DRV8323R: Using 3 x internal current sense amplifier for sensorless BLDC commutation

Hi Eli,

I don't see any detailed explanation on how sensorless applications works in  Field Oriented Control Made Easy for Brushless DC Motors Using Smart Gate Drive (Rev. B) (ti.com).  Hardware Design Considerations for an Electric Bicycle using BLDC Motor (Rev. B) .

But I did find some info in the following application note: https://www.ti.com/lit/ug/slvub12/slvub12.pdf?ts=1689559946474&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FBOOSTXL-DRV8323RS

This application note stated that it's using Back EMF integration technique for sensorless control. This application note is a supplement to BOOSTXL-DRV8323RX User's Guide. I believe it can be applied on motor circuit design that based on BRD8323RSRGZR.

I have attached a picture below. It's part of the schematics of BOOSTXL-DRV8323RS. Can you advise what's the purpose of the VSENA, VSENB and VSENC? Is it the Back EMF measurement for sensorless control? 

Other than Back EMF, I don't see any info that stated that sensorless FOC BLDC commutation can be done by current sensing.technique. Can you provide info that has detailed explanation on sensorless FOC BLDC commutation can be done by current sensing.technique?

Regards,

Yip Kok Loong

Hi Yip Kok Loong,

Thank you for the clarification. I am sorry those resources did not lend more insight. Sensorless Field Oriented Control of 3-Phase ... (DRV830x-HC-C2-KIT) (ti.com) is a document from the C2000 team that will help when understanding how to implement sensorless FOC, but it doesn't mention anything about using CSAs. Instead, it mentions the use of phases, which are related. The equation to compute VSOx varies depending on if you use bidirectional or unidirectional current sensing (see section 8.3.4 of the datasheet). I will connect with my team to confirm the functionality of VSENx and give you more information on how to implement this by Wednesday EST.

Best,

Eli

Hi Eli,

Thanks, looking forward for your reply on the VSENx functionality info.

Regards,

Yip Kok Loong

Hi Eli,

Ok, noted. Thanks for the info.

Regards,

Yip Kok Loong