Make This 1KVA (1000 watts) Pure Sine Wave Inverter

A relatively simple 1000 watt pure sine wave inverter circuit is explained here using a signal amplifier and  a power transformer.

As can be seen in the first diagram below, the configuration is a simple mosfet based designed for amplifying current at +/-60 volts such that the connected transformer corresponds to generate the required 1kva output.

Simulation and Working


Q1, Q2 forms the initial differential amplifier stage which appropriately raises the 1vpp sine signal at its input to a level which becomes suitable for initiating the driver stage made up of Q3, Q4, Q5.

This stage further raises the voltage such that it becomes sufficient for driving the mosfets.

The mosfets are also formed in the push pull format, which effectively shuffles the entire 60 volts across the transformer windings 50 times per second such that the output of the transformer generates the intended 1000 watts AC at the mains level.

Each pair is responsible for handling 100 watts of output, together all the 10 pairs dump 1000 watts into the transformer.

For acquiring the intended pure sine wave output, a suitable sine input is required which is fulfilled with the help of a simple sine wave generator circuit.

It is made up of a couple of opamps and a few other passive parts. It must be operated with voltages between 5 and 12. This voltage should be suitably derived from one of the batteries which are being incorporated for driving the inverter circuit.

The inverter is driven with voltages of +/-60 volts that amounts to 120 V DC.

This huge voltage level is obtained by putting 10 nos. of 12 volt batteries in series.

1000 watt or 1kva sine wave inverter circuit


The Sinewave Generator Circuit


The below given diagram shows a simple sine wave generator circuit which may be used for driving the above inverter circuit, however since the output from this generator is exponential by nature, might cause a lot of heating of the mosfets.

A better option would be to incorporate a PWM based circuit which would supply the above circuit with appropriately optimized PWM pulses equivalent to a standard sine signal.

The PWM circuit utilizing the IC555 has also been referred in the next diagram, which may be used for triggering the above 1000 watt inverter circuit.










Parts List for the sine generator circuit


All resistors are 1/8 watts, 1%, MFR
R1 = 14K3 (12K1 for 60Hz),
R2, R3, R4, R7, R8 = 1K,
R5, R6 = 2K2 (1K9 for 60Hz),
R9 = 20K
C1, C2 = 1µF, TANT.
C3 = 2µF, TANT (TWO 1µF IN PARALLEL)
C4, C6, C7 = 2µ2/25V,
C5 = 100µ/50v,
C8 = 22µF/25V
A1, A2 = TL 072

Part List for Inverter

Q1, Q2 = BC556

Q3 = BD140

Q4, Q5 = BD139

All N-channel mosfet are = K1058

All P-channel mosfets are = J162

Transformer = 0-60V/1000 watts/output 110/220volts 50Hz/60Hz

The proposed 1 kva inverter discussed in the above sections can be much streamlined and reduced in size as given in the following design:

How to Connect Batteries


The diagram also shows the method of connecting the battery, and the supply connections for the sine wave or the PWM oscillator stages.

Here just four mosfets have been used which could be IRF4905 for the p-channel, and IRF2907 for n-channel.


Complete 1 kva inverter circuit design with 50 Hz sine oscillator








In the above section we have learned a full bridge design in which two batteries are involved for accomplishing the required 1kva output. Now let's investigate how a full bridge design could be constructed using 4 N channel mosfet and using a single battery.

The following section shows how a full-bridge 1 KVA inverter circuit can be built using, without incorporating complicated high side driver networks or chips.

The Full-Bridge Inverter Concept


Driving a full bridge mosfet network having 4 N-channel mosfets is never easy, rather it calls for reasonably complex circuitry involving complex high side driver networks.

If you study the following circuit which has been developed by me, you will discover that after all it's not that difficult to design such networks and can be done even with ordinary components.

We will study the concept with the help of the shown circuit diagram which is in the form of a modified 1 kva inverter circuit employing 4 N-channel mosfets.

As we all know, when 4 N-channel mosfets are involved in an H-bridge network, a bootstrapping network becomes imperative for driving the high side or the upper two mosfets whose drains are connected to the high side or the battery (+) or the positive of the given supply.

In the proposed design, the bootstrapping network is formed with the help of six NOT gates and a few other passive components.

The output of the NOT gates which are configured as buffers generate voltage twice that of the supply range, meaning if the supply is 12V, the NOT gate outputs generate around 22V.

This stepped up voltage is applied to the gates of the high side mosfets via the emitter pinouts of two respective NPN transistors.

Since these transistors must be switched in such a way that diagonally opposite mosfets conduct at a time while the the diagonally paired mosfets at the two arms of the bridge conduct alternately.

This function is effectively handled by the sequential output high generator IC 4017, which is technically called Johnson divide by 10 counter/divider IC.

The Bootstrapping Network


The driving frequency for the above IC is derived from the bootstrapping network itself just to avoid the need of  an external oscillator stage.

The frequency of the bootstrapping network should be adjusted such that the output frequency of the transformer gets optimized to the required degree of 50 or 60 Hz, as per the required specs.

While sequencing, the outputs of the IC 4017 trigger the connected mosfets appropriately producing the required push-pull effect on the attached transformer winding which activates the inverter functioning.

The PNP transistor which can be witnessed attached with the NPN transistors make sure that the gate capacitance of the mosfets are effectively discharged in the course of the action for enabling efficient functioning of the entire system.

The pinout connections to the mosfets can be altered and changed as per individual preferences, this might also require the involvement of the reset pin#15 connection.










Waveform Images


The above design was tested and verified by Mr. Robin Peter one of the avid hobbyists and contributor to this blog, the following waveform images were recorded by him during the testing process.



























