Advanced SIMPLIS Training
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Advanced SIMPLIS Training
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To download the examples for Module 3, click Module_3_Examples.zip
In this Topic Hide
How a parameter can be stepped through a list of values, with one simulation executed per value.
Parameters can also be stepped over a range of values using a linear or decade scale to determine the step sizes.
Multiple processor cores can be used to reduce the time required to execute a Multi-Step simulation.
Multiple parameters can be stepped at once by hand-editing the multi-step configuration file.
Curves can be grouped by either selecting the Group curves check box or by editing the groupCurves= entry in the configuration file.
Open the schematic 3.1_SelfOscillatingConverter_POP.sxsch.
From the schematic menu, select Simulator
Setup Multi-Step...
Result: The Define SIMPLIS Multi-Step Analysis
dialog opens:
The dialog is already prepared to step the parameter RLoad
through a list of values. To view the list of values, click on the
Define List... button.
Result: The Define List dialog opens, displaying
the three RLoad step values: 5, 2.5, and 4.2.
Click Ok on the Define List dialog.
Click Run on the Define SIMPLIS Multi-Step Analysis dialog
Result: The simulation executes and the
periodic operating point waveforms for each RLoad value are displayed
on the graph viewer: Note the converter switching frequency, peak
inductor current, and output ripple changes for each simulated RLoad
value.
The SIMPLIS Multi-Step Analysis allows you to quickly verify how a design responds to parameter changes. In the next topic, 3.2 Monte-Carlo Simulations, you will learn how the SIMPLIS Monte-Carlo Analysis allows you to vary multiple design parameters with statistical distributions.
In this example, three RLoad values which couldn't be defined as a linear or decade sweep were chosen. The List sweep option allows you to choose any list of values. The SIMPLIS Multi-Step Analysis allows you to sweep parameters over linear or decade steps as well. More information on the different sweep types can be found in the help topic linked to by the Help button on the Define SIMPLIS Multi-Step Analysis dialog.
You may recall from the topic 3.0.1 What Happens When You Press F9? that the RLoad variable is set in the F11 window:
.var RLoad=2.5
When you ran the Multi-Step Analysis, the RLoad value defined in the F11 window was overwritten by the step value defined in the Define SIMPLIS Multi-Step Analysis dialog. For each step value, the netlist preprocessor:
In this example, three individual deck files were created, each new deck file over-writes the previous deck file. This example steps the RLoad parameter over three values in the order - 5 , 2.5, 4.2. In the last deck file, R3 will have a value of 4.2 ohms. In the next exercise you will verify the last value of R3 is 4.2 ohms.
From the command shell menu, select SIMPLIS
Edit Netlist (after preprocess).
Result: The Deck file opens in Notepad++:
Search for the text 4.2.
Use the shortcut key Ctrl+F to open the search dialog.
Type 4.2.
Click on the Find Next
button.
Result: the deck file scrolls to line
106 where the value of R3 is 4.2 ohms.
The SIMetrix/SIMPLIS Pro and Elite licenses can use multiple processor cores to simulate the stepped parameter values. Using multiple cores allows multiple step values to be simultaneously simulated. The number of cores allowed by the licenses are:
| License | Number of Physical Cores |
| Pro | 4 |
| Elite | 16 |
In addition to the maximum number of cores allowed by your license, you are obviously limited by the number of cores your computer has. For this limitation, SIMetrix/SIMPLIS only uses the physical cores, not the hyper-threaded cores. In the next exercise you will run a multi-core, multi-step simulation.
This exercise assumes your computer has more than one physical core and that you are using a SIMetrix/SIMPLIS Pro license.
Close the graph viewer.
From the schematic menu, select Simulator
Setup Multi-Step.
Result: The Define SIMPLIS Multi-Step Analysis
dialog opens:
Change the Number of cores to 4, the maximum allowed by the Pro license.
Note - if your machine has either a single core or two cores, the dialog will limit your Number of cores entry. If you have a single core, you can skip this exercise.
Click Run.
