RF Power Correction Device. Suggestions/Assistance requested

Discussion in 'Off-Topic' started by d333b, Nov 29, 2010.

  1. d333b

    Thread Starter New Member

    Nov 1, 2010
    To all,
    I have a project that I am working on and would like some suggestions/brainstorming help. Now from all the research that I've done it does not seem like anyone has taken this type of project to this level. Quite simply the goal of this project is to provide the correct power correction for a high frequency inductive circuit that has constantly changing frequency, inductance, and current. This device in question needs to be able to correctly choose a combination of capacitors to place in parallel to the inductive circuit to minimize the reactive power (as the field generated by the inductor is relevant only to the real power) automatically. It must be able to perform this calculation in the range of 500 mHz to 5 Hz, the capacitor array will likely be controlled via relays to reduce cost (as a 10 SSR's gets pricey fast!) I have attached a rough block-diagram type schematic.

    From the schematic:

    U1-2: High Speed Comparator TL714CPE4 From TI http://www.mouser.com/Search/ProductDetail.aspx?R=TL714CPE4virtualkey59500000virtualkey595-TL714CPE4
    U3: XOR with < 5nS propagation delay
    U4: AND with < 5nS propagation delay
    U5: Cyrstal Triggerable f-Gen f = 100MHz to 500MHz
    U6-7: High Speed Counters (Piggybacked to make 8 or maybe 16 bits (dependent upon f-Gen frequency)
    U8: An MCU likely to be a high end PIC but possibly a NI LabVIEW interface device. R1: Shunt wire (~1Ω)
    C1: Capacitor array controlled via the onboard processor or a off board LabVIEW controlled device.
    L1: Load Coil
    X1-2: Custom made transformers, both must be high in impedance and be capable of passing 20 MHz (for error padding).

    So my current theory on operation is that the comparators will take the waveform from the X-former and produce a corresponding square-wave. One of these waves will be of the voltage waveform (blue waveform) the other will be the current waveform (red waveform). These waveform's will then be compared in a XOR to find where the waveforms are not the same (orange waveform), this form will then be "AND'D" with the current waveform, or voltage. This will eliminate the double count per pulse (green waveform).It can also be used to figure out leading or lagging by comparing the lengths of both, I have not added this circuity into the digram yet to keep it simple. This pulse is then used to trigger a much higher frequency signal in bursts (purple waveform). These bursts are then counted by a counter, the current (or voltage) waveform is also counted by a counter to gain frequency so as that the counter on the purple waveform is divided by the frequency counter to get a fairly accurate understanding of the phase shift. The MCU will then place a capacitive value in parallel with the load, the corresponding phase shift from that action can then be used to calculate the best match capacitive value.

    Now I know full well how much (read little) experience I have with this sort of circuit. I am assuming that this might work and have ordered some of what I need to get started on an experimental phase (The comparators, gates, counters and my MCU.) I am having issues deciding on how to do the transformer. Obviously the power rating is not a factor (as its should be no more than a couple of mW.) I have been having a very hard time finding a X-former that has a very high impedance and can pass such high frequencies, even in the top end level. I am thinking that I will have to build my own, but I don't really know where to start. Most of what I find is more concerned about what your output power, power loss, output ratio is. And to me none of that is important as long as the comparator is able to create a respectable waveform. Any help on that front would be greatly appreciated. If anyone knows a possible bypass to the X-former route. I will of course require that whatever is used to isolate my digital electronics from the coils circuit. I would also like to ask if someone could tell me if I just completely off my rocker thinking this will work or not (the phase detection circuity). Let me know if I have missed something.

    TIA :D,

    Dan B
  2. SgtWookie


    Jul 17, 2007
    Yet another attempt to "re-create" ol' Stan Meyers' hogwash.

    We don't support discussions of this nature.

    The more quickly you abandon this project, the less time and money you will waste on it.

    No matter how hard you try, or how badly you would like to do so, you cannot change the laws of physics.

    Please see the "sticky" topics in the "Other Topics" forum.
  3. retched

    AAC Fanatic!

    Dec 5, 2009
    Friend, the problem finding parts for these types of circuit is easily explained.

    The folks who designed them designed them for the future when the items may be possible to build.

    Inductors "fill-up" with high frequency to the point they stop conducting.

    That is why they dont work.

    You can make the math work.. thats easy.. But you cant make the materials work.. thats the problem.

    Until superconductors are available at room temperature, these will not be feasible.

    The small amount of power savings will be crushed by the cost of the technology.

    The relays alone, as mentioned, are pricey.

    If you manage to balance PF and save a kWh a day, you will be saving 11 cents a day.

    At 11 cents a day, the superconductors made of pure platinum will set you back about 730 years.

    Remember, just because it can be written down, does not mean it can be made.

    Also, the value of inductor you choose will change it's inductance with your frequency changes. SO, you will require separate inductors for each frequency 'chunk' to keep things straight.
  4. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
    I didn't pick up it was a Stan Meyers design but more a power factor correction circuit. U5,6,7 could probably be omitted.

    edit: ahh 5Hz to 500MHz yep it's something odd. Probably HHO as mentioned earlier.
  5. beenthere

    Retired Moderator

    Apr 20, 2004
    Thanks to the Sarge on this one. I would have picked up on LM324's in a heartbeat.

    I though the thing was way overelaborated, but tuning over that range gets intense.

    Please do read through the material at the link - http://forum.allaboutcircuits.com/showthread.php?t=28067

    It explains why all this crud is a waste of time.
  6. beenthere

    Retired Moderator

    Apr 20, 2004
    I have a message from the OP. In part:
    So the thread is opened, but some real curiosity remains.