Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Best Regards
Tom.

On Fri, 15 Aug 2008 03:19:17 -0700, with neither quill nor qualm,
"azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Cool! It looks like the project is really coming together, Tom.

--
Challenges are gifts that force us to search for a new center of gravity.
Don't fight them. Just find a different way to stand.
-- Oprah Winfrey

In article ,
Larry Jaques wrote:

On Fri, 15 Aug 2008 03:19:17 -0700, with neither quill nor qualm,
"azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Cool! It looks like the project is really coming together, Tom.

The big power modules mounted on the heatsink - what are they and what
did they cost?

Thanks,

Joe Gwinn

On Aug 15, 6:19 am, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...zotic/inv7.jpg

Best Regards
Tom.

Just wondering, does the little bridge rectifier on the lower right of
picture inv6 provide the power to the much larger switching elements
on the heat sink. Is the large white cylinder in the last couple of
pics the rectified DC filter cap? What do you calculate the ripple
current in the DC filter cap to be?

Carl

On Aug 15, 11:26 am, Carl wrote:
On Aug 15, 6:19 am, "azotic" wrote:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...x.net/azotic/i...

Best Regards
Tom.

Just wondering, does the little bridge rectifier on the lower right of
picture inv6 provide the power to the much larger switching elements
on the heat sink. Is the large white cylinder in the last couple of
pics the rectified DC filter cap? What do you calculate the ripple
current in the DC filter cap to be?

Carl

Are you planning on making and selling the PC board?
Components?

Wolfgang

"azotic" wrote:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.


Put this in context. What are you going to run with this?

Wes

azotic wrote:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being assembled.


Looks real nice! Also looks like something even -I- could
put together from a kit. You going to offer plans/boards?
Hmm, maybe I shoulda held on to one of those heat sinks.... BG

Jon

"Larry Jaques" wrote in message
...
On Fri, 15 Aug 2008 03:19:17 -0700, with neither quill nor qualm,
"azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Cool! It looks like the project is really coming together, Tom.


Thanks, i plan on adding a jog and brake feature to the design
which i think will be handy to have.

Best Regards
Tom.

Progress !

Martin
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


azotic wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Best Regards
Tom.





----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= - Total Privacy via Encryption =---

"Joseph Gwinn" wrote in message
...
In article ,
Larry Jaques wrote:

On Fri, 15 Aug 2008 03:19:17 -0700, with neither quill nor qualm,
"azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Cool! It looks like the project is really coming together, Tom.

The big power modules mounted on the heatsink - what are they and what
did they cost?

Thanks,

Joe Gwinn


They are dual IGBT transistors also known as a GTR module. Basicly
they are 2 NPN transistors conected in series to form a half bridge which
means the are capable of switching both + and - DC power back and forth.
You get AC output in the form of a square wave as a result. You can achive
the same result by using 2 individual IGBTs.

The GTRs i am using have the capacity to switch 100 amps at 1200 volts,
they have built in free wheeling diodes which cuts down on the component
count. I bought these GTRs on ebay for $8.00 each, shipping was $7.55.

Best Regards
Tom.

"Carl" wrote in message
...
On Aug 15, 6:19 am, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...zotic/inv7.jpg

Best Regards
Tom.

Just wondering, does the little bridge rectifier on the lower right of
picture inv6 provide the power to the much larger switching elements
on the heat sink. Is the large white cylinder in the last couple of
pics the rectified DC filter cap? What do you calculate the ripple
current in the DC filter cap to be?

Carl


The output of the bridge rectifier is connected directley to the large white
filter cap ( 2700uF @ 420Vdc ). I didnt do any ripple calculations for
the HV dc buss since motors and transformers dont seem to have problem
with ripple. However there are seperate regulated power supplies for the
logic and gate drivers where ripple would be a huge problem. The large
white filter capacitor at the end of the buss just happened to have the
same center to center hole spacing as the GTRs which makes it possible
to mount it right on the buss bars and eliminate the additional wiring that
would be needed if i had to mount it elsewhere.

Best Regards
Tom.

wrote in message
...
On Aug 15, 11:26 am, Carl wrote:
On Aug 15, 6:19 am, "azotic" wrote:

Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...x.net/azotic/i...

