Other high side drivers like IR2110 and IR2125?

[Chris Carlen]

Greetings:

Until I can understand the way the IR2125 works, I'd like to research
other high side drivers similar to these IRF devices. I am getting
rather frustrated with IRF's sloppiness with regard to their web site
and the profuse errors in their documents.

Perhaps TI or others have these sorts of things that you folks know off
the top of your heads?

I'm looking for a high side driver for a MOSFET on a +150V rail. I want
to be able to do continuous on or off DC drive, and PWM over the 0-100%
duty range. Needless to say, this leads to difficulties when attempting
with pulse trannys which is why I want one of these chips. I will be
running around 50kHz max, so an isolated supply powering a good high
side chip should be lovely. I'll make my own little forward converter
with really low interwinding capacitance to juice the thing.

Oh yeah, I'd really like current sensing and shutdown to implement a
short-proof gadget.

Thanks for comments.


Good day!




--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[legg]

Until I can understand the way the IR2125 works, I'd like to research
other high side drivers similar to these IRF devices. I am getting
rather frustrated with IRF's sloppiness with regard to their web site
and the profuse errors in their documents.

Perhaps TI or others have these sorts of things that you folks know off
the top of your heads?

I'm looking for a high side driver for a MOSFET on a +150V rail. I want
to be able to do continuous on or off DC drive, and PWM over the 0-100%
duty range. Needless to say, this leads to difficulties when attempting
with pulse trannys which is why I want one of these chips.

Oh yeah, I'd really like current sensing and shutdown to implement a
short-proof gadget.

There isn't a very wide range of sources, if you are operating from
mains rectified voltages, especially if you also demand more
complicated integrated features. Below 65V, the options are more
wide-ranged.

Unless you resort to low-frequency high impedance PV, no integrated
option is likely to provide static operation, as you request. For that
you would have to use a hybrid driver, or make your own using similar
optical, magnetic or discrete circuitry and dedicated power supplies.

Note that most of the integrated devices use differential current
mirrors for level shifting.

The only one that specifically use internal integrated magnetic
coupling is the Eupec device.

Some, like the HV400 type is designed to interface with an external
magnetic coupler.There are various IC pairs (natsemi, TI, AD) that are
also designed to function with simpler magnetic coupling than most
standard drivers require. The same function is obtainable discretely.

The integrated devices tend to be specified over a restricted
temperature range. Watch out for junction rises from self-dissipation,
due to internal driver impedance. Note the dVdt restrictions.

..............
current

INT201 Power Integrations

L6571 STMicro
L5651/2 STMicro
L6387 STMicro

IX6R11 IXYS

IR218x IR

M63954P Mitsubishi

2ED020I12-F Eupec
.............
obsolete

RIC7113 ?
GS600 GE
HV250 Harris
SP600/601/605/606 harris
..................

Don't you think that you really should try to do some 'googling' on
the subject, before commenting on Vendor documentation?

RL

 

[Genome]

Greetings:

Until I can understand the way the IR2125 works, I'd like to research
other high side drivers similar to these IRF devices. I am getting
rather frustrated with IRF's sloppiness with regard to their web site
and the profuse errors in their documents.

Perhaps TI or others have these sorts of things that you folks know off
the top of your heads?

I'm looking for a high side driver for a MOSFET on a +150V rail. I want
to be able to do continuous on or off DC drive, and PWM over the 0-100%
duty range. Needless to say, this leads to difficulties when attempting
with pulse trannys which is why I want one of these chips. I will be
running around 50kHz max, so an isolated supply powering a good high
side chip should be lovely. I'll make my own little forward converter
with really low interwinding capacitance to juice the thing.

Oh yeah, I'd really like current sensing and shutdown to implement a
short-proof gadget.

Thanks for comments.


Good day!

