Simulink Control Design™ - MathWorks

Tuning Workflow

In general, the workflow for tuning this cascaded controller architecture is:

• Estimate the plant frequency model for the inner current loop between the PWM
  generator in the Controls subsystem and the inductor current measurement block.


• Use the PID Tuner to import this model and tune the current PI controller.


• Estimate the plant frequency model for the outer voltage loop between the voltage PI
  controller to be put in and the measured voltage.


• Use the PID Tuner to import this model and tune the voltage PI controller.

Estimate the Plant Frequency Model for the Inner Current Loop

In this example, you use the Linear Analysis Tool to estimate the frequency response

data of the inner current loop. Modify the setup to make the plant run to steady-state in

open loop. A steady-state duty cycle of 0.72 is required to obtain the voltage requirement

of 400V with a DC supply of 120V. The steady-state values of the inductor current and the

load voltage are measured to be 7.266A and 405.5V, respectively.

The linear analysis points to be used in the frequency response estimation need to be

established between the PWM generator to the measured inductor current, that is input

perturbation and output measurement. To set the input perturbation, right-click the signal

from the constant block, select Linear Analysis Points > Input Perturbation. For the

signal from the inductor current measurement block, choose Output Measurement from

the list of linear analysis points.

7 PID Controller Tuning