Buck-Boost Converter

Thread Starter


Joined Oct 11, 2011

I am working on some coursework that includes designing a buck-boost converter. I know the basic design of one and how it operates, but when I attempt to simulate one in pspice (I've tried several other programs--LTspice, CircuitMaker, NI Multisim, etc) I cannot get the darned thing to work.

I am using the example I found on this site to test before I start on my own calculations so I can verify I can make a working model. Unfortunately, I can't seem to make a functioning circuit, so I am posting here for some insight as to what I'm doing incorrectly.

I am attaching my pspice diagram so you can take a closer look at the circuit. I've tried using a MOSFET and a voltage controlled switch, but end up with the same failed result each time. When I run the simulation I obtain an output voltage that is effectively zero which is obviously wrong.

It should be about 18V according to the equation:

Vout = Vin*dutycycle/(1-dutycycle)
Vout = 12V*0.6/(1-0.6) = 18 V

Any help is greatly appreciated.