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'3fase ac power generator'
1998\05\18@043355 by marcel

picon face
I am interested to do an project to generate 3 phase ac mains on a ship
on board there are
two dc generators dc 220 volts and battery's
an old tow boat from russia
siemens makes power bridge's igbt  10 to 50 amps 600 volts
i saw a design with 80553 pwm to control this bridge
did any body do research on this which pic could do the job
the bridge contains rectifier and 6 igbt transistors so one needs 6 pwm
out puts




Marcel

spam_OUTmarbelTakeThisOuTspamxs4all.nl

Amsterdam

1998\05\18@060458 by Janet and Carl McIver

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   I think a product already exists.  When one wants to control the speed
of a 3 phase induction motor, one either uses a very cumbersome antique
method that I won't bother to explain, or uses a frequency drive.  A
frequency drive, or freq drive for short, takes two or three phase AC,
converts it to DC, then through a very powerful and computer controlled
inverter, converts it back to AC, and can range the frequency from around 40
to 400 hz.  By directly driving the DC into the freq drive, you can program
the frequency, then go away.  There are also bells and whistles that can be
employed if you would like.  These drives can control motors and also
provide you clean three phase power.  There are many safety features built
in as well.
   Of course, if you want to build one of your own, then that is even more
fun!



SO.....Whaddya REALLY  want??

Carl R, McIver  (usually)
or the wife (Janet) and kids

Pull your head out to send me e-mail!
.....jncmcivryourheadKILLspamspam@spam@gte.net

{Original Message removed}

1998\05\18@144524 by Peter L. Peres

picon face
>10 to 50 A igbts

 You can only use those if they can sustain switching at over 20 kHz. For
extra large units 5 kHz or even 400 Hz will do (but you don't want to deal
with 100 kW range units).

>220 V DC

 To make 220 V AC out of this, you need to raise it to 315 V dc at least
(i.e. disregarding losses, more like 350 to allow for some headroom when
switching and losses in diodes and chokes). You can't apply 220 DC to the
switching bridge and get 220 V AC from it because you can't reach the
required peak voltage like this. And you need more like 6 'H' switches to
drive such a thing (minimum 4).

>3 phase

 Concentrate on 1 phase, then add more as you go. There is no need to
complicate yourself from now. The electronic generation of 3 phases is so
much like 1 phase that the only thing really required on the controller
side is extra ROM to store the larger code table...

 imho, you will need to do some real good figuring on the output filter
that will make the high frequency switching waveform into 50 Hz sine. An
iron transformer (3 separate primaries, one 3~ secondary star/triangle)
will save the day if you can afford the weight. This also obviates the
need for a voltage raiser from 220 -> 315 V DC.

 Note that if you do NOT use a transformer, then you will have a
triangle-type output and will not be able to ground the center point (and
no star center in any load, which most motor and heating controllers do
not like at all, being compelled to use 380 V 3~ only).  The center of the
transformed 'triangle' will float at 158 V DC above the ground (i.e. - of
220 V DC).

 Looks like a serious project to me... probably not worth the effort for
one off. BTW I think that I heard of rotary converters (ancient). They are
made of a special motor running at 220 V (or whatever) and extra windings
on it that give the 3-phase for the load. Maybe you can obtain one of
these 2nd hand from where the tug comes...

Peter (plpspamKILLspamnospam.actcom.co.il)

1998\05\19@145054 by n M. Ranguelov

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Hi !


I have not done much projects for power transverters, but here
are my 2 cents:


Peter L. Peres wrote:
>
> >10 to 50 A igbts
>
>   You can only use those if they can sustain switching at over 20 kHz. For
> extra large units 5 kHz or even 400 Hz will do (but you don't want to deal
> with 100 kW range units).

Texas Instruments have nice aplication reports on controlling motors of
different types with their DSPs. Maybe you cabn find an algorithm
suitable
for implementing on a pic.

{Quote hidden}

IIRC Microchip has an 'Reference Design' on their page of an UPS (
uninteruptable
Power supply) where they do basicly the same for 1 Phase with a PIC.

Maybe you can employ some 'magic sinewave's ' as mentionet on this list
somtime last year ...


St.

