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Problem of directing current in brushed DC motor, plan for reducing drag

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  • Problem of directing current in brushed DC motor, plan for reducing drag

    My idea is to try to utilize the coil collapse current that exist in the brushed DC motor. I think when the commutator get disconnected from the brush there would be coil collapse current that go through the other two coil in the direction of opposite of the way it supposed to flow in the coil and creating drag. When the the motor slows down the current build up in the coil will increase and will generate more coil collapse current.
    See attachment, cross section image from Inside Story - February 2003 - RC Groups.

    I plan to get around it by adding another coil on top of original that has lower resistance than both other coil to allow the coil collapse current to pass trough this coil. By utilizing the coil collapse current I hope the drag will be reduced and the power consumption will also reduce. For winding direction I plan to make both current flow at the same direction.


    I do not plan to eliminate BEMF here, I just want to reduce the spark or reverse current created by coil collapse current. The spark reduce contact and reverse current make rotor go in the opposite way.

    The one that I want to eliminate is coil collapse current effect not BEMF effect, since it seems BEMF can only be fixed with different motor design.


    But the problem is, even if I add diode the motor still go both forward and reverse depend on the polarity. where it should only work on one direction only. I tried 1N4002 and some unknown diode type (attached). Anyone can suggest a diode that may work at around 4 Amp at 3 or 12 Volts? It need to be small because I want to put it inside a motor smaller than anyone toe thumb.
    Attached Files
    Last edited by sucahyo; 08-22-2009, 04:26 AM.

  • #2
    wow, this is what I had in mind a few days ago when I ask about the waveform of swipe magnet over coil. It seems like we're thinking on the same problem. I will share my design on how to eliminate drag and possible locked in frequency. This means it will accelerate or decelerate as necessary to synchronize with the BEMF in LC circuit(or resonant frequency).

    Design:
    My design contain a rotating magnet or magnets of similar poles. A coil connecting with capacitor forming an LC circuit. There exist an angular velocity of the wheel that synchronize with the LC circuit. When approaching this speed, the wheel will speed up or slow down as necessary to maintain synchronization.

    Theory of operation
    Each time the magnet cut the coil, a current is induce in the coil in accordance with induction law. The LC circuit is design such that this current will stop when the magnet pole reach the center of the coil. Current is then reverse direction as the magnet finish its final half pass. The change in the magneticfield induced cause the current to circulate even stronger. The current in reverse direction result in repelling the magnet. Not only that speed of the wheel increase, but the current also increase. This will reach the equilibrium point cause by friction losses.
    Attached Files

    Comment


    • #3
      What both of you said I also saw on the kromrey thread
      ie:
      "While you're at it, you may want to try another trick we found. First shown in Bob Teal's motor, the set-up consists of TWO inductors in parallel, operated by the same switch. What happens is the two inductors charge up in PARALLEL, but when the switch turns off, they have nowhere to discharge to except into each other! This produces a situation we call a "Lenz Law Clamp" where the collapse of the magnetic fields buck each other in the series loop. Maximum magnetic field strength and currents are sustained for periods far in excess of the time it takes to charge the inductors in the first place. Teal used this trick to produce long power strokes on his solenoid engine with only short ON-TIME impulses. Since heat will be produced any time there is both voltage and current on the inductive heating elements, this may be a simple way to use just one switch (instead of two) and to get the biggest heat production from a low duty-cycle input.
      And also from Bedini:
      The important part is reed switch.
      The reed is under the coil and when the magnet is pulled into the iron it shorts the coil out. When the magnet leaves the iron it opens causing a discharge, reverse polarity and pushes the magnet away,
      Very tricky to make work
      See the cap across the coil keeps the read from arcing
      need the capacitor to protect the reed switch.
      LC circuit with the inductor and a small capacitor about 47 uf.
      The resistor is just to bleed off extra energy, of no use
      Just think about it this way,
      magnet charges the iron under a short condition
      then the magnet leaves
      reed opens,
      coil discharges and pushes the magnet away.
      Timing is the important thing here. This really a very simple magneto
      engine.
      You can make this machine if you understand the
      timing and capacitance

      Comment


      • #4
        @quantumuppercut, thanks for showing the design, would magnet approaching coil and leaving the coil make same polarity in the coil or different?


        @nvisser, the design of the motor I show already has parallel induction although not at the same impedance. When the top coil being powered, the other two also got powered in the opposite polarity since three of them are connected together. It would be hard to use bifilar unless there is a way to direct the current in the coil, which is my problem right now.


        about the reed switch, maybe using Bodkins trick of adding magnet at certain distance for calibration may help.

