Method 4: CHR method for P/PI/PID loop tuning
July 29, 2022feedforward control
August 3, 2022
- pidtune function of Matlab is a very user-friendly method for PID/PI auto tuning.
- This controller design algorithm calculates the PD/PI/PID parameters such that at the desired gain crossover frequency the phase of the open loop system be equal to the desired value or gets as close as possible to it (crossover frequency is the frequency at which the magnitude of the open loop system equals one).
- Note that by adjusting the phase of the open loop system at the crossover frequency to an appropriate value we can adjust the phase margin to the desired value. Moreover, the crossover frequency approximately equals to the bandwidth of the closed loop system. So, in order to speed up the closed loop system response we can assign a larger value to the crossover frequency. Note that time constant of the step response of the closed loop system approximately equals to inverse of the crossover frequency.
- Predefined value for bandwidth (BW) equals 60 deg. It is a very favorite value in many real world applications.
- Matlab automatically considers an appropriate value for crossover frequency if the user does not specify it.
- Controller is considered in parallel form, that is .