50Vdc - 300Vdc to 15Vdc

[Ken Smith]

Hell. He could use an air-colled linear, if he split the current path
into a sufficiently large number of parallel elements

I'd thought of it as breaking up the voltage drop into several or many
steps.

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.

800W is not merely twice as hard as 200W. At 200W you don't have to worry
so much about heating the room up.

 

[Ken Smith]

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.

Why don't you just go buy a 15V power supply that plugs in the wall?
It is likely to be the least costly option.

 

[[email protected]]

vasile ha escrito:

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

Hi, thanks for your answer and your nice explanation, so is this
correct? http://img461.imageshack.us/img461/2725/dibujo3pc3.png, if is
that correct my "problem" is resolved, i said problem with quotation
marks, because my problem was just with the meaning of ground, and
another thing i suppose that no but i preffer to ask, when the 300v
power supply varies, are there problems with the 15V?

For the transformer specification(1000v dielectric isolation) do i need
a special transformer or just the typical transformer has that
characteristic?, with typical i mean the transformer that you buy when
you go to the shop and you say a 220v-25v transformer. I said the 7815
just reffering to a linear regulator, if i need 1Amp, i will put the
heatsink. Thanks again for your answer.


Ken Smith ha escrito:

Why don't you just go buy a 15V power supply that plugs in the wall?
It is likely to be the least costly option.

Thanks for your answer. My problem is not getting the 15V, the problem
is if the 15v that i get with a power supply are also 15V reference to
the ground of the 300V power supply.

 

[[email protected]]

jasen ha escrito:

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

Hi, thanks for your answer, finally i will use the transformer is
easier, i will reffer the 15V ground to the 300V ground and that's all,
my problem was, that i wasn't very sure if i could do that, and yes,
the dc dc converter is more fun, and that's because i initially post
here asking about a dc dc converter, and finally thanks for your answer.

 

[[email protected]]

vasile ha escrito:

[email protected] wrote:

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

Hi, thanks for your answer and your nice explanation, so is this
correct? http://img109.imageshack.us/img109/3972/dibujo3ri6.png , if is
that correct my "problem" is resolved, i said problem with quotation
marks, because my problem was just with the meaning of ground, and
another thing i suppose that the answer is no but i preffer to ask,
when the 300v
power supply varies, are there problems with the 15V?

For the transformer specification(1000v dielectric isolation) do i need
a special transformer or just the typical transformer has that
characteristic?, with typical i mean the transformer that you buy when
you go to the shop and you say a 220v-25v transformer. I said the 7815
just reffering to a linear regulator, if i need 1Amp, i will put the
heatsink. Thanks again for your answer.

Ken Smith ha escrito:

Why don't you just go buy a 15V power supply that plugs in the wall?
It is likely to be the least costly option.

Thanks for your answer. My problem is not getting the 15V, the problem
is if the 15v that i get with a power supply are also 15V reference to
the ground of the 300V power supply.

 

[John Woodgate]

Hi, thanks for your answer and your nice explanation, so is this
correct? http://img461.imageshack.us/img461/2725/dibujo3pc3.png,

Very definitely NOT. You have the 220 V mains connected via the
rectifier to the 7815. You have left out the 220 V:15 V transformer!

 

[jasen]

For the transformer specification(1000v dielectric isolation) do i need
a special transformer or just the typical transformer has that
characteristic?, with typical i mean the transformer that you buy when
you go to the shop and you say a 220v-25v transformer.

I would expect 1000V or more to be typical. You should check.

Bye.
Jasen