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New Generator Design

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  • New Generator Design

    Well, since we've been without power going on the sixth day now, I have had plenty of time to really get to know my generating capacity. Like many of you guys, my mind never, ever stops turning and yes I have laid awake in bed listen to a twenty HP Onan suck down $2.75/gal 87 Octane at the average rate of 1gal/hour which equates to roughly $75/day to run SSS's mini power grid.

    So... I was thinking.......

    Here's my idea and and you tech guys (and Miller Engineers...please) chime in and let me know what you think. My idea is for vastly improving the fuel effeciency of an engine drive when used in an AC generation setting. It involves marrying three established technologies into one unit. To begin with, basic prime mover power rotating magnetic field AC generation is a very established and mature technology. It has been around for roughly a century now. The problem is that in the case of my Bobcat and any other traditional gen set is that it has to sit there and run at 3600RPM (or 1800, depending on the unit, but a set RPM nonetheless) to provide standard 60 Cycle (or Hertz...don't want to take credit away, now do we!) power. This is the case whether I need 100 watts or all 10K. On the other end of the spectrum is the little Honda EU2000 inverter style gen set that I also use. It litterally sips fuel. This is because it has a variable idle on a small engine that turns a DC alternator. This power is then sent through an inverter to produce the 60 cycle power. The beauty of this design is that because the DC alternator can run at a varible RPM and still produce it's power (higher RPM equates higher amperage, but the voltage can be maintained at any reasonable speed). The little inverter has two throttle settings. One for full power and one for demand varied auto idle. The biggest draw back to the auto idle is it's lacking ability to handle inductive load starts. As we all know, inductive loads basically look like a dead short to a supply when the are energized and then taper off as the load comes up to speed, hence the term "motor starting capacity". So my idea is to take those two ideas and put them in a compactor along with my UPS from the computers and hopfully this is what will come out:

    Take the DC/CV ability of an engine drive and couple that with a 10KW inverter, but.....between the two put either a very large capacitor bank (think of a filter bank on an AC to DC regulated power supply that filters the post rectifier bridge, pulsating DC to usuable straight DC) or a small battery bank that would handle the brief spike in current so that the throttle could compensate and take up the load. This way you have the efficency and cleanliness of the inverter coupled with the effiecency of a variable RPM DC generator. Of course the mechnical governor would be best replaced with an electronic one, but that technology is readily available. That would give the ability to run the prime mover at the RPM just enough to produce the power being consumed.

    Ok, that's my idea

    Last edited by SkidSteerSteve; 12-15-2007, 09:33 AM.
    Bobcat 250, MM 210, Syncrowave 180, Spectrum 375
    Cat 242B Skid Steer, Challenger (Cat/Agco) MT275
    1 Thessalonians 4:11-12

  • #2
    add smaller better batterys

    seems like a simple solution.
    add in the new tec. of smaller more powerful battery's like the one's for electric car's. smaller lighter and more powerful.
    i gotta tag along and see how this plays out. i spend too much time on my genny not to tag along.
    thanks for the help
    hope i helped
    feel free to shoot me an e-mail direct i have time to chat. [email protected]
    summer is here, plant a tree. if you don't have space or time to plant one sponsor some one else to plant one for you. a tree is an investment in our planet, help it out.


    • #3
      interesting concept

      I think this is an interesting concept, and though im no electrical engineer, I think that the capacitors would be suffiecint to handle the inrush or should i say the better choice. The inrush current aspect of the inductive load is momentary so using batteries to provide for this 1-2 second occurance seems to be perhaps a little overkill, but it would be far more stable than a cap. do you know what a 10k inverter is worth? big big $$
      You could add some resistance to the capacitor bank and that would allow for a slower , more controlled drain of the voltage as the laod comes to speed. Im not sure how big of a cap you'd need to do this though..

      this is about the time i wish i had been looking more at my books rather than the girls in the class next door...
      Will it weld? I loooove electricity!

      Miller 251/30A spool
      Spectrum 625
      Precix 5x10 CNC Router12"Z
      Standard modern lathe
      Cheap Chinese mill that does the trick... sort of...
      horizontal 7x12 bandsaw
      Roland XC540 PRO III
      54" laminator
      hammer and screwdriver (most used)
      little dog
      pooper scooper (2nd most used...)


      • #4
        They beat me to it!

        Well, as with most things in life, I'm a dollar short and a day late. Apparently the good folks over at Cummins/Onan had this idea in their head already. It's not exactly what I was thinking, but a really close (and, personally I think even better).


        Bobcat 250, MM 210, Syncrowave 180, Spectrum 375
        Cat 242B Skid Steer, Challenger (Cat/Agco) MT275
        1 Thessalonians 4:11-12


        • #5
          Hello Steve..... just remember me after you get rich with your idea!

          Unfortunately I think it would just boil down to simply economics…..? Who’s the customer you’re seeking & how could you package all of this electrical equipment into package affordable enough to purchase…? I’m not asking you these questions, just thinking out load… Had a nasty ice storm here last year & I spent $700 on 5500w generator, but even though I used plenty of profanity as I bought fuel, I would have paid $10 a gallon at THAT time.

          In a kind of about way that is how these windmill generator’s that they’re building work. They’re a dc generator feeding batteries & then being inverted & then goes thru a transformer to match line voltage. I shouldn’t have said that because I know very little about that technology. Only reason I said that was because they installed one here at work to show the community that this big bad oilfield company was trying cleaner sources of energy. lol Fact be known, it can’t even power this building… but a learnt how they worked by looking over their shoulder when they installed it. anyway, I need to shut-up because I can’t even figure out this other guy’s 110v receptacle problem, little alone get involved in your project that could completely revolutionize the world’s power consumption……. lol good luck Steve! Rodney
          Last edited by handirod; 02-06-2008, 02:11 PM.


          • #6

            nevermind my post! i didn't see your previous post before i wrote mine. do they actually put a price tag on those units? my imput's lately are helping nobody..... so i'm sorry! & again, i'm going to shut-up for a while! later
            Last edited by handirod; 02-06-2008, 02:21 PM.


            • #7
              I was curious on the unit Cummins is now offering because I’m building a new house right now. After being without power last winter for almost 2 weeks I was wanting to install a home generator package that has its own foundation & is already hardwired to the house with an automatic throw over switch incase it ever happened again. Just got off the phone with the local Cummins dealer here & they quoted me a price of $18,000 for the 7500w unit. He said he’ll have to call the factory for the price of the inverter, but I told him there was no need. But they claim it saves 20% in fuel usage. Great idea, but who could afford it…? Rodney