This example shows how to optimize model parameters to meet frequency-domain requirements using the Response Optimization tool. Simulink® Control Design™ software must be installed to optimize a design to meet frequency-domain design requirements.
In this example, you specify the design requirements in a Check Bode Characteristics block. You optimize rectifier filter parameters to meet gain and bandwidth requirements by minimizing a custom objective.
sdorectifier includes the following blocks:
The design optimization problem has several objectives. The design must:
Have a –3 dB bandwidth of at least 2 Hz
Limit the gain across the frequency range 2 Hz – 60 Hz to at most 0 dB
Limit the gain above 60 Hz to at most –20 dB
Maximize the filter resistance R
Minimize the filter inductance L
The requirements ensure that the rectifier filter combination has minimal high frequency content, responds quickly to voltage changes, and limits filter currents.
Open the Response Optimization tool for the model.
The Bode plot 1 tab shows the gain and bandwidth requirements specified in the Filter Design Requirements block in the model. To see their values, double-click the block to open the Block Parameters dialog box, and select the Bounds tab.
Specify a custom objective to minimize the filter inductance and maximize the resistance.
The custom objective is already defined in the
function. The function accepts the design variables R and
L and returns the objective to be minimized.
edit sdorectifier_cost in the command line to view this
In the New drop-down list, select Custom Requirement.
Specify the following values in the Create Requirement window, and click OK:
In the Name edit box, enter
In the Type edit box, select
Minimize the function
In the Function edit box, enter
@sdorectifier_cost. The optimization solver calls the specified
A new requirement variable
MaxMinRL is created, and appears in the
Data area in the Response Optimization tool. The Iteration
plot 1 tab shows the value of
MaxMinRL at each iteration
during the optimization.
When you optimize the model response, the software modifies the design variable values to meet the design requirements.
In the Design Variables Set drop-down list, select New.
L, and R in the Create Design Variable
Set window. Click to add the selected parameters to a design variables
Specify the value range for each design variable, and click OK:
C in the range 1 µF–1 mF
L in the range 1–500 mH
R in the range 0.01–50 ohms
A new variable
DesignVars is created, and appears in the
Data area of the Response Optimization tool.
To view the current response of the model, click Plot Model Response.
The Bode plot 1 window in the Response Optimization tool shows that the model output goes out of the region bounded by the design requirement line segments.
Voltage scope window, you see that the filter voltage signal
overshoots its steady-state value and contains significant harmonic content.
Optimization converged message in the Optimization Progress Report
indicates that the optimization method found a solution to satisfy the filter bandwidth
The harmonic content in the filter voltage signal is reduced from the initial design.
Verify that the model meets the gain and bandwidth requirements.
The plot displays the output of the last five iterations. The final response using the optimized parameter values appears as the thick blue line.
The optimized response lies in the white region bounded by the design requirement line segments and thus meets the requirements.
DesignVars in the Data area and view the
updated values in the Variable Preview area.
The optimized values of the design variables are automatically updated in the Simulink model.