Need Help? Please send your queries through Comments for quick replies!




Comments

Swagatam said…
To make an UPS you will need to make a inverter first, so you can begin with the above circuit, once you finish this I'll help you to proceed with the further things.
Swagatam said…
The above circuit will work with 12V supply also, but with 12V supply a 1000 watt inverter will become too heavy with thick wires and huge heatsinks, that's why higher voltage is recommended.
Swagatam said…
Hi Kabir,

50 watt panel is too low to power an inverter directly, you will need at least a 100 watt solar panel for this.

You can try a simple inverter circuit that's explained in the following article:

https://homemade-circuits.com/2012/09/mini-50-watt-mosfet-inverter-circuit.html

Swagatam said…
That won't be enough, you will need a minimum 200 watt panel for charging a 200 AH battery within 6 hours, please confirm it further with your panel dealer
Swagatam said…
If possible I'll try to design it and post it for you soon
Chizom Wornu said…
hey, please i would like to know the function of the function of c2 in the 555 pwm circuit. I need to connect a comparator to the 555 timer circuit for my switching supply
Swagatam said…
C2 is for keeping pin#5 unresponsive to stray noise and disturbance that may be present in the supply and atmosphere
Hi, I'm building a hydro, as a generator I'm using truck alternator 24V 100A, could I use the above design inclusive PWM, and also what would I have to change in order to double its output to 2kV ?
Thank you for your reply. Ladia
Swagatam said…
Yes you can use it.

You can increasing the input voltage and the trafo primary voltage appropriately for increasing the output wattage to the desired levels, without increasing mosfets nos.
stev said…
Mr swagatam thank you for the good job sir i want to build this circuit named Make This 1KVA (1000 watts) Pure Sine Wave Inverter Circuit to power my house so please help me build it my 1th question im going for the LM555 where is that point show 3 to 15v dc from pin 4 of the ic lm555 going to connect second question in the TL072 A1,A2 where is the point show plus symbol from pin8 of the A1 connect and A2 pin7.can i use one of this mosfets IRFP250 IRFP260 AND 2N3205 OR 2N3055 please sir kindly help me cos we having a lots of problem in our electricity thank you i am looking forward to hear from you son.
Swagatam said…
Hi Stev,

you will need two 12V bats connected in series for operating the above inverter. Meaning together the battery will generate 24V

The series connection will become the ground (earth symbol) of the system.

For the IC 555, the positive of the battery which generates 24V will become its positive supply while the series link of the batts will become the ground of the circuit, same can be done for the A1/A2 circuit if it's being used in place of the 555.
This also means that the earth or the ground of all the circuits can be made into a common line.
pin7 of A2 will connect with the inverter input.
zinnaboy2 said…
than you sir for the respond but sir there is one thing i don't understand in the mosfet you named some of the mosfet Q6,Q7,and Q9,Q9,please which of them are the N-channel mosfet K1058) and P-channel mosfets J162) in the Make This 1KVA (1000 watts) Pure Sine Wave Inverter Circuit,thank you stay bless looking forward to hear from you.
Swagatam said…
I just cut/pasted the first mosfet section across for indicating the following identical moset stages, that's why it's showing a repetition of the same mosfet, please ignore it, and simply repeat all the section identically with 0.22 resistors on each and every mosfet source
zinnaboy2 said…
thank you for the replied but sir i still don't get you right can you please come again or you mean all the 20 mosfets should be the same mosfets? and also the diode (1s207) i never head that kind of that diode before any diode can be use or what is the value of it? thank you looking forward to hear from you stay bless.
Swagatam said…
all the upper n-mosfets are same and all the lower p-mosfets are same.
you can use 1N4148 diode in place of the shown unknown diode.
zinnaboy2 said…
ok sir thank you very much for the respond sir i build it but it dont work why sir is there anything i did not connected? ok let me tell you how i connect the circuit, in the 555 there is line that from it 7pin show (PWM pulses) i connected it with A1 pin8 that show positive symbol to the Btr positive im i right? and also i connected pin7 of A2 to the sine input sir in the 555 you connect pin4 and 8 together and you show 3 to 15v DC where is that going to? thank you sir for your time on me.i am waiting for you reply before i will continue the circuit Make This 1KVA (1000 watts) Pure Sine Wave Inverter Circuit.
Swagatam said…
There are many things that must be taken care of here. The circuit will require a dual battery supply, example 2nos 24V batts in series. the series connection will become the ground.
the preset will need to be adjusted correctly or alternatively it can be simply replaced with two series connected 1N4148 diodes, anode up, cathode down.
try with the 555 circuit first and using just two mosfets
zinnaboy2 said…
sir im very confused why becos in the parts list there is C4,C6,C7,C5,and C8 while its not in the circuit i can only see C1, C2, and C3 in the op am TL072 sir im talking about this circuit Make This 1KVA (1000 watts) Pure Sine Wave Inverter Circuit here are the parts list

All resistors are 1/8 watts, 1%, MFR
R1 = 14K3 (12K1 for 60Hz),
R2, R3, R4, R7, R8 = 1K,
R5, R6 = 2K2 (1K9 for 60Hz),
R9 = 20K
C1, C2 = 1µF, TANT.
C3 = 2µF, TANT (TWO 1µF IN PARALLEL)
C4, C6, C7 = 2µ2/25V,
C5 = 100µ/50v,
C8 = 22µF/25V
A1, A2 = TL 072

Part List for Inverter

Q1, Q2 = BC556

Q3 = BD140

Q4, Q5 = BD139

All N-channel mosfet are = K1058

All P-channel mosfets are = J162

Transformer = 60-0-60V/1000 watts/output 110/220volts 50Hz/60Hz
Swagatam said…
zinnaboy, please follow the diagram only, I might have put the parts list of "simple sine wave inverter" which is quite similar to the above design.

