Wind generator Voltage controller

Discussion in 'The Projects Forum' started by kronk, Jul 13, 2008.

  1. kronk

    Thread Starter New Member

    Jul 13, 2008
    3
    1
    Hi All,

    I am building a wind generator to charge a 12v bank of batteries and I am stuck on the design of one of the circuits i am going to use. Actually its not the design as much as its the selection of components and values... I am setting up the system like this Turbine -> Voltage Tripler -> Voltage Regulator -> Charge Controller -> Battery Bank -> Inverter.

    I have tested the turbine and estimate it will produce 1 - 6 amps and 1 - 11volts(before the tripler). The circuit that i am having difficulty designing is the Voltage Regulator because it will have variable voltage and current to the input. The output will go to the batteries which require approximately 14V to charge, the current is not a concern because the Charge Controller will prevent over charging and the tripler will keep the current reasonably low.

    I have researched some components and http://pdf1.alldatasheet.com/datasheet-pdf/view/56777/BURR-BROWN/OPA501AM.html seems to be my best bet for the opamp. But as for the other components such as the transistor, zener diode and resistor values i am not sure what to use??? its been a few years since i have done any circuit design, the tracing of current and such came back pretty quick but with selecting values I am still lost ...

    Here is the circuit i am going to use, a pretty basic voltage stabilizer where the operational amplifier opens the transistor more if the voltage at its inverting input drops significantly below the output of the voltage reference at the non-inverting input. R1 and D2 will set the Voltage reference, R2, R3, R4 will set the output voltage between D2 and Input.

    [​IMG]

    Thanks,
    Ken
     
    Last edited: Jul 13, 2008
    Hasan Yahya likes this.
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    You'll definitely want to replace the 2N2222A, it just won't handle the current you need. Consider using a PNP Darlington as a pass device. Perhaps a TIP105 or some such. (Naturally, you'd need to re-work the op amp inputs if you do this.)
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You're going to have a tough time with that, particularly if the turbine is producing less than 8v or so. Even with just a 5A output, a switching boost or flyback topology would require a huge amount of current at lower voltages.

    But don't take my word for it. Plug your numbers in yourself:
    http://www.national.com/analog
    Use their Webbench designer tool, upper right.

    If you use a voltage tripler, your current will be divided by more than three, even if you use Schottky diodes. If you triple 5V, you will only get about 14.1v depending upon the Vf of the diodes at the current flow. There is no free lunch in Electronics.

    You might have some kind of luck with a SEPIC supply. Have a look at Coilcraft's application note:
    http://www.coilcraft.com/pdfs/doc639_Selecting_SEPIC_Inductors.pdf
     
    Last edited: Jul 13, 2008
  4. kronk

    Thread Starter New Member

    Jul 13, 2008
    3
    1
    Thingmaker: multisim just defaulted to the 2n2222 the darlington pair is a good idea though

    Wookie: Thanks for the links those are definately getting bookmarked At first glance a
    few of those chips from National look like they would work. The output of the circuit will only need to be 14v @0.5A-3A it would just be trickle charging the battery bank at lower amps. Basically i am looking for a circuit that will regulate the voltage at 14v and pass low amps through and the Buck regulators seem to fit.
    LM25576
    Output Current = 3A
    Input Min Voltage = 6 Volt
    Input Max Voltage = 42 Volt
    Output Min (adjustable) = 1.23 Volt
    Output Max (adjustable) = 40 Volt
    As you were saying before they demand a lot of current which is concerning as this chip doesnt seem to list input current requirements just Vcc current which is 25uA. However there is a section called
    CURRENT LIMIT
    Cycle by Cycle Current Limit "RAMP = 0V(condition)" 3.6(min) 4.2(typ) 5.1(max) A

    Forgive my ignorance but this is confusing, why is there a minimum value in Current "Limit" and does this mean the minimum input current is 3.6A to generate an output?

    Thanks again for the help.
     
  5. offgrid

    New Member

    Jul 22, 2008
    1
    0
    I have just joined and am looking for an adjustable 30volt 400 amp generator controller and saw your post. In wind regulators you must use some sort of load diversion circuit to control battery voltage. The reason being that the overspeed of the blades must be taken into consideration. Under load the turbine can furl to prevent damaging itself. Therefore the output is connected directly to the battery and the circuit clamps the voltage to a large resistor capable of dissipating the full power of the turbine. Never unload a turbine blade as it will self destruct in high wind speeds which I have experienced. Southwest Wind Power have some manuals in Pdf format including circuits for their 900, 1000 and 3200 watt wind turbines.
     
  6. kronk

    Thread Starter New Member

    Jul 13, 2008
    3
    1
    Southwest Windpower has an interesting site and convinced me even more to build my own stuff those prices are Nutty!

    The controller circuit i plan on using will switch the output of the turbine to a dummy load as you say when the batteries are at full charge. Having it switch to the dummy load when the RPM's get to high is an idea i had been toying around though i was just planning on shorting out the leads. I do not want the output of the turbine to go directly to the batteries. I have read that batteries do act as somewhat of a governor by increasing the load as the power into them is increased. However putting too much voltage into the battery can cause damage if done for an extended period of time. I have decided to use a simple zener/ power transistor in parallel to achieve the regulation. I am still working out some of the controller but will post it when i am complete.
     
  7. wilfor03

    New Member

    Jan 12, 2009
    1
    0
    Hey "kronk"....just viewed your msg about the controller circuit you want to build (07-23-08). Have ya done any good with it yet? Have ya built it yet? Just curious down here in Alabama, USA......I've started building a controller board also for a Savonius ginny and hope it works for what I want. Let me know if yours worked or where you're at with it, 'n mabe I can help ya. See ya from Alabama.....Bill
     
  8. unomi

    New Member

    Jan 13, 2009
    6
    0
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