Buck converter doesnt work (simulink)

Hello,

i trying to simulate DC/DC converter in Matlab/Simulink. I am using Matlab 2015b and i can only use this version at the moment.

I build a boost converter and simulated it. It works pretty good, i am fine with that. I used for parametrization real hardware and the datasheets of the components.

After that i build a buck converter, also parametrization with real hardware. The buck converter model doesnt work as expected and i cant understand why.

Here you can see my model.

C1 = 2.2 uF ; C2 = 2.2 uF ; L = 100 uH ; C4 = 100 nF ; C3 = 2.2 UF; Ra1 = 100 kOhm ; Ra = 0.03 Ohm ; Ra2 = 0.01 Ohm ; L4 = L1 = 1500 nH ; PWM: amplitude = 12.3 , period = 1.998e-06 , duty cycle = 48.6808 % V input = 16 V

Here is the result of the simulation:

Normally with this settings V input = 16V ; I input = 0.180 A ; V output = 8.84 V ; I output = 0.3 A

I tested many other settings to find my problem but had no success. I changed input and output capacitors, i changed the inductor, i changed PWM amplitude, duty cycle and frequency. I also changed my mosfet. But every time i have the same result : i input = i output and i am loosing some voltage at output. So this modell doesnt working like a buck converter.

When i removed my coil L the model works like expected. But without the coil this isnt a buck converter. At my booster my coil is before the mosfet so maybe there is my problem. Maybe Simulink has there a problem to find the right potential ?

Maybe some of you had the same problem or have some experience to help me out?

Thank you

Answer 1

[cem inci]

no one any clue?