Buck converter 42V to 14V

This is an example of a buck converter which converts 42V input to 14V output. This design operates in a Continuous Current Mode (CCM) using Peak Current Mode (PCM) control method. It contains two loops: an inner current loop and an outer voltage loop. The inner current loop contains voltage comparator, latch, a triangular source, and a current sensor that senses the switch current "is". The "S" input of latch sets (or presets) the "Q" output to 1, and the “R" input of latch resets (or clears) the "Q" output to 0. The op-amp, comparator, and the latch form a current modulator, which modulates the inductor current. The analog control voltage vc is applied to the comparator inverting input, and the voltage proportional to the switch current "is" is applied to the comparator non-inverting input. Outer voltage loop contains Opamp, and feedback resistors (r1 and r2).

Circuit Snapshot:

Refer to the attached snapshot "buck_converter_42V to 14V.png".

How To Use:
  1. Download the attached design folder "Buck_converter_42V_to_14V.zip"
  2. Extract the files to any location on your PC.
  3. Launch SaberRD.
  4. Navigate to the directory where the unzipped file is available.
  5. Open the file that has the extension, ".ai_dsn".
  6. Perform the analysis as per the settings given in the Quick Analysis box inside the schematic and plot the signals listed to understand the behavior of the design.
For more information, please refer to README file available in the design folder


This example works in both SaberRD Commercial Edition and Student Edition.


  • Hello, 
     I'm interested in making a buck converter using SiC MOSFET, thus I've found your example very interesting. 
     At first glance, I replaced the ideal switch by an ideal MOSFET. 
    The simulation runs but the results are no more consistent. 
     Can you please look at my simulation? Do you have ideas why the simulation doesn't work as good as the origin program?
     I think that I have to change the control part. How can I change the circuit of control so that the MOSFET can be properly driven? 

     Thank you very much for your kind help.

  • SciebouSciebou Posts: 10
    edited November 2015

    I tried to implement another control circuit using PI controller as in the example "3_Phase_AC_DC_Conv_Level_1" for my SiC BUCK converter. 

     For the outer voltage loop, it works. However, I didn't obtain good results for the inner current loop. In fact, the MOSFET's current and the inductor's current are not realistic.

     You can find in the attached files, my program as well as all SiC components that are characterized by Power MOSFET Tool and Diode Tool. 

     Is it possible for you to have a look at my model? May you tell me how can I enhance the control circuit?
    I'm looking forward to your feedback. 
    Thank you very much for your help and advices.

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