SLUU885C March 2012 – June 2024 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
When fine tuning the feedback control loop, one would like to know each parameter in PID how to affect the control loop characteristics without going through complicated description of the above equations. Table 12-2 below helps this and is visually shown in Figure 12-16.
Control Parameters | Impact on bode plot |
KP | Increasing KP |
• | Pushes up the minimum gain between the two zeros. |
• | Moves the two zeros apart. |
KI | Increasing KI |
• | Pushes up integration curve at low frequencies. |
• | Gives a higher low frequency gain. |
• | Moves the first zero to the right. |
KD | Increasing KD |
• | Shifts the second zero left. |
• | Does not impact the second pole. |
α | Increasing α |
• | Shifts the second pole to the right. |
• | Shifts the second zero to the right. |
Ts = 1 / fs | Increasing the sampling frequency fs : |
• | Causes the whole Bode plot to shift to right. |