So please follow the diagram only.
biannz said…
thank you sir for the humble replied cos some time we asked questions that almost make you upset but becos of the sacrificed you ignore and answer thank. so if i understand well the out put of 555 and out put of A1/A2 should connect to the inverter in put right?
Swagatam said…
yes that's correct, but make sure you do the connections as instructed in the previous comment.
biannz said…
hi sir i build this circuit Make This 1KVA (1000 watts) Pure Sine Wave Inverter Circuit but the fets got hots without load please help me solve the problem thank you sir
Swagatam said…
Hi Bianz, connect small flashlight lamps in series with positive and the negative lines of the circuit...these lamps should be rated at the battery voltage level.
now without connecting any load switch ON power to the circuit.
The flashlights will light up brightly, now carefully adjust the preset until the lights just shut off. This setting will ensure that your mosfets stay cool when there's no load.
biannz said…
thank sir but one thing is that when i switch on the power to the circuit the 0.22 ohms resister blow i used only 2 fets (K1058),(J162) for trying before i go ahead and build bigger one please i need your help sir.
Simon Johnson said…
hi Sawagatam, I am new here but you seem to be in the know. I have some 250volt 250watt solar pannels and some 30 12 volt 240ah batteries, I want to make a transformerless inverter, do you have any sugestions for me? like battery pack voltage. I was thinking of about 216vdc before switching as I know that this will affect the ac voltage.
Swagatam said…
biannz, keep the trafo wire disconnected initially, and connect it after power switch ON, if still it the 0.22 blows off means there's something seriously wrong with your circuit.
Swagatam said…
Hi Simon, you will need a full-bridge inverter (without transformer) circuit for implementing the application.

I'll be publishing one such circuit soon in this blog, in the meantime you can search it online to get a idea about the design.

The batteries can be connected in series for getting the required 216V.

biannz said…
sir thank you sir i did it a exactly as you said but still blowing the fest and the resistor it happening to one side i used 2 most fest N-channel mosfet K1058
channel mosfets J162 , sir in the inverter i use 18pf in place of 15pf,and the resistors i used 5.6 in place of 5.1 cos it not aveable here im asking sir is it the cost of problem? sir i will be very glad if will be able to build this circuit so please sir help me sir thank you i hope to hear from you son.
Swagatam said…
biannz, the preset needs to set correctly first....alternatively you can replace the shown preset with two 1N4148 diodes back to back in series. anodes will be upwards and cathodes will be downwards.....
biannz said…
hi sir i understand but want to ask you a little question where is the 1k resistor which indicate ground connect to is it connect to the positive and negative center of th batt or directly to the negative of the batt which generate 24v? thank you your assistant.
Swagatam said…
hi biannz, pls see the last diagram, i have shown how to connect the batteries and the supply connections for the oscillator circuit
biannz said…
ok thank you sir but one thing is how can i post or upload so that you can see pics can you give me your email address if you don't mind? i prefer to chart with you live but i don't think that would be possible thank you sir.
Swagatam said…
you can use Google drive and create a image link through it and provide me with the link.
biannz said…
sir please can i use two 12v batt in series for test?
Swagatam said…
yes can be used but it will give 50% less power
Swagatam said…
.....than compared to two 24V batteries
biannz said…
sir please i have sent you a pic of the three circuit i have connect all so please kindly check it out if it correct or not im waiting for your reply sir thank you.homemadecircuits@gmail.com
Swagatam said…
The connections are wrong.
do it exactly as shown in the last diagram above.
Use only one pwm circuit out of the two which are shown, either the one which uses the two opamps or the the one with 555 IC.
biannz said…
sir so you mean only two circuit should be connect not all the three circuit,i should chose any of them to connect the inverter isn't it sir? i have sapirate them see the connection if not please correct it and send it to this email address(
danieladusie@gmail.com) this is the email address that i sent to(homemadecircuits@gmail.com)
Swagatam said…
biannz, please see the last design in the above article.
biannz said…
thank you sir so can i use the one with ne555 too if want? i mean can i chose one of the two circuit to feed the sine input any of them with the same connection?
Swagatam said…
Yes you can use 555 pwm input also, connect it in the same manner as done for opamp oscillator
biannz said…
ok sir thank you for respond,sir please i want to know if this circuit can handle or supply 5 BIRD ROM with one LCD flat-mar TV one refrigerator 5 ceiling fans and two computers? sir i want to use 4 12v solar the bigger and 0-48 Tranf and also good heat sink for the fets,sir if you confirm that this circuit
Complete 1 kva inverter circuit design with 50 Hz sine oscillator can handle the house then i use solar panall instead of electricity to charge the BTT,thank you sir.
Swagatam said…
Biannz, according to me the above design will be able to handle the specified appliances....however I cannot provide guarantee for anything.
Better to build a smaller version by using two mosfets, two 12V 7.5 ah batts, if everything goes right as per the expectations, you can proceed by upgrading the stages appropriately.
biannz said…
ok sir i understand you very well it a good i dear i will do exactly as you said.
biannz said…
sir please i need your help i finish build this circuit but unfortunately i did not gets 0.2E so i used 0.22E the problem is when i connect the 0.22E and the fets got very hot and it almost burn.
Swagatam said…
biannz, remove the sine oscillator input, and short circuit the inverter input to ground and then check whether the mosfets are getting hot or not.

