50Vdc - 300Vdc to 15Vdc

[[email protected]]

Hi, i need to design a 15Vdc power supply from an input with a range of
50Vdc - 300Vdc. I have been looking for regulators like 7815 but the
max Vin of that regulators is 40V, another solution could be to convert
my input to 40V and after with the regulator, obtain 15V, thanks in
advance.

 

[John Woodgate]

Hi, i need to design a 15Vdc power supply from an input with a range of
50Vdc - 300Vdc. I have been looking for regulators like 7815 but the
max Vin of that regulators is 40V, another solution could be to convert
my input to 40V and after with the regulator, obtain 15V, thanks in
advance.

Once again, HOW MUCH CURRENT? That profoundly affect your choice of
techniques.

 

[[email protected]]

Hi, i need to design a 15Vdc power supply from an input with a range of
50Vdc - 300Vdc. I have been looking for regulators like 7815 but the
max Vin of that regulators is 40V, another solution could be to convert
my input to 40V and after with the regulator, obtain 15V, thanks in
advance.

You can buy this from any broad-line distributor - most small universal
switching power supplies just diode rectify mains AC into a reservoir
capacitor, and use a switching regulator to get 15V DC (or 5V or 3,3V
as required). At least some of them let you by-pass the rectifier.

You need a decent text-book on switching regulator design - I've got
Abraham I. Pressman's "Switching Power Supply Design" ISBN: 0070522367
which is still in stock at Amazon nine years after it was first
published.

 

[[email protected]]

John Woodgate ha escrito:

Once again, HOW MUCH CURRENT? That profoundly affect your choice of
techniques.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
2006 is YMMVI- Your mileage may vary immensely.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Hi, thanks for your fast asnwer, the current is ver low, the maximum it
could be 1 Amp, i have been looking for schemes to obtain the 15v but
the only ones that i have seen have and input not bigger than 40v.


[email protected] ha escrito:

You can buy this from any broad-line distributor - most small universal
switching power supplies just diode rectify mains AC into a reservoir
capacitor, and use a switching regulator to get 15V DC (or 5V or 3,3V
as required). At least some of them let you by-pass the rectifier.

You need a decent text-book on switching regulator design - I've got
Abraham I. Pressman's "Switching Power Supply Design" ISBN: 0070522367
which is still in stock at Amazon nine years after it was first
published.

Do you think that my problem is difficult to resolve? if is difficult
to do i'll desist, and i will buy something that do it, i have seen
some schemes that converts 40v to 15v using a zener and some
capacitors, but i'm not sure if i can do the same with a input variable
and with a maximum value of 300v.

Thanks for all your response.

 

[John Woodgate]

Do you think that my problem is difficult to resolve?

For you to do it yourself, yes. 300 V in, 15 V at 1 A out, that's 285 W
that's go to go somewhere in a linear system. You need a switch-mode
system (even though I don't like them - nasty complicated things). And
you don't stand a chance of designing one with such a wide input voltage
range. That requires a very skilled designer.

 

[John Fields]

Do you think that my problem is difficult to resolve? if is difficult
to do i'll desist, and i will buy something that do it, i have seen
some schemes that converts 40v to 15v using a zener and some
capacitors, but i'm not sure if i can do the same with a input variable
and with a maximum value of 300v.

---
If you want a 15 volt output which can supply 1 ampere into a load,
then that means that if you place a linear regulator between the
300V source and the 15V load, the regulator must drop the voltage
from 300 to 15, while allowing 1A to pass into the load. That means
the regulator must dissipate:


Vin - Vout 285V
P = ------------ = ------ = 285 watts
I 1A

Find a DC to DC converter which will do what you want and you'll be
miles ahead than if you tried to design it yourself. Perhaps light
years, even.

 

[[email protected]]

John Woodgate ha escrito:


Hi, thanks for your fast asnwer, the current is very low, the maximum it
could be 1 Amp, i have been looking for schemes to obtain the 15v but
the only ones that i have seen have and input not bigger than 40v.


[email protected] ha escrito:


Do you think that my problem is difficult to resolve? if is difficult
to do i'll desist, and i will buy something that do it, i have seen
some schemes that converts 40v to 15v using a zener and some
capacitors, but i'm not sure if i can do the same with a input variable
and with a maximum value of 300v.

1A at 15V from a 300V source isn't a low current. If you wanted to use
a linear regulator. you'd have to be able to dissipate 285W in the
series element. This is difficult.

A switching regulator can offer efficienies of 95% and higher, which
would mean that you would need to dissipate less than a watt in your
switching series element, which is a lot easier to manage.

Switching regulators are relatively tricky, but - as I said - they are
a mass market product, so you should be able to buy an integrated
circuit that does most of the work. I've not worked in the area, but
Supertext does appear to have that kind of part

http://www.supertex.com/pdf/datasheets/HV9120.pdf

Here's hopng that we can get some advice from somebody who has worked
on this sort of circuit.

