Sine wave invertor with one winding in the primary

Discussion in 'Power Electronics' started by Motanache, Oct 23, 2017.

  1. Motanache

    Thread Starter Member

    Mar 2, 2015
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    I want to build an inverter 12VCC-230V Ac 60Hz.

    But all the schemes I've found have two windings in the primary:
    [​IMG]
    If I want the primary to have a single winding I should have had a H bridge.
    Do you have other simple ideas?

    If instead of the complicated waveform I simply put rectangle signal in primary can work?
     
  2. Reloadron

    Distinguished Member

    Jan 15, 2015
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    Actually what you see in your drawing is not two windings but a CT (Center Tapped) winding. Additionally if you look closely at most of these inverter drawings that center tapped winding is actually the secondary of a step down transformer. Transformers do work both ways and most of the online drawings use a step down transformer of 120 or 220 Volts to either 12 or 24 volt secondary having a CT.

    There are also schematics and drawings of transformers which are not center tapped. The idea here is you use a square or rectangular waveform to generate a higher voltage square of rectangular waveform. Today's inverters have several different types of outputs, for example a MSW (Modified Sine Wave), square wave or a TSW (True Sine Wave (as well as other waveforms based on the design. You choose an inverter output type based on your needs and application. You also need to choose a transformer which will deliver not only the desiredpower but work with the waveform.

    Overall when it comes to inverters you will find it easier and less costly to buy rather than build. You also make no mention of power you expect or need? Running on a 12 volt battery a simple 500 watt inverter would draw 42 Amps @ 12 VDC. That does not even take into account inefficiency so the current at 12 volts would be even greater.

    Ron
     
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  3. Motanache

    Thread Starter Member

    Mar 2, 2015
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    I want a portable source to test this:
    I could buy a UPS but ...............


    [​IMG]
    The ideal power would be 120W. But to find a light bulb at 10W. Let's say 10W minimum power.


    I have a transformer 230V 50Hz ->12V 1.6A 20VA

    Power Laptop battery 11V (3x3.7V) and 4Ah.
    Battery that I think has 1/3 of the original capacity.

    I have drivers IR2153 SG3525 and TL494

    "There are also schematics and drawings of transformers which are not center tapped."
    Sure, but if I solder center winding point, then I do 2x6V.
    If I still winding another coil has no space.

    I'll make H bridge and I'll ask you what signal to use.
     
  4. Motanache

    Thread Starter Member

    Mar 2, 2015
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    In principle, these are two variants:
    [​IMG]
    The rectangular wave would be the easiest taking into account the drivers I have.
    The signal in the figure called "Modified square wave" I get it more difficult.
     
  5. Reloadron

    Distinguished Member

    Jan 15, 2015
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    The first circuit you posted. labeled as Figure 1 is a basic triac circuit of the type commonly found in inexpensive lamp dimmer circuits. I don't see where that has much anything to do with building an inverter circuit and that triac circuit is designed to work with a sine wave input. The second circuit you posted are just examples of inverter outputs that I mentioned above, You have a square wave (Green), a modified Sine wave (Blue) and lastly a sine wave (Red). I still do not understand the association between the triac circuit and making an inverter?

    Any self oscillating driver like the IR2153 which you mention would be a good start. Using the IR2153 as an example there are plenty of application notes out there showing usage including MOSFETs which can be driven.

    Why are we suddenly looking at an H-Bridge? There are hundreds of basic inverter circuits out there. All you are doing is making an oscillator to drive a transformer at a known frequency.

    Ron
     
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  6. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    I would use the TL494 chip, you're better using a ct transformer for an inverter, with mosfets as the pushpull output.
     
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  7. Motanache

    Thread Starter Member

    Mar 2, 2015
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    This dimer is the load. For it I build the inverter. I posted the schematic to tell me how good the sinusoidal signal should be at the output of the inverter to go fed that dimmer.


    I have a square wave (Green), a modified square wave (Blue).
    Both give a nearly sinusoidal signal to the transformer output.
    But there is a difference between those two.

    I posted this to tell me which one to choose
     
    Last edited: Oct 24, 2017
  8. tcmtech

    Distinguished Member

    Nov 4, 2013
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    I've ran many dimmable (portable work flood lights) lights off of non sine wave inverters and most dimmers that used that basic two resistors and a capacitor RC timing circuit to delay the triac triggering tended to work fairly well. They were not as smooth and linear in their dimming rate in relation to the value of the variable pot as they were in a sine wave power source e but they did work well enough to worth noting.

    The bigger question os what is the load and to what degree of linearity and accuracy do you need in your range of min/max control of it?
     
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  9. Reloadron

    Distinguished Member

    Jan 15, 2015
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    While I never tried it I would run with tcmtech's post since he has done it. Just know your load verse what you have.

    Ron
     
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  10. Motanache

    Thread Starter Member

    Mar 2, 2015
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    I chose SG3525 and rectangular wave.
    There are many schemes on the Internet if I search with "SG3525 50Hz" from which I will inspire.

    Now I realize the schematic on the test PCB. if I have difficulties I will write to you.

    About linearity is not a very strict requirement.
    Anyway, I want to realize first with an inverter that works. Then to improve it.
    I think from SG3525's "recitation" (pins 1,2,9 err op amp), in fact, the pin 9 voltage I can obtain a modified square wave (Blue post #4).
     
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