Best Regards
Tom.

Just wondering, does the little bridge rectifier on the lower right of
picture inv6 provide the power to the much larger switching elements
on the heat sink. Is the large white cylinder in the last couple of
pics the rectified DC filter cap? What do you calculate the ripple
current in the DC filter cap to be?

Carl

Are you planning on making and selling the PC board?
Components?

Wolfgang

The thought had crossed my mind. If i do decide to sell circuit
boards for this project there will be a parts placement printed on
patern on the top side. I am thinking that building a board will work
like painting by the numbers, you would place the parts U-1, D-3 etc.
into the board with the locations marked U-1, D3, etc. then just
solder them in place.

Best Regards
Tom.

"Wes" wrote in message
...
"azotic" wrote:

Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.


Put this in context. What are you going to run with this?

Wes


Motors, Welders, maybe experiment with makeing an electric
go-cart. Being old school my thoghts were to make a VFD
with way more capacity than i would ever need. I also want
it to be repairable and user friendly. That is why i designed it
using discrete components that are in sockets comonly availble
from multiple sources at low cost. No custom sole source
propiorty stuff for me. The design of the driver board allows
for scaling up or scaling down the power, just select the right
size IGBTs for the application. If you only need enough power
to run a small motor you use small 15 amp IGBTs, if you want run a welder
you get some 400 amp IGBTs.

Best Regards
Tom.

"Jon Anderson" wrote in message
. ..
azotic wrote:

Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD being assembled.


Looks real nice! Also looks like something even -I- could put together
from a kit. You going to offer plans/boards?
Hmm, maybe I shoulda held on to one of those heat sinks.... BG

Jon


Thinking about it.

Best Regards
Tom.

"Martin H. Eastburn" wrote in message
...
Progress !

Dont you just love it when a plan comes together.

Best Regards
Tom.

On Fri, 15 Aug 2008 19:07:53 -0700, with neither quill nor qualm,
"azotic" quickly quoth:


wrote in message
Are you planning on making and selling the PC board?
Components?

The thought had crossed my mind. If i do decide to sell circuit
boards for this project there will be a parts placement printed on
patern on the top side. I am thinking that building a board will work
like painting by the numbers, you would place the parts U-1, D-3 etc.
into the board with the locations marked U-1, D3, etc. then just
solder them in place.

Au contraire, mon ami! I strongly suggest using sockets as you did.

--
Challenges are gifts that force us to search for a new center of gravity.
Don't fight them. Just find a different way to stand.
-- Oprah Winfrey

In article ,
"azotic" wrote:

"Joseph Gwinn" wrote in message
...
In article ,
Larry Jaques wrote:

On Fri, 15 Aug 2008 03:19:17 -0700, with neither quill nor qualm,
"azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg

Cool! It looks like the project is really coming together, Tom.

The big power modules mounted on the heatsink - what are they and what
did they cost?

Thanks,

Joe Gwinn


They are dual IGBT transistors also known as a GTR module. Basicly
they are 2 NPN transistors conected in series to form a half bridge which
means the are capable of switching both + and - DC power back and forth.
You get AC output in the form of a square wave as a result. You can achive
the same result by using 2 individual IGBTs.

The GTRs i am using have the capacity to switch 100 amps at 1200 volts,
they have built in free wheeling diodes which cuts down on the component
count. I bought these GTRs on ebay for $8.00 each, shipping was $7.55.

So each module is a a half-bridge containing two IGBTs plus some
frewheeling diodes. What make and model?


The reason I ask is I'm designing a homebrew impulse magnetizer, to be
built around three 2900 microfarad 350 volt computer electrolytics I got
surplus somewhere (no longer recall when or where). In this case, the
current is all surge and no continuous, and the modules I'm considering
are Diode-SCR half-bridges. (IGBTs don't seem suitable.) The circuit
protects the electrolytics from reverse voltage by returning the
inductive kick to the capacitor with the correct polarity to charge it.

The surge current will be something like 3000 amps for 10 milliseconds.
I'm still working out the details, such as how big a surge current is
needed. Even if the SCRs and diodes are happy, the capacitors have a
limit as well.

