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Transformerless inverter

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babinton

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transformerless inverter

Hi everyone, I am planning to build an Inverter with a step up DC-DC stage switching at 20KHz coupled to the Inverter stage directly without an High frequency transformer. After the Inverter stage I intended to filter the resulting mid voltage range PWM output and use a 60 HZ power transformer to step up the ouput to 230v(note the inverter stage will be switching at 60HZ).
My question is that is such an inverter design possible? and if it is possible, what are the drawbacks/limitation. Any comment will be greatly appreciated.
Regards
Babs
 

transformerless inverter circuit

Pure sine-wave inverters from China do not use a 60Hz stepup transformer.
They use a 12VDC to 325VDC high frequency circuit with a small ferrite transformer then use a PWM controller IC to switch high voltage Mosfets to make the PWM sine-wave and a small filter removes the high frequencies. They have feedback for voltage regulation.
 

three phase transformerless inverter

hi Audioguru

i need any study material or circuit layout or application notes ( for transformerless inverter/ ups)

i need some help


please..................

:D
 

sine wave converter transformerless

i am not understanding the step up voltage range before inverter stage! can you provide block diagrem by mentioning voltage levels.

i think you design is possible ..please give full detais

darla
 

transformerless high voltage multipler

If your mains is 230V then it has a peak-to-oeak voltage of 524V. So use a high frequency DC to DC converter to make 524VDC and use a pulse-width-modulation controller IC to drive high voltage Mosfets from the high DC voltage to make a PWM 60Hz sine-wave.
Simple.
 

boost converter transformerless inverter

230Vrms mains has 648Vpp
 

transformerless voltage multiplier circuit

My fingers slipped on my calculator. I calculate that a 230V mains has 650.44V peak-to-peak.
 

transformerless timer

Your fingers slipped at least twice. First time on calculator and second time when you were typing the second post. Third time is maybe in your third post.
But it does not matter.
 

transformerless step-up voltage

Borber said:
Your fingers slipped at least twice. First time on calculator and second time when you were typing the second post.
My second post has the p-p calculation for the 115V mains in North America
 

transformerless 230v inverter

Either that is not true. 115Vrms has 324Vpp and not 524Vpp. But it allso could be that now in North America mains voltage has different than sine shape.
 
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12 volt to 230 ac transformerless inverter

Borber said:
Either that is not true. 115Vrms has 324Vpp and not 524Vpp. But it allso could be that now in North America mains voltage has different than sine shape.

no... it's a sine wave, with a little 3rd harmonic in there from all those computer loads, but that depends where you live.

Consider the mains to be 115 to 125Vac
x 2 x root 2 = 325.269Vpp to 353.5523Vpp
 

full bridge inverter transformerless inverter

OK, I just wanted Audioguru to use the right formula.
 

sma transformerless north america

hi guys, thanks for your responses, however I know that I can use a DC-DC transformer for stepping the voltage to 650V DC and use PWM to drive the Power mosfet but the thrust of this project (which I decided to investigate by myself) is that Is it possible to realise the inverter without using a transformer but instead use a voltage multiplier circuit i.e. BOOST converter stage to get a voltage of 650V DC from a source of 24-48V DC.
 

high frequency transformerless inverters

You would need multiple stages of boost to keep switching losses low, but yes, you could.

however it will require more magnetics and switches than will a transformer. Needless to say will not be isolated from the input.
 

transformerless voltage doubler

First of all this formula is wrong.
There's no 2xroot(2) but one.
So if you wannt voltage pick to pick formula is:
Vpp=Vsin x sqr(2)
Vpp=115 x 1.41
Vpp=162.15V
For 230V is:
Vpp=230 x 1.41
Vpp=324,3V
Look some time in electrolitic capacitors what is writted on his case( 350V )
So if youre formula right but not,then voltage will be:
Vpp=230 x 2.82
Vpp=648,6 V -that is not possible,this high voltage will destroy capacitor?

Added after 6 minutes:

Oh i forget answer- THIS IS NOT POSIBLE WITHOUT TRANSFORMER OR BOBINE!!!
 

transformer 12vdc 325vdc

zlatkoMM said:
There's no 2xroot(2) but one.
So if you wannt voltage pick to pick formula is:
Vpp=Vsin x sqr(2)
Vpp=115 x 1.41
Vpp=162.15V
For 230V is:
Vpp=230 x 1.41
Vpp=324,3V
No.
Your formula is for the peak voltage, not the peak-to-peak voltage.

So if youre formula right but not,then voltage will be:
Vpp=230 x 2.82
Vpp=648,6 V -that is not possible, this high voltage will destroy capacitor?
Correct.
Where is the capacitor?
 

spanish transformerless inverters

You are realy hard.
I mean electrolitic capacitor after diode bridge(gretz) directly conected on 230 V.
And smart guy do you ever see capacitor with 700V in this kind of circuit.
Of course you dont.
I only see 350V or in some cases 400V capacitor in similiar cases.
And my formula is right.
If you think that formula is not right how you explain this:
After diode bridge(gretz) its capacitor.
For example if you dont have capacitor conected and if you measure voltage on
out of gretz you measure Vef--Vsin so if you have 10 V/AC in input you have
about 9V on out of gretz so when you conect capacitor voltage jump for sqr(2) up
So Vout =9 x 1.41 = 12.69.
I ask you why voltage not jump for 2x1,41 like you said that is Vpp.
Something is realy wrong with youre mathematics?
 

transformerless calculator

zlatkoMM said:
I mean electrolitic capacitor after diode bridge(gretz) directly conected on 230 V.
And smart guy do you ever see capacitor with 700V in this kind of circuit.
Of course you dont.

You would find that in a power supply running off 240/480Vac, two 400 volt caps in series, with a switchable voltage doubler for operation on 240.

If you have a pwm bridge out, then you only need Vp. so on 120Vac that's a 200 volt cap, or a 400v cap for 240Vac out.

IF you are using a half bridge inverter, then you NEED the voltage doubler because you can only drive the output halfway, using a split supply running off +325 and -325volts
 

transformerless boost inverter

I dont say to you Johansen i say to Audioguru....
 

calculator transformerless

Zlatko,
If you rectify and filter 230VAC then you will have 323VDC. Then if you use an H-bridge to make a PWM sine-wave with the 323VDC, the sine-wave will be only 114V RMS.

A 230VAC sine-wave is 650V peak-to-peak.
 

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