Electric governor

[veggie]

Hi Ken

Check out this thread in the Listeroid section. Topic is Overspeed Protection.
Romar points out a little relay that trips on high/low voltage.

http://www.microcogen.info/index.php?topic=156.15

Cheers,
Veggie

[BruceM]

Ken, An AVR on your generator head would solve the overvoltage problem, and one of the smart voltage monitoring relays would also be good insurance.

I have the schematics (scanned hand drawn) for my prototype AVR that does timed voltage monitoring and shut down, and also allows "manual reversion" to harmonic operation.  It is for a 240V head but is easily modified for 120. Let me know if that is something you want.  

I have schematic and PCB layout for a 120V bare bones AVR.  The board costs $53 for three ordered from expresspcb.com.  Parts are about $50 for one.

As for a monitoring processor, I recommend a Picaxe 40X1 or 40X2. Very capable, least cost.  Do a search on Picaxe for my previous discussion.  I have scanned hand drawn schematics and Basic source code for a serious user. I do rpm monitoring via Cherry brand gear tooth sensor mounted next to the flywheel spokes.

Bruce M

[akghound]

Ken, An AVR on your generator head would solve the overvoltage problem, and one of the smart voltage monitoring relays would also be good insurance.

I found one that works for 220vac but I need one for 120vac.

I have the schematics (scanned hand drawn) for my prototype AVR that does timed voltage monitoring and shut down, and also allows "manual reversion" to harmonic operation.  It is for a 240V head but is easily modified for 120. Let me know if that is something you want.  

Yes Bruce I could really use your ideas. Thanks for the offer.

I have schematic and PCB layout for a 120V bare bones AVR.  The board costs $53 for three ordered from expresspcb.com.  Parts are about $50 for one.

As for a monitoring processor, I recommend a Picaxe 40X1 or 40X2. Very capable, least cost.  Do a search on Picaxe for my previous discussion.  I have scanned hand drawn schematics and Basic source code for a serious user. I do rpm monitoring via Cherry brand gear tooth sensor mounted next to the flywheel spokes.

Bruce M

I'll be gone until after the first of November. Will check in when I get back.
Thank you  .... Ken Gardner  akghound[at]gmail.com

[akghound]

I'm thinking more along the lines of controling the engine speed. I found this goodie on ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290357196417&ssPageName=STRK:MEWAX:IT
Another option would be a Woodward APECS 500 but I'm having trouble finding out where to buy one.
http://www.traycana.com/catalogues/apecs/APECS500.PDF
Of course I am in a hurry today and don't have much time to shop.
Ken Gardner

[BruceM]

Hi Ken,
Some good finds in your post, Ken, thanks!

The Woodward unit looks like it has an ignition signal pickup for rpm- which wouldn't work for diesel.  Woodward does seem to have a nice selection of high power solenoids.

The APECS500 looks suitable for replacing the mechanical governor and looks like a nice setup.  It seems well suited to diesel since it has a magnetic rpm pickup. You'd have to buy the "calibration" software to keep it happy at 650Hz. The actuator appears to be a PWM modulated solenoid (burns a lot of power but is simple electro-mechanically).  I'll bet the whole package is not cheap, but it looks like it would do the job.

[BruceM]

My previous comment (10/10) on PWM was:
"There's nothing wrong with PWM'ing a solenoid, but why suffer."

I would still rather do it with an RC servo if designing it myself- it is cheaper and much lower power, and can be implemented as an augmenter instead of mechanical governor replacement.

But there is something to be said for buying off the shelf gear when possible- something like "Yes, thank God!"

[BruceM]

No worries, Jens.

Solenoids have been used for "not so linear" actuators since long before I was born (with analog drive circuitry), so someone suggesting that they can't be used as such is at least confused.

The advent of PWM'ing from microprocessor gives them a new lease on life as non-linearity from return spring and position of slug within field coil can be easily compensated for, if need be, with a simple table look-up.

Getting back on track-
My thanks to Ken for finding an off the shelf option for electronic governor, please fill us in on any future info you find. 

[dubbleUJay]

After reading this thread again, I have to change my view a little on some of the things I believed in at the time, mostly through ignorance on my side:
BruceM, now that I'm busy with a micro-processor controller, I see that it would be much easier to implement it to do speed regulation.
My plan is still to use a Governor Assisting Solenoid with a weaker spring, but to control it with the ATmega board, seeing that I'm already going to use it for other things.
It will also ensure that the engine will still work if the electronics fail. I wanted to proof the concept before hand, but it looks like I'll have to implement it myself for the 1st time.
Once we know it does work, we can maybe look at easier ways to implement it as a dedicated standalone unit.

[BruceM]

Almost every microcontroller with higher level language compiler or basic interpreter supports the PWM signal to RC servos, which makes using them very easy to use, just a resistor in hardware.  For longer runs (over 3 feet) I use an opto-isolator just before the servo with a balanced current loop drive on twisted wire to have solid, noise free control. With the opto-isolated current loop drive, there's almost no limit on cable length.

They have excellent performance and are cheap and low power. One of the giant scale servos would be very lightly loaded for this application if the mechanics are done well.

If you insist on banging a solenoid, be careful to filter (LCLC) the solenoid supply, and put a inductive spike suppressing diode on the solenoid coil, or other noise suppression (zeiner or RC) if the diode causes too much response delay (it shouldn't for this application).

[ndavid79]

Found an Arduino based diesel engine governor project:
Michael McKGyver McKinley / Firewood Processor Governor

[BruceM]

Good find, NDavid79, Micheal has some very interesting projects.
He notes this governor code is poor, and if he thinks the other examples are not, then it would be "sporting" to try and use/adapt it.  I didn't want to download the AVR program development environment just to look at his source code, which is not in a text format. (Grrr)

I'm baffled about the use of an optical encoder for rpm on an engine (grease and dirt will make it not work), and also the overkill use of a rotary encoder for "set point" adjustment (um, how about up/down buttons), but hey, it's cool, and he's obviously one sharp guy.

It didn't show now he maintained the manual mode, but it's a nice touch that he did.

[dubbleUJay]

Found an Arduino based diesel engine governor project:

Thanks David. 

Bruce, from your advice previously elsewhere on the forum, I'm going to use magnetic/Hall for RPM pickup on the Arduino, it just makes much more sense when I read your reasons.
I'll see if I can get the code "textified" (There's a new word for you )
Although I haven't gone through the site yet to know exactly what your talking about, if its a Arduino/Processing sketch (PDE extension), one should be able to "read" it, but you guys know that.

dubbleUJay