Project - Speed Control of a Direct Current (DC) motor

Ans:

inroduction of the PID tuner:

PID tuner provides a fast and widely applicable single-loop PID tuning methods for the simulink PID controller blocks.with this method you can tune PID controller parameters to achieve a robust design with the deisired response time.

a typical design workflow with the PID tuner involves the following tasks:

1) launch the PID tuner when launching the software automatically computes a liner plants models from the simulinks modes and designs an initial conroller.

2) tune dthe conroller in the PID tune by manually adjusting design criteria in two design modes. the tuner computes PID paramerters that robustly stabilize ststem.

3) export the parameters of the designed controller back to the PID contoller block and verify controller performances in simulinks.

open the model:

open the engine spped control model with PID controller bocks and take a few moments to explore it.

design overview;

inthis example you design a pi controller in an engine speed control loop. the goal of the design is to track the reference signal from a simulink step blocks. the design requirement are;

settling time under 5 seconds

zero steady-state error to the step reference inputs.

in this example you stabilize the feedback loop and achieve good reference tracking performance by desiging the PI controller.

open PID tuner:

to launch the PID tuner, double- click the PID controller blocks to open its blocks dialog. in the main tab, click tune.

initial PID design:

when the PID tuner launches the software computes a linearized plant model seen by the controller. the software automatically identifies the plant inputs and output, and uses the current operating point for the lineraization. the plant can have any order and can have time delays.

the PID tuner computes an initial PI controller to achieve a reasonble tradeoff between performance and robustness by default, step reference tracking performance desplays in the plot.

display PID parameters:

click show parameter to view controller parameter P and I and a set of performance and robustness measurement. in this example the initial PI controller design gives a settling time of 2 seconds, which meets the requirement.

adjust PID design in PID tuner:

the overshoot of the reference tracking response is about 7.5 percent. since we still have some room before reaching the settling time limit. you could reduce the overshoot by incresing the response time. move the response tie slider to the left to increse the closed loop response time. notice that when you adjust response plot and the controller parameters and performance measurement update.

complete PID design with performance trade-off:

in order to achieve zero overshoot while reducing the settling time below 2 seconds you need to take advantage of both sliders. you need to make control response faslter to reduse the settling time and increse the robustness to reduce the overshoot.

write tuned parameters to PID controller block:

after you are happy with the controller performance onthe liner plant models, you can test the design on the nonlinear model. to do this click update block in the PID tuner this action writes the parameters back to the PID controller blocks in the simulink model.

completed design:

the following figure shows the response of the closed-loop system.

the response shows that the new controller meets all the design requirements.

you can also use the control system designer to design the PID controller blocks, when the PID controller blocks belongs to a multi-loop designs task.