In this post I have explained a 3 powerful yet simple sine wave 12V inverter circuits using a single IC SG 3525. The first circuit is equipped with a low battery detection and cut off feature, and an automatic output voltage regulation feature.
This circuit was requested by one of the interested readers of this blog. I have explained more about the request and the circuit functioning.
You may also want to read how to design a sine wave inverter from the scratch.
Design#1: Basic Modified Sine
In one of the earlier posts I discussed the pin out functioning of the IC 3525, using the data, I designed the following circuit which is though quite standard in its configuration, includes a low battery shut down feature and also an automatic output regulation enhancement.
The following explanation will walk us through the various stages of the circuit, I have explained them:
As can be witnessed in the given diagram, the IC SG3525 is rigged in its standard PWM generator/oscillator mode where the frequency of oscillation is determined by C1, R2 and P1.
P1 can be adjusted for acquiring accurate frequencies as per the required specs of the application.
The range of P1 is from 100Hz to 500 kHz, here we are interested in the 100 Hz value which ultimately provides a 50Hz across the two outputs at pin#11 and Pin#14.
The above two outputs oscillate alternately in a push pull manner (totem pole), driving the connected mosfets into saturation at the fixed frequency - 50 Hz.
The mosfets in response, "push and Pull the battery voltage/current across the two winding of the transformer which in turn generates the required mains AC at the output winding of the transformer.
The peak voltage generated at the output would be anywhere around 300 Volts which must adjusted to around 220V RMS using a good quality RMS meter and by adjusting P2.
P2 actually adjusts the width of the pulses at pin#11/#14, which helps to provide the required RMS at the output.
This feature facilitates a PWM controlled modified sine waveform at the output.
Automatic Output Voltage Regulation Feature
Since the IC facilitates a PWM control pin-out this pin-out can be exploited for enabling an automatic output regulation of the system.
Pin#1 is the sensing input of the internal built in error Opamp, normally the voltage at this pin (non inv.) should not increase above the 5.1V mark by default, because the inv pin#1 is fixed at 5.1V reference internally.
As long as pin#1 is within the specified voltage limit, the PWM correction feature stays inactive, however the moment the voltage at pin#1 tends to rise above 5.1V the output pulses are subsequently narrowed down in an attempt to correct and balance the output voltage accordingly.
A small sensing transformer TR2 is used here for acquiring a sample voltage of the output, this voltage is appropriately rectified and fed to pin#1 of the IC1.
P3 is set such that the fed voltage stays well below the 5.1V limit when the output voltage RMS is around 220V. This sets up the auto regulation feature of the circuit.
Now if due to any reason the output voltage tends to rise above the set value, the PWM correction feature activates and the voltage gets reduced.
Ideally P3 should be set such that the output voltage RMS is fixed at 250V.
So if the above voltage drops below 250V, the PWM correction will try to pull it upward, and vice versa, this will help to acquire a two way regulation of the output,
A careful investigation will show that the inclusion of R3, R4, P2 are meaningless, these may be removed from the circuit. P3 may be solely used for getting the intended PWM control at the output.
Low Battery Cut-of Feature
The other handy feature of this circuit is the low battery cut off ability.
Again this introduction becomes possible due to the in built shut down feature of the IC SG3525.
Pin#10 of the IC will respond to a positive signal and will shut down the output until the signal is inhibited.
A 741 opamp here functions as the low voltage detector.
P5 should be set such that the output of 741 remains at logic low as long as the battery voltage is above the low voltage threshold, this may be 11.5V. 11V or 10.5 as preferred by the user, ideally it shouldn't be less than 11V.
Once this is set, if the battery voltage tends to go below the low voltage mark, the output of the IC instantly becomes high, activating the shut down feature of IC1, inhibiting any further loss of battery voltage.
The feedback resistor R9 and P4 makes sure the position stays latched even if the battery voltage tends to rise back to some higher levels after the shut down operation is activated.
Parts List
All resistors are 1/4 watt 1% MFR. unless otherwise stated.
