dc/dc converter ckt...

[John Larkin]

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1



--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[bitrex]

On 5/26/2022 8:16 PM, John Larkin wrote:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Maybe an appropriately-selected ferrite bead for the gates but perhaps
not a gate resistor or anything elaborate for the LT4444, looks like
they figure their adaptive shoot-thru protection can prevent any
misbehavior & that kind of fancy is what you pay the LTC device price
for I suppose.

Looks like just a fat trace is what they recommend.

 

[John S]

On 5/26/2022 7:16 PM, John Larkin wrote:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Oh. So you don\'t want to buy one or need help. You just feel compelled
to tell us about it, right?

 

[server]

On Thu, 26 May 2022 20:08:25 -0500, John S <Sophi.2@invalid.org>
wrote:

On 5/26/2022 7:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Oh. So you don\'t want to buy one or need help. You just feel compelled
to tell us about it, right?

It\'s an electronic design discussion group.

Design something. Discuss it. Or whine. Whatever you\'re best at.





--

Anybody can count to one.

- Robert Widlar

 

[server]

On Thu, 26 May 2022 21:07:57 -0400, bitrex <user@example.net> wrote:

On 5/26/2022 8:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1




Maybe an appropriately-selected ferrite bead for the gates but perhaps
not a gate resistor or anything elaborate for the LT4444, looks like
they figure their adaptive shoot-thru protection can prevent any
misbehavior & that kind of fancy is what you pay the LTC device price
for I suppose.

The LTC4444 is about $2.80. That\'s in the noise floor for this board.

The three half-bridges are more voltage, so need the UCC27712. It\'s
more like $1 so I may as well use it everywhere.

Looks like just a fat trace is what they recommend.

Gate resistors might be prudent, stuffed as 0 ohms initially. Could be
a resistor or bead if needed.

I might also put schottky diodes across the fets, in case the
substrate diodes get weird. Excess caution in both cases.



--

Anybody can count to one.

- Robert Widlar

 

[server]

John S <Sophi.2@invalid.org> wrote in
news:t6p8ag$iuu$2@dont-email.me:

On 5/26/2022 7:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I need
a roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts,
surface mount, under a cubic inch. They have a 4t tapped primary
and the two secondaries are available with 4, 5, 6, 7, or 8 turns
each. That has a lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=
1

Oh. So you don\'t want to buy one or need help. You just feel
compelled to tell us about it, right?

Pre fashioned, vertically mounted POL devices have been massaged
out pretty good. No need to try to design your own power source if
the pros already did the hard works for you and offer a far less
expensive solution than spending your own time trying to fashion your
own device. And most folks doing that examine and copy features from
the big boys as well. A bit of a cheat.

 

[server]

jlarkin@highlandsniptechnology.com wrote in
news:2la09ht44t87nlhccjm2660suj06t91gp7@4ax.com:

On Thu, 26 May 2022 21:07:57 -0400, bitrex <user@example.net
wrote:

On 5/26/2022 8:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I
need a roughly +-60 volt floating power supply. It will feed
three PWM half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts,
surface mount, under a cubic inch. They have a 4t tapped primary
and the two secondaries are available with 4, 5, 6, 7, or 8
turns each. That has a lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw
=1




Maybe an appropriately-selected ferrite bead for the gates but
perhaps not a gate resistor or anything elaborate for the LT4444,
looks like they figure their adaptive shoot-thru protection can
prevent any misbehavior & that kind of fancy is what you pay the
LTC device price for I suppose.

The LTC4444 is about $2.80. That\'s in the noise floor for this
board.

The three half-bridges are more voltage, so need the UCC27712.
It\'s more like $1 so I may as well use it everywhere.


Looks like just a fat trace is what they recommend.

Gate resistors might be prudent, stuffed as 0 ohms initially.
Could be a resistor or bead if needed.

I might also put schottky diodes across the fets, in case the
substrate diodes get weird. Excess caution in both cases.

For the primary, build a trough on the PCB where you then add a nice
Silver Plated Copper wire, or get a custom wire formed and stamped to
lay in the trough. Done. Your primary is of a large capacity wire
now, instead of a circuit trace. Then make a nice 0.032 secondary
PCB to sit under your core element. The is for the planar
transformer.

I think we used Transzorbs and beads on the FET leads.

 

[Jan Panteltje]

On a sunny day (Thu, 26 May 2022 17:16:56 -0700) it happened John Larkin
<jlarkin@highland_atwork_technology.com> wrote in
<uh509h9ki5momgqptatnult0fnkagcf7e8@4ax.com>:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Interesting circuit.
In the long ago past I used zeners between source and gate to protect against drain-gate spike injection.
Dunno much about this driver chip..
The zeners however caused oscillations to occur at many MHz, a few nF caps between drain and source killed that.
Scope the thing! Maybe some gate resistors too?

