SPRUHJ1I January 2013 – October 2021 TMS320F2802-Q1 , TMS320F28026-Q1 , TMS320F28026F , TMS320F28027-Q1 , TMS320F28027F , TMS320F28027F-Q1 , TMS320F28052-Q1 , TMS320F28052F , TMS320F28052F-Q1 , TMS320F28052M , TMS320F28052M-Q1 , TMS320F28054-Q1 , TMS320F28054F , TMS320F28054F-Q1 , TMS320F28054M , TMS320F28054M-Q1 , TMS320F2806-Q1 , TMS320F28062-Q1 , TMS320F28062F , TMS320F28062F-Q1 , TMS320F28068F , TMS320F28068M , TMS320F28069-Q1 , TMS320F28069F , TMS320F28069F-Q1 , TMS320F28069M , TMS320F28069M-Q1
IQ full-scale current serves the same purpose as the previous IQ full-scale values for the frequency and voltage, but for the current feedback. IQ full-scale current is used to normalize the current feedback into a per unit value. This value must be greater than any measurable current.
IQ full-scale current must be greater than any measurable current
For example, if the motor has a peak current value of 8 A per phase, the IQ full-scale value should be set to a higher value with 20-30% headroom, in this example, to 10 A.
//! \brief Defines the full-scale current for the IQ variables, A
#define USER_IQ_FULL_SCALE_CURRENT_A (10.0)
If the measured current is greater than the IQ full-scale current at any point, there might be a numerical overflow condition in the software. Make sure the measurable current is less than this value to avoid an undesirable software behavior. In order to avoid this issue, user must make sure that (USER_IQ_FULL_SCALE_CURRENT_A * 2) is always greater that the measurable current by the ADC. The "multiply by 2" factor is because the USER_IQ_FULL_SCALE_CURRENT_A parameter ranges from zero to maximum amplitude (peak), while the USER_ADC_FULL_SCALE_ CURRENT_A is from peak to peak.
Following the guideline below prevents numerical overflow on the current measurement:
(USER_IQ_FULL_SCALE_CURRENT_A * 2) >= USER_ADC_FULL_SCALE_CURRENT_A