HW13 Simulink Model

How do you go about adjusting Im and C in the Simulink model for HW13 parts d and e? All I can see to adjust is Vpv and the solar irradiation.

18.14 Vcontrol

I'm not sure how to go about finding Vcontrol. Using equation 18.50, and assuming we are in equilibrium so Pav=Pload, I get Vcontrol=500V. This is obviously wrong. So I'm missing something here. Any hints?

18.14 ripple

Is it correct to use equation 18.90 to find the capacitor voltage at pi/2 and 3pi/2? Then the difference should be the peak to peak ripple. Correct?

HW12 Spice simulation not converging

HW12 Spice simulation takes forever and is not converging. Any tips would be appreciated.
Regards,
Nitish

FInding Re

How do you go about finding Re when not operating at 100% efficiency?

18.10b.ii

In response to Jares, I believe you're correct. I think we use the equations found in table 18.3 for rms and peak inductor currents to answer 18.10b.ii. Does anyone disagree?

Equation 18.55 to 18.56

I'm not able to post comments to postings due to our IT security so I'm creating a post as a response. In the text it states that equation 18.56 is the averaged control to output transfer function. For that reason, vg(t) is set to zero in equation 18.55 before applying Laplace to get equation 18.56.

Chapter 18 Question (Equation 18.55)

I asked the professor about this, but it still did not make sense to me.

I do not see how you go from equation 18.55 to equation 18.56.

when I take the Laplace of equation 18.55 I get:
L*s*ig(s)= vg(s)-d'(s)*V

now I thought V is a constant. How do I get rid of the vg(s) term, and put the equation in the form of ig(s)/d(s) = V/(s*L) ????????????

thanks
Mark

18.14 output voltage dynamics

I am a little confused about the dynamics in problem 18.14.

When we came up with the linearized model for the feedforward boost rectifier in class, we neglected any changes in v_hat and assumed the output voltage to be basically DC. This led to a simple G_id(s) which I used for the current loop in the problem. However, this is not sufficient for the voltage loop of the problem since it is trying to regulate variations in output voltage. Does it make sense to be using a different small signal model to solve the different loops in the circuit? I was thinking about using the same average equations as in 18.3 but assuming that the input current is a perfectly regulated DC signal and deriving a new small signal model from there. Does this approach seem reasonable?

18.10a

Another question for clarity...in part 'a' of problem 18.10 we are to derive an expression for the duty cycle of the universal-input boost rectifier. It states that there are no losses and we can neglect converter dynamics. That being the case, I assume that this will just end up being the ideal version of the duty cycle as was discussed in lecture 39 for section 18.6.1. Is this an accurate assumption?

HW13 question a

It seems like the duty cycle in part should be a function of Ppv in addition to the other variables listed, because d controls the power flow in DCM, right? Anybody agree/disagree?

HW12 prob. 8.14 (shouldn't ramp slope of PWM be negative?)

In HW12 prob. 8.14, shouldn't the ramp slope of PWM be negative, so that when vg(t) is high, the duty cycle is low? But then if the ramp slope is negative, will it not make the loop gain negative...but don't we need the loop gain to be positive for negative feedback (because va=ig(t) is already being subtracted from the vref1)?
Any comments would be appreciated.
Nitish

Chapter 18 Question

In figure 18.29b on page 669 of the text it shows a model of the recifier output port with the constant and time-varying power souces separated. The time-varying source is negative and shown with a squared cosine function. Equation 18.93 is a calculation of the instantaneous output power which is a sum(in this case it is a difference due to the negative term) of the two power sources. In equation 18.93 the cosine function is not squared but in the model it is squared. What am I missing?

HW12 Prob1

I have a somewhat general question about problem 1 of homework 12. There is a statement in the problem description that says, "There is no compensator in the inner wide-bandwidth average current control feedback loop." Does this mean that we are to assume Gc(s)=1 for our bode plots of Ti(s)?