If yes, then there could be something not correct with the connections.
Swagatam said…
0.22 ohms is OK.
biannz said…
sir thank you sir please i did as you said but it still got hot sir i build the circuit as the way it is i go over and over i check every the circuit i connect everything where it should connected so sir my observation i didn't miss the connection so please help me
Swagatam said…
without an input signal the fets will never heat up, i have the tested the design and it worked perfectly for me.
you circuit has some fault for sure get it checked by a expert.

i had cautioned you before not to try something which you cannot troubleshoot yourself.
biannz said…
ok sir please i sent you some pics to this email homemadecircuits@gmail.com please check and correct it if any wrong connection.

March 24, 2014 at 3:41 PM

Swagatam said…
bianzz, i cannot check your circuit due to lack of time...you will have to do it yourself.
You should first make it on a general purpose board going for a PCB
biannz said…
sir i use Proteus and tell me IRF2907 have no model specified,simulation failed due to partition analysis error(s) sir tha is how it tell me so what does that mean? any help?
Swagatam said…
biannz, for simulation purpose you can use any n-channel and p-channel mosfets in the circuit.
biannz said…
sir please in this circuit it Q8 AND Q9 N-channel or P-channel?
Abu-Hafss said…
Hi Swagatam

Recently, the transformer of my UPS (purchased from market 3 years ago) is becoming very hot, such that strong smell can be felt in the room.

What could be the reason?
Swagatam said…
Hi Abu-Hafss,
May be it incorporates some kind of voltage regulation circuitry which has failed now and as a result excessive voltage and current is being fed to the transformer input winding.
syphou seng said…
Transformer = 60-0-60V/1000 watts/output 110/220volts 50Hz/60Hz
what do mean 60-0-60?
Swagatam said…
sorry, it should be 0-60V and not 60-0-60

it's the voltage rating of the primary side winding of the inverter transformer.
Shoaib Saleem said…
how to we can 20 volt dc convert into the ac 220 volt please
daniel adusei said…

please lm555 will produce the same sine wave as tlo72 oscillator?
Swagatam said…
you can try the following circuit:

https://homemade-circuits.com/2014/06/simple-high-voltage-generator-circuit.html
Swagatam said…
555 will produce pwm modified pure sine wave, A1, A2 will produce exact pure sine wave
daniel adusei said…
sir

i want to try this circuit again but my problem is the 15pf i search every where but i don't get it, it very difficult
Swagatam said…
daniel, you can try any closer value, it's not so critical
daniel adusei said…
sir please can i use variable resistor to adjust so that i can get 14k3 or 12k1 cos it difficult to get that value can i?
ainsworth lynch said…
in the parts list you have a "2µ2" value for C4, C6, C7 I cannot find such a value was that a typo?
Swagatam said…
yes it's a typo from the previous extraction, just remove the Â
ainsworth lynch said…
ok one more thing the 2uf capacitors which I should put two in parallel are they the big 250v/450v caps found in fans because that's mostly what I see.
ainsworth lynch said…
if thats correct which voltage caps should I use.
Swagatam said…
yes you can use presets for adjusting the values
Swagatam said…
No, these are small 25V rated, tantalum types are preferred for their low leakage properties and high accuracy.
daniel adusei said…
sir
please can i use this TL072 oscillator to connect to another circuit you named it simple pure sine wave? that simple pure sine oscillator also use tl072 but i don't want to use that circuit i prefer this the second oscillator, can i use it for that simple sine wave power stage? thank you.
Swagatam said…
daniel, yes you can use the PWM version with that circuit input
daniel adusei said…
ok sir thank you im going to try it
daniel adusei said…
sir please i build this oscillator TL072 it work very well i got correct pure sine wave but if i connect it to the inverter the fets and the 0.22 ohm resistor got very hot can you help me with that? i tried to send you the pic but it couldn't go through but i well try again after hearing from you,please don't forget to answer this too,sir please can i use irf540n in place of irf2907? thank you
Swagatam said…
on what situation are the fets heating up? on power switch ON... without input signal and without load...or under what conditions?? please specify.
daniel adusei said…
ok sir
im trying to troubleshot if i couldn't i well inform you so that you can you can help me,but please answer this for me sir please i want to use this TLO72 oscillate for center tap transformer may be one of your cd4017 circuit i think it have one in put or it can be possible?thank you hope to hear from you.
Swagatam said…
i did not understand what you are saying....
daniel adusei said…
sir i mean i want to use the tl072 circuit to feed cd4017 circuit so that i can use center tap transformer cos the cd4017 it have one input which is pin 14 the out put is many but we anomaly use pin2 and pin7,you have cd4017 inverter circuit so i want to cut it pmw and use this tl072 sine wave oscillator, can it work? sir please my English is not good so please try to understand what mean thank you.
Swagatam said…
No, that's not possible! It doesn't work that way.
daniel adusei said…
sir
please i have sent you some wave form of TL072 oscillator check it out if it better cos if i connect to the inverter it dont work one side got very hot almost blow my fets any help sir?, thank you.
Swagatam said…
Daniel, is the heating happening with loads connected or without loads?

and when the input sinewave input is removed are the mosfets returning to normal temperature?

what rating transformer did you use?

did you check the quiscent current of the circuit.

did you connect the two 1N4148 diodes at the collector of Q3?
daniel adusei said…
yes sir the diode is connected, it got hot without load ,i use IRF540N in place of IRF2907 cos IRF2907 it difficult to get it,or can you please tell me common N-CHANNEL MOSFETS?
Swagatam said…
daniel, do not connect any input signal, initially keep the input 22k end shorted to ground.

now power the circuit with small 12V flashlight bulbs in series with the battery supply lines (+) and (-).

If the bulbs glow brightly would mean something's wrong with your circuit.

