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
The first thing that happens when identifying the flux is for a closed-loop to be enabled internally by the motor identification state machine. This closed-loop is not enabled by the user. Current consumption lowers to a minimum current value needed to keep the mechanical load spinning at the same frequency when this closed-loop is enabled. The slope at which current is lowered is a fixed value, Rs estimation per second divided by 3. The dividing factor of 3 was selected during design of the motor identification process to provide a slower slope.
In order to calculate this slope, users can use the following equation. In this example, 1 A was used for resistance identification:
The 0.33 A/s slope can be seen in Figure 7-21, showing how current is reduced as soon as the Rated Flux state is present. Also in the same plot, the time it takes to identify the rated flux is also highlighted.