12v - 400v DC-DC convertor

[Mark]

hi,
i need a 400v supply to drive a multi spark CDI ignition. I was just
wondering what the best switch mode topology to use is?

I want it to be capable of 8 sparks per engine revolution with each spark is
about 100mJ. At 10,000rpm this works out as 133W.. i think.

I have had some experience with push-pull type convertors but that is about
it.

Yeah so what i waanna know is what type of switch mode supply would be
suitable for this.

Thanks.

 

[north_melb_man]

On Sun, 6 Jul 2003 14:21:20 +1000, "Mark" <higham@optushome.com.au>
wrote:

hi,
i need a 400v supply to drive a multi spark CDI ignition. I was just
wondering what the best switch mode topology to use is?

I want it to be capable of 8 sparks per engine revolution with each spark is
about 100mJ. At 10,000rpm this works out as 133W.. i think.

I have had some experience with push-pull type convertors but that is about
it.

Yeah so what i waanna know is what type of switch mode supply would be
suitable for this.

Thanks.

Just a silly idea, what about using a 12 volt to 240 volt modified
sine wave inverter, use a bridge rectifier and filter capacitor, will
get around 340 V DC, but its really cheap to get a 150 W inverter
around many places., see them at DSE, Jaycar and some Auto parts
places.

Regards

 

[Bob M]

Hi Mark,

Silicon Chip, September 1997, page 18 had a good article on the
construction of a multi-spark CDI. The power supply it used produced a
reasonably regulated 300 volts. It would very easy to adjust the turns
ratio and modify the regulator to output 400 volts. I would also
suggest using a bigger e core transformer and heftier power
transistors/heat sink. Make sure you use a coil that was designed for
400 volts @100mj on the primary, otherwise, expect to go through a lot
of them. They will break down and fail quickly.

Are you sure about 8 sparks at 10,000rpm? Typically, at high rpm,
ignitions produce only 1 or 2 sparks. I guess the reasoning is that if
the cylinder hasn't fired and completely burned by the second spark,
it is too late to fire it and get any usable energy from that
particular revolution.

Anyways, as a result of this article, I have designed an ignition
system that I am installing on my 1970 Evinrude 60hp engine. I have
much info that I can forward if you wish. Let me know.

Regards, and Cheers from Canada

Bob Morgoch


"Mark" <higham@optushome.com.au> wrote in message news:<3f07a3ba$0$5973$afc38c87@news.optusnet.com.au>...

hi,
i need a 400v supply to drive a multi spark CDI ignition. I was just
wondering what the best switch mode topology to use is?

I want it to be capable of 8 sparks per engine revolution with each spark is
about 100mJ. At 10,000rpm this works out as 133W.. i think.

I have had some experience with push-pull type convertors but that is about
it.

Yeah so what i waanna know is what type of switch mode supply would be
suitable for this.

Thanks.