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555 sine wave inverter schematic 2.0

Discussion in 'Alternative Energy' started by tcmtech, Mar 12, 2011.

  1. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    As a follow up design to the basic half bridge 555 timer IC based PWM shaped sine wave inverter circuit I came up with a second version that is a full bridge circuit intended for use at the 170 and 340 volt DC voltage levels needed for doing direct DC to 120 or 240 volt AC power conversion at line level voltages.

    The overall principal of how the PWM shaped sine wave is produced in this circuit is the same as in the basic half bridge circuit but in this application the voltage feedback is not needed. The other change change is that two IRF2110 driver IC’s are used and are working in their normal high side/low side gate driver configuration.
    Due to the overall similarity of the two circuits in both function and theory of operation I will not go into detail on this one being that the 555 half bridge sine wave inverter write up already gives a reasonable theory of operation relating to the components used in this circuit.

    The concept behind this circuit and its intended applications is to use the existing step up and power regulation systems found in common cheap off the shelf modified sine wave inverters as the source for the regulated 170 or 340 volt DC power but make it possible to have a PWM shaped sine wave output by replacing the original modified sine wave output stage with this circuit. A second application would be for producing AC sine wave power from modified alternators or other home brew alternative energy DC based generator systems that have their own voltage regulation systems.


    Power Switching devices.

    For the switching devices I recommend they have a 2x working voltage rating over the maximum DC voltage where ever possible and a 4x peak current capacity rating over what the unit is intended to have as a peak load as well.


    C17 and L1a/L1b.

    On the output there are two iron core type inductors shown that work with C17 as the final stage filter to dampen the 30 KHz carrier frequency on the 50 or 60 Hz sine wave. For these two inductors their values and design have to be matched to the power levels that this circuit is working at so there is no exact number or size I can give you size wise. The best rough rule would be to use a pair of common laminated iron transformer cores with approximately 10 - 30 turns of wire of a size adequate to carry the peak working amperage expected from this circuit.
    Ideally this inductor pair can be calculated to an exact value along with C17 to provide the best possible filtering but unfortunately numbers on paper do not tell you what your available parts actually have as real applied working values. However if a 1 uf poly capacitor was used for C17 it would exhibit roughly 5.6 ohms of impedance at 30 KHz and around 2650 ohms of impedance at 60 Hz. A suggested inductance value for the L1a and L1b inductors would be around 1.5 – 3 uh. At 30 KHz a 3 uH inductor would provide roughly 560 ohms of impedance but at 60 Hz it would only produce around 1 ohm. With those two approximate values you would be getting roughly a 100:1 attenuation of the 30 KHz carrier frequency on the output.

    555 Full Bridge Signwave Power Inverter (dual volt input).png
    Click on thumbnail for full size view.
     
    Last edited: Mar 13, 2011
  2. noviceonrun11

    noviceonrun11 New Member

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    a simple question

    I followed this circuit of yours for my project work. The only change I made is to use MOSFETs instead of IGBTs and supply voltage to the MOSFET is 16-18V dc. The prblem I'm now facing is that I'm not getting the desired output. I'm getting a nearly smooth sine wave at the output which shouldn't be happening I guess. Please guide me I'm lost. Also I'm looking for a square wave in the circuit which I cannot find at either of the 555 IC's. Please reply as soon as possible.
     
  3. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    I am not sure what you are saying exactly. If you are getting acolse aproximation to a sine wave at the power output then the circuit is working properly. Its actually a PWM shaped sine wave but once passed through the filtering circuit of the power output its going to be as close to a sine wave as any typical piece of electrical equipment is going to need.

    Relating to the square waves on the 555's I have no idea what you are referring too exactly as well. With a proper oscilloscope they should be visible and obviously if the power output is producing a sine wave then the 555's and the other related circuitry is probably working as well.

    Without further explanation I can only guess at what you are saying or implying and to how or what is going on.
     
  4. dave

    Dave New Member

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  5. noviceonrun11

    noviceonrun11 New Member

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    another doubt

    thanks pcmtech.. i want to know on which two points I'll find the pwm square wave pulses.. the one point i thought was the output pin of the 741 with respect to ground but couldn't find it there. Also if I want to change the duty cycle of the waveform how should I do it.. I tried to change the variable resistor but no matter how much i rotate the variable point there's no change in the waveform.. also when I reduce the supply voltage to zero the waveform still remains atlhough very less.. is it because of the capacitor discharging of the cicuit...?? and do i need to use a phase controlled circuitry if i want to connect the inverter output to a simple ac system with a load so as to keep the ac system voltage constant..??

    Thank you

    noviceonrun11
     
  6. tcmtech

    tcmtech Well-Known Member Most Helpful Member

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    The square waves still come out of the 555 IC's outputs. After that they get reshaped to other wave forms in order for the 741 to create the proper PWM shaped sine wave.

    The voltage output is not regulated so yes you need a have a stable DC voltage source to get a stable AC voltage out. The whole concept of this circuit was to be able to bypass the output stage of a cheap DC to AC power inverter and get a reasonable sine wave output.
     
  7. noviceonrun11

    noviceonrun11 New Member

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    Dear pcmtech,
    can you please write a full working description for the above circuit.. i went through thw half bridge circuit you posted earlier but there are some changes in this circuit so i thought i'll just ask you a favour. Also can you suggest me any changes I should make in the circuit components to make the circuit work on my voltage level.

    Thanks you,

    noviceonrun11
     
  8. noviceonrun11

    noviceonrun11 New Member

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    by the way my circuit voltage level is same as I posted earlier on this thread..

    thank you
    noviceonrun11
     
  9. Ronald_dm28

    Ronald_dm28 New Member

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    will you pls help me to find solution to my pc. Ifound out a defective RT 9214 dc converter, soft start inside my AMD mother board, is there any remedy to solve my problem. The Ic has no output voltage so, I have to replace it. but not available in my town
     
  10. lillian

    lillian Member

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    Hello can anyone tell me if the ic used is IRF2110 or IR2110 I want to build this circuit. Thank you anyone can reply
     
    Last edited by a moderator: Oct 10, 2011

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