Yarp... burp, werp..... The IR2125 is a bit unintuitive, data sheet and app
note (as given by R.Legg). The four terminal mosfet is, as you should know
by now, a hexsense device. The 0V23 offset is shown bass akwards but if you
stand on your head and unsuspend your disbelief then it should do what they
think it might. Me too, how dare they create a bit of dirt and then fail to
get the explanation right!!!!. In the mean time, wotcha want the added
functionality for? In fact, what the **** do they think they are doing by
providing it.? Arrrrrp, burp..... there's some sort of inductive load turn
off type scenario going on with big loady dump motor half a bum, fondle
tweak, type things where you don't want to wap off your IGBT 'just like
that' when the bucket is going down the toilet.... you want a nice
controlled turn off which is what this thing is trying to do, not that they
tell you the whys or wherefarts. Snert, phlegmmy regurgitate chew chew....
So wotcha trying to do, oh obnoxious one, AY? There are more than many ways
to skin a cat which don't necessarily involve boiling it alive first,
ba-ba-buh-barf. You might want to get rid of that 'oooh I just gotta have
0-100% duty cycle perlease' type itchy kneecap. If you do then those nasty
folks at IRF once presented a current fed converter whose front end
comprised a buck regulator using two mosfets operated in parallel
anti-phase. Do What? Do What!?, 'ave a banana. Get the picture? Grab a
UC3825 and a couple of gate drive transformerers, 50%ish driving one pluz
50%ish driving the other is 100%ish. Whacky in a couple of current
transformers and Bob could be your monkyhouse, don't worry it's a
colloquialism.. three bongs on the posh side of a tarbuck. Devo mondo yooo
though, iv yah got rid of the 'something or other' complex and just admitted
what you thought you wanted in the first place then you might get a super
trooper solution to your schperling.

DNA

 

[Winfield Hill]

legg wrote...

There isn't a very wide range of sources, if you are operating from
mains rectified voltages, especially if you also demand more
complicated integrated features. Below 65V, the options are more
wide-ranged.

Unless you resort to low-frequency high impedance PV, no integrated
option is likely to provide static operation, as you request. For that
you would have to use a hybrid driver, or make your own using similar
optical, magnetic or discrete circuitry and dedicated power supplies.

Note that most of the integrated devices use differential current
mirrors for level shifting.

The only one that specifically use internal integrated magnetic
coupling is the Eupec device.

Some, like the HV400 type is designed to interface with an external
magnetic coupler.There are various IC pairs (natsemi, TI, AD) that are
also designed to function with simpler magnetic coupling than most
standard drivers require. The same function is obtainable discretely.

The integrated devices tend to be specified over a restricted
temperature range. Watch out for junction rises from self-dissipation,
due to internal driver impedance. Note the dVdt restrictions.

.............
current

INT201 Power Integrations

L6571 STMicro
L5651/2 STMicro
L6387 STMicro

IX6R11 IXYS

IR218x IR

M63954P Mitsubishi

2ED020I12-F Eupec

............
obsolete

RIC7113 ?
GS600 GE
HV250 Harris
SP600/601/605/606 harris
.................

Don't you think that you really should try to do some 'googling'
on the subject, before commenting on Vendor documentation?

Nice list, RL.

I've had good results with IR's high-voltage high-side drivers,
and have found their data sheets to be adequate and useful. :>)

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Chris Carlen]

[edit]
Unless you resort to low-frequency high impedance PV, no integrated
option is likely to provide static operation, as you request. For that
you would have to use a hybrid driver, or make your own using similar
optical, magnetic or discrete circuitry and dedicated power supplies.

Yes, I plan to add an isolated DC supply to power an IC.

Note that most of the integrated devices use differential current
mirrors for level shifting.

The only one that specifically use internal integrated magnetic
coupling is the Eupec device.

I'll check that out.

[edit list]

Don't you think that you really should try to do some 'googling' on
the subject, before commenting on Vendor documentation?

I'm commenting only on IRF documentation. The point was that they make
quite frequent mistakes, which is apparent to anyone. Just look at the
datasheet for IR2125. While an expert might spot the backwards 0.23V
source right off, someone who does this sort of thing once in a while
has to sit for a couple hours figuring it out. That and the app notes
with mislabeled figures and other errors. I don't mind a few
grammatical errors and spellling errors, because I understand that the
authors are often not native english speakers, but the figures ought to
be labeled well and the math spot on.

