13.8v (or 15V), 8A switching power supply

[BengBear]

Hi,
I wish to build a switching power supply, input - 230Vac, 50Hz, output - 13.8Vdc (or 15V) and 8 Amp, instead of the conventional linear power supply.

I am a new member and new to switching power supply.

Appreciate an applicable and 'simple' circuit for such type of power supply from any kind soul.

Regards

 

[mvs sarma]

www.powerint.com has simple and good devices like TINY and LNK series, please see the site and they have lot of application notes.
there are many others like ST Micro's viper50,

 

[petrv]

I think for such power you'd rather need the TOPSwitch family, TINY family is for much smaller power supplies.
But if you are new to switching power supplies I don't think this is a good project for a start, complicated and can be even dangerous. Better to start e.g. with a buck controller - look at National Semiconductor, ON Semiconductor ....

Petr

 

[BengBear]

Hi,
After reviewing viper, power int., it seems getting special type of transformer is rather inconvenient. ST L4970A may be a good option to convert 230Vac (rectifying 28Vdc), 50hz to (0 to 25Vdc and 10A). And this is fed into pin 9, Vin. The question is what current input.

Referring to some design options, it appears the input should be

V0 times I0 div by Vin (V0 and I0 are output voltage and current) which is
25x10/40 =6.25, convert this to rms current 6.25/1.414 = 4.42 Amp ac.
Hence transformer VA is 28 x 4.42 about 124VA.

As this is the first time I am using this type of switching regulator, welcome any one who has this experience to review and comment.

 

[mvs sarma]

Hi,
After reviewing viper, power int., it seems getting special type of transformer is rather inconvenient. ST L4970A may be a good option to convert 230Vac (rectifying 28Vdc), 50hz to (0 to 25Vdc and 10A). And this is fed into pin 9, Vin. The question is what current input.

Referring to some design options, it appears the input should be

V0 times I0 div by Vin (V0 and I0 are output voltage and current) which is
25x10/40 =6.25, convert this to rms current 6.25/1.414 = 4.42 Amp ac.
Hence transformer VA is 28 x 4.42 about 124VA.

As this is the first time I am using this type of switching regulator, welcome any one who has this experience to review and comment.

Do you mean to use a transformer at 230V to 20V and rectify and then use a non-isolated SMPS using L4970?
Even then you might need an inductor of good current carrying capacity, I believe. The transformer would again be bulky at the 50Hz point.

 

[BengBear]

Hi Sarma,
Went into power int (PI), design the circuit and forwarded to PI but they could not support transformer and inductor locally (Singapore), based on the design needs.

Search around and found L4970A a switching regulator. Attached is the design using L4970A and expanded my required output voltage and current supply from 7A to 10A.

Agree, base on this design the transformer needed would be bulky again, not so much as before using conventional transformer and rectifier without switching regulator.

If somebody in Singapore can supply those PI transformer and inductor, it would be most welcome.

 

[mvs sarma]

Hi Sarma,
Went into power int (PI), design the circuit and forwarded to PI but they could not support transformer and inductor locally (Singapore), based on the design needs.

Search around and found L4970A a switching regulator. Attached is the design using L4970A and expanded my required output voltage and current supply from 7A to 10A.

Agree, base on this design the transformer needed would be bulky again, not so much as before using conventional transformer and rectifier without switching regulator.

If somebody in Singapore can supply those PI transformer and inductor, it would be most welcome.

do you want 0 to 25 V variable supply?
If so please see the other site where audioguru has moderated a circuit to give upto 5 amps.

 

[Ubergeek63]

there are a number of companies now that supply some of those transformers.

Of course the daring could roll their own. I do tend to prefer planars myself, but it is not easy to cut good windings and most do not have access to thin PCB core for the primary windings. One thing to watch out for is the reflected voltage: you will have upto about 400V on the supply plus the output multiplied by the turns ratio to the FET.

 

[BengBear]

Hi Ubergeek63,
Mind giving me details of these companies providing those transformer as detail in attachment. Hope some soul or companies in Singapore who are willing to sell them.

 

[Ubergeek63]

**broken link removed**

https://www.coilcraft.com/pdfs/pl140.pdf

You generally will not find them in apps for AC line apps because most off the shelf units do not pass the safety isolation requirements. (5KV isolation is not easily to get in such a small package. While I have done it, there is not space for high isolation and high current)

 

[BengBear]

Hi Ubergeek63,
Visited ww2.pulseeng.com, Pulse Technitrol Company, and contacted its local administrator. All supports are out of town.

