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dc/dc converter 12/200V

J

Jan Heijkamp

Jan 1, 1970
0
Hi,



I am building a cdi ignition for my motorbike.

There is enough available on the web but I can not find how to make a dc/dc
converter that is small enough to place on a motorbike. What I have found
has a large transformer.

I need a dc/dc 12/200V converter and the power is approximately 20 watt.

Knows anyone how to build this converter?



Tia



Jan
 
J

Jim Thompson

Jan 1, 1970
0
Hi,



I am building a cdi ignition for my motorbike.

There is enough available on the web but I can not find how to make a dc/dc
converter that is small enough to place on a motorbike. What I have found
has a large transformer.

I need a dc/dc 12/200V converter and the power is approximately 20 watt.

Knows anyone how to build this converter?



Tia



Jan

Why do it in to steps, conversion, then firing circuitry.

Do it in one pass, see....

http://www.analog-innovations.com/SED/CD-Ignition-Basic.pdf

...Jim Thompson
 
T

Ted Edwards

Jan 1, 1970
0
Jan said:
I am building a cdi ignition for my motorbike.

There is enough available on the web but I can not find how to make a dc/dc
converter that is small enough to place on a motorbike. What I have found
has a large transformer.

I need a dc/dc 12/200V converter and the power is approximately 20 watt.

Even at 30Khz, there is no reason to need anything larger than a 20 to
30mm diameter ferrite pot core for 20 watts but with today's much faster
switches, you should be able to go to a higher frequency and smaller core.

Ted
 
J

Jan Heijkamp

Jan 1, 1970
0
Your solution is not what i am searching for
Here the pro for CDI ignition.

CDI stores the ignition energy in an electric field of a capacitor,
Inductive ignition stores the energy in the magnetic field of an inductor
(coil). The CDI can switch a large current through a low
inductance/resistance pulse transformer very quickly so it is suitable for
extreme spark rates.
Inductive ignition needs time (dwell) to fill the coil with energy and time
to discharge that energy hence the longer spark duration of the inductive
system. A coil that is optimised for CDI system will not work properly with
an Inductive System and vice-versa. Commercially available CDI systems can
reliably push 150 amps at 450 volts or more through the primary windings of
a CD pulse transformer but do so in tens of microseconds so it works much
better at high revs.

Jan
 
J

Jim Thompson

Jan 1, 1970
0
Your solution is not what i am searching for
Here the pro for CDI ignition.

CDI stores the ignition energy in an electric field of a capacitor,
Inductive ignition stores the energy in the magnetic field of an inductor
(coil). The CDI can switch a large current through a low
inductance/resistance pulse transformer very quickly so it is suitable for
extreme spark rates.
Inductive ignition needs time (dwell) to fill the coil with energy and time
to discharge that energy hence the longer spark duration of the inductive
system. A coil that is optimised for CDI system will not work properly with
an Inductive System and vice-versa. Commercially available CDI systems can
reliably push 150 amps at 450 volts or more through the primary windings of
a CD pulse transformer but do so in tens of microseconds so it works much
better at high revs.

Jan

Wrong. My example is NOT inductive "storage"... it's CONVERT PER
FIRING... the example shown can manage a firing every 2.25ms with the
battery at 12VDC. AND: It HAS been run on many high RPM V8's, for
YEARS... not a FIGMENT like lots of designs seen here on S.E.D ;-)


...Jim Thompson
 
J

Jan Heijkamp

Jan 1, 1970
0
Hi Ted,

Thanks for your respond.
Do you have a idea how many winding i need for the primery coil?
Do i have to generate a perfect sinus for de primary if i use that high
frequenty?

Jan
 
J

Jan Heijkamp

Jan 1, 1970
0
Hi Jim,

I have take a second look at the schematic but i don't see how it works.
The only thing i can think of is that because the turning off Q1 if the
current is 5A trough L1 there a induction counter to the current is being
created.
That energie goes in C1 until Q1 is turning on and is pulling that energie
trough the ignition coil.
If this is not the case, can you explain in short how it works?
btw. Sorry for my bad english. I op you understand what i try to say.

