| jegandren |
hi all,
im building a half bridge smps for my project. Can anyone suggest where shall i start first, the control part , pfc part or shall i build the open loop SMPS first. please advise |
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| guitar_joe |
| have you built any smps before? |
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| Bootstrapper |
Hi, before you actually build anything, I recommend intense simulation with (for example) SwitcherCAD from Linear Technology. If you have access to a book Fundamentals of Power Electronics by Erickson et al, you should have enough basic information about the design constraints.
Personally I tend to start with the power devices and transformers. If you have somewhat clear specifications for your project, you can estimate the maximum voltage & current stresses and choose component based on the calculations. Once you have selected components for the power section, you can proceed with filters and control circuits.
I guess there are no single best starting point, but since the power section is perhaps the most crucial, you may want to check that first. My knowledge on this subject is rather limited, at least compared to experts like Eva, for example - so don't believe only me :)
Good luck on your project(s)! |
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| jegandren |
Hi
Actually i haven't built a SMPS before, but im done with the simulation using Matlab/Simulink. |
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| Tolik |
Hi,
The best, & most accurate simulator for SMPS is prototype board only :smash:
Trust me, that even with best in class software, you will not be able to simulate the whole design if you don't ABSOLUTLEY familiar with SPICE, physics of magnetics, RF etc. Because the performance of SMPS is strongly depending on a lot of things and conditions like PCB layout, temperature of your magnetics, quality of components and many others, that very difficult to simulate. What you can do - to simulate important parts of your project: feedback networks, filters, etc. |
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| S.G. Mahbub |
Dear jegandren,
Since you are stepping into the enormous world of power electronics, you can start from any where as you have to learn, try,mistake, learn,try........... But follow the safety rule in toto. Since you have done some simulation, you have gathered some idea, though the simulation may not be very useful in practical field. Try to gather working knowledge regarding the parts, circuits etc. In power electronics, knowledge means 100% knowledge regarding the circuit you try to make. Even 1% mistake is fatal here.
If you decide to step into, don't hesitate. Even the tallest building in the world starts from the first brick.
First, you can try with the proven circuits given in cookbook/internet.
Gather knowledge, follow safety rules, and try again and again. With the passage of time you will be able to do, what you thing impossible now. Don't listen to those so called experts, who discourage. Nothing is impossible but can take some time. Man can do what men have done.
Matsusita, the founder of National Panasonic Company of Japan didn't attend any school and started his career as a street light bulb boy whose duty was to remove the damaged bulbs from street of Tokyo. But with the passage of time he invented many electrical items and created the big company single handedly.
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IDEAS ARE MONEY, IF YOU CAN USE IT ON GROUND, NOT IN FORUM OR CLASSROOM ONLY.
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| S.G. Mahbub |
Dear jegandren,
Thank you for your E-Mail. |
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| N-Channel |
| quote: | Originally posted by jegandren
hi all,
im building a half bridge smps for my project. Can anyone suggest where shall i start first, the control part , pfc part or shall i build the open loop SMPS first. please advise |
Try searching this forum for threads on half-bridge PSUs. Perhaps the most commonly implemented smps is found in every AT & ATX pc smps: The TL494-controlled half-bridge. Also, try this link. This should serve as a good starting point. Voltage-mode w/feedback, soft-start, current-limiting, all the basic stuff you need. No current-mode (cycle-by-cycle current-limiting), but you can't have everything. This circuit has no PFC, but there's quite a bit of info on the web (and this forum) on PFC.
Before you start anything, please be advised: Voltages in these ckts are LETHAL, and you are advised to exercise to appropriate caution.
Hope this helps.
Cheers,
Steve |
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| Tolik |
Hi,
Here is another intresting example. |
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| wakibaki |
| quote: | Originally posted by jegandren
please advise |
| quote: | Originally posted by P. Horowitz & W. Hill
Don't. |
w |
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| S.G. Mahbub |
Hi jegandren,
While designing and working on smps, provide a discharge path for the reservoir/filter capacitors. These capacitors can store a huge amount of energy and if touched can release that energy on you, which may be fatal.
