Sine wave power inverter


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  1. #1
    Join Date
    Feb 2005
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    Default Yes Indeed.

    Hi Babalola,

    I am just recovering from a terrible financial set back. I work in a part of the country where embedded is not done much and low in returns. A joint venture and lack of paper works almost made be broke.

    I am learning that coding itself does not help, terms and conditions in black and white ensure that you get paid for the job. (The entire production aside)

    I have mentioned in another post by kvrajashekhar (if I remember the name correct) that I could not keep up to my promise so no more commitments. Also being a design house I cannot make the code public due to commercial restriction.

    Lacking an engineering background I do not clearly understand the equations and maths involved in a theoretically backed design. However I try to figure out by studying more and more.

    In my design I sample the output voltage (a dc average) pass it through a PI routine to derive error. The error is basically and inverse of my sinewave modulating quotient. Which gets multiplied with the look up table. To save instruction cycles during table interrupts the entire lookup table is recalculated during zero cross for a cycle and kept in an array. This does not result in a highly pure sine but THD measured was between 2.5% and 4%. Thus waves are corrected only every 10mS. In fact 20mS was the original design to avoid flux imbalance. Now the routine uses flux reset by just switching on the Lower MOSFETs every zero cross. This gives me enough time for housekeeping etc. Like battery capacity measurement, display, communication, discharge profile log and possible econo-mode change during long power outage hours based on previous history.
    All done on a 18F4520 @ 40MHz.

    This forum was the starting place and I require less assistance now but I am grateful to people especially....everyone.
    Regards

    Sougata

  2. #2
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    Default

    Hi Sougata
    Last edited by samrulezzz; - 29th April 2009 at 06:15.

  3. #3
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    Default

    Hi Sougata

    needed a bit of help on inverters using pic16f72
    read ur posts on thE thread
    this thread is a year or more old so i believe u have advanced ur inverter quite a lot

    can u help on pic 16f72 code as i'm very bad on coding weras i ve pretty gud hardware knowledge.......

    sam
    [email protected]

  4. #4
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    Default What help do you need ?

    Hi,

    I do not produce inverters commercially. I only developed the firmware. With the newer PICs having better peripherals design is even easier.
    Regards

    Sougata

  5. #5
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    Default sine wave inverter

    Hi Sougata,

    Its a long time to hear from you.
    To do voltage feedback on the output of inverter with PI routine, is it better done within the main interrupt scheme where the duty cycle is updated or within the background loop and why?.
    Iwanted to try the followings for my digital PI control of the inverter output: If my error is negative
    U(k+1) = -U(k)+ A*e(k) - B* e(k+1)
    If error is positive,
    U(k+1) = U(k)- A*e(k) + B*e(k+1), Does the above make meaning?

    Can any one advice,

    Babalola.

  6. #6
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    Default Please explain the formula

    Hi,

    With a quick look, I couldn't make anything out of the formula. Explain in details about U seems to be the desired voltage, K constant, e error, what about A and B. Are they the P and I .

    How are you tuning k ?

    Post Code.
    Regards

    Sougata

  7. #7
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    Default happy u replied!!!!

    hi Sougata

    Actly its like i'm a final engineering student.....n inverter is ma project for final sem.....i ve a hardware design fot inverter....n also interfacing circuits....which actly i got frm my guide...

    but now problem is no1 around knows PIC properly to write a accurate program.....


    so I was hoping if u could help me on some coding of PIC16f72 to be done.....Particularly PIC16f72 cuz the i ve the design ready for it.....


    can u help me to write a code....or if u cuold give some old code (i.e of PIC16f72 inverter code) u have so that it wud help.....

    sam
    [email protected]

  8. #8
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    Default Post the Schematic

    Hi,

    To help you with the software flow the schematic is needed. Wondering how you rigged up a schematic without having fully understood the programming philosophy and the 16F72 !!!!!!!!!!!
    Regards

    Sougata

  9. #9
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    Default Re: happy u replied!!!!

    hi
    I want to make a sine wave inverter with 310 vdc H bridge as the final stage driven by signal from sine tabled PWM from PIC microcontroler. can anybody suggest me a cheap and best controller from the pic family.

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