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
This decimation rate is to execute the speed controller inside of InstaSPIN with respect to the controller (CTRL). A typical value of the speed controller tick rate is between 5 and 10. This is to allow the current controllers to settle at a faster rate compared to a speed controller. The time constant of the speed controller is set by the mechanical load coupled to the motor's shaft, which is much slower than the time constant set by the inductances in the motor. The following example shows a typical value of 10 in the speed controller tick rate, and the timing diagram shows how this is decimated from the controller (CTRL).
A typical value of 10 is used, so that the current controllers are executed at a rate 10 times faster than the speed controller. This is typical since the speed controller usually sets the reference of the current controller, and current controller needs to have some time to control to a specific set point.
Figure 10-28 shows how a speed controller tick rate of 10 is used.
Figure 10-29 represents the values of this timing diagram in highlighted boxes.