HW13 (d)&(e)

Anyone having any luck with part (d) and (e) of HW13?  I'm trying to figure out if we're supposed to build our own model to do plotting, etc?

Problem 18.14 a. choosing value of C

For 18.14 part a. I assume that we must first determine a value for C to satisfy the Gvd transfer function for the loop gain of Ti = (va/ig) * (Gc) * (1/Vm) * (Gvd). Is this the same approach other folks are using?

18.10d&c RMS Ripple Assumptions

In these problems it asks us to find the worst-case rms currents of the inductor, MOSFET and diode.  When it refers to rms currents is that over a line cycle such as in Table 18.3?

Furthermore, the expressions in Table 18.3 neglect the effect of switching ripple.  Does this mean that we cannot use the expressions given in Table 18.3 and that we need to derive new expressions that take into account the switching ripple with the inductor that we have chosen?

Question for 18.1

Hello,

I am confusing about the define of the LOAD POWER in 18.1 (d). Does this contain only the power on the resistor or also contain the power both on resistor and capacitor?

Thanks.
NY

Re for 18.2

So I am starting to confuse myself on what Re should be for 18.2.  Do we use the DCM boundary to determine the Re for DCM or is it the standard 2L/d^2Ts?  What decides Re?
It seems that because the vg/ig=Re in both the DCM of Chpt 11and in our current model, Re is the same but if this were a Cuk or Sepic then Re would be different.  Is this correct?

Suggestions for OpAmp model

I have suggestions for the OpAmp model to use for HW10 if you have problems.

Try using "UniversalOpamp2" instead of LT1368.
The default parameters for this model is sufficient for our simulation.
The ideal opamp seems to not work well for many people.

If the design is done correctly, there should be no convergence problems, and no need for initial conditions.

Beom

PWM comparator questions

I have not been able to find a comparator that will work in this application. I'm sure there is one, but I'm not having much luck with getting the output for d correct. I have the sawtooth, and Vm , but I'm struggling with the comparator.
Suggestions?