The discharge path could be a high value resistor or a resistor in series with LED in both input and output section of your circuit. I personally prefer the later as after input supply is removed, the LEDs will indicate whether the Capacitors have discharged or not. Wait till the LEDs go off and after that you will have full freedom to put your hands anywhere in the circuit without any sort of risk of electric shock. Electric shock in smps can be fatal and please don't allow yourself to have that experience.
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IDEAS ARE MONEY IF THEY CAN BE USED ON GROUND.
বাস্তবে ব্যবহৃত চিন্তাধারাই মানুষের প্রকৃত সম্পদ। |
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| wg_ski |
| If you want to get your feet wet with switch mode supplies, may I suggest first starting with something relatively harmless - like a DC/DC upconverter. Something that starts with a (current limited) lab supply and goes to something that won't kill you if you touch something. Once you can reliably overcome the inevitable newbie hurdles, and the pile of vaporized HEXFETs you'll get along the way, then move on to something off-line. |
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| CHACALPOWERS |
Hi dears
I built some half bridge smps but, now, I want build a full- bridge, 13,8V - 60 amp. smps. Is there advantage in FB ?
Thank you very much |
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| wakibaki |
| quote: | Originally posted by Tolik
The best, & most accurate simulator for SMPS is prototype board only |
I don't want to rain on anybody's parade, but SMPS design is not to be undertaken lightly.
Before you embark on such a project, you should have a clear idea of what your objective is. Then think whether you can achieve the same result with a conventional power supply. These are much better suited to home construction.
SMPS are often problematic in terms of emc. EMC.
EMC regulates the permitted emissions of equipment.
It is the designers responsibility under European law to ensure that devices do not emit excessively. This legislation is part of the criminal code, and successful prosecutions can result in jail sentences.
I am not suggesting that you run the risk of prosecution, but you should be aware of the potential antisocial consequences of your designs.
Fullscale EMC testing is impractical (uneconomic) for amateurs.
Unless you anticipate a career in SMPS design, it is a field better avoided.
w
OK, you may not be in Europe... |
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| Tolik |
| quote: | | This legislation is part of the criminal code, and successful prosecutions can result in jail sentences. |
Did anybody here heard about a person, that was thrown in to the prison for unsuccessful SMPS design ? |
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| wakibaki |
| quote: | Originally posted by Tolik
Did anybody here heard about a person, that was thrown in to the prison for unsuccessful SMPS design ? |
It's not a good idea to trivialise this subject.
Before EMC legislation background noise levels were rising globally to the point where, if unrestrained, the normal functioning of many devices we take for granted such as mobile phones might nowadays be difficult or impossible.
The legislation was successful in reversing this rise.
If you operate an untested SMPS you run the risk of minor or even severe interference to your neighbours and even, in rare instances, to safety critical services.
In my book, this constitutes antisocial behaviour, however minor.
Radio noise is environmental pollution.
Do you deny that this is the case?
w
Tolik, I'm not taking a dig at you. One of the things we most need prototypes for is EMC test. |
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| Tolik |
| quote: | | If you operate an untested SMPS you run the risk of minor or even severe interference to your neighbours and even, in rare instances, to safety critical services. |
| quote: | | Radio noise is environmental pollution. |
I agree...
Generally we are talking about power supplies for audio equipment. Excessive EMI, will first interrupt functioning of whole audio system... So building of LOW noise PSU is main target here. Next, almost 80% SMPS discussed here, are low power - less than 300...500W, and almost neither of these projects not going to be produced in quantities more than 1-2 units. I don't really think, that several, even bad designed, low/ medium power supplies are containing a threat to ecology, or communications.