Other than that, yes I can google, which is how I will track down all
the parts in your list. But your list is the point. Because of your
experience, you could spit out a list in a few minutes that would take
me a few hours, and still not be as complete. For that I say:

Thanks for the reply!


Good day.



--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[Chris Carlen]

Nice list, RL.

I've had good results with IR's high-voltage high-side drivers,
and have found their data sheets to be adequate and useful. :>)

Thanks,
- Win

Did anyone say they weren't adequate or useful?


--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[Chris Carlen]

Yarp... burp, werp..... The IR2125 is a bit unintuitive, data sheet and app
note (as given by R.Legg). The four terminal mosfet is, as you should know
by now, a hexsense device.

I didn't know that, until now. Thanks. Enjoying the brew today?

The 0V23 offset is shown bass akwards but if you

stand on your head and unsuspend your disbelief then it should do what they
think it might.

Yes it took me a while, but eventually figured it out.

Me too, how dare they create a bit of dirt and then fail to

get the explanation right!!!!. In the mean time, wotcha want the added
functionality for? In fact, what the **** do they think they are doing by
providing it.? Arrrrrp, burp..... there's some sort of inductive load turn
off type scenario going on with big loady dump motor half a bum, fondle
tweak, type things where you don't want to wap off your IGBT 'just like
that' when the bucket is going down the toilet.... you want a nice
controlled turn off which is what this thing is trying to do, not that they
tell you the whys or wherefarts. Snert, phlegmmy regurgitate chew chew....
So wotcha trying to do, oh obnoxious one, AY? There are more than many ways
to skin a cat which don't necessarily involve boiling it alive first,
ba-ba-buh-barf. You might want to get rid of that 'oooh I just gotta have
0-100% duty cycle perlease' type itchy kneecap.

Driving a fuel injector solenoid with very fast current risetime. 150V
boost voltage into 130uH + 2.8ohms. Need 30A pull-in current in about
50us. This requires turning on the switches for potentially more than
one cycle of the PWM frequency for the initial current rise, which then
moves into a linear PWM constant current drive. I don't want jitter
from when the trigger is received to when the current starts to ramp, so
the error voltage from the error amp is allowed to go above the sawtooth
amplitude to produce 100% duty. Likewise, the thing must be able to do
0% duty for more than one PWM cycles to turn off the solenoid.

I want current limiting in case someone shorts the output terminals, or
if there is a coil failure in the shorted mode.

If you do then those nasty

folks at IRF once presented a current fed converter whose front end
comprised a buck regulator using two mosfets operated in parallel
anti-phase. Do What? Do What!?, 'ave a banana. Get the picture? Grab a
UC3825 and a couple of gate drive transformerers, 50%ish driving one pluz
50%ish driving the other is 100%ish. Whacky in a couple of current
transformers and Bob could be your monkyhouse, don't worry it's a
colloquialism.. three bongs on the posh side of a tarbuck. Devo mondo yooo
though, iv yah got rid of the 'something or other' complex and just admitted
what you thought you wanted in the first place then you might get a super
trooper solution to your schperling.

DNA

Thanks for the input.

Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.536 / Virus Database: 331 - Release Date: 11/3/03

Incoming mail program and Linux OS is virus immune.


Good day!


--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[Zdenko]

There isn't a very wide range of sources, if you are operating from
mains rectified voltages, especially if you also demand more
complicated integrated features. Below 65V, the options are more
wide-ranged.

Unless you resort to low-frequency high impedance PV, no integrated
option is likely to provide static operation, as you request. For that
you would have to use a hybrid driver, or make your own using similar
optical, magnetic or discrete circuitry and dedicated power supplies.

Note that most of the integrated devices use differential current
mirrors for level shifting.

The only one that specifically use internal integrated magnetic
coupling is the Eupec device.