I got the circuit idea from an expired US patent, 4,258,405 to
Steingroever. Steingroever uses Mercury-pool ignitrons, as nothing else
will withstand the currents necessary to use pulsed magnetic fields to
form metal. http://en.wikipedia.org/wiki/Ignitron

For more information on metalforming, see US patents 5,586,460;
5,684,341; 5,813,264; and 5,953,805. Also see the website of Dr
Steingroever's company: http://www.magnet-physik.de/.

They use very high voltages and small inductances, to yield very short
pulses, the better to create the eddy currents against which they push
to apply force to the metal being formed.

For our purposes, and with some care, the ignitrons may be replaced with
big SCRs. But even the biggest of SCRs is a wimp compared to a big
ignitron.

Richardson Electronics still offers ignitrons and hydrogen thyatrons:

http://industrial.rell.com/et_ignitrons.asp

http://industrial.rell.com/et_Hthyratrons.asp

But they tend to be expensive.


Joe Gwinn

Don't you want a 3 phase sine wave output?
SE

azotic wrote:
"Joseph Gwinn" wrote in message
...
In article ,
Larry Jaques wrote:

On Fri, 15 Aug 2008 03:19:17 -0700, with neither quill nor qualm,
"azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg
Cool! It looks like the project is really coming together, Tom.
The big power modules mounted on the heatsink - what are they and what
did they cost?

Thanks,

Joe Gwinn


They are dual IGBT transistors also known as a GTR module. Basicly
they are 2 NPN transistors conected in series to form a half bridge which
means the are capable of switching both + and - DC power back and forth.
You get AC output in the form of a square wave as a result. You can achive
the same result by using 2 individual IGBTs.

The GTRs i am using have the capacity to switch 100 amps at 1200 volts,
they have built in free wheeling diodes which cuts down on the component
count. I bought these GTRs on ebay for $8.00 each, shipping was $7.55.

Best Regards
Tom.

"Shabtai Evan" wrote in message
...

Don't you want a 3 phase sine wave output?
SE

A sine is not nessesary to run a 3 phase motor.

Best Regards
Tom.

"Joseph Gwinn" wrote in message
...
In article ,

So each module is a a half-bridge containing two IGBTs plus some
frewheeling diodes. What make and model?

Joe Gwinn

I am using Toshiba MG100Q2Y51A GTR modules.

Intresting project your working on, there are IGBTs that might work
for your application but there going to be pricey. I did see some 600 amp
IGBTs on ebay this week that were reasonably priced. If your going to
buy some on ebay make shure you ask the seller if you can return them
should they be blown. Some sellers are selling units they claim are tested
but they are not. I had to return some that had blown gates and would not
fully turn off.

Best Regards
Tom.

"Larry Jaques" wrote in message
...
On Fri, 15 Aug 2008 19:07:53 -0700, with neither quill nor qualm,
"azotic" quickly quoth:


wrote in message
Are you planning on making and selling the PC board?
Components?

The thought had crossed my mind. If i do decide to sell circuit
boards for this project there will be a parts placement printed on
patern on the top side. I am thinking that building a board will work
like painting by the numbers, you would place the parts U-1, D-3 etc.
into the board with the locations marked U-1, D3, etc. then just
solder them in place.

Au contraire, mon ami! I strongly suggest using sockets as you did.


Oops, all the ICs will be socketed.

Best Regards
Tom.

On Aug 15, 8:19 pm, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...zotic/inv7.jpg

Best Regards
Tom.

Nice PCB - did you use a CNC router to do it? - if so, was it homebrew
- did a good job...

Andrew VK3BFA.

wrote in message
...
On Aug 15, 8:19 pm, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...zotic/inv7.jpg

Best Regards
Tom.

Nice PCB - did you use a CNC router to do it? - if so, was it homebrew
- did a good job...

Andrew VK3BFA.


Thanks, the circuit was drawn out with a freeware PCB program. The image was
printed out with a laser printer on some enameled paper, the image was then
transfered
from the paper to the copper clad using a regular clothes iron and the paper
disoleved in water.
The copper clad was then etched in a DIY etchant consisting of muratic acid
and
hydrogen peroxide. There are several articles on the web that describe this
methode
of making DIY PCBs on the web in greater detail.