Jan
 
J

Jim Thompson

Jan 1, 1970
0
Hi Jim,

I have take a second look at the schematic but i don't see how it works.
The only thing i can think of is that because the turning off Q1 if the
current is 5A trough L1 there a induction counter to the current is being
created.
That energie goes in C1 until Q1 is turning on and is pulling that energie
trough the ignition coil.
If this is not the case, can you explain in short how it works?
btw. Sorry for my bad english. I op you understand what i try to say.

Jan
[snip]

Turning ON the transistor does two things... dumps the capacitor
through the ignition coil primary (firing the plug) and begins
charging L1.

When the L1 current reaches 5A a control circuit (not shown) turns off
the transistor, which dumps the L1 energy into the capacitor.

Next point opening, or star wheel control signal, turns on the
transistor, repeating the cycle.

...Jim Thompson
 
N

Nico Coesel

Jan 1, 1970
0
Jim Thompson said:
Wrong. My example is NOT inductive "storage"... it's CONVERT PER
FIRING... the example shown can manage a firing every 2.25ms with the
battery at 12VDC. AND: It HAS been run on many high RPM V8's, for
YEARS... not a FIGMENT like lots of designs seen here on S.E.D ;-)

I doubt the V8 can reach 12000 rpm like a motorcycle engine can.
 
N

Nico Coesel

Jan 1, 1970
0
Jan Heijkamp said:
Hi,



I am building a cdi ignition for my motorbike.

There is enough available on the web but I can not find how to make a dc/dc
converter that is small enough to place on a motorbike. What I have found
has a large transformer.

I need a dc/dc 12/200V converter and the power is approximately 20 watt.

Knows anyone how to build this converter?

I think a lot of people reading this group (including myself) know how
to build such a converter. However, I think you are looking for a
diagram and a part list. I think the easiest way to get there is by
building a step-up converter in the so called continuous mode.

You can look on the websites of TI and National Semiconductor for
chips which can control these sort of circuits. Basically, you would
need a controller chip, a high voltage mosfet, a fast high voltage
diode and a standard inductor (one you buy, instead of winding your
own) and some resistors and capacitors.
 
C

colin

Jan 1, 1970
0
Jan Heijkamp said:
I am building a cdi ignition for my motorbike.

There is enough available on the web but I can not find how to make a dc/dc
converter that is small enough to place on a motorbike. What I have found
has a large transformer.

I need a dc/dc 12/200V converter and the power is approximately 20 watt.

Knows anyone how to build this converter?

ive built a few of these many years ago while I was at Uni for my suzuki
gs550, some more reliable than others, I managed to get one down close to
the size of a cigerette packet but this was too small and was unreliable as
it got hot.

if you look at several of the ferrite manafacturers you find data sheets for
their cores wich give tables for the size of the transformer you need versus
operating frequency. you should be able to get quite small for 20w.
especialy as you can go quite high frequency with a mosfet where as i was
having to use discrete darlintgon setup.

i used the circular pot core for my designs, and an auto transformer style
winding.

I used 2 gates of a cmos hex inverter IC as a simple relaxation oscilator to
control the switching transistor wich sensed when the colector voltage of
the transistor fell below 12v to switch it on, it also sensed when the
capacitor voltage reached full voltage.

the other 4 gates to control the 2 firing signals for the thyristors - two
coils for 4 cylinders as motorbikes dont have distributors like cars.

the charge per cycle design is interesting here but the size of inductor you
would need to store 0.1 joules every cycle is rather large i would think.

Colin =^.^=
 
J

Jim Thompson

Jan 1, 1970
0
ive built a few of these many years ago while I was at Uni for my suzuki
gs550, some more reliable than others, I managed to get one down close to
the size of a cigerette packet but this was too small and was unreliable as
it got hot.

if you look at several of the ferrite manafacturers you find data sheets for
their cores wich give tables for the size of the transformer you need versus
operating frequency. you should be able to get quite small for 20w.
especialy as you can go quite high frequency with a mosfet where as i was
having to use discrete darlintgon setup.

i used the circular pot core for my designs, and an auto transformer style
winding.

I used 2 gates of a cmos hex inverter IC as a simple relaxation oscilator to
control the switching transistor wich sensed when the colector voltage of
the transistor fell below 12v to switch it on, it also sensed when the
capacitor voltage reached full voltage.

the other 4 gates to control the 2 firing signals for the thyristors - two
coils for 4 cylinders as motorbikes dont have distributors like cars.

the charge per cycle design is interesting here but the size of inductor you
would need to store 0.1 joules every cycle is rather large i would think.

