Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Sinewave Inverter

Status
Not open for further replies.

JTECH

New Member
Hi all!
I've already built a 12V to 230V inverter in the not so distant past and have modified it to work off 24V (which was an improvement). The design was a simple pulse-width-modulated stepped squarewave and it works well for certain applications, but obviously it is not the answer for all applications.
Does anyone have a proper design for a pure sinewave inverter that will be capable of delivering between 2kW and 3kW? I have searched the web, but the results lead me to some patents and you have to become a member before you can access any info.
Will appreciate any info in this regard.
Thanks!
 
For what reason do you need a pure sine wave? A stepped PWM through a decent filter will work just fine for all but the most demanding situations, and I'm not sure exactly what kind of situation would actually require a pure sine.
 
JTECH said:
Hi all!
I've already built a 12V to 230V inverter in the not so distant past and have modified it to work off 24V (which was an improvement). The design was a simple pulse-width-modulated stepped squarewave and it works well for certain applications, but obviously it is not the answer for all applications.
Does anyone have a proper design for a pure sinewave inverter that will be capable of delivering between 2kW and 3kW? I have searched the web, but the results lead me to some patents and you have to become a member before you can access any info.
Will appreciate any info in this regard.
Thanks!

Basically what you are asking for is a very ineffecient design. But if you really want to try it look at the amplifier section of a standard class AB audio amplifier design at the same power scale!, that is basically what you would have to come up with. Really big heat sinks, tons of dual rail DC current and lots of large device power transistors.

Good luck
 
A class-D audio amplifier can have a pure sine-wave output and is very efficient. It switches its outputs at a very high frequency.
 
He forgot to say that the PWM followed by a lowpass filter is very efficient. Everybody else talked about wasting a lot of power in a linear amplifier.
 
audioguru said:
A class-D audio amplifier can have a pure sine-wave output and is very efficient. It switches its outputs at a very high frequency.

Thanks,audioguru!
I refer here to something that is available nowadays which looks like a pwm smpsu; i.e. there are no bulky low frequency transformers in the unit, rather the smaller version (HF type). The ones that the Chinese build and market, have efficiencies of up to 95% according to their published specs. I don't know exactly how it is done, but the output is a 50Hz or 60Hz pure sinewave when viewed on an oscilloscope. This is perfect for running ac motors such as refrigeration motors, etc.
Do you know of any links that can direct me towards the design of such a circuit?
Thanks!
 
I am in Canada where the electricity is very reliable so I have never looked at inverters.
A few people buy cheap Chinese ones to take camping or hunting or fishing.
People who live in the wilderness use their own generator.

I haven't seen the circuit for a pure sine-wave inverter.
 
Thanks, audioguru! I'll keep on searching because since 1994, the authorities here got onto the gravy train and forgot to plan ahead! No expansion of our power grid was done for many years, so now we have to deal with planned and unplanned power cuts, hence the need for alternative arrangements!
 
Do some research on "variable speed drives" for electric motors and you will see how they modulate the igbt transistors to create the variable frequency 3 phase for the motor. The modulation seems complicated, because of the voltage/frequency ratio having to remain constant. To do this they use a "lookup" table in the uP to avoid making "realtime" calculation. Since you only need constant frequency of 50Hz, using a three phase transformer from, say 24V to 220 (delta/star) connection, a 6 power mosfet bridge circuit, a microcontroller to control the the system you could build a 220/380v three phase inverter. The transformer's impedance will filter the pwm input into a clean sinewave output. (3~+N)
 
I can imagine a few ways of doing this .
Most efficient ways are pwm in the form of *magic sine waves*
(followed by low pass filter like for class D amplifiers & conventional 50Hz trafo)
More efficient (but harder) make a smps for plus & minus top value of youre output (308 volt for 220 volt ac)
Chop out that same *magic sine* with igbt or mosfet & filter like before :)
Depending on the power i would say beware :p
mosfets are very good in being fire emitting transistors when you mistreat them

Good luck
 
"Magic Sine-waves" (from Don Lancaster) are more efficient than PWM.
 
On my search for the same reference material i bumped into this .
**broken link removed**
Personally i still think i stick to smps + magic sine waves on the high side .
The proposed plans of that website are to bulky in my opinion .
Then again its a complete design including software etc. etc.
As reference its intresting :)
Busy days at work stopped my toying for a few months but after the busy days i will finish my experiments .

Goodluck and beware .
3Kw is a evil flamethrower on your desk ;P
 
hi all,
i'm a student of electronics who needs do build a cheap 12V standard inverter.can you help me with the choise of the driver IC(it's needs to be cheap and powered by a car battery 12v) thanks
 
the min required output power is 15 20 watts. the driver must be at 12V power suply(car battery) wich means that it shoud be able to run at voltages like 10.8 and cheap :) the uot voltage is 220 volts but that is secondary goal to reach to .mainly i need a cheap dviver ,which is capable of working on 12v
 
A cheap 20W sine-wave inverter would be a sine-wave generator driving an audio amplifier driving a stepup transformer. The power from the battery will be almost 40W (3.3A).
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top