HW 11, Prob 2

I know this is coming in last minute, but I'm stuck on finding the normalized equation describing the DCM input characteristic for the buck-boost. In following the buck example in the book, I looked at the DCM buck-boost averaged large-signal circuit from Fig 11.11. However I'm not sure if I'm supposed to develop equations from this model or simplify it into a DC equivalent model and go from there. Also, am I supposed to try to solve for input current "ig" like in the buck example? Any pointers would be appreciated.

HW#10 prob.1 solution

Hello everyone,
I am aving trouble understanding the solution posted for HW10 prob. 1:

The solution states: Tc(fci) = (Rf*Gio*Ki/VM)*fo^2/(fz*fci) = 1. I do not understand how this expression was arrived at. It appears as though (Rf*Gio*Ki/VM) was assumed to be equal to the flat gain, say, Tco, of the compensator. I don't see how that is true. Even if it were true, I don't see how the rest of the expression makes sense.

I can see that (fci/fi)*(fi/fo)^2 = Tco, the flat gain of the compensated loop gain. However, one cannot know Tco without knowing the fi (the zero of thecompensator)….so there are three unknowns here (fi, fci and Tco).

My thinking would be: Choose fi first (say, for instance, fi = fci/10)….and assume fci = fs/5 = 200/5 = 40kHz. Then fi = 4kHz. Once we know fi, onlythen we can get Tco and then determine fci.

I would really appreciate if someone can shed light on this (or perhaps the grader or the student who did the solution).

Regards,
Nitish

HW11 Problem 1

This seems like a straightforward problem to me, but I am having trouble getting results for the CCM/DCM boundaries that make sense.

The fundamental difference for the buck-boost compared to the boost is that the inductor current is not equal to i_g, but rather only equal to i_g when the MOSFET is on and equal to the output current otherwise.

I used the normal buck-boost conversion ration to determine my d(t) equation, and I replaced d(t) in the inductor current equation with this. Then I calculated the CCM boundary by < delta i_L(t). This is a little more complicated then the boost since in the boost = .

Basically, I am getting a value for R_e,crit that is a function of Ts, L, and R. It is not dependent on V or v_g so it creates a hard boundary for CCM/DCM. This doesn't seem right. Does anyone see where my approach might be wrong?

HW10 Problem 1 Spice simulation

Hello, In verifying the solution for the HW10 problem 1 (ACMC), when I simulate the uncompensated loop gain in LTSpice, it matches the hand calculation (here the duty cycle was input using a voltage source). However, as soon as I put the PI compensator in the loop and connect the output to the duty cycle input of the CCM-DCM1 model, all currents and voltages of the converter go out of range (the inductor current becomes in kilo amps and the output of the compensator is in megaVolts)....I am not sure what is going on. I would expect the output voltage of the compensator to be twice the steady state value of the duty cycle (when multiplied by 1/VM would give the duty cycle). Any hints would be greatly appreciated. Regards, nitish

HW10 Prob 1

I'm working on finding the range for Vc in problem one. I found the range of duty cycle using V/Vg=1/D' and used it as a reference for finding Vc. Looking at the mid-band gain I come up with Vm(t)=(R2/R1)Vrf, with Vrf=Rf*I. At turn-off Vm(t) should be at maximum. I used R2=(R1/Vrf)*Vm(t) to find R2. I get R2=350K. This results in a range of .286 to .5 for Vc, using Vc=(10R1/R2)*Vm(t), but it ends up being a lot of mid-band gain for the compensator, ~30dB. I'm not confident in this approach. I'm using Vrf=Rf*I=.05V which is true at steady state but it doesn't account for the inductor current ripple. I haven't had a chance to simulate it yet. Is my lack of confidence in this approach warranted?

New Edtion of text book?

the information presented in this course, that is not in the book is quite valuable. It was mentioned that some of this material would be in the new edition of the book.

Is there any estimate of when the new edition would be made available?

thanks
Mark

HW #9 Solution ?

How come there is no HW #9 solution?

thanks
Mark

any way to re-create a schematic using .cir files from HW7 solution ?

