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LAUNCHXL-F28027F: Current calculation using input power

Awantha Jayasiri
Intellectual 270 points
Part Number: LAUNCHXL-F28027F


I am trying to calculate the current based on the input power estimation presented in following thread

. e2e.ti.com/.../406263

(Basically, the calculated  input power is divided by gMotorVars.VdcBus_kV*1000).

The calculated current is verified by measured current and it worked fine for some motors but not for all.

Some defies of my user.h for a specific motor (which I couldn't calculate the current correctly) is as follows:

USER_IQ_FULL_SCALE_FREQ_Hz       (1134)

USER_IQ_FULL_SCALE_VOLTAGE_V      (30) // The rated motor voltage is 30V and the bus voltage is set to 30V as well

USER_ADC_FULL_SCALE_VOLTAGE_V       (44.30)

USER_IQ_FULL_SCALE_CURRENT_A         (24.0) 

USER_ADC_FULL_SCALE_CURRENT_A        (47.14)

 What would be the reason for error in current calculation?  Does it have anything to do with the difference of IQ_FULL_SCALE_VOLTAGE_V and ADC_FULL_SCALE_VOLTAGE_V?

Any help is greatly appreciated!

Thanks

  • 0
    TI__Guru** 116110 points
    What current do you want to calculate? Only can calculate the input current of power supply by input power and voltage, can't calculate the motor phase/line current which depends on motor and inverter efficiency, only if you know both factors.

    ADC_FULL_SCALE_VOLTAGE_V is based on voltage sensing circuit of the hardware board, and IQ_FULL_SCALE_VOLTAGE_V is a scale value for system control. As a rule, set IQ_FULL_SCALE_VOLTAGE_V is equal to or less than ADC_FULL_SCALE_VOLTAGE_V.
  • 0 in reply to Yanming Luo
    Intellectual 270 points
    Thanks for the reply. I need to calculate the input current of power supply.