Make 400 watt MOSFET Sine Wave Inverter

The post explains probably the most easiest 400 watt sine wave inverter circuit, which requires lowest number of components and yet is able to produce optimum results. The circuit was requested by one of the active participants of this blog.

The circuit is not actually a  sine wave in true sense, however it's the digital version and is almost as efficient as its sinusoidal counterpart.

How it Works


From the circuit diagram we are able to witness the many obvious stages of an inverter topology. The gates N1 and N2 form the oscillator stage and is responsible for generating the basic 50 or 60 Hz pulses, here it has been dimensioned for generating around 50 Hz output.

The gates are from the IC 4049 which consists of 6 NOT gates, two have been used in the oscillator stage while the remaining four are configured as buffers and inverters (for flipping the square wave pulses, N4, N5)

Until here, the stages behave as an ordinary square wave inverter, but the introduction of the IC 555 stage transforms the entire configuration into a digitally controlled sine wave inverter circuit.

The IC 555 section has been wired up as an astable MV, the 100K pot is used for optimizing the PWM effect from pin#3 of the IC.

The negative going pulses from the IC 555 are only utilized here for trimming the square wave pulses at the gates of the respective MOSFETs, via the corresponding diodes.

The MOSFETs used may be any type able to handle 50V at 30 amps.

The 24 batteries need to be made out of two 12V 40 AH batteries in series. The supply to the ICs must be provided from any of the batteries, because the ICs will get damaged at 24Volts.

The 100K pot should be adjusted using an RMS meter for making the RMS value at the output as close as possible to an original sine wave signal at the relevant voltage.

The circuit has been exclusively developed and designed by me.


Feedback from Mr. Rudi regarding the waveform issue obtained from the above 400 watt inverter circuit


hi sir,

i need your help sir. i just finished this circuit. but the result is not as what i expected,  please refer to my pictures below.

This is the wave measure from the gate side (also from the 555 and 4049 ic): it look just nice. freq and duty cycle almost at desire value.



this is the wave measure from mosfet drain side. everything is mess up. freq and duty cycle are changes.



this is i measure from output of my transformer (for testing purpose i used 2A 12v 0 12v - 220v CT).



how to get the transformer output wave just like a gate one? i have a ups at home. i try to measuring the gate, drain, and transformer output. the waveform is almost the same on that small ups (modified sinewave). how do i achieve that result in my circuit?

please kindly help, thanks sir.

Solving the Waveform Issue


Hi Rudi,

it's probably happening due to transformer inductive spikes, please try the following:

first increase the 555 frequency a bit more so that the "pillars" across each square wave cycles look uniform and well distributed..may be a 4 pillar cycle would look better and more atable than the present waveform pattern.

connect a large capacitor, may be a 6800uF/35V right across the battery terminals.

connect 12V zener diodes across gate/source of each of the mosfets.

and connect a 0.22uF/400V capacitor across the transformer output winding....and check the response again.

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Comments

Swagatam said…
yes it is possible if manual changeover switches are used.
Swagatam said…
if i get time i will surely try to update it.
Swagatam said…
if its rated as per the circuit specs then yes you can use it.
Swagatam said…
Hi Pranav,

No that won't be a good idea because the transformer will handle only that much for what it's designed for, above that it can start getting hot and might burn
Swagatam said…
All UPS have their own specific rating, you can check the labeled details of the UPS for knowing it.
Swagatam said…
Hello Kabir,

