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TMS320F28388S: current scaling factors calculation for IDDK

Linda Zhang84708
Expert 6940 points

Part Number: TMS320F28388S
Other Parts Discussed in Thread: TMDXIDDK379D, C2000WARE

Hello Champs,

In "fcl_f2838x_tmdxiddk_settings_cpu1.h" of "fcl_f2838x_tmdxiddk_cpu1" project in below folder: C:\ti\c2000\C2000Ware_MotorControl_SDK_3_02_00_00\solutions\tmdxiddk379d\f2838x\ccs,

there are below codes:

-------------------------------------------------------------------------------------------------------------------------------------------------

// Scaling factors to bring all current feedbacks to normal scale

// matching with shunt based measurement

// With shunt, 1.0pu current == 9.945A

// LEM, 1.0pu current == 12A

// SDFM, 0.8906pu current == 12.5A

//

#define LEM_TO_SHUNT 1.206637 // (12.0/9.945)

#define SDFM_TO_SHUNT 1.41131 // (12.5/0.8906)/9.945

-------------------------------------------------------------------------------------------------------------------------------------------------

Would you please kindly help how to calculate the "1.0pu current" value in shunt/LEM/SDFM modes? Thanks! 

Best Regards,

Linda

  • 0
    TI__Mastermind 27240 points

    Linda,

    The individual current sensors have slightly different gains. In order to get same performance regardless of current sensing method, the suggested scale is required, and this will match up to the SHUNT method as it has the lowest measurable range. This is mainly for our demo purpose and is not necessary for any other case.

    Each sensor's 1pu current is given in the comment section itself. For SDFM, we can get to full scale of 0xFFFF as it can get to non linearity after 89% range.  That is why it shows 0.89pu as max, and it corresponds to 12.5A. Hope it helps.