Average Modeling BUCK PWM voltage Mode Control..

Hi all...

can any one tell me how to do "Average Modeling BUCK PWM voltage Mode Control.."

I mean i need to do state space average modeling for complete BUck converter which includes PWM also...

Thanks a lot...

you can take a look on this note :http://encon.fke.utm.my/nikd/Dc_dc_converter/Converter/rogers.pdf

simply replace

If u r doing in spice,
1) replace the power stage switch network with a average switch model ( just pick up the buck model given in erickson's and maksimovic's book on fundementals of power electronics.
2) Keep the Error Amp (compensator) as circuit in spice.
3) Replace the PWM comparator with 1/Vm gain where Vm is ramp height. And generate the average duty cycle with a vcvs (voltage controlled voltage source). Look at the last appendix of the book.

If u r doing in Matlab and want to do ac analysis,

1) Create the duty cycle to output voltage transfer function of the buck (standard formulae available everywhere in the web) or generate using state-space, average switch etc...lots of methods available
2) Write a transfer function of the compensator and and include 1/Vm and use bode for Gvd*Gc/Vm.

If u want switching waveform in Matlab,

1) Create a simulink of the switch network (just like in spice) and have a transfer function model of the error amp and 1/Vm.

my project is 48v to 12 v buck converter in continuous conduction mode using matlab simulink.but it is difficult to me to make a simulink model of PWM which hass as out put duty cycle 0.12.can some body help me plz?