The above circuit is to be used with battery not with panel....2 batteries would be required, you can use two 12v batteries, for 300/400 watt load you will require 100AH batteries.
Swagatam said…
You can try the the last circuit given on this page, it uses a single battery:

https://homemade-circuits.com/2012/02/how-to-make-500-va-pwm-controlled.html
Jerico Vicente said…
great day sir, if i add more mosfet to this circuit to make it 4 on each side,mosfet will be connected in series but i wonder,in N5 will i insert another 470 ohms resistor to be connected to the additional mosfet's gate,the same through N4,N3 and N6?or no need for additional just tap the gate of the mosfet to the same resistor?i have transformer rated 12-0-12 24 amp, if i'll use this center tap will be directly to the 12 volts supply could this work fine?and yes what would be the calculated output wattage of this modification if the power supply is 12 volts 50AH battery?kindly help me sir especially for the connection of the mosfet's gate and resistor.thanks in advance..im interested in this circuit cause of its list parts ..jerico here from Philippines..
Swagatam said…
Hi Jerico,
you will have to connect the mosfets in parallel not in series. meaning the drains and the sources of the mosfets will combine and become common points on each channel while the gates will join with N3, N4, N5,N6 outputs through individual gate resistors.

yes individual gate resistors will be required for each mosfet, and the mosfets should be mounted on a common heasinks for each channel

As shown in the diagram, the center tap will connect with the positive of the battery.

The wattage will be around 200 watts with a 24amp traf and 50ah battery.
Jerico Vicente said…
hi again sir,
yes that must be parallel i didn't recheck my post after publishing it.i found out this design you made for 500va pmw....and they are mostly the same only using 12-0-12 trans and 12v supply exact for my transformer.i think i'll choose this for my inverter.

so for the part list;(to verify)
all resistor are 1/4 watts
82k for 60Hz,100k would be a potentiometer
all capacitor are rated 50 volts

if i add 2 mosfet on each channel to make it 3,i will be needing 2 more 1k resistor for each gate also 2 more 1n4148 right?

i'll be needing more of your help..thanks again..jerico
Swagatam said…
Hi jerico,

yes those stats are correct.
I would suggest that you to try with one mosfet first on each channel, and if it works perfectly only then go ahead with more devices in parallel.

Also exclude the 555 stage initially, once the upper basic inverter working is confirmed proceed with the 555 pwm section.
Swagatam said…
You can check the following 1 amp designs which can be upgraded to 3 amps by modifying the output winding wire gauge or by using bifilar winding.

https://homemade-circuits.com/2012/03/how-to-make-simple-12-v-1-amp-switch.html

https://homemade-circuits.com/2013/10/12v-24v-1-amp-mosfet-smps-circuit.html
Jerico Vicente said…
hi sir,
I've done this on a breadboard as for testing and it works. Actually I chop everything, At the 4049 con i referred at the 500 watts PWM controlled mosfet and the ic 555 I used the one shown above. I couldn't find any 5815 diodes and I'm using mosfet here.
And sir do you have any idea about this black sand that could be collected trough magnet? Can be found any where at ground specially at river sand. I wonder if I could use this as a ferrite core to make a bigger transformer.
jerico
Swagatam said…
Thanks jerico!

5815 diode can be replaced with 1N4148.

I have no idea about black sand I'll do some research and see if i can find more info about it
Josep Yoga said…
Jose
Sir, how to create ac stabilizer
HI Swagatams...
Did you test this practically? thanks...
Swagatam said…
Hi eshkariel
No I haven't tested it, but i am confident about its feasibility.
Arun Dev said…
Sir, after searching for many prototypes of inverters, i found this one helpful for my need... The only doubt remains is whether i could connect sophisticated components like Laptops to this inverter ???
Arun Dev said…
Sir will this inverter be able to support sophisticated equipments like Laptops ??
Swagatam said…
Arun, it will be perfect for your applications.
Remember the 4049 supply must be done exactly as done for the 555 IC, meaning the ICs must be supplied with 12V, not 24V.

