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RIsense Value for Basso's PWM-CM Model

Started by Anand P. Paralkar January 30, 2015
Hello,

I am trying to simulate a buck and a boost converter using Christophe 
Basso's generic PWM models (in LTSpice) for voltage mode controlled and 
current mode controlled switched mode power supplies.  These models have 
an integrated PWM generator and power switch.

These models can be found here: 
http://cbasso.pagesperso-orange.fr/Downloads/IsSpice/Final%20models.zip 
  (alternative, go through: http://cbasso.pagesperso-orange.fr/Spice.htm)

The Current Mode Controller model has the following pinout:

   nA nC nP nVCtrl nD : Active Pin, Common Pin, Passive Pin, Control 
Voltage Input, Duty Cycle Output;

   with the following parameters: Params: Lsw=100uH Fsw=100kHz 
DCMax=0.95 DCMin=0.05 RISense=1 Slope=100m

For the current mode controller, the slope parameter (used as external 
slope compensation) and RIsense are critical to using the model 
correctly.  I set the Slope to half the value of the downward slope of 
the inductor current.

However, I do not understand what value should be used for RISense.
I would like to know if anybody has used the current mode modulator 
(PWM-CM) and can help me with this.

(The examples directory in the download has a current mode controlled 
boost converter with a RISense value of -40m.  The negative value 
confuses me all the more.)

Regards,
Anand