Some, like the HV400 type is designed to interface with an external
magnetic coupler.There are various IC pairs (natsemi, TI, AD) that are
also designed to function with simpler magnetic coupling than most
standard drivers require. The same function is obtainable discretely.

The integrated devices tend to be specified over a restricted
temperature range. Watch out for junction rises from self-dissipation,
due to internal driver impedance. Note the dVdt restrictions.

.............
current

INT201 Power Integrations

L6571 STMicro
L5651/2 STMicro
L6387 STMicro

IX6R11 IXYS

IR218x IR

M63954P Mitsubishi

2ED020I12-F Eupec
............
obsolete

RIC7113 ?
GS600 GE
HV250 Harris
SP600/601/605/606 harris
.................

Don't you think that you really should try to do some 'googling' on
the subject, before commenting on Vendor documentation?

RL

Hi,

I also have a big problem with this high side drivers and here are
some remarks which might help you:
a) those from IRF are to slow
b) I used optocoupler 74OL6010 Fairchild
c) the driver was TC4422

you can use another speed driver because you don't need high voltage
Mosfet. This gives a wonderfull results ad my THD was after PDM filter
only less than 1%.

REgards
Zdenko

 

[Winfield Hill]

Zdenko wrote...

I also have a big problem with this high side drivers and here are
some remarks which might help you:
a) those from IRF are to slow
b) I used optocoupler 74OL6010 Fairchild
c) the driver was TC4422

you can use another speed driver because you don't need high voltage
Mosfet. This gives a wonderfull results ad my THD was after PDM
filter only less than 1%.

What FETs were you using? At what voltage & load current?
And at what switching frequency?

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Chris Carlen]

Hi,

I also have a big problem with this high side drivers and here are
some remarks which might help you:
a) those from IRF are to slow
b) I used optocoupler 74OL6010 Fairchild
c) the driver was TC4422

you can use another speed driver because you don't need high voltage
Mosfet. This gives a wonderfull results ad my THD was after PDM filter
only less than 1%.

REgards
Zdenko

Sounds like you're making an amplifier. Well, your suggestions are
worth looking into. Thanks for the reply!

--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[Winfield Hill]

Chris Carlen wrote...

Sounds like you're making an amplifier. Well, your suggestions
are worth looking into. Thanks for the reply!

Not necessarily. IR's drivers are 600V parts, and have reasonable
typical 150ns logic delays, as clearly stated in their data sheets.
If you're making an amplifier where the difference between ON and
OFF delay means distortion, or any other application where delay is
the most important factor, then, yes by all means engineer a more
complex scheme. But properly used, IR's HV drivers are fast enough:
I'm happy with the 10ns switching speed I've achieved. That's not
SLOW in most people's books! Sure I've done better (e.g. 2.5ns as
detailed in today's "HV power fet?" thread), but 10ns is still fast!

My advice is to stick with the IR parts until you understand them
and their data sheets. After more experience most details that may
be weak or confusing may well disappear in your mind because you'll
be on the same wavelength as the IC engineers and datasheet writers.

Thanks,
- Win

whill_at_picovolt-dot-com

 

[Fritz Schlunder]

Greetings:

Until I can understand the way the IR2125 works, I'd like to research
other high side drivers similar to these IRF devices. I am getting
rather frustrated with IRF's sloppiness with regard to their web site
and the profuse errors in their documents.

Perhaps TI or others have these sorts of things that you folks know off
the top of your heads?

I'm looking for a high side driver for a MOSFET on a +150V rail. I want
to be able to do continuous on or off DC drive, and PWM over the 0-100%
duty range. Needless to say, this leads to difficulties when attempting
with pulse trannys which is why I want one of these chips. I will be
running around 50kHz max, so an isolated supply powering a good high
side chip should be lovely. I'll make my own little forward converter
with really low interwinding capacitance to juice the thing.

Oh yeah, I'd really like current sensing and shutdown to implement a
short-proof gadget.

Thanks for comments.


Good day!