Hi, For HW7 flyback solution, we were provided .cir Spice files. Is there any way for Spice to create a schematic (.asc file) out of it? Regards, Nitish

SPICE Boost

Hey everybody,

I was having trouble getting a fast enough op-amp for my comparator to handle the sawtooth at 200kHz. I found an op-amp that has a good enough gbw, but the slew rate kills everything and I cant turn the MOSFET on.

Any thoughts?

danny

HW9 P1 - Voltage Loop Gain

For HW9 P1a, I was using figure 12.25a of the text as a guide, and as such I was able to get an equation for Gvc based on eqn 12.73. However, the voltage loop gain using this model would incorporate Fv as a multiplier (Tv = Gc(s) * Fv * Gvd(s)), and since Fv = 0 in model 4, I am inclined to think maybe I need to change the model in 12.25a to compensate for model 4 in some way. Could anyone give me a hint here?

HW 9 part(c)...do we use model(4) results that match 2nd order Pade approx, sampled data model results?

In HW9, problem 1(a), it appears that to evaluate the given compensator design, we need to use averaged model (4) results that match the first order Pade approximation results of the sample data model. Then in 1(c), we are asked to use the "more accurate" model to design the compensator. Are we expected to use the modified averaged model (4) whose results match the 2nd order Pade approx. of the sampled data model (or do we still use the first order results)?

HW10 Boost ACM (a)

I was just wondering if anyone out there had looked at part (a) for the Boost ACM problem from HW10. I'm a little confused on exactly what parameters we can set for the sawtooth since the switching frequency and the amplitude are given.

I'm thinking it has something to do with the minimum voltage of the sawtooth. I've read the papers on ACM posted online, and Dixon makes it seem like the slopes need to be the focus, though we have no control over these.

The problem does say to just sketch the "waveshape," so perhaps numbers are not important?

Anyways, can anyone point me in the right direction?



Thanks,

Danny

IEEE 1547 standard used in USA for connecting distributed sources to the power grid

In reference to the standards discussion in lecture 31, I would like to state that all distributed power sources in USA (anyone producing power other than the utilities) must meet the IEEE1547 standard, in order to legally connect to the power grid.

Lecture 28 Slide 9

My question is regarding the CPM Buck converter example on slide 9 of lecture 28. If Ma = M2 = M1 = 1A/us, how do we arrive at .11/A for Fm?

line commutated rectifier applications

In lecture 30, it was mentioned that the chapter on line commutated rectifiers may be eliminated as they don’t provide power factor correction (PFC) and thus not much used. I talked to Prof. Maksimovic about that statement and he clarified that there are indeed applications where such rectifiers are well suited for relative simplicity, low cost, or power levels. I would like to take this opportunity to mention one such application.

The application I am familiar with is where the ac voltage is not from the power line, but from an alternator (for instance, the generator in a small wind turbine system). The alternator source has no PFC requirement, per se, as it is isolated from the power grid. In such systems, the simple (line commutated type) rectifier is used to convert the variable frequency ac output of the wind turbine generator, i.e., alternator, to (variable) DC, which is then boosted and then inverted to power line AC (for connection to the power grid). The line commutated rectified DC is generally boosted using a simple conventional boost circuit. That boost circuit does provide some power factor correction action. As a result, the alternator current no longer looks like current spikes (when the rectifier diodes conduct), but actually with a nice current waveform (although, not quite sinusoidal). In my experience, the generator current lags the generator voltage by no more than, say, 15degrees, in the worst case (which is generally under light loads and also depends on the generator winding inductance and resistance). With such a design, one does has to be careful about the alternator current waveform at various operating powers. Even though there is no requirement for PFC, it is important that the alternator current waveform be not too much distorted or too much out of phase with the alternator voltage, as it results in torque ripple and acoustic effects. High current harmonic content may also lead to excessive loss in the windings.

Component differences in peak vs. avg. current mode control?

