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shunt-resistor in each phase in( Directly measurement on the phase line ).

Dave Hunson
Expert 1720 points
Other Parts Discussed in Thread: CONTROLSUITE

hi every one!

I am using motorware18  prog_lab3a (for ACIM).

as you may know in most of IGBT packs we do not access to leg of each low-side IGBTs .(like 7MBR50SB120)

I want to use Directly measurement on the phase line rather than Measurement on the low side of the half-bridge I am going to use ACS758LCB-050B as Measurement sensor .

my questions:

1. what change should be made in CCS code?

2.do you think this sensor (ACS758LCB-050B) is suitable for current measurement,(Please explain about it)

thanks for attention

Regards.

Dave.

  • 0
    TI__Genius 17175 points
    You will need to provide the current feedback to the ADC in a similar manner, depending on how your circuit looks. You will most likely need a op amp buffer between the current sense IC and microcontroller. You could refer to the LEM current sense design used in the IDDK for some more information about what I'm referring to: C:\ti\controlSUITE\development_kits\TMDSIDDK_v2.0\IDDK_HwDevPkg_r2.2.1\IndutrialDrivesRev[2.2.1].pdf, page 4

    That device looks acceptable, given you select the correct variant for your expected phase current magnitude

    Sean
  • 0 in reply to Sean Bigley
    Expert 1720 points
    Thanks dear Sean :)
    Sure I will use Opamp after that OPA3250

    but the reason which I choose the ACS758 is:
    1 .this cheap.
    2.the output of it between 0~3.3V by(-50~50A).
    3 .isolated output
    4.so easy to scale the output of it.

    so,do you think is that a good device?

    since I am using the proj_lab 03a.c ,it is a leg shunt resistor ,now I have phase line sensor ,so how to change the code in HAL.c and etc..?

    thanks
    Regards.
    Dave.
  • 0 in reply to Dave Hunson
    TI__Genius 17175 points
    The device seems a reasonable choice, but I am not able to endorse any device for your design due to company policy. Hope you understand.

    From S/W point of view, there is no real change, just ensure the polarity is correct. You can change the polarity easily by changing the sign of current_sf in HAL_readAdcData()

    Sean
  • 0 in reply to Sean Bigley
    Expert 1720 points
    Thank you very much Dear Sean :)
    your reply is fast ,and correct.
    Good luck!
  • 0 in reply to Sean Bigley
    Expert 1720 points
    as you know FAST needs to have voltage feed back sensors as well as current ,since the ground of HV(1200v) is directly connected to vss Microcontroller ,it is not good I think, is there any way to to without Voltage feed back or at least Isolate from HV (1200v)?

    thanks for attention
    Dave.
  • 0 in reply to Dave Hunson
    TI__Genius 17175 points
    FAST needs the voltage feedback, so you will need to find some way to provide it. You could look into something like SDFM for isolated voltage sensing, which is a typical design choice

    Sean
  • 0 in reply to Sean Bigley
    Expert 1720 points
    thanks again dear Sean :)
    best wishes
    Dave.