The bulb glow will suggest that the quiescent current is too high for the circuit and it has not been configured correctly.

in a good circuit the bulbs will stay shut off
God day Sir
I would like to ask for your help if you have a 5kw pure sine wave inverter. with an input/output 24Vdc/250Vac 60 hertz design. I'm very much fascinated with your designs. I would highly appreciate it if you could help me with this.
Thanks and best regards.
Radley
I'm very much fascinated with your design. I would like to ask for your help if you also have a design for 5kw pure sine wave inverter and an input/output of 24Vdc/250Vac 60hertz. I would highly appreciate it if you share it with me.
Thanks and best regards.
Radley
Swagatam said…
Hi Radley, you could probably try the following design, you can try replacing the ferrite core trafo with a standard iron core transformer having 5kva rating

https://homemade-circuits.com/2014/07/5kva-ferrite-core-inverter-circuit.html
daniel adusie said…
hi sir long time yes am was very busy,so now am back to the blog th last time i said this circuit got hot you answer me but unfortunately i couldn't do it as you said so now i have a time am going to stat it so i will come for your aid if
daniel adusei said…
sir plse can i use irf540n in place of irf2907? thank you.
Swagatam said…
yes it can be used.
ainsworth lynch said…
the transformer used in this circuit has a 60v primary and 110/220 output at about 10amps where can I get such a transformer?
Swagatam said…
60v or higher trafo is used for minimizing the current requirement of the inverter, you could as well use a 12V trafo with a 12-0-12V batt for the same results, but that would mean the amp rating going up significantly.........
Tanmaya Mitra said…
Oops forgot to mention in the tricky challenge.........it would be far better if a swich for sinewave,squarewave,traingle and sawtooth wave. if not at all possible,make it sinewave alongwith PAM/PWM/PPM controller
ainsworth lynch said…
Could a 12-012 transformer at 10amp be used and does it mean I could only use a single 12 volt battery
Swagatam said…
yes a 12-0-12 trafo can be used with a single 12V battery, in fact the trafo could be a 9-0-9v ideally.
ainsworth lynch said…
In that case look at the connection in the diagram that the positive lead from the battery on the right connected to q7 would that connection still be made using one battery or just the portion with the battery to the left?
Swagatam said…
I am sorry, ignore the previous comments by me...a center tap trafo and a single battery will not work for the above 1000w inverter concept....
ainsworth lynch said…
The transformer i have is 12-0-12 i used on 12v battery and i didnt get any out out, the fets got hot in seconds so can i use 2 12v batteries in series and use that same transformer that i have
Swagatam said…
yes a dual battery is required for the design so use two 12v batts iin series...
in the transformer, use any of the 0-12 tap
ainsworth lynch said…
I tried but still no volt out from the transformer the fets get hot
Swagatam said…
remove the trafo and the input and then check if the fets are getting hot or not
Asim Inam said…
Dear swagatam r u test this design by ur self or just present your theoretical view on this design because your most viewers complaining about geting hot issue of fets's and 0.22 ohms resistor plz answer sincerely thanks
Swagatam said…
Dear Asim, it's based on theoretical simulation, but if I happen to make it i would be able to achieve 100% results from this design....if others are not able to succeed it's their inability.
ainsworth lynch said…
The fets dont get hot at all when i remove the transformer
daniel adusei said…
sir please can you tell me what is the purpose of the two 1n4148 diode pleas tell cos i got 12v at the collector of Q5 and Q3 it is okay to to get that kind of voltage at these two Q3 and Q5?
Swagatam said…
it means something's wrong in your circuit, because without any input frequency and without any load the fets should not conduct and should not become hot....
what's the quiescent current that you have measured?

Swagatam said…
the two diodes help to get the required variable duty cycles from the IC

if your batteries are 12-0-12 then the results are OK...
Swagatam said…
sorry if the batts are 24-0-24 then 12V across the fet gates is OK...
ainsworth lynch said…
ok will connect and check if I am getting 12v accross each gate, but if thats the case and I re-connect the transformer and still no output what do you think would be the problem, because I am using a 24-0-24 battery setup and the transformer is 12-0-12 5amp
Swagatam said…
please don't comment with different names...it gets very confusing...are you daniel adusei??

you have been attempting the circuit since last 6 months and still having problems, i advised to quit this project and I repeat it once again....try some other easier inverter design... there are plenty of them in this blog.
ainsworth lynch said…
I started the circuit last week im ainsworth lynch.... You told me to remove the transformer and test accross the gates of each fet...
ainsworth lynch said…
I got 12 volts accross gate and grounds of each fet...
Swagatam said…
check the quiescent current by shorting the input of the circuit ground and trafo connected. it should be around 50mA, in the second last circuit
ainsworth lynch said…
probably Ill just try another design, I wanted to complete this but I dont know why I can get any output from the transformer.
Swagatam said…
sure, there are many good designs in this blog, much effective and easier than the above design but will not produce pure sine wave...
ainsworth lynch said…
Ill try the 3kva sine wave inverter that i see you posted
daniel adusei said…
hi sir please i did not sent you a message with different name my name is daniel adusei and my profile pic is sine wave symbol sir i now got out put of transformer and the sine wave but what im facing now is if i power the circuit the out put of transformer raise up and it drop down within a seconds the upper fet got worm any help?
Swagatam said…
daniel, you'll have to use large heatsinks to control the heating issue because since this is not a PWM based circuit, some heating will be take place.
hello sir,
In your sine wave generator circuit, i cannot figure out ground pin of a1 and vcc pin of a2. are you missing them?
and where should i add a trimmer in circuit in place of resistor to set the freq. precise to 50Hz.
What should be min. input voltage and current to circuit?
Please help.
Swagatam said…
Hello Sherwin, A1, A2 could be a dual opamp such LM358,