 

[martin griffith]

On 2 Aug 2006 04:55:25 -0700, in sci.electronics.design

Hi, i need to design a 15Vdc power supply from an input with a range of
50Vdc - 300Vdc. I have been looking for regulators like 7815 but the
max Vin of that regulators is 40V, another solution could be to convert
my input to 40V and after with the regulator, obtain 15V, thanks in
advance.

try the viper from st.com


martin

 

[[email protected]]

Hi, thanks for all your answers, i explain for what i'm going to use
the ciruit, sorry for not explain before. The circuit is needed for an
inverter, the inverter uses a power supply that is going to be in a
range of 50v to 300v, and to drive the igbt's i use a ir2110, that
needs a 15v supply reference to the same ground than the 300v, i'm not
going to make the 300 v power supply, i will buy one, and my idea is
connect the power supply to the inverter and using a dc converter
obtain my 15v to the ir2110, another solution is from the 220Vac source
of the 300v power supply, obatin the 15V using a transformer and a 7815
or something similar, this is much easier but i'm not sure if the 15v
that i obtain from the 7815 are reference to the same ground than the
300v. I said that i need to obtain a 1 amp current, i think that the
two ir2110 (there are 4 igbt's), aren't going to consume that current,
and it will be lower. I hope that everybody understand what i mean.


[email protected] ha escrito:

1A at 15V from a 300V source isn't a low current. If you wanted to use
a linear regulator. you'd have to be able to dissipate 285W in the
series element. This is difficult.

A switching regulator can offer efficienies of 95% and higher, which
would mean that you would need to dissipate less than a watt in your
switching series element, which is a lot easier to manage.

Switching regulators are relatively tricky, but - as I said - they are
a mass market product, so you should be able to buy an integrated
circuit that does most of the work. I've not worked in the area, but
Supertext does appear to have that kind of part

http://www.supertex.com/pdf/datasheets/HV9120.pdf

Here's hopng that we can get some advice from somebody who has worked
on this sort of circuit.

Hi, thanks for your answer, that circuit is ideal for my case, and i
have been looking for some applications, and i have found this
http://www.circuitrydesigns.com/dc/1209/flyback-converters.htm, and is
not a difficult circuit, and i think i could do it by myself. Thanks
for the help.


martin griffith ha escrito:

On 2 Aug 2006 04:55:25 -0700, in sci.electronics.design

try the viper from st.com


martin

Thanks for your answer martin, i have been looking for the viper, and
it's another good solution, the viper support a 265Vac input that in dc
is 375, i think if finally i use the dc converter, i will use the
viper, st has excellent information about them.

Finally, thanks again for all your answers

 

[[email protected]]

[email protected] wrote:

Finally, thanks again for all your answers

Our pleasure. It often takes longer to get the right advice, and we
don't always get the original poster coming back and saying what they
are going to do, though we really do appreciate it.

 

[Ken Smith]

For you to do it yourself, yes. 300 V in, 15 V at 1 A out, that's 285 W
that's go to go somewhere in a linear system. You need a switch-mode
system (even though I don't like them - nasty complicated things)

He could use a water cooled linear. It would be easier for the unskilled
in the mysteries of switchers.


How well regulated does the 15V need to be? Do you have the room for an
assembly the size of a 2 drawer filing cabinet?

 

[[email protected]]

He could use a water cooled linear. It would be easier for the unskilled
in the mysteries of switchers.

Hell. He could use an air-colled linear, if he split the current path
into a sufficiently large number of parallel elements, but to a large
extend that would be swapping the mysteries of heat dissipation for the
mysteries of switchers - heat sinks don't perhaps offer the same
breadth of opportunity to get things wrong that you can find in
switchers, but I blew up my share of TIP3055 power transistors working
out how to get rid of 800W into a water-cooled heat-sink after making
exactly that choice back in 1972.

 

[[email protected]]

Ken Smith ha escrito:

He could use a water cooled linear. It would be easier for the unskilled
in the mysteries of switchers.


How well regulated does the 15V need to be? Do you have the room for an
assembly the size of a 2 drawer filing cabinet?

Hi, thakns for your answer, the 15v according to the ir2110 datahset,
it must be between 10V and 20V, and yes i got a room with that size.

I think that i'm killing butterflies with boms, this is a common
expression here in my country spain, and i hope that everybody
understan what i mean, i only need a 15V supply for my ir2110, i got a
300 v power supply for the inverter, and i need to get 15v reference to
the same ground that the 300v, the 300v power supply is connected to
the power line (220Vac), if i get my 15v from the 220Vac using a
transformer and a 7815, the 15V that i get, will be 15v reference to
the 300v ground?, i hope that everybody understand me, sorry if my
english sounds a little bad, thanks again for all your answers.

 

[[email protected]]

Ken Smith ha escrito:

- Ocultar texto de la cita -
- Mostrar texto de la cita -

He could use a water cooled linear. It would be easier for the unskilled
in the mysteries of switchers.