        Comment


        • #5
          Originally posted by sucahyo View Post
          @quantumuppercut, thanks for showing the design, would magnet approaching coil and leaving the coil make same polarity in the coil or different?
          You are prefering to the voltage polarity? It is different. I believe this is the misconception between those who speaks of Hertzian waves (transverse) and Scalar wave (longitutional). Though the voltage reverse polarity each time the magnet enter and leaving the coil (hence a hertzian wave), the current start and stop in a longitutional manner. Similar to EM waves. The voltage detected in Hertzian but the actual current movement is Scalar, or unidirectional.

          Comment


          • #6
            Originally posted by quantumuppercut View Post
            You are prefering to the voltage polarity? It is different. I believe this is the misconception between those who speaks of Hertzian waves (transverse) and Scalar wave (longitutional). Though the voltage reverse polarity each time the magnet enter and leaving the coil (hence a hertzian wave), the current start and stop in a longitutional manner. Similar to EM waves. The voltage detected in Hertzian but the actual current movement is Scalar, or unidirectional.
            I see. That explain it.

            I wouldn't doubt that meter can not detect all of the energy stored or pass if it also contain unusual electric. A couple of days ago, hopefully not because of defecting meter, I measure the amp of three pair of battery unsing analog meter. Two pair was charged using common charger, where a pair was charged using bedini like charger. The bedini charged one is already being played with by my kids, so I thought it already depleted, so I don't surprise to see it register to have low amp. The other two measured to have a bit higher charge from about 8 hour of charging.

            I tried both pair of commonly charged battery to my kids toy, both make the toy run slow, just like ordinary zinc carbon battery. But when I use Bedini charged one I got surprise because it ran double as fast. And when I measure it again it register to have more amp than previous measurement.

            I also notice that if the battery charged with common charger it would have short life, while using bedini charged one will be enough to make the motor literally smoking if let run continuously, it beat even alkaline battery.

            Comment


            • #7
              bedini charged batteries

              That sounds awesome Sucahyo, ssshmokin'
              Atoms move for free. It's all about resonance and phase. Make the circuit open and build a generator.

              Comment


              • #8
                Originally posted by sucahyo View Post

                I wouldn't doubt that meter can not detect all of the energy stored or pass if it also contain unusual electric. A couple of days ago, hopefully not because of defecting meter, I measure the amp of three pair of battery unsing analog meter. Two pair was charged using common charger, where a pair was charged using bedini like charger. The bedini charged one is already being played with by my kids, so I thought it already depleted, so I don't surprise to see it register to have low amp. The other two measured to have a bit higher charge from about 8 hour of charging.

                I tried both pair of commonly charged battery to my kids toy, both make the toy run slow, just like ordinary zinc carbon battery. But when I use Bedini charged one I got surprise because it ran double as fast. And when I measure it again it register to have more amp than previous measurement.

                I also notice that if the battery charged with common charger it would have short life, while using bedini charged one will be enough to make the motor literally smoking if let run continuously, it beat even alkaline battery.
                I have proposed that the battery will never depelete itself if you run on ultra low current. I came to conclude that battery charging effectively proportional to voltage and not the current passing through them. Bedini charger discharge high voltage low current to the battery making it more charging efficient. Normal charger only use voltage just above battery rating voltage, making it less efficient.

                Comment


                • #9
                  Originally posted by Inquorate View Post
                  That sounds awesome Sucahyo, ssshmokin'
                  lol, never thought it could happen.

                  Originally posted by quantumuppercut View Post
                  I have proposed that the battery will never depelete itself if you run on ultra low current. I came to conclude that battery charging effectively proportional to voltage and not the current passing through them. Bedini charger discharge high voltage low current to the battery making it more charging efficient. Normal charger only use voltage just above battery rating voltage, making it less efficient.
                  Maybe, the current may exceed 3 Amp in my case though since the coil resistance is under 0.6 ohm. I don't think normal high voltage would do the same though, since it already available as zapper product and some people mention to have different result.

                  My charger voltage is measured to have +0.1 Volt higher than current battery voltage, the current is about 50mA. My battery seems to store more capacity with higher stored voltage. At some mini 4WD site it is suggested to use alkaline battery for the best performance compared to charged battery, but this only true on common charger. I believe that at first but I regret I have to buy 6 alkaline battery to know that bedini charged battery simply much more powerfull that the toy car look like crawling.

                  The very significant performance of bedini charged battery has a bad effect on me though, I usually share everything I know but seeing big smile of my son trounching everyone else with exact similar toy car or higher spec make me wonder if I have to share this knowledge or not......I know everyone else do not use it because they keep touching the battery while charging to know if it is charging or not, and I would never do that because my battery would never got hot in just few hours.

                  Comment

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