1998\05\19@145503 by Morgan Olsson

picon face
...
>  Note that if you do NOT use a transformer, then you will have a
>triangle-type output and will not be able to ground the center point
...
I have distant plans of a small wind power plant.
I have been thinking about a 400V 3-phase generator like this:
DC input is +340VDC, GND/Neutral, and -330VDC
Switching stages are one pair IGBT(or something) for each phase, conecting
to +, -, or both off.
The wind generator charges large lead batteries.
For best performance i connect series of batteries to achieve the named
voltages above (lowest loss, cheapest, and best peak power), but it is very
lethal *:(
Safer to use a 48 or 60V battery configuration and a push-pull converter to
get high voltage DC...
/Morgan

/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
\  .....mrtKILLspamspam.....iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /

1998\05\19@191205 by Dennis Plunkett

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At 04:39 PM 19/05/98 +0200, you wrote:
{Quote hidden}

I agree on the 48 to 60V stuff, as this is a Telecoms standard power supply,
and is also used by lots of solar power type companies. So there are quite a
few companies that already make the inverters, eq. Solarex, Solartron, BP
Solar just to name a few

1998\05\20@074907 by Peter L. Peres

picon face
> At 04:39 PM 19/05/98 +0200, you wrote:
> >...
> >>  Note that if you do NOT use a transformer, then you will have a
> >>triangle-type output and will not be able to ground the center point
> >...
> >I have distant plans of a small wind power plant.
> >I have been thinking about a 400V 3-phase generator like this:
> >DC input is +340VDC, GND/Neutral, and -330VDC
> >Switching stages are one pair IGBT(or something) for each phase, conecting
> >to +, -, or both off.
  ^^^^^^^^^^^^^^^^^^^^ Gulp. What is going to filter that ? Do you know
what happens if you put an inductive load on such a 'phase' ? Seriously,
to anyone looking into high power electronics, take a GOOD look at such
trifle things like 5 % distortion on a 1 kW sinwave (which works out to a
"mere" 50 Watts turned instantly into HV by any coil impedance in the
circuit, such as a transformer, and ready to fry any semiconductors in the
consumer circuits, and send EMI to Australia, China and who knows where
else in the long wave range ;).

Peter

1998\05\20@102145 by Morgan Olsson

picon face
At 10:26 1998-05-20 +0000, you wrote:
>> At 04:39 PM 19/05/98 +0200, you wrote:
>> >...
>> >>  Note that if you do NOT use a transformer, then you will have a
>> >>triangle-type output and will not be able to ground the center point
>> >...
>> >I have distant plans of a small wind power plant.
>> >I have been thinking about a 400V 3-phase generator like this:
>> >DC input is +340VDC, GND/Neutral, and -330VDC
>> >Switching stages are one pair IGBT(or something) for each phase, conecting
>> >to +, -, or both off.
>   ^^^^^^^^^^^^^^^^^^^^ Gulp. What is going to filter that ? Do you know
>what happens if you put an inductive load on such a 'phase' ? Seriously,
>to anyone looking into high power electronics, take a GOOD look at such
>trifle things like 5 % distortion on a 1 kW sinwave (which works out to a
>"mere" 50 Watts turned instantly into HV by any coil impedance in the
>circuit, such as a transformer, and ready to fry any semiconductors in the
>consumer circuits, and send EMI to Australia, China and who knows where
>else in the long wave range ;).
>Peter

A little exaggregation, i presume... It is a question of design.

Actually I have been studying a 48VDC to 230VAC 250W converter I bought
before, that uses the above design.  Works very well.

Im am interested if anyone can describe how theese class 600MW converters
for long distance power lines work.  (Made by ABB (Asea) to transfer power
to other side of seas, from distant power plants etc.  How do they do the
600MW HVDC to AC conversion??