Best Regards
Tom.

In article ,
"azotic" wrote:

"Joseph Gwinn" wrote in message
...
In article ,

So each module is a a half-bridge containing two IGBTs plus some
frewheeling diodes. What make and model?

Joe Gwinn

I am using Toshiba MG100Q2Y51A GTR modules.

I'll look these up.


Intresting project your working on, there are IGBTs that might work
for your application but there going to be pricey. I did see some 600 amp
IGBTs on ebay this week that were reasonably priced.

My original instinct was that SCRs were better suited than IGBTs for
this application, but I have not really dug into the issue. I'll get
the datasheet for the Toshiba IGBT and think about it.


If you're going to
buy some on ebay make sure you ask the seller if you can return them
should they be blown. Some sellers are selling units they claim are tested
but they are not. I had to return some that had blown gates and would not
fully turn off.

Good point. The price differential probably makes it worthwhile to eat
the expense of a few bad devices, if it comes to that. But I would buy
more units than strictly needed. And to cover lab accidents.

Joe Gwinn

azotic wrote:
"Joseph Gwinn" wrote in message
...

In article ,

So each module is a a half-bridge containing two IGBTs plus some
frewheeling diodes. What make and model?

Joe Gwinn


I am using Toshiba MG100Q2Y51A GTR modules.

Intresting project your working on, there are IGBTs that might work
for your application but there going to be pricey. I did see some 600 amp
IGBTs on ebay this week that were reasonably priced. If your going to
buy some on ebay make shure you ask the seller if you can return them
should they be blown. Some sellers are selling units they claim are tested
but they are not. I had to return some that had blown gates and would not
fully turn off.
Joe is right, IGBTs are not well suited to high current pulses.
You have to keep them fully saturated, or the current hogs
to the hottest part of the die, in a positive-feedback death
spiral. The design of the FET to BJT drive scheme built into
the transistor only allows so much base drive. SCRs are better
at this, as increasing current increases drive to the internal
transistor-like structures it is built from. You could also use
a bank of parallel MOSFETs, although the 350 V supply requires
using more of them. MOSFETs are so cheap, you might be able to
buy a couple dozen new for what a used monster SCR or BJT would
run you surplus. MOSFETs are quite tolerant of pulse overloads,
too.

Jon

"azotic" wrote in message
...

wrote in message
...
On Aug 15, 8:19 pm, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...zotic/inv7.jpg

Best Regards
Tom.

Nice PCB - did you use a CNC router to do it? - if so, was it homebrew
- did a good job...

Andrew VK3BFA.


Thanks, the circuit was drawn out with a freeware PCB program. The image
was
printed out with a laser printer on some enameled paper, the image was
then transfered
from the paper to the copper clad using a regular clothes iron and the
paper disoleved in water.
The copper clad was then etched in a DIY etchant consisting of muratic
acid and
hydrogen peroxide. There are several articles on the web that describe
this methode
of making DIY PCBs on the web in greater detail.

Best Regards
Tom.

That board is far better than I've ever achieved with toner transfer, what
paper and printer did you use?
Martin
--
martindot herewhybrowat herentlworlddot herecom

"Martin Whybrow" wrote in message
...

That board is far better than I've ever achieved with toner transfer, what
paper and printer did you use?
Martin
--

The printer is a HP laserjet 3200m, paper is HP presentation paper which is
a gloss
paper.

Best Regards
Tom.

azotic wrote:
A sine is not nessesary to run a 3 phase motor.

Does that mean that you just use a variable freq square wave, or is it
like the commercial VFDs & use PWM on a carrier?

Bob

--
Nota for President

On Aug 15, 9:57 pm, "azotic" wrote:
"Carl" wrote in message

...



On Aug 15, 6:19 am, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...x.net/azotic/i...

Best Regards
Tom.

Just wondering, does the little bridge rectifier on the lower right of
picture inv6 provide the power to the much larger switching elements
on the heat sink. Is the large white cylinder in the last couple of
pics the rectified DC filter cap? What do you calculate the ripple
current in the DC filter cap to be?