- R1, R7 = 22 Ohms
- R2, R4, R8, R10 = 1K
- R3 = 4K7
- R5, R6 = 100 Ohms
- R9 = 100K
- C1 = 0.1uF/50V MKT
- C2, C3, C4, C5 = 100nF
- C6, C7 = 4.7uF/25V
- P1 = 330K preset
- P2---P5 = 10K presets
- T1, T2 = IRF540N
- D1----D6 = 1N4007
- IC1 = SG 3525
- IC2 = LM741
- TR1 = 8-0-8V.....current as per requirement
- TR2 = 0-9V/100mA Battery = 12V/25 to 100 AH
The low battery opamp stage in the above shown schematic could be modified for a better response as given in the following diagram:
Here we can see that pin3 of the opamp now has it's own reference network using D6 and R11, and does not depend on the reference voltage from the IC 3525 pin16.
Pin6 of the opamp employs a zener diode in order to stop any leakages that might disturb pin10 of the SG3525 during its normal operations.
R11 = 10K
D6, D7 = zener diodes, 3.3V, 1/2 watt
Another Design with Automatic Output Feedback Correction
Circuit Design#2:
In the above section I have explained the basic version of IC SG3525 designed to produce a modified sine wave output when used in an inverter topology, and this basic design cannot be enhanced to produce a pure sine wave waveform in its typical format.
Although the modified squarewave or sine wave output could be OK with its RMS property and reasonably suitable for powering most electronic equipment, it can never match the quality of a pure sine wave inverter output.
Here I have explained a simple method which could be used for enhancing any standard SG3525 inverter circuit into a pure sine wave counterpart.
For the proposed enhancement the basic SG3525 inverter could be any standard SG3525 inverter design configured to produce an modified PWM output. This section is not crucial and any preferred variant could be selected (you can find plenty online with minor differences).
I have discussed a comprehensive article regarding how to convert a square wave inverter to a sine wave inverter in one of my earlier posts, here we apply the same principle for the upgrade.
How the Conversion from Squarewave to Sine wave Happens
You might be curious to know regarding what exactly happens in the process of the conversion which transforms the output into a pure sine wave suitable for all sensitive electronic loads.
It is basically done by optimizing the sharp rising and falling square wave pulses into a gently rising and falling waveform. This is executed by chopping or breaking the exiting square waves into number of uniform pieces.
In the actual sine wave, the waveform is created through an exponential rise and fall pattern where the sinusoidal wave gradually ascend and descend in the course of its cycles.
In the proposed idea, the waveform is not executed in an exponential, rather the square waves are chopped into pieces which ultimately takes the shape of a sine wave after some filtration.
The "chopping" is done by feeding a calculated PWM to the gates of the FET via a BJT buffer stage.
A typical circuit design for converting the SG3525 waveform into a pure sine wave waveform is shown below. This design is actually an universal design which may be implemented for upgrading all square wave inverters into sine wave inverters.
As may be in the above diagram, the lower two diodes are connected to a PWM feed or input, which causes the transistors to switch according to the PWM ON/OFF duty cycles.
This in turn rapidly chop the 50Hz pulses at the bases of the BC547/BC557 coming from the SG3525 output pins.
The above operation ultimately force the mosfets also to turn ON and OFF in the same pattern as the SPWM for each of the 50/60Hz cycles. This SPWM is then induced into the transformer primary by the MOSFETs, consequently producing a sine waveform at the output or the secondary side of the transformer.
If an ordinary PWM is used as I have explained below, then its frequency should be 4 times more than the base 50 or 60 Hz frequency. so that each 50/60Hz cycles are broken into 4 or 5 pieces and not more than this, which could otherwise give rise to unwanted harmonics and mosfet heating.
PWM Circuit
The PWM input feed for the above explained design can be acquired by using any standard IC 555 astable design as shown below:
This IC 555 based PWM circuit can be used for feeding an optimized PWM to the bases of the BC547 transistors in the first design such that the output from the SG3525 inverter circuit acquires an RMS value close to mains pure sine wave waveform RMS value.
Using an SPWM
Although the above explained concept would greatly improve the square wave modified output of a typical SG3525 inverter circuit, an even better approach could be to go for an SPWM generator circuit.
In this concept the "chopping" of each of the square wave pulses is implemented through a proportionately varying PWM duty cycles rather than a fixed duty cycle.
I have already discussed how to generate SPWM using opamp, the same theory may be used for feeding the driver stage of any square wave inverter.
