DC-AC Inverter Output Improvment

Discussion in 'The Projects Forum' started by yuvi1, Feb 1, 2013.

  1. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    Hi everyone
    i'm working on a project and i'm trying to simulate in Orcad
    an Inverter

    I have made a simple Inverter , and im trying to receive an output that is similar to a sine or rectangular wave in the range of (220V AC)

    here is the circuit and the received output :

    any suggestion will be appreciated to improve

    thanks a lot
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,790
    What you have is not an inverter but a useless circuit that is not even doing anything interesting. I think the output is virtually at ground with excursions of plus or minus 40 picovolts. I would start by getting the oscillator to oscillate at a fixed frequency instead of what looks like a Weiner process.
     
  3. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    R6 should be ZERO ohms. Then the oscillator will oscillate but the reverse emitter-base voltage of each transistor will cause avalanche breakdown which slowly destroys the transistors and takes away most of the output power. It also blows up the capacitors.

    If diodes are added to prevent avalanche breakdown then the extrermely simple inverter has the problem of having a square-wave output instead of a sine-wave from the mains and no voltage regulation.

    Another problem is that the base current of the transistors is way too low to make an inverter.

    That lousy circuit is a project on Aaron Cake's site http://www.aaroncake.net where there are hundreds or thousands of complaints about it. Originally the polarity of the capacitors were backwards. I explained why it DOES NOT WORK.
     
  4. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    first of all , i would like to thank you guys , you are very helpfull
    i have built another inverter based on 555 (which i took from one of the posts in the forum) , and i got the square wave i have wanted to achieve.
    after the transformer i have putted a filter that gave me a sine wave.

    my question is , how can i get the sine wave in the value of 220Aac ?
    any suggestions on how to improve the circuit will be appreciated

    thanks guys
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,790
    You might get there with a different transformer, but don't forget that the power out of the inverter will always be less than the power in. Each time you double the output voltage you cut the current in half. I would be surprised if the power out was enough to light a light bulb. Each Ampere you draw from the battery will be result in a bit less than 50 milliamps at the output.
     
  6. ronph

    New Member

    Feb 4, 2013
    25
    1
    I have just completed a circuit similar in design as yours using only two 2N3055 and two 220Ω 5watt resistors (very simple) and of course a transformer. It works up to 10watts only but lights an LED bulb brightly powere by 8AA batteries.

    As to your question on the sine wave/hz...I do not have equipment to give you an answer.

    Cheers.
     
  7. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The output is only 6W.
    What do you have that uses only 6W from 220VAC?
     
  8. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    i just want to simulate for now (using orcad) , and to learn the basics of inverters ( for solar energy).

    can you tell me how can i increase the current of the source
    to get more than 6W at the output ?
    thanks
     
  9. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    You have a low power square-wave inverter circuit and a simple filter that reduces the output level.

    Modern sine-wave inverters use pulse-width-modulation to make a stepped sine-wave from a high frequency carrier. Then a simple low loss filter removes the high frequency.
     
  10. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    Hi guys

    i'm trying to simulate this PWM Inverter based on SG3524
    and i get this error message :

    ERROR -- Convergence problem in transient analysis at Time = 745.1E-21
    Time step = 745.1E-21, minimum allowable step size = 1.000E-18


    I tried to use SG3524 DATASHEET and it didn't help me.

    I tried also to change the values in the SG3524 parameters under the device and it didn't help me also

    p.s
    i took the circuit from :

    http://www.circuitstoday.com/pwm-inverter-circuit

    maby you got any idea which parameters i should use ?

    thanks

    My circuit :
     
    Last edited: Feb 6, 2013
  11. yuvi1

    Thread Starter Member

    Feb 1, 2013
    37
    0
    i have fixed the error in the earlier post
    and now im getting this error :

    WARNING -- Pulse Period < (Rise Time + Fall Time + Pulse Width) for X_U12.xinstsg3524.II8
    ERROR -- Pulse Rise Time must be >= 0 for X_U12.xinstsg3524.II7

    someone knows how can i make the rise time big than zero ?
     
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