Result: The Multi-Step simulation runs
on the maximum number of physical cores. Assuming you have a 4 Core
machine, all 3 step values are executed simultaneously using 3 SIMPLIS
processes, one per processor core. The SIMPLIS Status window has four
tabs, one for each SIMPLIS process. The fourth tab is empty as no
step value was run on this process:
In your exercise a very small circuit was simulated, yet you probably noticed a significant speed improvement in the time required to execute the Multi-Step Analysis. As circuit size grows, this effect becomes dramatic, and in experiments, speed improvements of approximately 3.5 times when using 4 cores vs. a single core have been found.
The information entered in the Define SIMPLIS Multi-Step Analysis dialog is written to a Multi-Step Configuration file. This file is saved in the same directory as the schematic and has the same name as the schematic except the file extension is ".sxscf." Although the editing dialog allows one parameter to be stepped over a range of values, by hand editing the Multi-Step Configuration file in a text editor, you can step multiple parameters each over its own range of values.
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CAUTION: This is an "unsupported" feature. Yes, it "works", but as you will see, this approach can generate results that are difficult to analyze. |
In this exercise, in addition to stepping the load resistor over a range of three values, you will also step the converter input voltage over a range of three values. Because the steps are nested, a total of 9 simulation steps will be executed. In other words, for each value of RLoad the input voltage will be varied over each of value of its parameter range. This test verifies the converter operation over the minimum, typical, and maximum values of both the input voltage and output load.
Right click on the schematic tab:
Select the Open Containing
Folder menu option.
Result: a Windows Explorer window opens
to the schematic directory.
Select the 3.1_SelfOscillatingConverter_POP.sxscf
file, and right click, selecting the Edit
with Notepad++ menu item:
Result: The file opens in Notepad++:
This file contains the commands which the program interprets when executing a Multi-Step Analysis. The second line has the RLoad parameter information. To step the Vin parameter, you will copy the second line and enter the copied line on the third line of this file.
Select all the text on line 2.
Copy to the windows clipboard with the keyboard shortcut Ctrl+C.
Move the cursor to line 3.
Paste the data using the keyboard shortcut Ctrl+V.
Result: The text file now has three
lines. Line 3 is a duplicate of line 2.
Edit Line #3:
Change RLoad to Vin.
Change the values at the end of the line from 5,2.5,4.2 to 300,310,320.
Result: the final text file should
appear exactly as follows:
Save the file using the keyboard shortcut Ctrl+S.
Result: the disk icon turns from red to
light blue indicating the file has been saved.
Close the graph viewer.
In SIMetrix/SIMPLIS, run the Multi-Step Analysis with the menu
Simulator Run Multi-Step Analysis.
Result: The Multi-Step Analysis executes
and curves for the 9 step value combinations are output to the graph
viewer. As three probes are enabled, 27 curves are output to the graph
viewer.
As you can see, multi-step analyses with multiple parameters increases the number of simulation runs geometrically. You can easily fill up the graph viewer legend with curve information to the point where it is hardly navigable. You can reduce the cluttered graph legend by telling the program to "Group" the curves that each probe outputs into a single curve with a single color. In the next exercise you will edit the Multi-Step Configuration file to group the output curves into a single curve for each probe.
In the Notepad++ window, find the groupCurves=False
text on the first line:
Change the groupCurves=False
text to groupCurves=True.
The final file will appear exactly as follows:
Save the file using the keyboard shortcut Ctrl+S.
Result: the disk icon turns from red to
light blue indicating the file has been saved.
Close the graph viewer.
In SIMetrix/SIMPLIS, run the Multi-Step Analysis with the menu
Simulator Run Multi-Step Analysis.
Result: The Multi-Step Analysis executes
as before, but three curves are output, each curve has nine traces
representing the nine stepped values.
Each curve listed in the graph legend depicts data generated by the 9 steps of Multi-Step data. The nine steps use the same color and a single entry in the graph legend. A few points should be made:
The grouped data presented in the graph above is written to a Multi-Division data group. Analysis of Multi-Division data is extremely challenging, and has to be performed using custom scripts via the SIMetrix/SIMPLIS script language. The built-in measurement system used by the graph viewer was not designed to handle Multi-Division data.
The Design Verification Module, which was specifically designed to analyze and present data from multiple single-step simulations in which more than one parameter is stepped, outputs multiple single step data files, one for each combination of parameter values. The analysis of this data is both trivial, and supported by the built-in measurement system.
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