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Help me design a DC-AC inverter controlled by PWM

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bctang

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DC-AC Inverter

Hi,

I need to design dc to ac inverter from DC +12Volt to AC 230. But i need to use PWM to control the inverter. I using "Sinusoidul Pulse Modulation" to control the MOSFET transistor.

When i using PWM to control the MOSFET transistor (inverter). The PWM signal will distortion. I have testing connect the AC load (lamp 230Vac/5W) , the output voltage from inverter drop to ~120Vac.

How to control or maintian the output voltage always 230Vac when connect AC-Load? :cry:
 

Re: DC-AC Inverter

Feedback loop will regulate the o/p voltage and also stabilize the ckt.

bimbla.
 

Re: DC-AC Inverter

bimbla said:
Feedback loop will regulate the o/p voltage and also stabilize the ckt.

bimbla.
Click to expand...

can u explain more detial about it. TQ! :roll:
 

Re: DC-AC Inverter

Your design is of the driven type.
To regulate the o/p voltage, you need to feed part of the o/p voltage (step-down tapping---->rectify---->filter) and give it to the input. The fed back signal will generate an erroe voltage and o/p correction will take place based on this error voltage.

As far as the o/p waveform is concerned, you have not included (indicated) any form of filter to remoce the carrier. This o/p filter will integrate the pulses to give you sinewave.

bimbla.
 

Re: DC-AC Inverter

bimbla said:
Your design is of the driven type.
To regulate the o/p voltage, you need to feed part of the o/p voltage (step-down tapping---->rectify---->filter) and give it to the input. The fed back signal will generate an erroe voltage and o/p correction will take place based on this error voltage.

As far as the o/p waveform is concerned, you have not included (indicated) any form of filter to remoce the carrier. This o/p filter will integrate the pulses to give you sinewave.

bimbla.
Click to expand...


U mean the o/p voltage(AC 230Volt) need to step-down tapping---->rectify---->filter.
So that,
step 1) the filter signal will feedback to input
step 2) than compare the input signal with the feedback signal the
step 3) than generate the error signal
step 4) than ??

can you have a block diagram from me, may be i more understand from your block diagram. Your block diagram size don't so big because i no enough point to down load. TQ :oops:

How to do the o/p filter will integrate the pulses to give you sinewave?
 

Re: DC-AC Inverter

In your case, if the o/p voltage reduces, increase in sine wave amplitude is required and vice- versa.

The o/p filtre can be nothing more than an LC filter acting as a low pass (integrator) circuit.

If you still do not get the idea, I'll try and come up with some refrences or give you a block dia.

bimbla.
 

Re: DC-AC Inverter

bimbla said:
In your case, if the o/p voltage reduces, increase in sine wave amplitude is required and vice- versa.

The o/p filtre can be nothing more than an LC filter acting as a low pass (integrator) circuit.

If you still do not get the idea, I'll try and come up with some refrences or give you a block dia.

bimbla.
Click to expand...

if the sine wave is distortion are u sure the amplitude can increase? i am using the IC 8038 Waveform Generator.

i have no idea about the o/p filter.

Bellow is my schematic circuit diagram for Inverter-Controller
 

Re: DC-AC Inverter

Would you please STOP uploading your circuits as big proprietary file formats????

People are not gonna download a 1.7MB file and help you if it just contains a simple block diagram...

Please use either Acrobar PDF or GIF/JPEG for circuits!!

No more word/powerpoint documents please!
Next time warning...
 

Re: DC-AC Inverter

Thanks SuperMod, makes my job a little easier.

Your circuit is very simple. Some basic rules of inverter such as complimentary drive with deadzone to drive the o/p bridge are missing. This will result in decreased efficiency, o/p distortion and heating.

I recommend you hit the books and work on some basics. As far as ready reference is concerned, get hold of 12V DC to 230V AC inverter circuit published in ElekTor*

bimbla.
 

Re: DC-AC Inverter

I just realised that you are comparing sine wave with astable o/p. You have missed converting astable o/p to trianglular wave.

You should brush- up your basics. (I hope you take it positively)

bimbla.
 

Re: DC-AC Inverter

bimbla said:
I just realised that you are comparing sine wave with astable o/p. You have missed converting astable o/p to trianglular wave.

You should brush- up your basics. (I hope you take it positively)

bimbla.
Click to expand...


Thank you for your suggestion i will brush- up my basics but now i no have time. I need to complete my project 2 month and this is just of the one part i need to do. Can u help me, i really need your help. How can i improve my inverter? How to design converting astable o/p to trianglular wave?
 

DC-AC Inverter

Consider Close Loop Control through output volatge feedback .. A pid may be considered ...
 

DC-AC Inverter

I just realised that you are comparing sine wave with astable o/p. You have missed converting astable o/p to trianglular wave.

You should brush- up your basics. (I hope you take it positively)
 

Re: DC-AC Inverter

It's called DAC. Digital-Analog Converter. You can find info. easily from the web.
Cheers.
 

Re: DC-AC Inverter

you can type " inverter dc ac power schema " at yahoo search
 

Re: DC-AC Inverter

Well, I've already searched through Google or Yahoo.
I need more specific info from some experts in this board.

Thanx anyway.
 

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