To identify a plant model, first obtain input/output data by simulating your model. On the
Plant Identification tab, click Get I/O Data > Simulate Data.
On the Simulate I/O Data tab, configure the input signal with the following settings.
- Signal Type of Step.
- Sample Time of 5e-06.
- Onset Lag of 0.025, which is enough time for the plant to reach steady state.
- Stop Time of 0.07, which is enough time for the plant output to return to steady
state after the step input. - Offset of 0.736, which is the value of the PID Controller block output at the
computed operating point. For this model, the offset corresponds to the value of the
state in the Computational delay block. If you do not have such a corresponding state
in your model, you can attach a scope to the output of the PID Controller block and
simulate the model at the computed operating point.
To specify the step amplitude, click. Then, in the Step Input Specifications dialog box,
in the Amplitude field, type 0.01. This value is large enough to sufficiently excite the
system and small enough to prevent the controller from entering discontinuous-current
mode.
Click Run Simulation. To obtain the input/output response of the plant, PID Tuner
injects the specified input signal at the output of the PID Controller block and measures
the corresponding output response at the input of the controller. The software runs two
simulations, an offset response without the input signal and an input response with the
input signal. The difference between these responses is the output response.
Design Controller for Power Electronics Model Using Simulated I/O Data