/MOrgan
/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
\  mrtspamspam_OUTiname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /

1998\05\20@142350 by Peter L. Peres

picon face
On Wed, 20 May 1998, Morgan Olsson wrote:

> At 10:26 1998-05-20 +0000, you wrote:
> >> At 04:39 PM 19/05/98 +0200, you wrote:
> >> >...
> >> >>  Note that if you do NOT use a transformer, then you will have a
> >> >>triangle-type output and will not be able to ground the center point
> >> >...
> >> >I have distant plans of a small wind power plant.
> >> >I have been thinking about a 400V 3-phase generator like this:
> >> >DC input is +340VDC, GND/Neutral, and -330VDC
> >> >Switching stages are one pair IGBT(or something) for each phase, connectin
g
> >> >to +, -, or both off.
> >   ^^^^^^^^^^^^^^^^^^^^ Gulp. What is going to filter that ? Do you know
> >what happens if you put an inductive load on such a 'phase' ? Seriously,
...
>
> A little exaggeration, i presume... It is a question of design.

Yes, but 1kW is something you might work with soon, if you own a computer
and OSes go the way they go... I use a 400 W one ;)

> Actually I have been studying a 48VDC to 230VAC 250W converter I bought
> before, that uses the above design.  Works very well.

If it does not use some 'sinus magic' then you had better use it ONLY for
what it is designed, unless there is some filter on the output (LC).

'sinus magic' is the key, and it usually consists of a chopper DC/DC
converter disguised as the switching IGBT pair, with the transformer coil
being the other key ingredient: its inductance integrates the HF switched
DC voltage into reasonable sinus, aided by a few large capacitors that
tune the circuit properly to remove the chopper frequency from the output.

 This works from 5 W, up to about 10 kW. After that you start having
problems with components and stray radiation. SERIOUS problems. The
mentioned 5% distortion becomes 500 Watts, mostly HF, and keeping those
out of the consumer's power grids is awful hard to put it mildly. Remember
that pesky light dimmer that hummed into all the radios in the house no
matter what you did, in despite of its miserly 50 Watt bulb load ? Well,
think of the same effect, only about 200 *times* worse.

> Im am interested if anyone can describe how theese class 600MW converters
> for long distance power lines work.  (Made by ABB (Asea) to transfer power
> to other side of seas, from distant power plants etc.  How do they do the
> 600MW HVDC to AC conversion??

Why, you must have seen them, only they were so big you did not see them
as what they were. Remember when you drive past something called 'an
electrical substation' ? And drive, and drive, and drive, and drive, and
then there is an end to it and you can listen to the radio again ? Well,
that's the place. Ah, and, did you notice that I said 'listen to the radio
again' ? Hehehe. You were saying something about my exaggerating with my 5%
above, yes ?

As to the components, well, I had to do with some low power ones <G>. They
were thyristors for 8 kW loads at 380 V AC, and each was about the size of
an onion, with wires the size of my thumb, and a screw terminal that makes
a 1/2" pipe thread look tiny, for the water-circulated heatsink block.
They were used in groups of 6 for stage lighting control... This was 10
years ago. So figure...

Peter

1998\05\24@082446 by Humberto Pinheiro

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marcel wrote:

> I am interested to do an project to generate 3 phase ac mains on a ship
> on board there are
> two dc generators dc 220 volts and battery's
> an old tow boat from russia
> siemens makes power bridge's igbt  10 to 50 amps 600 volts
> i saw a design with 80553 pwm to control this bridge
> did any body do research on this which pic could do the job
> the bridge contains rectifier and 6 igbt transistors so one needs 6 pwm
> out puts
>
> Marcel
>
> @spam@marbelKILLspamspamxs4all.nl
>
> Amsterdam

 Hi Marcel

Usually it is needed just 3 PWMs , since the  top and  bottom trasistors
of the each leg
of the inverter are controlled in a complementary fashion.

Humberto
KILLspamhumbertoKILLspamspamece.concordia.ca
Montreal

1998\05\25@015902 by Russell McMahon

picon face
If you want to take a lot of the control load off the PIC
you could look at ICs like the Mitel (was Plessey?) SA828.
This does total 3 phase sinusoidal PWM control with lots of
bells and whistles. (There is a single phase version too
(SA838)). You can set the amplitude and frequency and leave
the device to itself until you need to change them - in your
application this would largely be set-and-forget. Its meant
for motor control as well (where you often DO need to change
the frequency ). Price is good - about $NZ6.50 in 1's (about
$US3.50) and they are even in stock in NZ (from GEC).

Look at http://www.mitelsemi.com/products/ for details including
data sheets and application notes.

{Original Message removed}

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