• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 82 subscribers
  • Views 323 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

How important are identical current shunt amplifiers for FOC

Sam Hawker
Intellectual 850 points

Other Parts Discussed in Thread: DRV8301

Does it really matter if all three phases use identical current shunt amplifiers or is it sufficient to design them for nominally the same sensitivity? As we are all aware the DRV8301/2 has two built-in current shunt amplifiers. In the EVM kits external op amps are added for all three phases but I was wondering if it was possible to use a mixture of internal and external. I can't really spare the board area to go entirely external. On the other hand I think I can get away with just two current measurements. But if I could just add one external op amp to get the third current measurement that might be worthwhile.

 

  • 0
    TI__Guru** 119680 points

    It's not ideal, but it is possible. You can look at placing it similar to the DRV830x so that traces match the other two phases, or you can place it as close to the Piccolo ADC channel as possible to reduce noise post amplification.  The latter is probably best.

    We looked at doing that with one of the kits, just having a single external OPA so you could use the two in the DRV830x devices for operation under 1.15 modulation and add the third for 1.16-2.0 modulation.  We are looking forward to the next DRV830x device which includes three on-chip...or just a DRV830x with no PGAs on-chip would work as well (don't think that's happening).