the trafo must have lower rating than the battery for facilitating RMS output adjusting with the hep of the 555 pot.
Arun Dev said…
Sir i have used two IRF3205 mosfets to form the upper output stage.....
and the remaining mosfets selected were IRF540N,..
Also i am getting very high value of oscillations ( say 935 Hz ) when the frequency has been measured at the gate resistance......so afraid of connecting a sophisticated load........ I need your help...
Swagatam said…
Arun, measure the frequency at the output of the transformer, also put a 0.22uF/400V capacitor across the output of the transformer for removing harmonics and wrong frequency results
Arun Dev said…
Sir how can i measure the frequency of that high voltage(230 V) with my frequency meter.... that frequency meter is completely designed by me....and i have never used it to measure frequency of high voltages.....
Swagatam said…
I think you should use a commercial meter instead of a homemade for getting more reliable results.
Arun Dev said…
Sir, can i connect an another 230/12-0-12 250 mA transformer at the output side of the inverter transformer and check the frequency at the output of the new transformer ?
Mike Clems said…
Sir, Can this design maintain steady output voltage?
Swagatam said…
No. the output will change with load and battery voltage.
syphou seng said…
I don't know this number 230/12-0-12 250 what's do mean?
Kevin TN said…
Hello Swag,

I have been studying this circuit and I'm still confused with the was the IC555 is coupled o the transistors. Would you explain to me briefly how the clock signal is being channeled from the IC to the mosfets since it appears as if the diodes a blocking the signal.

Also whats the relationship between the two ICs.

Kind Regards
Swagatam said…
Hello Kevin,

the pin3 of IC555 is active only during its negative clocks, which ground the gate square waves only for those sections of the PWMs. Since the PWM frequency (timing) is much higher compared to the gate clocks (timing), the PWM negatives are able to slice the momentary gate voltages into many discrete sections depending upon the frequency of the 555.

I have discussed one similar example here:

https://homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html
Kevin TN said…
Hello Swagatam,

Thank you so much. I have been simulating Ic555 with that configuration and few capacitor value adjustments and got 17Mhz at pin 3. Should the frequency be adjusted?.

Regards
Swagatam said…
Hello Kevin,
Thanks!
try 1uF for the capacitor and a 10k preset for the control, and then check the response, I think 1nF is far too low for the shown configuration and therefore it's generating frequencies at that level which could create wrong results.
Kevin TN said…
Hello Swagatam,

Thank you for the feed back. Changes were made and the operation is now at 116.363Hz. The initial reading was recorded at 17 Khz not Mhz, that was a wrong quote of yesterday. Is this a better level of frequency or adjustment is required as well and if so, to which extent?.

kind Regards
Swagatam said…
Hello Kevin, thanks!

According to me approximately 500Hz frequency is recommended for an appropriate PWM reproduction...
Kevin TN said…
Hello Swagatam,

Thank you, a feedback will come shortly.

Kind Regards
Hi sir.

I'm an electronics engineering student from the Philippines. Me and a group of students are currently running a capstone paper regarding power electronics, particularly design and development of 12Vdc to 220Vac 60Hz Pure Sine Wave Inverter that has two-way input power, (1) through Solar Panel, and (2) through 12V Lead-Acid Battery.

I have problems with regards to output waveform of our project ckt. Can you help me out with this? Thank you.

Here is the link to our project design ckt:
https://docs.google.com/file/d/0B0bMf4IRmN6VQklzR291SlF4T1E/edit

Hoping for your positive response,
Michel
Swagatam said…
Hi Michel.

The output from the shown schematic will be square waves not sine waves.
Hi sir,

Based on our schematic, what suggestions can you offer in order for the output wave form to be a sine wave?