Eye. Good day indeed Mr. Carlen. Did you ever do anything to work towards
your cheap 1MV idea? I found that thread particularly interesting and ever
since then I've wanted to generate 1MV as well. Actually since then I've
made my goals (err... dreams) even loftier still to include a 1GeV 40mA
proton beam. Not quite sure yet how to build that on a reasonable sized
budget yet (or for that matter build it at all). I keep my eyes peeled
whenever I visit yard sales, but I have been having trouble procuring the
requisite 40MW+ generator needed among other things.

Sorry to hear you don't care for International Rectifier. International
Rectifier has become my favorite semiconductor company. Although it is my
opinion that all manufacturer's datasheets/application notes are never quite
as adequate as I would like (IR not excluded), I've always found
International Rectifier's datasheets and application notes extemely good
especially compared against their competitors such as General Semiconductor
(now part of Vishay).

That said, are you sure you really need transformers and isolated supplies
and all that jazz? Have you read International Rectifier's AN-978 regarding
high voltage floating MOS gate driver ICs?

http://www.irf.com/technical-info/appnotes/an-978.pdf

Section 8 of that document suggests using a 555 arrangement to obtain
continuous drive capability. If practical for your application such a
solution might have definite advantages.

You can learn more about "HEXSense" devices by reading International
Rectifier's AN-959:

http://www.irf.com/technical-info/appnotes/an-959.pdf

Although the idea is neat, I don't think they are very popular devices.
Trying to use them is often rather constraining for discrete applications
since they don't normally come in the latest, greatest, lowest on-resistance
flavors that standard MOSFETs are so cheaply available in. I'm not sure how
many other manufacturers make these type of current sensing MOSFETs. I know
the part of Motorola that became On-Semi used to make a few of these types
of devices. I'm not sure if On-semi still makes these or not. Of course
they won't call them "HEXSense" MOSFETs since that is a trademark of
International Rectifier. I should imagine they would be particularly useful
in power control integrated circuits with on-die MOSFETs like the Viper100A
for instance:

http://www.st.com/stonline/books/pdf/docs/5137.pdf

 

[Genome]

Oh right, your still on that one....

Go on then...... are you measuring the characteristics of the engine or the
injector. I mean, if this is a research type project then there's got to be
the opportunity to vary things a bit. I might be able to do a nice low side
drive thingummybob that meets your requirements and also snuffs things off
just as fast.... that'd be 50uS to 30A and 50uS back down again (errrr, I
think). Just means you have to rewind the injector, Ho Ho.

DNA

 

[Chris Carlen]

Chris Carlen wrote...



Not necessarily. IR's drivers are 600V parts, and have reasonable
typical 150ns logic delays, as clearly stated in their data sheets.
If you're making an amplifier where the difference between ON and
OFF delay means distortion, or any other application where delay is
the most important factor, then, yes by all means engineer a more
complex scheme. But properly used, IR's HV drivers are fast enough:
I'm happy with the 10ns switching speed I've achieved. That's not
SLOW in most people's books! Sure I've done better (e.g. 2.5ns as
detailed in today's "HV power fet?" thread), but 10ns is still fast!

My advice is to stick with the IR parts until you understand them
and their data sheets. After more experience most details that may
be weak or confusing may well disappear in your mind because you'll
be on the same wavelength as the IC engineers and datasheet writers.

Greetings:

Heh heh, I meant it's worth looking into for the sake of learning about
stuff. But in my case, I agree, the IRF switching speeds should be
fine. I'm only looking at the 20-50kHz range.

Thanks for the input.

Good day!


--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[Chris Carlen]

Eye. Good day indeed Mr. Carlen. Did you ever do anything to work towards
your cheap 1MV idea? I found that thread particularly interesting and ever
since then I've wanted to generate 1MV as well. Actually since then I've
made my goals (err... dreams) even loftier still to include a 1GeV 40mA
proton beam. Not quite sure yet how to build that on a reasonable sized
budget yet (or for that matter build it at all). I keep my eyes peeled
whenever I visit yard sales, but I have been having trouble procuring the
requisite 40MW+ generator needed among other things.