Colin =^.^=

About the size of a SMALL filament transformer, but with a gap.

5mH @5A, rated to 140°C

When I was doing my research in this area I was having them made by
Arizona Transformer Company, Arizona City, AZ, at a cost of about US$1
per each.

...Jim Thompson
 
J

Jan Heijkamp

Jan 1, 1970
0
I did put the schematic in a simulator.
The speed is ok, the voltage over C1 is 100V. It can work.
I wonder how bic a 5mH coil is with can take 4 ampere.


Jim Thompson said:
Hi Jim,

I have take a second look at the schematic but i don't see how it works.
The only thing i can think of is that because the turning off Q1 if the
current is 5A trough L1 there a induction counter to the current is being
created.
That energie goes in C1 until Q1 is turning on and is pulling that energie
trough the ignition coil.
If this is not the case, can you explain in short how it works?
btw. Sorry for my bad english. I op you understand what i try to say.

Jan
[snip]

Turning ON the transistor does two things... dumps the capacitor
through the ignition coil primary (firing the plug) and begins
charging L1.

When the L1 current reaches 5A a control circuit (not shown) turns off
the transistor, which dumps the L1 energy into the capacitor.

Next point opening, or star wheel control signal, turns on the
transistor, repeating the cycle.

...Jim Thompson
 
J

Jim Thompson

Jan 1, 1970
0
I did put the schematic in a simulator.
The speed is ok, the voltage over C1 is 100V. It can work.
I wonder how bic a 5mH coil is with can take 4 ampere.
[snip]

Using what for a simulator?

5A thru 5mH is 62.5mJ ~ 350V on 1uF

As I mentioned in a prior post, 5mH (laminated iron core) with a gap,
is about the size of a small filament transformer.

...Jim Thompson
 
F

Frithiof Andreas Jensen

Jan 1, 1970
0
I doubt the V8 can reach 12000 rpm like a motorcycle engine can.

The Formula 1 V12's can - they do tend to replace them often though.
 
J

John Larkin

Jan 1, 1970
0
Arrr - how annoyingly simple and obvious after the fact - Smarty-Pants Git,
You ;-)

That's a *very neat* & *elegant* idea - in case you missed the smiley -
Cheap too!

That is very elegant. But is there an advantage to having an
energy-storage inductor, an energy-storage capacitor, and a coil, when
all three can be combined into one part, namely the coil?

John
 
C

colin

Jan 1, 1970
0
John Larkin said:
That is very elegant. But is there an advantage to having an
energy-storage inductor, an energy-storage capacitor, and a coil, when
all three can be combined into one part, namely the coil?

To get a much bigger spark with one coil it would need to dispate a lot more
power, when its not sparking its drawing direct current wich is wasted
power, maybe you could have variable dwell angle to save power though but
thats probably more dificult. many ignition systrem just replace the points
with a sensor and transistor wich is a big improvement on its own, but CDI
gives much more rapid and powerfull spark.

Colin =^.^=
 
J

Jim Thompson

Jan 1, 1970
0
That is very elegant. But is there an advantage to having an
energy-storage inductor, an energy-storage capacitor, and a coil, when
all three can be combined into one part, namely the coil?

John

As Frithiof say, "CHEAP".

Power dissipation is much lower... device is always saturated.

Simple control requirements allow use of star-wheel-magnetic pickup OR
points.

Inductive storage requires either a shaped pickup or complex control
system for low dissipation and avoidance of coil current all over the
map. Remember, charging an inductor takes a fixed TIME, NOT a fixed
number of degrees.

Timing advance is there to fake out a constant TIME before firing...
flame front movement.

...Jim Thompson
 
J

Jim Thompson

Jan 1, 1970
0
Arrr - how annoyingly simple and obvious after the fact - Smarty-Pants Git,
You ;-)

That's a *very neat* & *elegant* idea - in case you missed the smiley -
Cheap too!

At last! Someone understands!

Actually not my original concept. It was an idea by a Philco-Ford
(Sunnyvale) design manager that I replaced in 1968, (first name I
can't recall) Josephson (not of "junction" fame :).

But he couldn't figure out how to control it. I did.

...Jim Thompson
 
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