How well regulated does the 15V need to be? Do you have the room for an
assembly the size of a 2 drawer filing cabinet?

Hi, thakns for your answer, the 15v according to the ir2110 datahset,
it must be between 10V and 20V, and yes i got a room with that size.

I think that i'm killing butterflies with boms, this is a common
expression here in my country spain, and i hope that everybody
understan what i mean, i only need a 15V supply for my ir2110, i got a
300 v power supply for the inverter, and i need to get 15v reference to
the same ground that the 300v, the 300v power supply is connected to
the power line (220Vac), if i get my 15v from the 220Vac using a
transformer and a 7815, the 15V that i get, will be 15v reference to
the 300v ground?, i hope that everybody understand me, sorry if my
english sounds a little bad, thanks again for all your answers.

I have looking for ac/dc converters and i have seen this
http://es.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU=1005643&N=401,
that circuit adapts perfect to my case, and is not very expensive
30€.

 

[John Woodgate]

if i get my 15v from the 220Vac using a transformer and a 7815, the 15V
that i get, will be 15v reference to the 300v ground?,

It will if you connect the ground sides of the 15 V DC and the 300 V
together. I'm really worried that if you have to ask that question, you
are trying to work a long way ahead of your technical insight. I think
you need local assistance, not help from 1000-plus kilometres away.

 

[[email protected]]

John Woodgate ha escrito:

It will if you connect the ground sides of the 15 V DC and the 300 V
together. I'm really worried that if you have to ask that question, you
are trying to work a long way ahead of your technical insight. I think
you need local assistance, not help from 1000-plus kilometres away.
--
OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
2006 is YMMVI- Your mileage may vary immensely.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Of course it will if i connect both ground sides, but my question is i
connect the 300V power supply, and with the same connector, i connect
to the transformer and the 7815, then the grounds will be the same? i
suppose that yes, but i preffer to ensure me.

 

[John Woodgate]

Of course it will if i connect both ground sides, but my question is i
connect the 300V power supply, and with the same connector, i connect
to the transformer and the 7815, then the grounds will be the same? i
suppose that yes, but i preffer to ensure me.

I'm sorry to have to emphasise the point, but your response is nonsense
and you need local help.

 

[vasile]

understan what i mean, i only need a 15V supply for my ir2110, i got a
300 v power supply for the inverter, and i need to get 15v reference to
the same ground that the 300v, the 300v power supply is connected to
the power line (220Vac), if i get my 15v from the 220Vac using a
transformer and a 7815, the 15V that i get, will be 15v reference to
the 300v ground?, i hope that everybody understand me,

It's not necessary to be english to understand your problem.

The ground is just a name for a wire. Usualy the ground coud be
connected to the earth potential (called also protective ground) but
is not allways necessary
So, you may use without any fear a different power supply from 220V ac
(with transformer, rectifier, filter and a 15V stabiliser) and connect
the "-15V wire" named say "local 15V ground " with your 300V DC
"ground" wire.

In that way you have a common ground and a +15V for your driver. The
transformer used for this power supply must met insulation requirements
(at least 1000V dielectric isolation between primary and secondary) and
if indeed you need 15V/1A, the 7815 must be a 3A TO3 package mounted on
the heatsink because it need at least +4V more than 15Vdc (so it will
dissipate at least 4V*1A = 4W at minimum main value and much more when
the main voltage is at maximum value (the power main supply could be
220V -15% +10%)

greetings,
Vasile

 

[jasen]

Hi, i need to design a 15Vdc power supply from an input with a range of
50Vdc - 300Vdc. I have been looking for regulators like 7815 but the
max Vin of that regulators is 40V, another solution could be to convert
my input to 40V and after with the regulator, obtain 15V, thanks in
advance.

sounds like some sort of "buck converter" would fit the bill

google for "switched mode" "buck converter" and "design" and you should get
a few leads.

Bye.
Jasen

 

[jasen]

Hi, thanks for all your answers, i explain for what i'm going to use
the ciruit, sorry for not explain before. The circuit is needed for an
inverter, the inverter uses a power supply that is going to be in a
range of 50v to 300v, and to drive the igbt's i use a ir2110, that
needs a 15v supply reference to the same ground than the 300v, i'm not
going to make the 300 v power supply, i will buy one, and my idea is
connect the power supply to the inverter and using a dc converter
obtain my 15v to the ir2110, another solution is from the 220Vac source
of the 300v power supply, obatin the 15V using a transformer and a 7815
or something similar, this is much easier but i'm not sure if the 15v
that i obtain from the 7815 are reference to the same ground than the
300v. I said that i need to obtain a 1 amp current, i think that the
two ir2110 (there are 4 igbt's), aren't going to consume that current,
and it will be lower. I hope that everybody understand what i mean.

if it's from a transformer you can typically reference it to any one
point you wish. with a DC-DC converter you typically end up with the
same ground as the supply.

The DC-DC convertter sounds like more fun, but using a prefabricated 15V
supply will be easier.

Bye.
Jasen