The design is already calculated for generating the required 50 Hz so there's no need for any further adjustments.

voltage/current parameters will depend on the specs of the opamps used, typically it could be around 4.5V and 5mA
Yes sir,
I will be building the sine generator circuit first and tell me:
1. What is RMS value and what does it mean?
2. Approx. what will be sine voltage and current at output if my input is regulated 5v.
3. What is amplitude adjustment?
4. Do i need any LC circuit at the sine output to further enhance the waveform quality.
Please guide me,
since i'm doing the inverter project i'm also preparing the charging system seperately.
Again, you are really great in your works, i do appreciate it.
Swagatam said…
Sherwin,

RMS refers to the average voltage magnitude of a pulsed voltage.

with a 5V supply sine peak will be 5V and RMS = 2.5V

No LC circuit would be required for enhancing the sine, but could be required for eliminating unwanted harmonics or ripples.
Sir,
I feel like building this inverter but, the transfo and the batteries is my problem.
How I wish, the circuit can be build with any 12v, 9v or 8v transfo so that a simple 12v battery can be use.

Anyway, thanks very much for this great work. May God help you and protect you.
Swagatam said…
Aminu, without a center tap trafo it can be impossible to create a push pull effect unless two batteries were used or a full-bridge IC was used...therefore in the above design two batteries are preferred instead of the other alternatives, because using a couple of batteries is easily achievable...
Fidelis said…
I have a friend with a young child that has some mental problems and whenever they are out in stores or malls he will wander off . I am looking for 2 circuits in order to keep up with him . One to put on him and when he gets 12 to 30 feet from them. It will sound a buzzer or alarm on a circuit on them. Would you have any idea? Thank You tmitch51@gmail.com
Swagatam said…
Please refer to the following circuit, it might just serve the purpose:

https://homemade-circuits.com/2014/06/key-finder-circuit-pet-or-kid-tracker.html
Mark Treth said…
Hello Swagtam,

I have built your inverter circuit only. I am using a professional signal generator to provide the sine wave input. The circuit is built on a professionally laid out and manufactured FR4 PCB. It is being powered from a +/-15 volt lab power supply. All appears to power up OK with nothing getting hot. When I measure the output with no load there is a good clean signal with a gain of about 22 as expected.

The problem occurs when a load is applied to the output. A 1k resistor across the output causes the output signal to drop from 22 volts peak to peak down to 8 volts peak to peak with the top of the positive peak clipped. Lower value resistors make the output lower. The power supply rails stay stable at +/- 15 volts with no AC ripple. I have changed the FETs and confirmed the transistor are connected correctly. The circuit is exactly as per your diagram.

Do you have any idea why this is happening?. I can see that Q4,Q5 are a differential amplifier configuration, but am unsure of the purpose of Q3. Is Q3 a form of current source?.

Would appreciate any help. Best regards
Mark
Swagatam said…
Hello Mark,

The above design is basically a 300 watt RMS audio amplifier, so I believe that if the circuit is able to drive a 300 watt loudspeaker then definitely it would be able to drive an equivalently rated transformer too with the same amount of output.

I have checked it in the form of an amplifier (using 4 fets) and with +/-25V, 5 amp supply and I could achieve well over 150 watts from it, raising the voltage could have allowed me to reach above 200 watts

so i would recommend you to test the circuit like an amplifier first and then appropriately convert it into an inverter.

use one of the last two circuits which uses two 1N414148 diodes for biasing the lower transistor section instead of the the shown preset in the first diagram....the use of two diodes relieves the user from the complex setting-up procedure of the quiescent current for the design
Swagatam said…
yes your assumptions are are right regarding the Q4, Q5 and Q3 transistors
Amos Zaks said…
hi sir Swagatam, my name is Amos Zaks i have been your follower for long on this platform and recently i came across one of your inverter diagram that uses a micro contoller pic16f72, i like the diagram and i want to biuld it for home use but the problem is i dont know anything about micro controller, sometimes i do here people say you must configure it or use a code before it will work in the circuit. i dont know anything about it so please i need your help on this before i start the project.thanks. iam looking forward for seeing your reply. my mail is:mrzakson@gmail.com
shane alam said…
Hi swagatam can you please tell me that from where I can get this 1000watt transformer and how much it will cost
Bilal Suliman said…
Hello Mr. Swagatam , may you Please clarify How are batteries connected (Negative to Positive) Then this joint is connected to the ground ? And Since in Electronics usually the negative pole of the battery is considered as ground for the circuit , What would the ground in this 1KVA inverter schematic be ? I am so confused about this point , I highly admire your efforts for spreading knowledge thanks so much.
Swagatam said…
Hi Shane, you will have to get it from professional trafo designer manufacturer....give him the details and he will make it for you
Swagatam said…
..the cost could be anywhere around Rs.5000/-
Swagatam said…
hello Bilal,

the use of two batteries and the relevant connections allow the transformer winding to switch from top to bottom and then from bottom to top alternately via the mosfets.

since the transformer does not have a center tap therefore two batteries become essential for the alternate up/down switching of the trafo winding.

the up/down switching ensures positive and negative half cycles for the AC at the secondary of the trafo.
Bilal Suliman said…
Thank you Mr. Swagatam for this clarificatios, but still there's something not clear in my mind, what is the 'ground' in the schematic ? If I am to Implement this circuit what will be the ground that I should connect the two batteries poles to ? Thank you for the reply Mr.Swagatam.
Swagatam said…
Thanks Blal, all the points marked with the "earth" sign will connect together and this becomes the ground line for the entire circuit, the transformer primary switches across the two batteries with the reference to this common central ground.....meaning for every switching the transformer is using power from a single battery..

