londark Posted January 2, 2019 Share Posted January 2, 2019 (edited) Long story short On Xmas break right now, will be back at uni on monday, with an exam (damn right). Professor is on break too and won't respond to our mails...So i'll be seeking some help here as well. Subject is System and Control Theory. Here are some question i'm stuck on. Will add other problems later if someone can help. For other feel free to ask for help on whatever you are studying Edited January 2, 2019 by londark DoubleJ 1 Link to comment
Bilburt Posted January 2, 2019 Share Posted January 2, 2019 so now you come crawling back londark 1 Link to comment
londark Posted January 2, 2019 Author Share Posted January 2, 2019 Just now, Bilburt said: so now you come crawling back ye, now help me Link to comment
shervinz Posted January 2, 2019 Share Posted January 2, 2019 im studying the human anatomy, send pics Malorne 1 Link to comment
londark Posted February 11, 2019 Author Share Posted February 11, 2019 (quite easily) done with that. Next one will be about Electromagnetic Compatibility axx 1 Link to comment
axx Posted February 12, 2019 Share Posted February 12, 2019 21 hours ago, londark said: (quite easily) done with that. Next one will be about Electromagnetic Compatibility first fix your sig, noob Link to comment
londark Posted September 10, 2019 Author Share Posted September 10, 2019 @axx i need some help with Simetrix/Simplis Do you know something about it? Link to comment
axx Posted September 11, 2019 Share Posted September 11, 2019 Never used either sorry; but if it's not a software-specific question I might be able to help. - On related news, I was in Italy last week and met a few guys from polimi. Link to comment
londark Posted September 11, 2019 Author Share Posted September 11, 2019 Nice, if you ever come near Venice tell me. I think I got the solution actually, was just a simulation setting problem. I have to make a dc/dc flyback converter from scratch and was having problems with the transformer model used by the software Link to comment
axx Posted September 11, 2019 Share Posted September 11, 2019 Yeah, usually the trick is in configuring the parts. Not sure about these software, but other simulators provide manufacturer-defined models as well as template parts which you can customize to obtain something closer to your application. Have you ever used Spice? -- I spent two weeks in Trieste a couple years ago and got to visit a few of the northern cities, might return there some time. In fact I'll be moving to Spain this year, plan to spend a few months there. Link to comment
londark Posted September 11, 2019 Author Share Posted September 11, 2019 Yeah, used PSpice, and Simetrix is quite similar actually. My problem was that the ideal DC transformer doesn't have a Primary Inductance value, that I need to define some target values for the converter. I added an inductor to simulate the primary inductance and apparently it didn't work out, but I had just to change some settings on the simulation details. Anyway, I'm in Udine if you ever get back here. Trieste isn't far away as well axx 1 Link to comment
Spaintakula Posted September 12, 2019 Share Posted September 12, 2019 The answer is 1 Link to comment
Vaeldras Posted September 18, 2019 Share Posted September 18, 2019 On 9/11/2019 at 9:49 PM, londark said: Yeah, used PSpice, and Simetrix is quite similar actually. My problem was that the ideal DC transformer doesn't have a Primary Inductance value, that I need to define some target values for the converter. I added an inductor to simulate the primary inductance and apparently it didn't work out, but I had just to change some settings on the simulation details. Anyway, I'm in Udine if you ever get back here. Trieste isn't far away as well get back on steam so we can play dead by daylight and rust Link to comment
londark Posted September 29, 2019 Author Share Posted September 29, 2019 @axx So, i'm almost done with everything, i just need to design a regulator. I went for a type 2 scheme with an Opamp and a feedback with 2 capacitors and 1 resistor. These are the specs: Vin = 9-36V Vout = 5V Iout = 0-4A f = 100KHz I got a Rout of 1.25, an Lm of 23u and a Cout of 40u ( it's big but i had required ripple of less than 0.5V peak). To design the compensator i usually set the cutting frequency at around f/10, and i choose the components so that the compensator zero is equal to the flyback pole and viceversa the compensator pole is equal to the flyback pole. I don't know why this time i'm getting weird numbers, could it be because this time i'm having a step down type converter and so the gain is less than 1? Link to comment
axx Posted September 30, 2019 Share Posted September 30, 2019 wtf it took me longer to get in than the actual question assuming you are using tantalum capacitors for reasons flc = 1 / (2 x pi x sqrt(0.00000023 x 0.00008) = 37103 hz (1) fesr = 1 / (2 x pi x 2 x 0.00004) = 1989 hz (2) f0 = fs/10 = 10000 hz (3) flc < fesr < f0 < fs/2 (4) 37khz < 2khz < 10 khz < 50 khz you need to check those capacitors if (4) does not hold, the type II will go haywire or you can cheat and say lm = 140u londark 1 Link to comment
londark Posted October 1, 2019 Author Share Posted October 1, 2019 (edited) Hope like this It's easier to understand I increased a little the cut off frequency to 33K, the rest should be correct. The ESR is 170m. EDIT: I also did a fast stability check on the regulator and it's stable using those values. The poles and zero frequencies are also really close to the chosen ones, and it should be pretty cool. Using simplis to simulate the regulator and PWM on a Buck converter using the flyback values it works decently enough. I also don't really need a perfect regulator, but i just needed to do some math on it, the actual feedback control on the circuit is done by the LT3758 Edited October 1, 2019 by londark Link to comment
londark Posted October 2, 2019 Author Share Posted October 2, 2019 Not sure I understand what you mean honestly. The output current is already at 4A (5/1.25), used the max output current cause during lessons I was told to always use the minimum possible Rout when making this kind of regulator. Unless you mean to use a Norton load with a current generator of 4A Link to comment
axx Posted October 2, 2019 Share Posted October 2, 2019 was just implying that you should now build the protorype, thats the fun part Link to comment
londark Posted October 3, 2019 Author Share Posted October 3, 2019 Ah ok, yeah, if I get the ok I'll start. Got already the shopping list ready Link to comment
estrellamamoneseg8 Posted October 30, 2022 Share Posted October 30, 2022 God for me it's just a set of incomprehensible letters. How is it possible to understand anything here. I would just drop my studies and that's it. Math is just not my thing, I can't even look at numbers! Link to comment
tTow Posted April 25, 2023 Share Posted April 25, 2023 (edited) I hate homework! Edited June 5, 2023 by tTow jasean 1 Link to comment
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