I am looking for a suitable Planar transformer and workable regulator and circuit to convert 230Vac to anything equal or more than 18Vdc, 10Amp.
Appreciate any recommendation.

 

[Ubergeek63]

you will never be able to walk into a store and get a 200W switching transformer or a 300VA (what you would need for 50-60Hz) transformer.

I can design the things, but they still have to be built. You either need to order from a company who makes them, where ever they may be, or order a 50Hz unit from someone who has them and pay the shipping.

 

[mvs sarma]

Hi Ubergeek63,
Visited ww2.pulseeng.com, Pulse Technitrol Company, and contacted its local administrator. All supports are out of town.

I am looking for a suitable Planar transformer and workable regulator and circuit to convert 230Vac to anything equal or more than 18Vdc, 10Amp.
Appreciate any recommendation.

I wonder, whether you really need a 8 amps rated charger at 13.8V?

What capacity batteries you wanted to us the charger for?

 

[BengBear]

It is for powering something else, not for charging.

There are standard off the shelf 250Watt Planar transformer, but I need a matching regulator and associated circuit, as Planar is new to me. Reason for going for planar is that it is compact and much lighter than a traditional transformer, rectifier and etc. As for pure switching power supply, special wound transformer is needed.

 

[mvs sarma]

It is for powering something else, not for charging.

There are standard off the shelf 250Watt Planar transformer, but I need a matching regulator and associated circuit, as Planar is new to me. Reason for going for planar is that it is compact and much lighter than a traditional transformer, rectifier and etc. As for pure switching power supply, special wound transformer is needed.

Perhaps your concept is right, if you source the L4970A, perhaps you can complete it. You may have to use a high power bridge rated 20 amps to safely deliver 8 amps.

Please see this pdf
https://www.electro-tech-online.com/custompdfs/2008/05/powsupply.pdf

 

[BengBear]

Yes, you are correct, L4970A can do the job, but again the transformer would be somewhere 100VA for a 18Vdc and 10Amp (I up the required output). This is like meeting the traditional power supply and the switching power supply half way.

Well, if I continue to have problem getting matching regulator IC versus the off the shelf planar supplied by Pulse Engineering or Technotrol company in Singapore, I may revert to L4970A.

Appreciate any kind soul could help.

 

[mvs sarma]

Yes, you are correct, L4970A can do the job, but again the transformer would be somewhere 100VA for a 18Vdc and 10Amp (I up the required output). This is like meeting the traditional power supply and the switching power supply half way.

Well, if I continue to have problem getting matching regulator IC versus the off the shelf planar supplied by Pulse Engineering or Technotrol company in Singapore, I may revert to L4970A.

Appreciate any kind soul could help.

I saw a SMPS for 13.8 V 40mps. He has packed the Ferrite tranformer using three ETD cores and combined them and wound over it. So a 150watt power supply would really need a ETD 34 size core.
Perhaps please see whether you can salvage a TV power supply and try to rewire the Ferrite transformer with suitable secondary winding. It would nearly meet your needs.

 

[BengBear]

Hi,
Attached the off the shelf planar transformer from Pulse Engineering.

Any kind soul could help match the regulator IC and circuit for these Planar models detailed in the attachments.

 

[Hero999]

I saw a SMPS for 13.8 V 40mps. He has packed the Ferrite tranformer using three ETD cores and combined them and wound over it. So a 150watt power supply would really need a ETD 34 size core.
Perhaps please see whether you can salvage a TV power supply and try to rewire the Ferrite transformer with suitable secondary winding. It would nearly meet your needs.

A 550W SMPs is nothing, I've seen datashseets for 5000W 48V SMPses before - we're thinking of buying one for a project at work.

 

[mvs sarma]

A 550W SMPs is nothing, I've seen datashseets for 5000W 48V SMPses before - we're thinking of buying one for a project at work.

oops
I typed wrongly 150 watts -- it should have been 550 watts.
Neither a normal TV SMPS core would do for this.

Yes Hero999, I too worked with 5KW SMPSs in the Indian Telecom scenario. We used to stalk 3 of them, one across each phase (230V 50Hz) and thus balance the load on public mains for a 300Amp 50V DC power needs of telecom switches in villages.