I am trying to figure out the difference in components between a peak and an average current mode control (ACMC) setup. There doesn't appear any difference between the block diagram of fig. 12.12 (which is in the peak current mode control section) and the block diagram presented for ACMC. Both have the voltage loop and the current loop as well as the comparator to compare iL and ic. I am guessing, then, the differences are: 1) The current sensor in peak control will be sensing the instantaneous inductor current, while the one in average control will sense the average inductor current. 2) The comparator comparing iL and ic in peak control operates in the open loop condition (no feedback to reduce its gain) and hence puts out either "1" or "0", whereas the one in ACMC operates with a finite gain (closed loop form). 3) Finally, the current command (variously called i^c*Rs and i^c*Rc in class) would need to reflect the peak and average inductor currents respectively. Would these be the only differences between a peak control and ACMC setup? Nitish

HW8 Prob 2

At the risk of coming across as a simpleton, how do you go about calculating the steady state duty cycle for differing loads in part a? Every time I try a different approach I come up with the same duty cycle for all loads which cannot be the case.

Midterm Exam Solution?

Will there be a midterm exam solution posted?

I do not see one, nor do I see anyway to get a PW for it on the CU Learn.

thanks
Mark

HW 7 Spice solution , part D link ?

the link for the HW 7 Spice sims netlist for part D,. points to the same as part C. Is this a mistake?

thanks
Mark

HW7 Prob2(b)

In deriving the loop gain T for this converter, I'm trying to understand what the impact R1 has. Can anyone please explain what it's supposed to do? Does it affect the sensor gain H(s)? Thanks.

Post replies

Has anyone else had an issue making replies to posts? I can make a new post - like this one - but I can not reply (or add to) any post. When I click 'post comment' or 'preview' nothing happens. I am definitely signed in. I have tried with both safari and explorer. Unfortunately if someone else is having the same issue, you will not be able to reply to this post! :-)

Also I have never been able to stream a continuous un-interrupted feed of any lecture. It always eventually hangs and I have to restart it and forward to where it hung up. Is anyone else having this issue? Has anyone found a fix to either issue?

Thank-you! Tim

HW7 Problem 1 Zout

How do you go about getting plots for Zout on problem 1? For Gvd I sweep Vg with Vd at the duty cycle voltage, for Gvg I reverse that by sweeping Vd and setting Vg to 48V but I am unable to get plots for Zout. I've tried placing another source across the output and sweeping it while plotting V/I but that doesn't work. Someone drop me a note if you get a chance. Thanks.

HW 7 problem 2 steady state

HW 7 problem 2a seems pretty straightforward in nature, but I am having a difficult time with the number of unknowns in the problem. It seems like the problem does not give us R, R1, or V. Because of this, I am having trouble finding equations for D1 and D2 that are not dependent on these unknown quantities. I have solved for I(D1,D2) as the average value of the inductor current, and I have the buck equation for M(Re, R) and Re(D) in DCM from the book, but I am still having trouble piecing it together with these unknowns. Could anyone give me a hint on what I am missing?

solving DCM buck, and boost for M

on page 420, we see the steady state model for the buck, and boost converters in DCM.

I do not understand how to solve these for M (M= output Volage/Vg in steady state). The buck-boost on page417 was easy.

Can anyone help me to understand how to solve for these?

thanks
Mark

HW5, prob.1, determination of s^2 numerator zero contributed by L2C1

Hello,
In HW5, problem 1, I cannot seem to determine the s^2 numerator zero contributed by L2,C1. For determining the first order zero contributed by C1, I assumed a samll resistance 'r' in series with L2 and the result was: v^test/i^test = r. Now, to determine the zero contributed by L2C1 together, I have set C1 as short (abnormal) and put the test source across L2 (with shorted L1 represented by a small resistance 'r') . I was expecting the resistance see would be 1/r....but I cannot get that.
Any hints would be useful.
Regards,
nitish

Null Loop Gain Question

For question 1 of HW6 I have expressions for G0, Ginf, and T. I'm now chasing Tn. It's tempting to just use reciprocity to find it but the next step is to check the reciprocity relationship so that would be somewhat redundant. Starting with iy/ix with vout = 0, it appears that ix would be zero since vout = 0 (This is with the test source between gm and R0 and ix is the current between gm and R0). That being the case, Tn will either blow up or be zero depending on the value of iy. Obviously I'm missing something here. Any hints on how to find Tn?