Carl

The output of the bridge rectifier is connected directley to the large white
filter cap ( 2700uF @ 420Vdc ). I didnt do any ripple calculations for
the HV dc buss since motors and transformers dont seem to have problem
with ripple. However there are seperate regulated power supplies for the
logic and gate drivers where ripple would be a huge problem. The large
white filter capacitor at the end of the buss just happened to have the
same center to center hole spacing as the GTRs which makes it possible
to mount it right on the buss bars and eliminate the additional wiring that
would be needed if i had to mount it elsewhere.

Best Regards
Tom.


Filter Caps do have a problem with ripple currents. You should also
consider stored energy in the motor magnetics (1/2 * I * I * L)
versus the capacitor (1/2 * V * V *C). Inductive kickback into the
supply caps in a PWM system can cause some really spectacular
capacitor failures. I highly recommend you have that cap in a stout
box before you test at more than an amp or 2. If the cap blows you
will be releasing 500+ joules explosively.

I think your rectifier bridge looks too small for the rest of the
circuit.

Best of luck
Carl

"Bob Engelhardt" wrote in message
. ..
azotic wrote:
A sine is not nessesary to run a 3 phase motor.

Does that mean that you just use a variable freq square wave, or is it
like the commercial VFDs & use PWM on a carrier?

Bob

--
Nota for President


Just variable frequency square wave.

Best Regards
Tom.

"Carl" wrote in message
...
On Aug 15, 9:57 pm, "azotic" wrote:
"Carl" wrote in message

...



On Aug 15, 6:19 am, "azotic" wrote:
Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD
being
assembled. As soon as time permits i will post a video of the VFD in
opperation.
I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.j...x.net/azotic/i...

Best Regards
Tom.

Just wondering, does the little bridge rectifier on the lower right of
picture inv6 provide the power to the much larger switching elements
on the heat sink. Is the large white cylinder in the last couple of
pics the rectified DC filter cap? What do you calculate the ripple
current in the DC filter cap to be?

Carl

The output of the bridge rectifier is connected directley to the large
white
filter cap ( 2700uF @ 420Vdc ). I didnt do any ripple calculations for
the HV dc buss since motors and transformers dont seem to have problem
with ripple. However there are seperate regulated power supplies for the
logic and gate drivers where ripple would be a huge problem. The large
white filter capacitor at the end of the buss just happened to have the
same center to center hole spacing as the GTRs which makes it possible
to mount it right on the buss bars and eliminate the additional wiring
that
would be needed if i had to mount it elsewhere.

Best Regards
Tom.


Filter Caps do have a problem with ripple currents. You should also
consider stored energy in the motor magnetics (1/2 * I * I * L)
versus the capacitor (1/2 * V * V *C). Inductive kickback into the
supply caps in a PWM system can cause some really spectacular
capacitor failures. I highly recommend you have that cap in a stout
box before you test at more than an amp or 2. If the cap blows you
will be releasing 500+ joules explosively.

I think your rectifier bridge looks too small for the rest of the
circuit.

Best of luck
Carl


The rectifier is only rated at 600V @ 25A. As soon as i find a deal on
something bigger i will be upgrading. For the time being i am limiting the
power during the current testing phase. Eventually i will build a box out
of perferated metal to house the finished unit before i test at full power
at 220V.

Thanks for the heads up on the caps.

Best Regards
Tom.

On Fri, 15 Aug 2008 18:38:48 -0700, "azotic" wrote:


On Fri, 15 Aug 2008 "azotic" quickly quoth:

Just in case anyone is intrested, here are some pix of my 100 amp DIY
VFD being
assembled. As soon as time permits i will post a video of the VFD in
opperation. I still have to make a remote control pannel.

http://members.cox.net/azotic/inv1.jpg
http://members.cox.net/azotic/inv2.jpg
http://members.cox.net/azotic/inv3.jpg
http://members.cox.net/azotic/inv4.jpg
http://members.cox.net/azotic/inv5.jpg
http://members.cox.net/azotic/inv6.jpg
http://members.cox.net/azotic/inv7.jpg


Best Regards
Tom.

Any progress on drawing up a circuit diagram?

RWL