Thanks for the reply.

I have purchased a big pile of 2.2nF 25kV capacitors, and am building my
collection of variacs, isolation transformers, HV transformers, and HV
rectifiers needed to do this Marx Bank project. I am hoping to get
1.2MV. I think this is entirely practical and not terribly difficult,
considering the web site I'm sure you've seen demonstrating a rather
easily built 500kV Marx Bank.

The particle accelerator is another story. That is really much more
involved. I don't think I'll actually attempt that. But the
considerations weren't just whimsical, but a serious thought about how
large an accelerator might actually be within the reach of an amatueur,
albeit very serious, scientist/hobbyist. I remain convinced that the
1-2MeV range is about the upper limit of what could be done in a garage
or basement with a less than $50k budget. I think however that a
microwave pumped accelerator might be able to do better, with a
correspondingly larger knowledge requirement to build it. But
truthfully, without a background in more EM theory, nuclear physics, and
radiation safety, I wouldn't try to do any of this. I don't want to get
burned, just have some fun. Marx Banks and Tesla coils are a safer venue.

Sorry to hear you don't care for International Rectifier. International
Rectifier has become my favorite semiconductor company. Although it is my
opinion that all manufacturer's datasheets/application notes are never quite
as adequate as I would like (IR not excluded), I've always found
International Rectifier's datasheets and application notes extemely good
especially compared against their competitors such as General Semiconductor
(now part of Vishay).

Hmm, I seem to have made too strong an impression about IRF. Really, I
was a bit frustrated with some errors in the datasheets, but in general
I like IRF devices and continue to use them.

That said, are you sure you really need transformers and isolated supplies
and all that jazz? Have you read International Rectifier's AN-978 regarding
high voltage floating MOS gate driver ICs?

Yes, I have read AN-978. At first I didn't like it because it seemed to
not be useable with a situation in which there are truly massive step
changes in duty, like 0% for a long while, then step to 100% for a ms or
so, then step to 50% or so for a few more ms, then back to 0% for a long
while again. The most straightforward way in this case seemed to be the
use of a little forward converter to statically supply the high side
driver power for an IR2110, like the AN-937 document describes.

http://www.irf.com/technical-info/appnotes/an-978.pdf

Section 8 of that document suggests using a 555 arrangement to obtain
continuous drive capability. If practical for your application such a
solution might have definite advantages.

At this point, I really see little difference in the complexity of the
555 vs. a forward converter arrangement for powering the high-side.

You can learn more about "HEXSense" devices by reading International
Rectifier's AN-959:

http://www.irf.com/technical-info/appnotes/an-959.pdf

Yes, I have yet to delve into this subject.

BTW, your article on the gate drive transformer circuit is one of my
favorites. Learned a lot from that one.

Good day!


--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[Chris Carlen]

Oh right, your still on that one....

Go on then...... are you measuring the characteristics of the engine or the
injector. I mean, if this is a research type project then there's got to be
the opportunity to vary things a bit. I might be able to do a nice low side
drive thingummybob that meets your requirements and also snuffs things off
just as fast.... that'd be 50uS to 30A and 50uS back down again (errrr, I
think). Just means you have to rewind the injector, Ho Ho.

DNA

Thanks for the reply.

We are interested in measuring engines, and to do so need very
repeatable injection performance. There is considerable variation in
injectors just from mechanical and hydraulic considerations, that leads
to a standard deviation in the injected quantity per pulse as well as
some jitter of when the inject happens relative to triggering. We are
capable of seeing changes in the engine load from just 1us of change in
the duration of injection.

The injector drivers that are commercially available typically apply
about 25-30A pull in current for 200-400us followed by 15-20A hold
current. Current rise to 30A is preferrably around 50us, the same for
the drop from 20A to 0, which of course could be a little faster since
it has less dA to go.

We would like to have the following adjustments available: pull-in
current about 15-30A, hold current about 10-25A, pull-in time about
50-1000us, hold current time controlled by trigger pulse, and some
adjustablility of the max drive voltage to tinker with the current rise
time. If the external trigger is shorter than the set pull-in current
duration, the hold-current period is never reached.

