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ZFM Advanced Explorations Part II

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  • #46
    6 Pole ZFM with Coils in Parallel

    Completing the test program of the 6 Pole ZFM was a series of experiments with the bifilar coils wired in a parallel configuration versus the prior Post's series configuration. The overall three coil parallel resistance was 1.5 ohms compared to 6.0 ohms for the prior series arrangement. The parallel configuration was tested with and without the BEMF recovery circuit and with the 60v Power supply and 24v LABs for comparison. Only the 24v data will be presented at this time.

    The coils in parallel create a different mode of ZFM operation. The amperage draw is nearly double the series mode value for a given run voltage, while the RPM is also nearly twice the series value. The impression is that the motor is running at a much higher voltage. All in all, this mode creates a very tractable motor for certain applications with power efficiencies very close to or at 50%. The 4 Pole ZFM will display similar characteristics when properly configured in parallel mode.

    Below is a sample of the data points for both options. The ZFM has slightly different characteristics between the two types of applied power - the LAB runs required a timing adjustment to compensate. The attached pics were all generated under no Load. Pic 2 demonstrates the oscope wave form for the LAB without the BEMF circuit, while Pic 3 with the BEMF circuit engaged. The Power supply mode with the BEMF circuit engaged is nearly identical to Pic 3 and not included.

    Parallel Mode with Power Supply no BEMF Circuit (Pic 1)
    4360 RPM 24.01v 0.60A 0gr Load
    3234 RPM 24.40v 1.46A 800gr Load 47.3% Eff
    2662 RPM 24.29v 2.12A 1350gr Load 44.5% Eff

    Parallel Mode with LAB and BEMF Circuit (Pic 2 and 3))
    4640 RPM 24.88v 0.65A 0gr Load
    3616 RPM 24.71v 1.52A 800gr Load 50.1% Eff
    2825 RPM 24.64v 2.22A 1400gr Load 47.1% Eff

    Pretty much done with this particular 6 Pole rotor after achieving all the initial design goals and ready to move on to the next phase.

    Pic1
    pic_174_2.JPG

    Pic 2
    pic_174_5.JPG

    Pic 3
    pic_174_4.JPG

    Yaro

    "The Universe is under no obligation to make sense to you." -Neil Degrasse Tyson

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    • #47
      Great report ,Yaro. Looking forward to anything about the 60v results. thanks

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      • #48
        Yo Dennis,

        Thanks for the reply and your suggestions are in mind. This particular 6 pole rotor config has been operated up to 60v in series mode - it is a bit of a monster at this voltage and it yields comparable efficiencies, but the limits of the torque testing apparatus are pushed. In parallel mode the apparent voltage and amperage are magnified by a factor of two or so

        In parallel mode the highest voltage has been limited by the LAB's at 24 volts. The BEMF circuit in its present config has its voltage limitations. I can use the 60v power supply but the motor operation is not as smooth as with the LAB's. In the past the parallel coil circuit has been pushed to 36v with comparable results, but the coils start to overheat due to the higher amperage draw. There is a give and take here that imposes limitations inherent to the coil design parameters.

        I will give it a shot this coming week using the power supply to jack up the voltage in parallel mode. Better yet, build your own ZFM and play to your heart's satisfaction.

        Later,
        Yaro
        Yaro

        "The Universe is under no obligation to make sense to you." -Neil Degrasse Tyson

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        • #49
          ZFM Video - 6 Pole in Parallel

          To finish the documentation on the parallel mode of operation for this rotor (2"Lx1/2"Wx1/2"T) the following video was completed to flesh out the information.

          The setup was the normal arrangement with the exception of the individual coils being wired in parallel and then connected in series. Parallel mode compresses the operation by reducing the voltage required to drive a load at a desired low usable RPM. Very useful for the lower RPM range in that it can be a direct drive type of arrangement for transmitting power; powered either through a solar panel or LAB. The nominal power efficiency throughout the test was 50%+/-.

          RPM Volts Amps Load gr %Eff
          4182 24.08 0.57 0 0.0
          3350 24.42 1.37 800 52.1
          2550 24.98 2.02 1400 46.1
          5186 30.18 0.69 0 0.0
          3343 30.03 2.03 1400 49.5
          6014 36.03 0.77 0 0.0
          4167 35.99 1.99 1400 52.7
          I may add some more info to this post later, but ready to move on...

          Yaro Happy Valentines Day
          Last edited by Yaro1776; 02-15-2020, 05:18 AM. Reason: Added Data Table
          Yaro

          "The Universe is under no obligation to make sense to you." -Neil Degrasse Tyson

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          • #50
            Great to see you're still at it Yaro

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            • #51
              Originally posted by John_Koorn View Post
              Great to see you're still at it Yaro
              Thanks for the encouragement John!

              Not done with this motor as yet and am preparing another rotor design for the 6 Pole. I expect to put this modification into testing shortly with the goal being an efficiency of 60% under load while staying within the dimensional constraints of the existing motor body and three coll config for the 6 Pole.

              The virtual pole concept for the air core coils is still in play...
              Yaro
              Yaro

              "The Universe is under no obligation to make sense to you." -Neil Degrasse Tyson

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              • #52
                ZFM Video 20.4 6 Pole

                So the next rotor configuration was designed to further explore the displaced magnetic poles of the coil. The static arc width of the individual coil poles was set to 560 by increasing the width of the Neo's to 0.75", unfortunately the Neo lengths and thicknesses available for this width are very limited. As a compromise the length was set at 1.5", a bit shorter than the rotor length of 2", with a coil to Neo gap of 0.130" +/-. Not ideal but useful nevertheless for exploring.

                So the coil arc dimension is 450 and the Neo's are separated by an arc of 600. So there remains a bit of play here that needs to be considered. That is the fun part and the most tedious to explore. For this config the overall length of the coil power on period is 490 taken directly from the screen shot. This value can be expanded or contracted a bit by the positioning of the reed mount with respect to the timing rotor face. The start of the power-on pulse (advance) can be controlled by rotating the reed mount cylinder.

                Since the coil's magnetic poles function in a simultaneous push/pull manner on the 6 pole rotor the coil magnetic pole arc value becomes very important. One can design for the static configuration, but does this hold true dynamic operation? Good question...

                Anyway, for the video the ZFM was operated at 48v to demonstrate the major point - BEMF value and its influence. By nature, adding more Neo's and coils for a given design will increase the BEMF. For this config the peak BEMF is typically ~15% higher than the input voltage at unloaded speeds. Reducing the number of rotor poles and motor coils will reduce the BEMF value for a given RPM. The reverse is true also.



                The load for the video was 1400 gr. yielding 25.5 watts or 18.8 ft lbs/sec of useful power at an efficiency of 46-47%.

                Changing the wiring from series to parallel mode at 24v yields nearly identical results.

                Yaro
                Yaro

                "The Universe is under no obligation to make sense to you." -Neil Degrasse Tyson

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