Problem 11.1

For Problem 11.1,

are we supposed to derive a model of the switches for DCM?

The problem does not actually say to do that, however part 1 is a step in that direction.

thanks
Mark

Lecture 21 Quesion?

In the slides for Lecture 21, the professor showed a signal "c" and "c^", are these supposed to represent the Vc(t) input from the compensator to the PWM ?

thanks
Mark

prob. 11.1(e); Lp =0; does Re become 0? which means j1 and j2 = infinity?

Hello everyone,
In prob. 11.1(e); Lp =0; Does that allow us to make Re = 0 as it has Lp in its Numerator ? Making Re=0 would make j1 and j2 = infinity as they have Re in their denominator.
Any comments would be useful.
Thanks,
Nitish

DCM waveform levels for the buck-boost converter (fig. 11.3)

Hello everyone,
In fig. 11.3, the buck-boost converter DCM waveform levels are shown in terms of instantaneous values of vg and v....but shouldn't they be written in terms of their average values ,vg> and ?
For example, v2(t) waveform level during interval d1Ts is shown to be vg-v. But shouldn't it be - ? Similarly, the vL(t) voltage level during d1Ts is shown as vg. It appears to me that it should be shown as .....and so on, for the rest of the levels. If representing only in terms of vg and v, the implicit assumption is that they are constants.
Also, eqn. 11.1 should be written as ipk = d1.Ts/L instead of vg.d1.Ts/L.
I would appreciate any comments.
Regards,
Nitish Agrawal

General Feedback Theorem

I came across this paper on General Feedback Theorem



I have not read it, but it looks well written.

Mark

lecture 18, slide 34 (when expressed in terms of R, L, C....)

Hi everyone,
I did not understand the lecture 18, slide 34 summary statement, "when expressed in terms of R, L, C, and M (not D), the small signal transfer functions are he same in DCM and in CCM".
Can anyone shed light on this?
Regards,
Nitish

Digital Control Question

so with digital control, can you dynamically change the coefficients that are used to compensate a Converter.

I read in the past, that one of the benefits of Digital Control was that you could change the coefficients in the last minute of production, but I was wondering if you could have an algorithm where one changes the coefficients during run time?

thanks
Mark

HW 7 - Simulation of G_vg and Zout

Hi,

I am able to plot G_vd but when I try plotting G_vg and Zout, the graphs do not get plotted? Spice does not indicate there are any errors in the circuit!

Anyone has suggestions?

HW #5 Solution?

I do not understand the HW #5 solution for the SEPIC nEET problem where we are told the solution has an error.

I do not understand the first line of the solution. I do see that the secondary voltage, referred to the primary is -vtest(D'/D) .


Also, for the s^3 pole term, I got a value R/(1+D/D')^2. I have attached that, I do not see any error in that, which does not agree with the HW solution.



thanks
Mark

HW6 Problem 1

This is a sanity heck. Should I be running into a lot of algebra when finding G? When I established reciprocity I ended up with a fraction with 16 terms in the numerator and 13 terms in the denominator. Should these results be more manageable?

DCM boost converter example

I think I am missing something in understanding how the equation for the power source value was derived in equation 11.57.Can someone elaborate on this?

CCM-DCM2 Model

Hello Folks

Did anyone find the model of CCM-DCM2 work? I can't get the output with this model.

Chapter 8, Factoring Polynomials

for pages 290-291 of book, using the inequalities of the coefficients, to factor a polynomial into an approximate form:

Must *ALL* inequalities be true to use, for example in equation 8.95.

If in equation 8.95, the first several inequalities are met, However one, such as |a4/a3| >> |a5/a4| is not met(an inequality that is later than the first two)..., could you still factor this into a form such as 8.94., and then do you go back and try and factor out the other terms into an approximate form?

