Design of 5v 40 Amp SMPS power supply

[piyushpandey]

Hi guys

I want to know the basics of power supply design and want to know the topics required for the design of the power supply of this level.

Specs are :

Input Voltage = 230 V AC.
Output voltage = 5V DC.
Output current = 40 A DC current.
Power = 200 Watt.


regards

 

[marce]

Start here:
http://www.compliance-club.com/keitharmstrong.aspx

 

[yassin.kraouch]

Start here:
http://www.compliance-club.com/keitharmstrong.aspx

you are advertising here ? the guy is asking for help not for advertising.

 

[marce]

No I am not advertising I was trying to help you, this is not a commercial site you log on for free and have access to lots of EMC information. You have to log to access the information.
You might want to read and get your fact right before you start accusing someone who has gone out of his way in the past to help people before you start your accusations.
The links are there because one of the biggest factors relating to SMPS design is understanding EMC and there are many links on that page related to good EMC practice.
I am disgusted with your attitude towards me and you accusations and to the rest of the forum, EMC UK is a well know free resource for EMC topics and has been referred to before by myself and probably others...
I quite often give up a lot of free time to find and compile answers for many who ask on here I have never been so insulted in my life by people who throw accusations yet cant be bothered to check things properly
Another active member lost.

 

[yassin.kraouch]

No I am not advertising I was trying to help you, this is not a commercial site you log on for free and have access to lots of EMC information. You have to log to access the information.
You might want to read and get your fact right before you start accusing someone who has gone out of his way in the past to help people before you start your accusations.
The links are there because one of the biggest factors relating to SMPS design is understanding EMC and there are many links on that page related to good EMC practice.
I am disgusted with your attitude towards me and you accusations and to the rest of the forum, EMC UK is a well know free resource for EMC topics and has been referred to before by myself and probably others...
I quite often give up a lot of free time to find and compile answers for many who ask on here I have never been so insulted in my life by people who throw accusations yet cant be bothered to check things properly
Another active member lost.

i don't understand why you need to write a long paragraph, i just asked if you are advertising, i do not see any insult in my post, sorry if you understood it as insult, it was not the intention, and i didn't accuse the rest of the forum, i don't know how you made this conclusion.
piyushpandey was asking for basic question how to design 5V, 40A power supply, so the question for me is clear, and the answer also should be clear for someone asking basic questions.

 

[marce]

My apologies, other factors also upset me as I don't really do frivolous posts and try to pass on some of the knowledge I have built up doing PCBs for 30+ years.
There is a reason why I sometimes don't post an elaborate reply, so that the question asker is hopefully prompted to do a bit of background research. Doing quite a few SMPS and other power supply layouts for some quite interesting and critical projects I was going to build up my replies as time allowed. In 2011/2012 Keith Armstrong did n excellent series of articles directly related to all switching circuits EMC problems, it was these I was looking for above but didn't have the time to dig them out so linked the general article page which is full of good advice.

For the OP.
How many layers are you allowed, what cost constraints etc. Is the input always going to be 230V. Time allowing I will have a look at previous designs I have worked on for controllers and external switching transistors.

 

[Warpspeed]

Hi guys

I want to know the basics of power supply design and want to know the topics required for the design of the power supply of this level.

A few years back it was just a case of designing suitable magnetics and hooking it up to a control circuit with a few power mosfets, some electrolytics, and a heat sink and getting it all to work.
It was all a lot easier back then.

These days, its more about design for EMC and knowing and understanding all the rules and regulations that need to be complied with, and how to jump through all the Government hoops to get compliance.

If this is for yourself, buying either a secondhand or Chinese 5v 40A supply on e-bay will save you both a lot of grief and money.

If this is for your employer for eventual commercial production, then fully understanding the EMC aspect must be the starting point for the whole exercise if its going to be a success.
Sad, but that is the reality these days.

 

[piyushpandey]

Hi guys

first of all very much sorry for the late reply.

and I would like to thanks marce and other who has replied to my this post and for the link which marce shared here.

That link is very precious link which I think would not be able to get easily via the google search.

but here I am elaborating little bit my question.

Actually what I want to know is that what are the various engineering terms used in the SMPS design. I want to study all of them in detail and also want to know that what role each term play in the design of the power supply so that I can design a power supply of any rating.

As pointed by marce he pointed to one of the term EMC which is quite critical in SMPS design, similarly I want to know other factors which are as important as the EMC in the SMPS design.

I hope I made myself pretty clear.

Thanks and regards.

 

[marce]

Not the best answer but I have zero time at the moment, but here is a list of documents in my SMPS folder. You can use the names to look on google at the documents, all are pretty relevant, but one in particular will be what you want.... The trouble is I cant remember which one, sorry.

Some will be irrelevant because I am trying to tidy up my documentation.....

 

[CataM]

A few years back it was just a case of designing suitable magnetics and hooking it up to a control circuit with a few power mosfets, some electrolytics, and a heat sink and getting it all to work.
It was all a lot easier back then.

Sad, but that is the reality these days.

This will sound veryy stupid, so apologize in advance.

Why it is not as simple as take the 230 V rms AC (~311 amplitude) (50 Hz) that come to your house and with some rectifiers and filters get a decent DC voltage?

 

[Warpspeed]

Why it is not as simple as take the 230 V rms AC (~311 amplitude) (50 Hz) that come to your house and with some rectifiers and filters get a decent DC voltage?

That method is commonly used within some equipment that is totally enclosed and of very low power.

One problem when not using a transformer, is that the dc output would not be isolated from the incoming mains supply, and that could pose an electrical safety hazard if the dc voltage is required to be made available externally.

Another problem of not using a step down transformer is it becomes very inefficient to generate low dc voltages that can supply a reasonably high current.

And yet another problem is that mains supply voltages vary widely in different parts of the world, and your circuit may not work very well if exported to different countries.

A lot of this is both sensible and fairly obvious, but was not until recent years written into actual law.

There are now a massive number of rules and regulations that must be both understood and complied with before you even start to design something for manufacture and sale.

 

[CataM]

These days, its more about design for EMC

fully understanding the EMC aspect must be the starting point for the whole exercise if its going to be a success.

Step down transformer is needed, but can not see why for this is needed EMC theory. A simple transformer will interfere the electromagnetic environment ?

 

[Warpspeed]

Step down transformer is needed, but can not see why for this is needed EMC theory. A simple transformer will interfere the electromagnetic environment ?

There are all kinds of funny rules now in force.

For example these commonly available dc wall packs used to have a transformer and a rectifier. The transformers are always made as small as possible, mainly for cost reasons, so there is minimal copper and iron.
As a result they always run warm, even under no load, and are very inefficient.

So the politicians decided (to save us all) to make these illegal in many countries.
So now we have the smaller more efficient switching power supply type.
Just one example of how the law has intruded into what you are now allowed to design and sell.

And as every appliance MUST comply with EMC regulations, those laws are not just about electrical interference, but electrical safety, and even energy efficiency is now included.

Its crazy !!

 

[marce]

EMC regulation and compliance is necessary....
As to power efficiency, again why waste energy if you don't have to...
No its not crazy.

- - - Updated - - -

Step down transformer is needed, but can not see why for this is needed EMC theory. A simple transformer will interfere the electromagnetic environment ?

I would suggest some more reading, a transformer interferes with its surroundings quite strongly and then there is noise from the rectifiers and charging pulses.......