 

[piglet]

On 27/05/2022 1:16 am, John Larkin wrote:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Neat transformer! How much do they weigh? I\'d be wary of relying just on
surface mount pads on anything over a couple grams in case the unit gets
dropped one day.

piglet

 

[legg]

On Thu, 26 May 2022 17:16:56 -0700, John Larkin
<jlarkin@highland_atwork_technology.com> wrote:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Take care. Chances are, core loss estimates are for a regulated
system with \'48V\' input. For straight DC-DC unregulated, your
flux swings will be double the typical application for 48V \'primary\',
and triple for a 60V \'primary\' - core losses scale with a positive
exponent greater than one.

You might make this up due to lower current and crest factor in the
copper, but . . .

RL

 

[server]

On Thu, 26 May 2022 19:08:21 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Thu, 26 May 2022 21:07:57 -0400, bitrex <user@example.net> wrote:

On 5/26/2022 8:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1




Maybe an appropriately-selected ferrite bead for the gates but perhaps
not a gate resistor or anything elaborate for the LT4444, looks like
they figure their adaptive shoot-thru protection can prevent any
misbehavior & that kind of fancy is what you pay the LTC device price
for I suppose.

The LTC4444 is about $2.80. That\'s in the noise floor for this board.

The three half-bridges are more voltage, so need the UCC27712. It\'s
more like $1 so I may as well use it everywhere.


Looks like just a fat trace is what they recommend.

Gate resistors might be prudent, stuffed as 0 ohms initially. Could be
a resistor or bead if needed.

I might also put schottky diodes across the fets, in case the
substrate diodes get weird. Excess caution in both cases.

Take a look at the UCC27712 data sheet, fig 44. It\'s absolutely
decorated with parts.

With 150 ns of anti-shoot delay, why all that gate junk?

The LTC works fine without all that stuff. 98 more parts if I use the
TI as shown on my board.



--

Anybody can count to one.

- Robert Widlar

 

[server]

On Fri, 27 May 2022 03:55:04 -0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

jlarkin@highlandsniptechnology.com wrote in
news:2la09ht44t87nlhccjm2660suj06t91gp7@4ax.com:

On Thu, 26 May 2022 21:07:57 -0400, bitrex <user@example.net
wrote:

On 5/26/2022 8:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I
need a roughly +-60 volt floating power supply. It will feed
three PWM half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts,
surface mount, under a cubic inch. They have a 4t tapped primary
and the two secondaries are available with 4, 5, 6, 7, or 8
turns each. That has a lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw
=1




Maybe an appropriately-selected ferrite bead for the gates but
perhaps not a gate resistor or anything elaborate for the LT4444,
looks like they figure their adaptive shoot-thru protection can
prevent any misbehavior & that kind of fancy is what you pay the
LTC device price for I suppose.

The LTC4444 is about $2.80. That\'s in the noise floor for this
board.

The three half-bridges are more voltage, so need the UCC27712.
It\'s more like $1 so I may as well use it everywhere.


Looks like just a fat trace is what they recommend.

Gate resistors might be prudent, stuffed as 0 ohms initially.
Could be a resistor or bead if needed.

I might also put schottky diodes across the fets, in case the
substrate diodes get weird. Excess caution in both cases.




For the primary, build a trough on the PCB where you then add a nice
Silver Plated Copper wire, or get a custom wire formed and stamped to
lay in the trough. Done. Your primary is of a large capacity wire
now, instead of a circuit trace. Then make a nice 0.032 secondary
PCB to sit under your core element. The is for the planar
transformer.

The Coilcraft is stock and is pick-and-place. That\'s sure easy.

I think we used Transzorbs and beads on the FET leads.

--

Anybody can count to one.

- Robert Widlar

 

[Dimiter_Popoff]

On 5/27/2022 3:16, John Larkin wrote:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

The transformer certainly looks very interesting, thanks for posting.

I don\'t check on that sort of products frequently enough (not being in
high quantities and being battle hardened by winding in house our
5kV transformers, recently there was a hiccup running out of 0.07mm
wire... one of the attempts to get new supply ended me up with about
100-200 grams of.... 130 Ohm/meter 0.07 wire, noticed it after I
got home .
I\'ll explore these now though.