You better tell us how to measure or avoid EMI/RFE . It will be much more intresting here. |
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| wakibaki |
Typical EMI probes can be seen here
Uncalibrated probes can be fabricated quite readily from rigid co-ax, although the sheild must be perforated to permit correct connection in the case of the loops. You can find the connection details in e.g. the ARRL Antenna Book. The straight probes simply have a small stub of the inner conductor exposed.
It is unfortunately not possible to quantitatively test equipment in the absence of a quiet environment, which usually means a shielded room.
It is an unusual SMPS that passes EMC test on first submission, be it ever so small.
w
Most SMPS fail on conducted emissions. These can be detected by coupling to the supply cable. Oh, keep your current loops small. Watch your risetimes. IIRC CISPR B testing goes up to 2GHz. You ain't gonna hear that on no audio system... |
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| Eva |
| Simulation is great for control-loop modelling. |
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| jahonen |
I have seen hugely excessive EMI levels (20-30 dB over the B-requirement level 30/37 dBµV) even with very small non-isolated power supplies. I don't think that such excess will affect the audio system in any other way than FM/AM-reception. Most problematic frequencies are generally around 50-200 MHz.
Personally, for me, low EMI levels indicate carefully designed circuit/PCB and gives also other performance benefits. I feel that excessive EMI-levels are a clear indication that something is very wrong and must be fixed.
Most of the cases I have seen, it is rarely the PCB itself which radiates, but the cables attached to the PCB form an effective antenna for common-mode noise. Differential mode is seldom a problem, due to small loop areas. Common mode radiation is much harder to suppress.
A very good cheap test for EMI (requires reasonably wideband oscilloscope, though) is to short circuit a oscilloscope probe right at the tip to the ground collar. Throw that ground clip away though, it is pretty much useless for SMPS and digital measurements due to excessive loop area it creates, thus it picks all the magnetic noise.
Then connect this short circuited probe to the ground of the PCB. Now, do you see any high-frequency noise at mV levels? If you do, then don't bother to try EMC-testing until you have fixed what you see using this test. Remember, it only takes few µA of common mode RF-current to create high EMI levels. Higher the frequency you see, then more serious the issue is.
Regards,
Janne |
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| S.G. Mahbub |
I appreciate the genuine concern of wakibaki regarding the emission of EMI/environmental pollution. Wakibaki is really a law abiding citizen of this world, who always think in bigger prospective and which is actually required for us all and specially for the leaders of his/every countries before indulging themselves in any harmful actions like involving in unjust war and engendering the environment by dropping million of Missiles/Bombs/Chemical agents on people/country, which is ultimately endanger our environment/ very existence. Sometimes they adopt measures like creating EMI for obstructing the radio signal/telecommunication, radar etc. which is more harmful than what jegandren is trying to do. I hope, wakibaki's concern will be heeded by all including his/our leaders.
However, jegandren, you please abide by the rules and regulations and continue your effort regarding smps, which is a just and noble effort.
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IDEAS ARE MONEY IF THEY CAN BE USED ON GROUND.
বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ। |
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| ashok |
Quote by S.G. Mahbub
"...................specially for the leaders of his/every countries before indulging themselves in any harmful actions like involving in unjust war and engendering the environment by dropping million of Missiles/Bombs/Chemical agents on people/country.........etc "
This is a DIY audio forum and I think we should restrict the discussion to matters relating to electronic/acoustic design.
I think this post is getting political and that has no place here.
You can try forums that cater to that trend of thought.
You have a right to vent your personal opinions on anything you want but with this kind of material it would be nice if you took it on to a forum that caters to such discussion.
Trust you are otherwise having a great time building and discussing audio matters with like minded members.
Cheers. |
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| Bas Horneman |
| Dear S.G. Mahbub. Please stay on topic. Political discussion or remarks are not allowed.:cop: |
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| Cal Weldon |
While you are at it, would you please change your sig line so it isn't all caps and eliminate those annoying question marks. It's all very distracting.
Thank you. |
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| MartyM |
Hi jegandren, some of the posts above mention the importance of getting a prototype working & I agree.
