Making a 2 Volt 400 Amp bridge rectifier?

B

BoyntonStu

Guest
The 400CNQ center tap, high current, Schottky rectifier
module series has been optimized for very low forward
voltage drop, with moderate leakage. The proprietary barrier
technology allows for reliable operation up to 150 °C junction
temperature.

The cathode base is common.

How do you use 4 of these with respect to heat sink mounting and
electrical isolation?
 
BoyntonStu wrote:
The 400CNQ center tap, high current, Schottky rectifier
module series has been optimized for very low forward
voltage drop, with moderate leakage. The proprietary barrier
technology allows for reliable operation up to 150 °C junction
temperature.

The cathode base is common.

How do you use 4 of these with respect to heat sink mounting and
electrical isolation?
Click to expand...
That part is not normally intended to be used as part of a
bridge, but for a half bridge (center tap of a winding as
the negative output, common cathode as positive output)
rectifier. I also know of no standard way to isolate the
common cathode mounting bar from the heat sink. If I had 4
of these and had to make a bridge, I would connect each pair
of diodes in parallel (use each unit as one rectifier) and
mount them on 4 electrically isolated heat sinks.


--
Regards,

John Popelish
 
BoyntonStu wrote:

4 isolated heat sinks is a reasonable solution.

A fan wouldn't hurt.
Click to expand...
That depends on how much current you push through those 400
amp rated diodes and how large the heat sinks are.

Any Shottkey 400 Amp bridges available for less than a tank of gas?
Click to expand...
Not to my knowledge.

Or a better way?
Click to expand...
Look for doubler configuration diodes (connected in series,
cathode to anode), instead of common cathode. Two of those
can be used to make a bridge by connecting the AC to the
common nodes and tying the cathode ends together as positive
output and anodes together as negative output. Only two
isolated heat sinks needed.

I.e. (though not a Schottky:
http://cgi.ebay.com/1-UNIT-P-N-TDM30012D-BY-MICROSEMI-Dual-Diode-Doubler_W0QQitemZ370044891657

--
Regards,

John Popelish
 
John Popelish wrote:

Look for doubler configuration diodes (connected in series, cathode to
anode), instead of common cathode. Two of those can be used to make a
bridge by connecting the AC to the common nodes and tying the cathode
ends together as positive output and anodes together as negative
output. Only two isolated heat sinks needed.

I.e. (though not a Schottky:
http://cgi.ebay.com/1-UNIT-P-N-TDM30012D-BY-MICROSEMI-Dual-Diode-Doubler_W0QQitemZ370044891657
Click to expand...
Here is a better example, and one with an isolated mount, so
only one heat sink can be used:
http://www.irf.com/product-info/datasheets/data/400dmq035.pdf

Good luck finding two of them for less than $50.

--
Regards,

John Popelish
 
BoyntonStu wrote:

At 400 Amps I believe that the power dissipation would be too much in
a non-Shottkey rectifier.
Click to expand...
I agree. I was not recommending that device, just using it
as an example of the doubler configuration.

Also, the forward voltage drop is a major consideration at such low
voltages.
Click to expand...
No kidding!

Also, my intention is to supply 1-1/2 Volts DC at 400 Amps and I would
need to wind additional high current carrying cables around the
xformer core to make the output higher.
Click to expand...
Have you considered winding a center tapped output so you
can use just two diodes (or your original part)? At this
voltage and current, synchronous rectifiers made of large
MOSFETs with a separate gate drive winding might be a lot
better.

What kind and value smoothing cap would you recommend and ditto
bleeder resistor?
Click to expand...
What is the frequency? An inductor filter may work better.
--
Regards,

John Popelish
 
On Aug 8, 9:46 am, John Popelish <jpopel...@rica.net> wrote:
BoyntonStu wrote:
The 400CNQ center tap, high current, Schottky rectifier
module series has been optimized for very low forward
voltage drop, with moderate leakage. The proprietary barrier
technology allows for reliable operation up to 150 °C junction
temperature.

The cathode base is common.

How do you use 4 of these with respect to heat sink mounting and
electrical isolation?

That part is not normally intended to be used as part of a
bridge, but for a half bridge (center tap of a winding as
the negative output, common cathode as positive output)
rectifier. I also know of no standard way to isolate the
common cathode mounting bar from the heat sink. If I had 4
of these and had to make a bridge, I would connect each pair
of diodes in parallel (use each unit as one rectifier) and
mount them on 4 electrically isolated heat sinks.

--
Regards,

John Popelish
Click to expand...
John,

4 isolated heat sinks is a reasonable solution.

A fan wouldn't hurt.

Any Shottkey 400 Amp bridges available for less than a tank of gas?

Or a better way?

BoyntonStu
 
On Aug 8, 10:35 am, John Popelish <jpopel...@rica.net> wrote:
BoyntonStu wrote:
4 isolated heat sinks is a reasonable solution.

A fan wouldn't hurt.

That depends on how much current you push through those 400
amp rated diodes and how large the heat sinks are.

Any Shottkey 400 Amp bridges available for less than a tank of gas?

Not to my knowledge.

Or a better way?

Look for doubler configuration diodes (connected in series,
cathode to anode), instead of common cathode. Two of those
can be used to make a bridge by connecting the AC to the
common nodes and tying the cathode ends together as positive
output and anodes together as negative output. Only two
isolated heat sinks needed.

I.e. (though not a Schottky:http://cgi.ebay.com/1-UNIT-P-N-TDM30012D-BY-MICROSEMI-Dual-Diode-Doub...

--
Regards,

John Popelish
Click to expand...
John,

At 400 Amps I believe that the power dissipation would be too much in
a non-Shottkey rectifier.

Also, the forward voltage drop is a major consideration at such low
voltages.

Also, my intention is to supply 1-1/2 Volts DC at 400 Amps and I would
need to wind additional high current carrying cables around the
xformer core to make the output higher.

What kind and value smoothing cap would you recommend and ditto
bleeder resistor?
 
BoyntonStu wrote:

It's for electrolysis. Frequency?
Click to expand...
That you are rectifying. You didn't say, up till now if the
transformer is a line frequency device or the output of a
switching supply. I'm guessing line frequency.

For electrolysis, an inductor filter is probably better than
a capacitor, if one is needed, at all. It will lower the
average output voltage, but load the rectifiers and
transformer more efficiently.

--
Regards,

John Popelish
 
On Aug 8, 11:01 am, John Popelish <jpopel...@rica.net> wrote:
BoyntonStu wrote:
At 400 Amps I believe that the power dissipation would be too much in
a non-Shottkey rectifier.

I agree. I was not recommending that device, just using it
as an example of the doubler configuration.

Also, the forward voltage drop is a major consideration at such low
voltages.

No kidding!

Also, my intention is to supply 1-1/2 Volts DC at 400 Amps and I would
need to wind additional high current carrying cables around the
xformer core to make the output higher.

Have you considered winding a center tapped output so you
can use just two diodes (or your original part)? At this
voltage and current, synchronous rectifiers made of large
MOSFETs with a separate gate drive winding might be a lot
better.

What kind and value smoothing cap would you recommend and ditto
bleeder resistor?

What is the frequency? An inductor filter may work better.
--
Regards,

John Popelish
Click to expand...

What is the frequency? An inductor filter may work better.
Click to expand...
It's for electrolysis. Frequency?

Thanks
 
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