 

[John Larkin]

On Fri, 27 May 2022 03:48:29 -0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

John S <Sophi.2@invalid.org> wrote in
news:t6p8ag$iuu$2@dont-email.me:

On 5/26/2022 7:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I need
a roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts,
surface mount, under a cubic inch. They have a 4t tapped primary
and the two secondaries are available with 4, 5, 6, 7, or 8 turns
each. That has a lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=
1

Oh. So you don\'t want to buy one or need help. You just feel
compelled to tell us about it, right?



Pre fashioned, vertically mounted POL devices have been massaged
out pretty good. No need to try to design your own power source if
the pros already did the hard works for you and offer a far less
expensive solution than spending your own time trying to fashion your
own device. And most folks doing that examine and copy features from
the big boys as well. A bit of a cheat.

Where would I buy a 48v to +-60 volt isolated 200 watt dc/dc
converter? What would that cost?

My circuit will cost maybe $20. Besides, designing things is what I
do.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Larkin]

On Fri, 27 May 2022 05:27:58 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Thu, 26 May 2022 17:16:56 -0700) it happened John Larkin
jlarkin@highland_atwork_technology.com> wrote in
uh509h9ki5momgqptatnult0fnkagcf7e8@4ax.com>:

I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1

Interesting circuit.
In the long ago past I used zeners between source and gate to protect against drain-gate spike injection.
Dunno much about this driver chip..
The zeners however caused oscillations to occur at many MHz, a few nF caps between drain and source killed that.
Scope the thing! Maybe some gate resistors too?

I\'ve used the LTC4444 before and it works great with no gate
resistors. But in my output stages I need more voltage than it can
handle, hence the UCC27712 part.

Maybe I\'ll hack a proto board with the TI, to avoid surprises.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[John Larkin]

On Fri, 27 May 2022 09:57:03 +0100, piglet <erichpwagner@hotmail.com>
wrote:

On 27/05/2022 1:16 am, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I need a
roughly +-60 volt floating power supply. It will feed three PWM
half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts, surface
mount, under a cubic inch. They have a 4t tapped primary and the two
secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a
lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1




Neat transformer! How much do they weigh? I\'d be wary of relying just on
surface mount pads on anything over a couple grams in case the unit gets
dropped one day.

piglet

22 grams. It has 9 giant nail-head pins. Should be fine.

--

If a man will begin with certainties, he shall end with doubts,
but if he will be content to begin with doubts he shall end in certainties.
Francis Bacon

 

[server]

John Larkin <jlarkin@highland_atwork_technology.com> wrote in
news:h8429h9rsii1vur3sv33o2v8dd86omf94i@4ax.com:

On Fri, 27 May 2022 03:48:29 -0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

John S <Sophi.2@invalid.org> wrote in
news:t6p8ag$iuu$2@dont-email.me:

On 5/26/2022 7:16 PM, John Larkin wrote:
I\'m designing another 3-phase PM alternator simulator, and I
need a roughly +-60 volt floating power supply. It will feed
three PWM half-bridges to make the three output phases.

Here\'s my first pass at the dc/dc thing.

https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1

Those Coilcraft planar transformers are radical. 300 watts,
surface mount, under a cubic inch. They have a 4t tapped
primary and the two secondaries are available with 4, 5, 6, 7,
or 8 turns each. That has a lot of possibilities.

https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?ra
w= 1

Oh. So you don\'t want to buy one or need help. You just feel
compelled to tell us about it, right?



Pre fashioned, vertically mounted POL devices have been massaged
out pretty good. No need to try to design your own power source
if the pros already did the hard works for you and offer a far
less expensive solution than spending your own time trying to
fashion your own device. And most folks doing that examine and
copy features from the big boys as well. A bit of a cheat.

Where would I buy a 48v to +-60 volt isolated 200 watt dc/dc
converter? What would that cost?

I doubt there is much market for that in a POL scenario, which is
what I spoke on. A small PCB. Maybe I did not read the original
thread, because I would not have answered with POL had I seen the
numbers you gave.

48V to +-60V @ 200W is a little big for that form factor.

My circuit will cost maybe $20. Besides, designing things is what
I do.

DC to DC converters are things which power engineers spend years
massaging.

At a mere $20 outlay, I doubt you will get the DC power you desire.
PARD and other elements make it hard to get right the first time. If
noise is an issue with the circuit, you may have a hard time
providing that DC power cleanly in a one off first time doing it
design. And then there is the cubic inches of space you pack it all
into, and the operating efficiency numbers.

Lots of reasons to use the boys that have been doing it for
decades, especially if the input power requirements of the circuits
require it to be clean and free of noise throughout it load range.
Good luck.