Half of anything in engineering is actually trying to get it working, not just simulating it or putting it "on paper."
I built several SMPS units for a giant car chip amp amplifier I built (in photo). Also I modified the same design for my +260V tube preamp SMPS.
I can tell you that the only way I got real progress and discovered real-world problems that I didn't expect was by:
1. Building a rough prototype...in my case etched my own PCB
2. Figuring out how (and with what parts) to build the transformer
3. Verifying the SMPS IC is working ok
4. Testing, debugging, and fixing a the little mistakes!
5. ...and so on.. (RC snubbers, optional regulation, etc.)
I did not see where you specified the power requirements & output voltages required, but it's fairly easy to get a "split rail" (both positive & negative voltages) step-up design working. You can look at the high-power 12V car SMPS designs on the web as a starting point.
Now, if you mean step-down AC-DC SMPS, I'm not sure about that.
PS: You need to be sure to keep plenty of MOSFETs on hand!!!
Good luck :)
EDIT: Ooops, I guess you did mean AC power source?? If so please overlook unrelated topics in my post. |
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| S.G. Mahbub |
Cal Weldon,
Thank you for letting me know.
I have changed my sig from caps. But I do not see any question marks.
Thank you.
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Ideas are money if they can be used on ground.
বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ। |
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| S.G. Mahbub |
Cal Weldon,
You said:
| quote: | | While you are at it, would you please change your sig line so it isn't all caps and eliminate those annoying question marks. It's all very distracting. |
You mentioned "While you are at it". Does that mean you do not want me to be a member of DIY Audio? If you want, I can quit your forum.
Thanks.
____________________________________________
Ideas are money if they can be used on ground.
বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ। |
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| planet10 |
| quote: | Originally posted by S.G. Mahbub
I have changed my sig from caps. But I do not see any question marks.
¬¾¸Í¤¬Ç ¬Í¯¬¹¾°¯Ë—ͯ š¿¨Í¤¾§¾°¾‡ ®¾¨Á·Ç° ªÍ°•Ã¤ ¸®Íª¦d |
It is this last bit that Cal is talking about... it is, i'm guessing, meant to be a line in a non-roman letter language -- it is showing up in Cal's browser as question marks, in mine as a row of glyphs (all the same) and as jibberish in the edit window,
We welcome everyone (who is willing to broadly follow the rules) to the forum. We try to be very liberal but we do insist on keeping things civil.
dave |
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| ashok |
Dear S.G. Mahbub ,
I think you misunderstand the term "While you are at it".
It means , while you are doing one thing ( editing.........changing caps ) do something else also.
In this case the character below your sig line. On my browser it looks like empty squares.........lots of them ! It doesn't really mean anything and does take up some bytes of storage . Takes many drops of water to make the ocean !
You shouldn't get upset at such small things . |
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| S.G. Mahbub |
Dear planet10,
In Unicode, the Bengali meaning of my sig is written. Since it is in Unicode, it should be visible to the viewer. I use Mozilla Firefox and I can clearly see what I have written. I have seen it in other computers also.
Thanks.
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Ideas are money if they can be used on ground.
বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ। |
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| Tahmid |
Hi,
I do not understand the problem here.
It is visible in my browser as well.
I also write Bengali which is the translation of my sig as well.
Tolik has written in Hebrew, so we should be allowed to write in Bengali.
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The strongest man in the world is one, who stands alone for achieving something good.
পৃথিবীতে সেই সবচেয়ে শক্তিশালী ব্যক্তি, যে ভাল কিছু অর্জনের জন্য একাই নিরন্তর চেষ্টা চালিয়ে যায়। |
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| ashok |
Dear S.G. Mahbub ,
Different browsers seem to display the Bengali characters differently. You don't seem to accept that.
Here is a screen grab of what I see on my browser.
Now that everyone understands what their displays should have been , let's go ahead from here and drop this matter and continue with the smps design.
