CU Learn Submissions

I am able to log in to CU learn, but it is not obvious to me how to upload my HW files from my home PC to the website.

I go to ECEN 5807 => Homework 1 => Add Attachments

it then brings up a new window, that says "Your location: My Files". I can not browse to anyplace, nor does the help menu give me any information.

I did verify 2 weeks ago I could log in, but I assumed that I would just easily upload the files.

Lecture 5 for CAETE students

Did lecture 5 work for anyone?

It would get stuck in buffering for me....

HW2 Pb 1b

Any ideas on finding Rload1 numerically using Matlab?

HW2 Prob 2

Is anyone else getting a huge algebraic quagmire whenever trying to incorporate switching loss, as well as conduction loss, into their perturbation/linearization steps?

I'm really doubting this is even possible.

Mathworks student version is currently unavailable

Mathworks has some technical issues regarding student version. I cannot download add on" Simulink Control design" from Mathworks. They are unsure how long it's going to take to fix the issue. No idea what to do. Please suggest

HW #1, problem 7.15

for problem 7.15 for HW #1.

When I replace the switches by the model of 7.50 c. I see that for Gvg=vout/vg, then the d^ sources are set to zero. I tried to solve the resulting schematic by doing a mesh current analyses (i1, and i2). However, I end up with a lot more math than I would expect.

Am I missing something? Is there some easier approach or some trick? *If* it was a DC-steady state, I see that the voltage across the inductor would be zero, and the solution is rather simple.

trouble operating Simulink Control Design R2009a with MATLAB R2010a

Hi,
I only version of Simulink Control Design I was able to purchase as a student was R2009a. This doesn not seem to work with MATLAB R2010a that I have.
Can anyone help with this?
Regards,
Nitish Agrawal

Echo360

HI,

i figure out some problem with this new version of Echo.
it doesn't work with mozilla and bug with explorer.

hm1 pb2

i'm having some trouble with the fonction of the LC filter, i do not know the state equation.
i follow the step by step exemple.....; but i stuck on the state equ, i wrote two equ :
icf = ........; capacitor current
vlf =........; inductor voltage

%output
y = [icf/Cf vlf/Lf];

then i got the following message:
Embedded MATLAB Interface Error: Propagated size of data 'y' (#79) changed when propagating type.
The size was fixed to be '[2]' and now became '[1 2]'.

My question is should i wrote the T(s) equ of the LC filter ? did i miss some state equ?

HW2 Prob1 Error

When trying to run the BodePlotter_script.m file for the condition of Rload = 0.2 Ohm I receive this error:

??? Error using ==> feval
Trouble solving algebraic loop containing 'syncbuck_OL_Fil_Mak/LC filter/LC filter' at time 0. Stopping simulation. There may be a singularity in the
solution. If the model is correct, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances).

Error in ==> BodePlotter_script at 8
op = findop(model,op) %calculate model operating point

I'm thinking the problem is related to the load current because I had no issue with Rload = 1kOhm.


Any thoughts on reducing step size or tightening error tolerance so that I still get a reasonable answer...?

Lecture 5

The lecture 5 download doesn't look like the correct video (it looks like short demo video). Do others see the same?

Error in Sim, for Introduction

Hello,

I am going through the Matlab_Simulink_introduction.pdf, and am stuck on page 10 when I try to run the simulation.

Specifically, I get this error:

" Embedded MATLAB Interface Error: Can not resolve Simulink signal object 'y' for output port 1 of 'syncbuck_OL/SyncBuck/CCM buck'. "

The code in the Embedded Matlab looks fine to me I (I entered the code given on p. 6 ), however, maybe it is not. Any ideas ?

thanks
Mark

HW1,prob2 help!!

Embedded MATLAB Interface Error: Port width mismatch. Input "u"(#681) expects a one dimensional vector with 5 elements. The signal is a one dimensional vector with 4 elements.

I am having some trouble with getting the simulation of problem2 to work. I have attached an image of the simulink block diagram along with the error. Any help/suggestions are highly appreciated.

Error during simulation

I keep getting this error while trying to simulate my sync buck simuling file. Cant seem to get around it. Can anyone help me with it?

The error is below.

Unable to locate 'mexopts.bat', and therefore cannot determine which compiler to use for simulation builds.
Use 'mex -setup' to select a supported compiler.

HW1 Problem 2 Algebraic Loop

Hi all,

Is anyone else having a problem with an "algebraic loop" in problem 2 of HW#1? I hooked up the ig output of the synchronous buck block to the ig input of the LC filter block, thus creating said loop. I think the problem is that the synchronous buck block requires vg to compute ig, and the LC filter block requires ig to compute vg, thus creating a circular reference. But I'm not sure how to accurately model it otherwise.

Thanks,
Josh

Simulink linearization issue

Hi all,

I am going through the professor's paper on the sync buck model and I am stuck on page 16 (Linearization inputs and outputs). I was able to set the control System Toolbox Preferences but when I right-click on the vc signal, I don't see the option for Linearization Points. Has anybody seem the same issue?

how to specify eps in comparator block

I am assuming that in the comparator block, if "Enable zero crossing detection" is checked, then the value of eps is zero. How do we specify the value of eps if "enable zero crossing detection" is not checked?

Linux and Matlab

Hi,

Just in case anyone can help, I'm chucking this out here in addition to the Ubuntu forums.

I'm running Ubuntu 11.04 and Matlab R2010a, and I get errors trying to simulate due to gcc being too new a version. The forums say it should compile anyway, but it clearly doesn't work. I'm trying to install gcc 4.2.3 - the latest supported by R2010a - but for whatever reason this version of Ubuntu hates it.

If anyone can help me, you can email me directly at sean.gale@gmail.com so this nonsense doesn't take up space on this blog. I'd be grateful, because it's difficult for me to get to campus on my off days to work on this stuff.

Thanks,

S

Lecture 3 question

It's a very interesting approach. But it seems like it can be used with perfect switches. How about RDS on on MOSFETS and reverse recovery on diodes? Can this approach still be used?

Course Slides are missing on Tegrity Player

Has anyone else experienced the Video being ok but the slides are not showing on the Tegrity player? Thanks, Tim