..the use of two batteries is just for ensuring an alternately changing polarity for the trafo.
shane alam said…
We can get a microtek 1125va ups at around rs 5000 then why a single 1000watt transformer will cost around rs 5000 .then what is benefit of making a inverter ourselves if it will cost more than a ready made inverter?
Swagatam said…
benefit is that you get the oppurtunity to learn how to make your own inverter and tell the world that you can build your own inverter.

moreover I was referring to a good quality iron core inverter not a ferrite core one...and also a single piece will always cost you 5 to 10 times more than when you buy the same in bulk.
shane alam said…
Thanks swagatam for giving me such valuable information. Can you please give me a 15amp lead acid battery charger circuit diagram I want to charge my 150ah tobular battery.
Swagatam said…
My pleasure shane! you can try the following circuit for charging your 150AH battery

https://homemade-circuits.com/2011/12/high-current-10-to-20-amp-automatic.html
My dear brother, I have a reflective capacity of 800 watts , but not enough to run my refrigerator 200 Watt and I want to increase their value to appropriate what is the solution?
darkDemon said…
Hi Swagatham,
Great resource.. I learned how inverter works, I actually needed some help, I bought an 1000 watt inverter couple of years ago, few days ago due to low voltage it started beeping, before i could turn it off I seen spark inside the inverter, I quickly switched it off.. Then after a while later I turned it on, from led panel everything was working fine, power flow remained continuous during AC on and battery mode or inverter circuit remained functional.. However with one exception the battery charging is not happening, I first thought my battery was totalled, I have had a seperate battery which I revived and put in to tickle charge for 12 hrs, put it back on and monitored it, the charge depleted after a day even it showed it was charging but upon checking it with multimeter on terminals I found out it's not feeding any flow to batt.. If I am not wrong is the spdt relay is gone?! Or the could be something else.. Please guide and help me out cause where I am we mostly face power outs.. If needed I can upload pics of internals of ups inverter...tha
Swagatam said…
Thanks DD, actually a low voltage should not have caused any problems, because at low voltage the net power gets reduced so overload or over-current cannot happen, so it looks little strange to me.

However from your analysis it appears that some part in the battery charging section has malfunctioned, you can track the wires which are responsible for carrying the voltage from the charger output to the battery, and check which part is causing this issue....prior to this confirm whether the battery charger is producing the required charging voltage or not, otherwise the issue could be in the charger controller stage.

yes the SPDT could be also responsible for this....you can replace it with a wire link to confirm the same.
Chris said…
Hi Hitman, in your final diagram, you connect your sign wave direct to the input of the inverter circuit, now can you please tell me where the PWM of the sign wave is generated? As far as I know, the Mosfets are not analog devices, and can not handel the analog sign wave signal.
Chris said…
Hi veniyan, where do you get your 220V DC from? remember DC in high voltage is lethal and can kill you instantly with AC you still have a chance to get away but not with DC.
Swagatam said…
Chris, if you think mosfets cannot be used in analogue circuits then how are mosfets used in audio amplifiers??

the fact is mosfets can be used in digital as well as in analogue circuits, here the mosfets are connected as source follower meaning their sources will follow their gates in tandem...therefore if a sine wave is applied at their gates, then the output will be an exactly amplified sinewave.
Swagatam said…
here's an example simulation

www.falstad.com/circuit/e-mosfollower.html
Please work on the simulation of circuit simulation and testing of electronic circuits program file
windows mobile said…
Hi sir,
Thanks you so much for your post. But sir i want to make a drive circuit for my pulse transformer. the primary is only 10 turns. the output voltage is about 4kv. i have a sine wave input signal with frequency variable from 1khz to 100khz. So my question is can i use this circuit or which circuit is more suitable could you recomment? i'm waiting reply from you and thanks again.
Swagatam said…
You are welcome WM
you can use the same circuit which is shown in the above article, just make sure that the frequency is properly matched with the 10 turn primary and the core is a ferrite based material, otherwise the fets could instantly burn and get damaged
rax said…
Hi Swatagam, how can this circuit be modified to work on higher voltage (380v dc) like ones found in dc-ac stage of pure sinewave inverter. Or I just have to use higher voltage transistors ? thanks !
Swagatam said…
Hi Rax, yes it's possible, if all the BJTs and the mosfets are rated to handle this voltage

the resistors will also need to be appropriately upgraded
Lubna Yasmeen said…
I want full 1KVA UPS circuit diagram for simulation
Ainsworth Lynch said…
this looks like an amplifier circuit, I was thinking about using a 12v battery but also I would have to build a circuit which can convert a single voltage dc supply into a high voltage dual polarity supply at 12v or even higher voltage. Do you think you can design such a circuit?
Swagatam said…
you can search for a BTL amplifier circuit or a bridge tied load amplifier and use it for your desired application
Bhushan Borse said…
Hello Swagatam I want to make a Sine pulse width modulation Inverter which can control the speed of induction motor ..Ihave the 12 V Dc i want it to particular ac for the rating of 1KVA inverter so plz will u guide me which circuit will be the perfect and will i have to simulate it first if yes then which circuit i shall simulate will u plz provide me that circuut
Swagatam said…
Hi, I think you can study the concepts explains in the following article and make the design accordingly for your specific application