Thank you very much sir.
Swagatam said…
You can try adding a 1uF/400V capacitor across the output terminals of the bridge and check the response
ainsworth lynch said…
for the above schematic if I use irfz44n will the 470 resistors work or does should I use something higher?
Swagatam said…
it'll do, may be reducing them to 100 ohms will help the mosfets to perform better, this is for any mosfet that may be used in the design..
ainsworth lynch said…
Has anyone tested this circuit, just want to know if its working fine.. and about how much whats really can I get from this and is it pure sine wave.
ainsworth lynch said…
Are the diode 4amp diodes or can I use 1amp
ainsworth lynch said…
Is the starting of the gate n1 represented by pin 3
Swagatam said…
all gates inside the IC 4049 are identical, meaning any gate can be used in any position in the circuit
Hari said…
According to your comment "The IC 555 section has been wired up as an astable MV, the 100K pot is used for optimizing the PWM effect from pin#3 of the IC."
But can't find a 100k pot??
Swagatam said…
the 5k preset is mistakenly referred to as 100k pot, so it should be the 5k which needs to set for the desired RMS out
Dr. Love said…
Sir Swagatam, is this a three steps modified sine wave or multi steps sine wave that almost follow the sine wave function.
Swagatam said…
Hi Dr. it is a multi step sine wave but not with following PWMs, rather with uniform PWM blocks, however it doesn't make any difference since it would still be able to produce an RMS that may be equivalent to a standard sine wave RMS.
swapan said…
SIR, IN THIS CIRCUIT, THERE IS A TRANSFORMER LIKE 500VA. SO, CAN I USE 5 PIECES OF 18 AWG MAGNET WIRE IN PARALLEL (FOR PRIMARY WINDING) WITHOUT USING A SINGLE WIRE........PLEASE HELP ME.
Swagatam said…
Swapan, I am not sure about the number of turns, but you can use parallel wires instead of a single wire to increase efficiency
Rudi Chan said…
hi sir, i follow your design and do some simulation in proteus. but the result is look something wrong. the wave shape and freq is different. could you please correct me?

picture link: https://drive.google.com/drive/folders/0B7Tz2wqP_2vvM3Y5cXdHTFhhZm8?usp=sharing

thanks.
Swagatam said…
Hi Rudi, please remove the 555 PWM and check the response using only the NOT gates......if it works correctly then try reducing the 555 frequency to 200Hz and check again by connecting the PWM.....

but if the NOT gate inverter without the 555 PWM does not respond then the simulator might be wrong...
Rudi Chan said…
Hi sir, my repied is not shown. What happen with this forum?
Swagatam said…
Rudi, which reply are you referring to? please repeat it if possible...
Rudi Chan said…
Hi sir,

I plan to make this design. The pcb layout is just finished.
But before continue my works, i try cd4049 with breadboard. The pulse is made using 100k resistor along with 0.01uf (10n).

The result display at my oscilloscope is freq +- 500hz and duty cycle +- 77%

Is it correct with this freq and duty cycle? Please advise.

Thanks sir.
Rudi Chan said…
Hi sir,

I always get this "Your comment will be visible after approval." After posting in this forum.

And never get approved and show my post until now.

But sometime my post are shown immediately (no approval needed). But most of a time is show this approval msg.

Is it normal?

Thanks.
Swagatam said…
Hi Rudi, since you are checking with an instrument your measurement can be considered more accurate than the assumed values in the diagram...you can try increasing the cap value 0.1uF and check the frequency again....if it comes down to 50Hz then you may consider it to be OK....77% duty cycle does not look OK to me because it should be always 50% in such oscillator circuits....anyway you can carry on with it and see how the inverter performs.
Swagatam said…
Hi Rudi, all your comments until now have been answered by me and published.

Not a single comment will be posted immediately...each and every comment has to go through my moderation and only then replied...this procedure may take anywhere between 1 hour to 24 hours depending on my availability during the period.
Rudi Chan said…
Hi sir,

Thanks you for your kindly assist.

I begin to understand the concept working of this design.

This circuit is produce 2 pulse, 1 from 555 timer which around 200hz freq and duty circle is adjustable to get a closest rms.

Another one is from cd4049, this ic must produce a 50hz freq and the exact 50% duty circle.

Combine 2 pulse at the end of not gate and go throught all mosfets.

Is that correct?

I make some changes to fullfil the above concept. Cap on 555 side change to 1uf (1nf is insanely fast), cap on 4049 side change to 100uf, this will give me around 50hz.
The only problem is the duty cycle of 4049. Try to reduce 77% down to 50% without success.
Do you have any idea to get it done? Or
Can i replace the second pulse (4049 one) with another ic to getting 50hz 50% result?

