They shouldn't, they're MOS and SOI (AFAIK).
They have some newer, larger dies that are maybe practical for commodity PCB fab. The original (narrow die, row of elliptical bump) style are definitely challenging without HDI ($$$).
I'd love to use some, but I haven't had any jobs needing quite that much power density!
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
RC snubber parallel with the coil R maybe 10 times the coil R pick C for critical damping, use a 250V transistor.
-- This email has not been checked by half-arsed antivirus software
RC snubber parallel with the coil R maybe 10 times the coil R pick C for critical damping. expect hundereds of volts on the transistor.
-- This email has not been checked by half-arsed antivirus software
The simplest circuit is just a resistor across the coil, forget the diode. Size from the peak current at switch off and highest permissible transistor voltage. e.g. Use 30R for 8A 240V. If efficiency not paramount and a robust solution wanted as in OP app then it is the KISS answer.
piglet
Look at the LM1949 as a starting point
-- Chisolm Republic of Texas
This may also be useful <
-- Chisolm Republic of Texas
The epc parts are unpackaged bga/flipchip GaN parts. Outrageous transconductance and low capacitances per amp, but hard to use and especially rework. Pity they don't package them.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Looks that way. These engines use PWM to fire the solenoid injectors, so yes you have to shorten the timing interval as you speed up, but you also need to increase the pulse width to get more juice in there per detonation. You also have to worry about retard/advance on top of all that, but that's another matter.
PWM is just for current limiting, much easier to just use series resistors
then all you have to figure out is when and how long to turn it on
pwm also complicate things because you want a slow decay when PWM'ing and a fast decay when closing
This was about driving a solenoid, in the context of pumping fuel? I'm a bit confused. That will be inductive when the plunger is stationary, resistive when the plunger is moving, and inductive again when the plunger hits bottom. So, to get metered fuel, don't you need to repeat the pulses? And, to atomize the fuel, don't you want to modulate the stroke velocity?
Driving 'a solenoid' in this context is intrinsically going to be complicated.
the solenoid in a regular fuel injector is just an on/off valve atomizing is done by the nozzle at the tip, metering is done by how long it is open and the (constant) fuel pressure
Peak and Hold is the game.
Inital pulse is wider to obtain staturation to get the injector open as fast as possible. Some use a current sense to detect others use time.
Once the initial Peak demand period has past, then it uses PWM to adjust holding current and keeps with this for the required duration to meet the fuel/fluid demand, then it turns off.
Etc..
I saw a system that did not use PWM at all, it has a switching powersupply that could be set for the holding current that simply set the output voltage. So the initial peak current had full voltage for a periode and then it just switched to low voltage. This system did not use the induction of the injector. there were two power fets per injector to select the source of voltage Peak/Hold Voltage.
Jamie
Den onsdag den 25. januar 2017 kl. 01.02.14 UTC+1 skrev M Philbrook:
many gasoline cars use high impedance injectors (8-16 Ohm), they don't need current limiting
the injectors for direct gasoline injection can get much more complicated
You don't need anything complicated, just one higher voltage capacitor per injector and a single common lower voltage power supply. Fire the capacitor into the injector to get it open, then as the capacitor discharges and the voltage acrosss the coil drops, holding current flows through a diode from the lower voltage supply.
I used this system on the play solenoid of a cassette tape drive for a telephone answering machine: 50v discharge to pull it in and 12v to hold it. The electronics have worked flawlessly for over 20 years (although bits of the mechanism have shaken loose from time to time).
-- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
Yup, I've d "A firing event only occurs every two revolutions (per cylinder) and typically lasts just a few milliseconds."
If the solenoid gets up to 30A in a few mS at 12V, we can surmise the inductance is, for example, L ~= = 12V * 5mS / 30A = 2mH-ish.
Stored energy = 1/2 (Li^2) = .5 * 2mH * 30^2 = 900mJ.
If dissipated: 4,000 rpm = 67 Hz. 67Hz * 900mJ = 60W.
Could be doable.
Cheers, James Arthur
Thanks for that. Seems a lot of folks here are veering off into all sorts of exotic injector types and indeed there are quite a family of them. But this question is concerned solely with common rail diesel injectors where the pressure behind the injectors is upwards of 30,000psi.
Maybe half that if it fires every other rev.
And there was talk of current-limiting resistors. That could change things. This thing needs numbers and a Spice model.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Yes, and it's an absolute PIG to get in-depth tech details on them from the manufacturers. My only realistic option is to whip one out and try to carry out some measurements, but it won't give the full picture. :(
"diesel fuel injector inductance" pulls up a few relevant hits.
This random paper (pg 109) says 137uH:
This paper from the U.S. Dept. of the Army is more interesting electrically, as it gets a bit into drivers, but I didn't see what fuel they were using in my quick skim. They report 1.9-3.9mH for their example coil.
Cheers, James Arthur
Here's a fabulous set of posts on fuel injectors from sed's own Neon John...
"The injector is from a Datsun Z car. It is a low impedance (2.3 ohm,
6.5 millihenry)) injector and is driven by a saturated driver through a ballast resistor in its native environment. In the test setup, A 13.5 volt power supply supplies power to one terminal of the injector. The other terminal is sunk to ground with a darlington transistor pair (2n3055 pair connected as a darlington.) The base is driven from a function generator that is driven from another function generator (so that width and frequency can be varied completely independently.) A 0.1 ohm resistor is in the emitter lead of darlington pair to measure current.An Endevco piezo accelerometer is attached to the injector with a rubber band and serves to detect the mechanical opening and closing of the injector. (A cheap substitute for the Endevco is a phono cartridge with a #8 or #10 lead shot glued to the stylus.) The endevco is attached to one channel of the Fluke scope and the other channel is connected either to the resistor for current or to the collector of the darlington for voltage.
The first test involved driving the injector saturated at full current, about 4 amps. The pulse width was increased from zero until the injector opens. The injector started lifting at 1 ms and exhibited full opening at 1.25 ms. Pretty much what we expected. Here's the interesting part. The closing time is over 1 ms! This is with no flyback diode - the kick goes to over 40 volts."
Cheers, James Arthur
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.