Cheers.
I'm going to bed. It's late over here. |
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| golam |
Cal Weldon,
You are a moderator and you must see more than others. In this forum, people from all over the world are taking part and most of them are using their valuable time in this forum to take and give something. So, if you cannot see anything in your browser, try to install new software/modalities to see what others can see. And your language and approach is also not commensurate with a moderator, who should be an example in approach and language. If chief moderator does not like anything, he is having means to correct/erase/advice but should not use a tool like you.
With thanks. |
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| wakibaki |
In my comments about EMC I didn't mean to provoke an argument (although God knows I love an argument).
Obviously this is an smps forum, and there are going to be people discussing smps and building them.
All I intended was to give some serious advice to somebody contemplating building an smps, much as the advice would be to somebody contemplating building a radio transmitter. Sure, put together a spark-gap transmitter and wipe out half the neighbourhood? 100 years ago yes, but not in today's environment.
I don't suggest that the combined efforts of smps-building audiophiles have a serious impact on worldwide EM radiation levels. I don't intend my remarks to inhibit anyone's enthusiasm or desire to learn, and nor can I take seriously the idea that they would.
I just used the legislation to draw attention to a non-trivial aspect of a non-trivial design exercise, and deliver a warning that I would have thought even a diehard smps enthusiast would have endorsed. Ask (another) radio amateur how he feels about your intention to build a transmitter. If he has a licence, I guarantee his enthusiasm over your interest will be moderated by cautions.
w |
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| Cal Weldon |
Hi SG,
Yes, as ashok says, my intent was to suggest that while you were taking note of our policied here and the political nature of your posts, to also look after the signature line. I still see the question marks so if you'd like I'll see if I can do something about it. Thank you for reducing your sig line to small letters. |
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| Cal Weldon |
| quote: | Originally posted by golam
but should not use a tool like you. |
I trust this is another language barrier kind of thing. ;) In English, calling someone a tool is an offensive and denigrating term.
As for the rest of your concerns, I am not one to mince words. My typing skills are limited so I tend to get right to the point. I am trying trying to offend. |
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| Cal Weldon |
| quote: | Originally posted by golam
So, if you cannot see anything in your browser |
Quite the opposite, I see a line of question marks under his sig line. |
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| MJL21193 |
| quote: | Originally posted by Cal Weldon
I am trying trying to offend. |
Sorry for the quote Cal, but...
:) |
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| planet10 |
| quote: | Originally posted by S.G. Mahbub
Dear planet10,
In Unicode, the Bengali meaning of my sig is written. Since it is in Unicode, it should be visible to the viewer. I use Mozilla Firefox and I can clearly see what I have written. I have seen it in other computers also.
Thanks.
____________________________________________
Ideas are money if they can be used on ground.
���ͤ�� �ͯ�����˗ͯ ���ͤ������ ����ǰ �Ͱ�ä ��ͪ�d |
Firefox gives me a row of question Marks. Unicode 16 turns the whole page into Chinese.
Tried a whole whack of text encodings , none brought anything but questions marks or goobldegook -- that is how most people will see it.
dave |
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| golam |
planet10
MJL21193 can see, why cannot you? Try to collect free modern software from internet to cope up with modern advancement. We will not write anything in this Forum basing on the shortcomings of your obsolete Browser. Why unnecessarily you bring forward the thing which is already settled as said by Ashok? Please, keep up the pace with modern tech. and allow us to concentrate on the Power Supply topic.
Thanks. |
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| golam |
Cal Weldon
You have written," I am trying trying to offend." Probably it is mistakenly written or you don't have proper command on English, because a Moderator can not do that. This is a Multinational Forum and being a Moderator, you must be careful when you are committing something in black and white.
Thanks. |
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| golam |
S.G. Mahbub,
You are correct. It is visible and readable in Mozilla Firefox 2.0.5 and above and in Internet Explorer 6 and above. When I was in U.S.A., I could see it clearly. Probably those who argue, they use obsolete version and please advice them to copy this in Microsoft word and see what is written if they are unable to use latest versions.
