. The controller and modulators appear to be capable of operating in current-control mode at 100 kHz, albeit not with the full resolution of the modulators. With proper code optimization and understanding that the elevated frequency might degrade the accuracy of the measurements, this design could likely achieve current measurements every 10 us. However, this design has not been tested at these operating conditions, nor was it designed specifically for current-mode control at 100 kHz. It is up to the operators to perform the due diligence and develop the code to support this operation.

Thanks,
Chris N.

milovanmajstorovic

Chris,

Thank you for the clarification.

Best regards,

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.