My plan was to make a two-part system: a power driver that basically
implements a voltage controlled current source capable of driving an
inductive load with up to +/- 150V and currents of up to 30A for a duty
cycle of up to 5%. The typical injector solenoid parameters are 130uH
and 2.8ohms (that's the one sitting on my desk).

The second part would be a voltage step generator that responds to the
TTL level trigger, and outputs the appropriate voltage levels to command
the current source (with a slope like 5A/V). So, for a 400us 30A
pull-in followed by 20A hold with the trigger pulse lasting 1ms, we
would generate a voltage of 6V at the start of the trigger, lasting for
400us, then stepping down to 4V and lasting until the end of the trigger.

The adjustable parameters won't be set very frequently, so they don't
need any fancy user interface. The times and levels also don't need
much better than 1-2% accuracy.

One other caveat: The system must be capable of delivering multiple
injections per engine cycle, up to at least four. Thus, the energy
reserves must be such that the B+ supply voltage doesn't droop very
much. The maximum amount of time that the injector would have to be
opened during any engine cycle is perhaps 5ms. So up to 4 inject pulses
must be possible within that time with adequate energy reserves. The
programming of pulse sequences will be handled by other systems. This
system need only respond to individual inject pulses, and produce the
appropriate current profiles.

This is my plan. The voltage step generator is easy, the power driver
isn't. I have evaluated several topologies, and perhaps I will post a
summary of my evaluations and discoveries for review, and suggestions as
to whether I'm heading in the right direction or if there is another way.

Good day!

--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

 

[R.Legg]

The injector drivers that are commercially available typically apply

about 25-30A pull in current for 200-400us followed by 15-20A hold
current. Current rise to 30A is preferrably around 50us, the same for
the drop from 20A to 0, which of course could be a little faster since
it has less dA to go.

We would like to have the following adjustments available: pull-in
current about 15-30A, hold current about 10-25A, pull-in time about
50-1000us, hold current time controlled by trigger pulse, and some
adjustablility of the max drive voltage to tinker with the current rise
time. If the external trigger is shorter than the set pull-in current
duration, the hold-current period is never reached.

My plan was to make a two-part system: a power driver that basically
implements a voltage controlled current source capable of driving an
inductive load with up to +/- 150V and currents of up to 30A for a duty
cycle of up to 5%. The typical injector solenoid parameters are 130uH
and 2.8ohms (that's the one sitting on my desk).

One other caveat: The system must be capable of delivering multiple
injections per engine cycle, up to at least four. Thus, the energy
reserves must be such that the B+ supply voltage doesn't droop very
much. The maximum amount of time that the injector would have to be
opened during any engine cycle is perhaps 5ms. So up to 4 inject pulses
must be possible within that time with adequate energy reserves. The
programming of pulse sequences will be handled by other systems. This
system need only respond to individual inject pulses, and produce the
appropriate current profiles.

This is my plan. The voltage step generator is easy, the power driver
isn't. I have evaluated several topologies, and perhaps I will post a
summary of my evaluations and discoveries for review, and suggestions as
to whether I'm heading in the right direction or if there is another way.

Depending on whether or not the injector coil(s) are isolated from
adjacent metalwork, or whether a terminal is grounded, the
non-isolated assymetrical bridge is probably the simplest drive
topology.

A configuration (injart01) is posted on ABSE.

One switch is PWMed, the other is assynchronously opened to produce
reducing injctor current.

Current rise and fall rate limits are determined by the DC supply
voltage.

The drawing illustrates the use of 3842-type 8 pin current mode
controller, programmed by your analog input signal, representing the
instantaneous current demand. Negative current demand signals are
ignored.

If your current pattern is repetative, 4 groups every 500uSec, the DC
supply will need a KW rating.Switches and freewheeling diodes rated
for the 30A injector current and DC supply voltage.

