Why is my Transistor Reducing Voltage in Buck Converter Modeling?

[Chacabucogod]

Hi I'm currently modeling a 5-12Vdc buck converter, and just out of nowhere decided to put a transistor between the output resistance and the diode. Now, this transistor is always connected to voltage so it shouldn't do anything at all, it's just a closed switch. What happens is that the transistor ends up eating a lot of the voltage. I don't really understand what's happening.

Resistance Voltage. It's 2... when it should be 12.

 

[Chacabucogod]

Actually it's a boost. My bad...

 

[Windadct]

What is the V at the Emitter of Q2 Relative to the base of Q2?

 

[zoki85]

Looks like that a demand for a transistor DC gain (I_collector/I_base) must be pretty high in this example.
Check out 2N2222A transistor's characteristics curves.

 

[alphy]

Hello, thank you for sharing your experience with modeling a buck converter. Based on your description, it seems like the transistor you added is acting as a voltage regulator, which is not necessary in a buck converter circuit. The purpose of a buck converter is to step down the input voltage to a lower output voltage, not regulate it.

It's possible that the transistor is creating a voltage drop, causing the output voltage to be lower than expected. I would recommend double-checking your circuit design and making sure the transistor is not causing any unexpected effects. If you are still experiencing issues, I suggest consulting with a more experienced engineer or seeking help from a reputable source to troubleshoot the problem.