I just wanted to make sure that maybe the book did not completely explain the issue.

thanks
Mark

Getting error when "getZDZN" function gets called (written by Riley)

Hi,
I am getting the following error when the "getZDZN" function (written by Riley Pack) gets called:
??? Undefined function or variable "Z".
Error in ==> getZDZN at 59 ZD = 1/Z;
Anyone else see that? Would appreciate any help.
Nitish

HW #5, nEET problem, identifying the wrong "R"

for the HW #5 problem where you identify the wrong value in the "solution" given, does it have the value
Z=R/(1+D/D')^2 ?

that is what I got, but I do not see any other terms, which makes me suspicious that it might be wrong.

thanks

"u" in DCM simuluation model

is u ("mew") for DCM in the simulation model for the averaged swith model always < 1 ?

HW 5, problem10.9 of book

Do we need to do Spice sims for this problem?

thanks
Mark

getZDZN function written by Riley

Hello,
In the getZDZN function written by Riley, I am trying to understand how the statement works and what it does. Can someone help?
if (strcmp(ssm(i,j).InputName, input) && strcmp(ssm(i,j).OutputName, output))
disp('Found G')
G = ssm(i,j);

Thanks,
Nitish Agrawal

setting "n" in the CCM3 model for flyback converter

Hello everyone,
This is regarding problems 10.4 and 10.10. I am trying to clarify if the CCM3 model should only be used when the transformer in the converter circuit is connected across the diode in the switch (as in the CCM3 equations it is the voltage across the diode switch, E(3,4) that gets divided by the transformer turns ratio). If the transformer in the converter circuit is not connected across the diode (as in the flyback converter), then shouldn't one be able to use the CCM1 model for the switch in that converter?
Thanks,
Nitish Agrawal

transformer.asy problem!!!

Is anyone having problems downloading the transformer symbol? I tried various browsers, but simply could not get a working symbol. In case anyone has a working transformer.asy file, kindly let me know. Thanks in advance.

HW4 P1: simulation

How are people simulating problem 10.4d in Spice? The averaged switch models say "no transformer," which I thought meant you can't use them with a converter with with a transformer like the flyback....

Matlab/Simulink Parameter alteration ?

in the first MATLAB/Simulink assignment, we had Rload as a top level parameter b/c the gain block was at the top of the schematic hierarchy. That made it easy to change the value of Rload.

How can you change a value of a parameter that is down lower in the hierarchy? For example, if you wanted to change Cf of the input filter?

thanks
M

HW3 problem 1a (Finding Zn)

So what it Zn found on item a? Is it infinite?

Code Question, salient.m

Quesiotion:

What does the 3 lines do near the end of the code of salient.m .... what is the purpose of doing this?


features.z = z;
features.p = p;
features.dc = dc;

HW 2, problem 1

I am confused by the instructions telling us to simulate with Rload equal to a value.

How do we set the Rload?

Rload = Vout/Iload.
Vout is set by the loop, but b/c we have losses I do not know exactly what Vout is for a given Duty cycle. If I did know it, I could specify the load current based on Vout & the expected Rload. I could derive (by hand) Vout as a function of all losses and elements, then set Iload, but I am assuming I should not do that.

Also, the problem says "Iout = 0", I assume this is meant to be referring to Iload?

HW2 Problem 1b (second question)

Are we supposed to find 2 RHP zeroes? I can only find 1 with my script (at around 0.224)

HW2 prob1

What does "standard normakised form" indicate?

tilde operator in Matlab?

hello,

can you explain to me what the tilde (~) operator does in Matlab?

ex #1: if ~isempty(z)

ex #2: if rem(n,2) ~= 0

thanks
M

HW2 Problem 1b

Hey all,

I understand I need to do a loop to find out the pair of RHP zeroes. The question I have is how to transfer the resistance value to the Simulink model. How did you guys do?

Thanks,

Fabio

HW2 Prob1

HW2 Prob 1 asks to use getSSM and salient files from 5807 library. I think I am not running the files correctly, I understand for getSSM file sys is the .mdl file, however for salient what is sys?

Is the output of one the input of other? I think I am missing something here...dont know what..

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