Such niceties as chip decoupling and controller slow-start, fault
detection and power fusing, missing from the drawing, should not be
ignored.

RL

 

[legg]

A configuration (injart01) is posted on ABSE.

One switch is PWMed, the other is assynchronously opened to produce
reducing injctor current.

Current rise and fall rate limits are determined by the DC supply
voltage.

The drawing illustrates the use of 3842-type 8 pin current mode
controller, programmed by your analog input signal, representing the
instantaneous current demand. Negative current demand signals are
ignored.

The current sensing is screwed up on the injart01 dwg. No freewheeling
current is sensed. This will not control injector current as intended.

PWMing both switches with the same drive signal could, with a limited
duty cycle, produce an AC current through the R1 position. This would
allow R1/U1 to be replaced by a current transformer (full wave
rectified), possibly restoring the control function.

The problem of getting current information when braking to zero; when
the duty can go to the unlimited extreme of zero, may not be serious,
if the current fall time is as short as was intended.

RL

 

[Genome]

We are interested in measuring engines, and to do so need very
repeatable injection performance. There is considerable variation in
injectors just from mechanical and hydraulic considerations, that leads
to a standard deviation in the injected quantity per pulse as well as
some jitter of when the inject happens relative to triggering. We are
capable of seeing changes in the engine load from just 1us of change in
the duration of injection.

The injector drivers that are commercially available typically apply
about 25-30A pull in current for 200-400us followed by 15-20A hold
current. Current rise to 30A is preferrably around 50us, the same for
the drop from 20A to 0, which of course could be a little faster since
it has less dA to go.

We would like to have the following adjustments available: pull-in
current about 15-30A, hold current about 10-25A, pull-in time about
50-1000us, hold current time controlled by trigger pulse, and some
adjustablility of the max drive voltage to tinker with the current rise
time. If the external trigger is shorter than the set pull-in current
duration, the hold-current period is never reached.

My plan was to make a two-part system: a power driver that basically
implements a voltage controlled current source capable of driving an
inductive load with up to +/- 150V and currents of up to 30A for a duty
cycle of up to 5%. The typical injector solenoid parameters are 130uH
and 2.8ohms (that's the one sitting on my desk).

The second part would be a voltage step generator that responds to the
TTL level trigger, and outputs the appropriate voltage levels to command
the current source (with a slope like 5A/V). So, for a 400us 30A
pull-in followed by 20A hold with the trigger pulse lasting 1ms, we
would generate a voltage of 6V at the start of the trigger, lasting for
400us, then stepping down to 4V and lasting until the end of the trigger.

The adjustable parameters won't be set very frequently, so they don't
need any fancy user interface. The times and levels also don't need
much better than 1-2% accuracy.

One other caveat: The system must be capable of delivering multiple
injections per engine cycle, up to at least four. Thus, the energy
reserves must be such that the B+ supply voltage doesn't droop very
much. The maximum amount of time that the injector would have to be
opened during any engine cycle is perhaps 5ms. So up to 4 inject pulses
must be possible within that time with adequate energy reserves. The
programming of pulse sequences will be handled by other systems. This
system need only respond to individual inject pulses, and produce the
appropriate current profiles.

This is my plan. The voltage step generator is easy, the power driver
isn't. I have evaluated several topologies, and perhaps I will post a
summary of my evaluations and discoveries for review, and suggestions as
to whether I'm heading in the right direction or if there is another way.

Good day!

--
____________________________________
Christopher R. Carlen
Principal Laser/Optical Technologist
Sandia National Laboratories CA USA
[email protected]

Ahaaaaaa.... Rattles head about, wot your looking for is really a sort of DC
motor controller type arrangement.

Conceptual thing posted in the binaries.schematics newsgroup as 'Injector
Driver'.

DNA

 

[legg]

Ahaaaaaa.... Rattles head about, wot your looking for is really a sort of DC
motor controller type arrangement.

Conceptual thing posted in the binaries.schematics newsgroup as 'Injector
Driver'.

DNA

Assymetric driver, with output, is on abse. See injector2.

RL