I also planning to use sig with Bengali meaning.
With thanks. |
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| planet10 |
| quote: | Originally posted by golam
[B]planet10
MJL21193 can see, why cannot you? Try to collect free modern software from internet to cope up with modern advancement. We will not write anything in this Forum basing on the shortcomings of your obsolete Browser. |
Please don't presume to judge the software running on my computer.
All my browsers (i have a primary & 3 backups) are up-to-date & modern (i just updated my Firefox to 3.0.1 and i still get goobledegook).
IE ism't available on my platform, and i figure you are putting your life (or your computer's) at stake running it.
dave |
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| Tolik |
| quote: | Ideas are money if they can be used on ground.
বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ।
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I`m don't preformed any special setup or installed special charsters sets to my PC, just these that coming on WinXP installation CD. But I clearly see the text of S.G. Mahbub signature...
Tahmid,
The first line of my signature is not in hebrew, it's in russian. |
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| wakibaki |
It is well known that browsers are flaky, and the characters displayed may be in error dependent on the locale (Windows term) of the host machine, or other factors.
I can see Bengali signatures on this machine, but not Cyrillic.
On my machine at home I can see Cyrillic.
Members should exercise some tolerance with respect to other members expressions of their individuality, and be aware that the posters may not appreciate that their tags do not display correctly on all machines.
Many people here are pursuing their interest in electronics in a second language. This is to be applauded not derided.
Surely we can find something less trivial to argue about. Power supplies perhaps?
w |
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| Tolik |
| quote: | | Many people here are pursuing their interest in electronics in a second language. This is to be applauded not derided. |
ABSOLUTLEY RIGHT :up::smash: |
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| Bas Horneman |
| quote: | | Surely we can find something less trivial to argue about. Power supplies perhaps? |
:yes: |
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| jackinnj |
Getting back to the topic -- Sanjaya Maniktala over at National Semi has written several application notes and power points on SMPS and the magnetics therein, readable, sometimes humorous. He also has 2 books on the topic, but they are pretty expensive. You might find a copy of Pressman's "Switching Power Supply Design" in a university library.
The folks at Linear Tech have some switcher chips which modify the slew rate == you trade off efficiency for lower noise.
The first time I built an SMPS was 10 years ago and it knocked out every a.m. radio in the house. If someone with a pacemaker had been nearby they would have been tachycardia city. |
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| Cal Weldon |
| quote: | Originally posted by golam
Cal Weldon
You have written," I am trying trying to offend." Probably it is mistakenly written or you don't have proper command on English, because a Moderator can not do that. This is a Multinational Forum and being a Moderator, you must be careful when you are committing something in black and white.
Thanks. |
Thanks for the advice. Ever consider just asking if it was a typo or do you feel it's necessary to offer such words of wisdom?
If you wish to discuss this further please contact me via email. |
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| golam |
Dear jegandren,
The books refered by jackinnj are useful and those will certainly help you. When jackinnj built his first SMPS 10 years before, then helping material was very less and now the scenario is completely different and you can get lot of information from internet and from different Forum, E Books etc. and those are free. Just keep on trying to learn and apply on ground and you will be successful. Man can do what Men have done.
With thanks. |
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| Tolik |
| quote: | | You might find a copy of Pressman's "Switching Power Supply Design" in a university library. |
This is SMPS bible, any new power supply designer MUST TO READ IT :smash: It expensive, & not easy to find...
Who need this book just drop an email. |
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| golam |
Dear Tolik,
Good Book.I have read that Book online but could not download. What else Books on smps do you have in your possession?
Thanks. |
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| Tolik |
| quote: | | What else Books on smps do you have in your possession? |
Hi Golam,
Generally I`m going with appnotes from Unitrode, TI, Microchip, Magnetics & IRF. It`s free but awesome good source of knowledge. |
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