https://homemade-circuits.com/2016/07/3-phase-induction-motor-speed.html

I don't trust simulators therefore i cannot suggest about simulators...because they will mostly give you incorrect/misleading results unless you are an expert and exactly know how to handle them..
Swagatam said…
Hello Bhushan,
Hi, I think you can study the concepts explained in the following article and make the design accordingly for your specific application https://homemade-circuits.com/2016/07/3-phase-induction-motor-speed.html I don't trust simulators therefore i cannot suggest about simulators...because they will mostly give you incorrect/misleading results unless you are an expert and exactly know how to handle them.
Liezl said…
Hello Sir, I'm still a student and I will do this circuit as my project. If I used 12V battery for this circuit, what will be the possible output?
Swag said…
Hello Liezl, you can multiply 12V with 50% of the AH rating of the battery that will give the max power of the inverter....
Abdulnoni said…
I av a square wave inverter using sg3524, pls help me with circuit Dat we convert it to sine wave
Swag said…
you can apply the following concept

https://homemade-circuits.com/2016/08/sg3525-pure-sinewave-inverter-circuit.html
CHRISTIAN said…
HOW DO WE DETERMINE THE POWER OF AN INVERTER IS IT BY THE AMOUNT OF MOSFET USED OR BY THE TRANFORMER
Swag said…
Transformer and battery Ah.

according to the above specs you can dimension the mosfets
CHRISTIAN said…
SIR PLEASE EXAMPLE HOW CAN I DIMENSION THE MOSFET MAYBE FOR INSTANCE I HAVE A 1KVA TRANSFORMER WITH 12V 100AH BATTERY. NOW HOW DO I THEN KNOW HOW MANY MOSFET TO CASCADE PLS EXPLAIN
Swag said…
Christian, check the datasheet of the selected mosfet and find out the Vds(Drain-Source Voltage) and Id(Continuous Drain Current) specs of the mosfet, multiplying them will give you absolute max power or wattage of the mosfet. So you can use this data to calculate how many mosfets you may require to achieve the required inverter wattage output safely.

the above figures will be valid only when the mosfets are mounted on adequately large heatsinks.
Sherwin Baptista said…
Dear Sir Swagatam,
Most people think circuit ground means negative pole of the battery. That is not true. I've seen many negative voltage regulators and can now understand that circuit GND and negative in certain cases can
not be the same.

When we say circuit Ground we refer to an electrical circuit where AC is involved.

In DC circuits there is nothing called ground but still people call that as negative terminal of battery.

This page shows the best example of a case where there is a separate positive and separate negative with respect to GND. The GND here is both positive and negative.

So people here need to be much more careful as to how they do their battery connection to the inverter in this circuit.

Let me first get this clarified from you.
THANKS
Swag said…
Hi Sherwin,

In circuits operating with dual supplies where a separate negative is involved with reference to a ground then this ground becomes different and a critical thing to observe, but in single supplies where there's no separate negative with reference to a ground then the negative terminal itself is considered as the ground.

Therefore in DC circuits with single supply the negative is considered as ground which simply means a common zero voltage line.

Such parameters are a matter of understanding and the users must be aware of these facts.
Sherwin Baptista said…
What is the advantage of using dual supplies with respect to GND in this inverter circuit. Does it affect the output AC waveform?

If we compare this circuit with other circuits in your blog that uses one battery to run an inverter, does it have any difference?
Swag said…
since it is an audio amp circuit, it had to use a dual supply, because originally the loud speaker had to be operated in a push pull mode.
When we are replacing the loud speaker with a trafo we are implementing the same concept, that is using a two wire trafo and achieving a push pull operation on it.

Whenever a two wire push pull trafo is used in an inverter, the supply has to be dual, or the circuit has to be an full bridge or H-bridge topology employing 4 mosfets in tandem.

if the above concept is to be avoided, a center-tap trafo will come into the picture
Sherwin Baptista said…
Just recently i purchased an old computer UPS and the transformer had 2 wires on the low voltage side. On the circuit board there was an heat sink with four mosfets attached of the same number.
Does it mean that this UPS provides a push pull effect to the 2-wire transformer connected using a full bridge circuit?
The UPS was operated from one battery.
Swag said…
yes it is using an H-bridge network for operating the two wire trafo in a push pull mode...
bradradocad said…
Hello friend, I am trying to make a 100W inverter with a 12V input to 120V output and was wondering what I need to change? Also, are there alternatives for the K1058 and J162 mosfets? Thanks!
Swag said…
Hi, you won't have to change anything in the design expect the number of mosfet which can be limited to just one pair, meaning just one pair of mosfet will be enough to give you the required results.

You can use IRF540, IRF9540 mosfets
Good day Mr Swagatam, pls can you show how to fix a relay on1kva using sg3525 so that when light comes it wil be automatically charging the battery. God bles you sir.
Swag said…
Yusuf, you can use a simple relay driver stage using a transistor and a double contact relay, then connect the pair of center poles of the relay to the appliance, connect the pair of N/O contacts with the mains AC phase/neutral....and connect the pair of N/C contacts with the inverter mains phase/neutral.

for the relay driver stage connect the emitter of the transistor with negative supply of a 12V adapter connected with mains AC, positive of the relay with the positive of the adapter output, and the base also with the positive of the adapter...the base resistor can be calculated from the following article:
https://homemade-circuits.com/how-to-make-relay-driver-stage-in/
youngking said…
sir , please can you give me a link where i can found 1000kva square wave inverter because the one i build from other site is not working. i have 12v 1000watt centre tap transformer and 230v as the output , 12v 62ah battery just a diagram that can fit my specification i just want to start with square wave, although i have came across some of your pure sine wave inverter but i want to start with square wave . i hope my request will be put into consideration . thanks
Swag said…
Youngking, you can use any square wave design, and modify it for getting 1kva output by appropriately upgrading its mosfets, transformer and battery for handling 1000 watts.

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