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
Inside of the estimator, and in particular, the part of the estimator that runs the Rs Online feature, the actual value of the resistance is updated by adding and/or subtracting fixed delta values, depending on the direction where the resistance is going. In general this parameter does not need to be changed, unless the change in resistance is too fast, for example, due to rapid motor heating. By default both the delta increment and delta decrement are set to a value of 0.00001, represented in IQ30 format, which can be verified with the following code example:
CTRL_Obj *obj = (CTRL_Obj *)ctrlHandle;
_iq30 delta_dec = EST_getRsOnLine_delta_dec_pu(obj->estHandle);
_iq30 delta_inc = EST_getRsOnLine_delta_inc_pu(obj->estHandle);
In order to change those deltas, use the following code example, to for example, twice the default value, or 0.00002, in IQ30:
CTRL_Obj *obj = (CTRL_Obj *)ctrlHandle;
EST_setRsOnLine_delta_dec_pu(obj->estHandle, _IQ30(0.00002));
EST_setRsOnLine_delta_inc_pu (obj->estHandle, _IQ30(0.00002));
Notice that these two functions set the deltas, as opposed to get the deltas, so they expect a parameter besides the handle.
Figure 16-14 shows how the resistance will respond to an initial value difference according to the delta values. For example, right at the beginning when Rs Online is first enabled, there is an initial resistance value which is different than the steady state value. Having a value of 0.00001 will lead to the following plot, which shows a slope = (0.77-0.4)/3.1 = 0.12 Ω/s.
When the delta values are changed to double the default value, a much faster settling time is shown in Figure 16-15, with twice the slope = (0.71 - 0.4) / 1.3 = 0.24 Ω/s.
It is recommended that the rate of change selected for this delta is slow enough to provide smooth variations of the resistance, and fast enough to track the temperature changes of the system. Generally the initial value of 0.00001 will work, but keep the deltas in mind when fine tuning a particular application, especially when drastic temperature changes are expected.