Need your advise. Thanks sir
Swagatam said…
Hi Rudi, you can try configuring the relevant 4049 gate in the manner which is shown in the following concept, just pick the N1 section, rest can be ignored

https://homemade-circuits.com/2014/09/automatic-pwm-door-openclose-controller.html

this will allow you to adjust and set the PWM as per your own preference.
Rudi Chan said…
Hi sir,

Thanks for your advise. I will try add 2x 1n4148 and pot at the gate 1 of 4049.

Many thanks for your kindly help.

Best regards,
Rudi
Rudi Chan said…
hi sir,

i need your help sir. i just finished this circuit. but the result is not as what i expected.
please refer to my pictures below.

this is the wave measure from the gate side (also from the 555 and 4049 ic):
it look just nice. freq and ducy cycle almost at desire value.
https://drive.google.com/open?id=0B7Tz2wqP_2vvRjdXaEtydTVHMms


this is the wave measure from mosfet drain side.
everything is mess up. freq and duty cycle are changes.
https://drive.google.com/open?id=0B7Tz2wqP_2vvYUZkZDRiampTa2s

this is i measure from output of my transformer (for testing purpose i used 2A 12v 0 12v - 220v CT).
https://drive.google.com/open?id=0B7Tz2wqP_2vvWFl6bmhkZWpTdFk


how to get the transformer output wave just like a gate one?
i have a ups at home. i try to measuring the gate, drain, and transformer output. the waveform is almost the same on that small ups (modified sinewave). how do i achieve that result in my circuit?


please kindly help, thanks sir.

Swagatam said…
Hi Rudi, it's probably happening due to transformer inductive spikes, please try the following:

first increase the 555 frequency a bit more so that the "pillars" across each square wave cycles look uniform and well distributed..may be a 4 pillar cycle would look better and more atable than the present waveform pattern.

connect a large capacitor, may be a 6800uF/35V right across the battery terminals.

connect 12V zener diodes across gate/source of each of the mosfets.

and connect a 0.22uF/400V capacitor across the transformer output winding....and check the response again.
Rudi Chan said…
Hi sir,

Many thanks for the reply.

The current setting at ic555 is around 200hz and this will produce 2 pillars on each half cycle.
Did you means increase this freq to 400-500hz to get 4 pillars on each half wave?

And second correction, did you means connect a 12v zener in between a gate and source on each mosfet? Or connect the zener in between gate and gnd?
Sorry for this stupid question. Haha.. just to make sure i am not do anything in incorrect way.

Will update you and post the result later once i have done these above suggestion.


Thank you sir.
Rudi Chan said…
Hi sir,

I am sorry about the previous stupid question. The source is always connect into gnd net. Hahaha... zener connect in between gate and source or gate and gnd is the same way.
Swagatam said…
No problem Rudi, the more we discuss the more we learn

yes all your above understandings are correct and you can proceed in the mentioned way...hopefully you may see things improving...
Unknown said…
Hi sir my self Harsha
Wt is the transformer rating for the output load of led bulb(20x10watts) and the input is 12v 7amp pls reply fast to my Gmail
Harshaharshagowda26@gmail.com
Swagatam said…
Hi Harsha,

the transformer rating should be at least equal or higher than 20 x 10 watts that's more than 200watts

a 12V 7ah will not be enough for operating a 200 watt load....it must be at least a 40AH rated battery
fred said…
hello sir can i have a fully design of 2000watts inverter complete from assembly of parts placing components pcb designs thank you sir
Swag said…
Hello fred, what is the required output waveform spec of your inverter? is it square wave or sinewave?
fred said…
a pure sine wave sir having an output of 220v 60hz or if you have wattage range from 500 to 2000watts you help is very important to me sir thank you...
Swag said…
You can try the SG3525 sine wave circuits explained in this article, however you should proceeded only if you are well versed with all the basics of electronics and have prior experience of building inverter circuits.

https://www.homemade-circuits.com/?s=SG3525

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