S Pspice Hints 2014 Switch mode power supplies Page 1/11

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1 Switch mode power supplies Page 1/11 PSpice hints. Here is some tips for PSpice simulator software. Capturing images You can use screenshots or windows snipping tool to capture images for you report. However, it is possible to obtain high quality vector images from the PSpice. First the screen color should be changed to more preferable from Tools > Options. Following window should appear: Use colours in picture above. From Windows drop down menu choose > Copy to clipboard. From the menu choose values shown in following picture: Pop up window for Copy Clipboard. After pressing OK, the image is on clip board and it has to be pasted to Word or some vector graphic software(adobe Illustrator or similar). Here is example with Incscape software. Just pres CNTRL + V and the image is placed to the canvas.

2 Switch mode power supplies Page 2/11 Vector image pasted to Incscape. Picture zoomed. Vector graphics can be magnified heavily without them getting blurry. Images can be saved in.pdf format and included to Latex report for example. Multiple Plots Plots can be added by choosing drop down menu Plot > Add plot to Window. Traces (curves) can be moved between the plots with Copy Paste method. Press trace Legend from bottom left and press CTRL + C. Select the empty and press CTRL + V. When the plot is selected a sign SEL>> appears to the bottom left corner. I(Ls) is selected. Current Plot is selected (SEL>>). Multiple Y-axis

3 Switch mode power supplies Page 3/11 Sometimes its useful to have have different Y axis for current and voltage for example. First choose the Plot you want to operate with. Then from the Plot drop down menu choose Add Y axis. Traces can be added to new Y axes with Copy Paste method. Y axes can be moved to other side by double clicking it and changing Axis Position. Changing the Y axis position Different Y axes on opposite sides of the graph. Notice different Trace widths and patterns. Trace Color and patterns If the traces seems to be too weak, the width can be changed. Choose trace and press Left mouse button and from the menu select Trace Properties. Make some changes and test.

4 Switch mode power supplies Page 4/11 Change Trace width and Pattern. Schematic layouts in report It is good practice to import schematic picture to the report. It is very informative. The picture also holds the references for the Current and Voltage probe placement. Especially if the report is examined in future, the schematic picture is very handy. Use Snipping Tool or Printscreen. Schematic picture for the report. Functions Plots You can add different functions to the Plot by choosing Trace > Add Trace. In the field Trace Expression an expression can be formulated. There is a list of functions in the right hand side. Useful functions can AVG(), RMS(), MAX(), MIN() and such.

5 Switch mode power supplies Page 5/11 Add a Trace expression. A sine waveform and its RMS value added to the plot. Bode Plotting Bode plot is a useful tool to determine phase and gain margins. In this example schematic project Forward_Controller.opj is used. If AC voltage source must be added it can be done by choosing Place Part. Press Add Library icon in the Libraries section and choose source.olb file from the browser. In Part List press V to find VAC voltage source. Add the part to the schematic.

6 Switch mode power supplies Page 6/11 Add AC voltage source to schematic. Choose source.old to find voltage sources.

7 Switch mode power supplies Page 7/11 Forward_Controller.opj schematic. In this example vo and d_tilda are chosen voltage to obtain the bode plot. Simulation settings are as follows. Simulation settings. After pressing Run the plot appears. However there is now Traces in. They can be added from Trace > Add Trace. In following table expressions for the bode plot are shown.

8 Switch mode power supplies Page 8/11 Expressions for gain and phase margins. Expression for gain plotting DB(V(vo)/V(d_tilda)) Expression for phase plotting P(V(vo)/V(d_tilda)) Bode plot: Phase and Gain waveforms. Second method for Bode Plot Choose Trace > Add Plot. From the pop up window press Functions and Macros dropdown menu and choose Plot Window Templates. Choose Bode Plot db separate and add the output voltage V(vo) inside the brackets.

9 Switch mode power supplies Page 9/11 Setup for bode plot Forward_power_stage.dns is used for second bode plot example.

10 Switch mode power supplies Page 10/11 Bode plot obtained with second mehtod. Cursors A cursor can be used to obtain values from the waveforms. Trace > Cursor > Display Cursors.

11 Switch mode power supplies Page 11/11 Adding data points to graph After you have chosen the datapoint in the graph with the cursor, the point can be marked. Place the cursor to the point of interest and press Mark Label. The values are placed to the graph. The added label can be moved after disabling cursors by pressing Toggle Cursor. Toggle Cursor and Mark Label buttons highlighted. Added datapoint shown in the graph.