A simple circuit for generating SPWM can be seen below:
Using IC 741 for Processing SPWM
In this design we see a standard IC 741 opamp whose input pins are configured with a couple of triangle wave sources, one being much faster in frequency than the other.
The triangle waves could be manufactured from a standard IC 556 based circuit, wired as an astable and compactor, as shown below:
#UPDATE: The above "slow triangle waves" can be directly acquired from the Ct pin of the IC, that means you can now eliminate or ignore the above IC 555 stage for the slow triangle waves.
As can be seen in the above two images, the fast triangle waves are achieved from an ordinary IC 555 astable.
However, the slow triangle waves are acquired through an IC 555 wired like a "square wave to triangle wave generator".
The square waves or the rectangular waves are acquired from pin#4 of SG3525. This is important as it synchronizes the op amp 741 output perfectly with the 50 Hz frequency of the SG3525 circuit. This in turn creates correctly dimensioned SPWM sets across the two MOSFET channels.
When this optimized PWM is fed to the first circuit design causes the output from the transformer to produce a further improved and gentle sine waveform having properties much identical to a standard AC mains sine waveform.
However even for an SPWM, the RMS value will need to be correctly set initially in order to produce the correct voltage output at the output of the transformer.
Once implemented one can expect a real sine wave equivalent output from any SG3525 inverter design or may be from any square wave inverter model.
Finalized SG3525 Pure Sine Wave Inverter Circuit
The following diagram shows the finalized design of the pure sine wave inverter using IC SG3525 and SPWM, as per the above explanations.
If you have any doubts regarding the above SG3525 pure sine wave inverter circuit you can feel free to express them through your comments.
UPDATE
A basic example design of a SG3525 oscillator stage can be seen below, this design could be integrated with the above explained PWM sine wave BJT/mosfet stage for getting the required enhanced version of the SG3525 design:
Complete circuit diagram and PCB layout for the proposed SG3525 pure sine wave inverter circuit.
Courtesy: Ainsworth Lynch
Design#3: 3kva Inverter circuit using the IC SG3525
In the previous paragraphs we have comprehensively discussed regarding how an SG3525 design could be converted into an efficient sine wave design, now let's discuss how a simple 2kva inverter circuit can be constructed using the IC SG3525, which can be easily upgraded to sine wave 10kva by increasing the battery, mosfet and the transformer specs.
The basic circuit is as per the design submitted by Mr. Anas Ahmad.
The explanation regarding the proposed SG3525 2kva inverter circuit can be understood from the following discussion:
hello swagatam, i constructed the following 3kva 24V inverter modified sine wave (i used 20 mosfet with resistor attached to each, moreover i used center tap transformer and i used SG3525 for oscillator).. now i want to convert it to pure sine wave, please how can i do that?
Basic Schematic
My Reply:
Hello Anas,
first try the basic set up as explained in this SG3525 inverter article, if everything goes well, after that you can try connecting more mosfets in parallel.....
the inverter shown in the above daigram is a basic square wave design, in order to convert it to sine wave you must follow the steps I have explained below The mosfet gate/resistor ends must be configured with a BJT stage and the 555 IC PWM should be connected as indicated in the following diagram:
Regarding Connecting parallel mosfets
ok, i have 20 mosfet(10 on lead A, 10 on lead B), so i must attached 2 BJT to each mosfet, that's 40 BJT, and likewise i must connect only 2 BJT coming out from PWM in parallel to the 40 BJT? Sorry am novice just trying to pick up.
Answer:
No, each emitter junction of the respective BJT pair will hold 10 mosfets...therefore you will need only 4 BJTs in all....
Using BJTs as Buffers
1. ok if i may get you right, since you said 4 BJTs, 2 on lead A, 2 on lead B, THEN another 2 BJT from the output of PWM, right?
2. am using 24 volt battery hope no any modification to the BJT collector terminal to the battery?
3. i have to use variable resistor From oscillator to control the input voltage to the mosfet, but i don't know how i will go about the voltage that will go to the base of the BJT in this case, what will i do so that i want end up blow up the BJT?
Yes, NPN/PNP BJTs for the buffer stage, and two NPN with the PWM driver.
24V will not harm the BJT buffers, but make sure to use a 7812 for stepping it down to 12V for the SG3525 and the IC 555 stages.
You can use the IC 555 pot for adjusting the output voltage from the trafo and set it to 220V. remember your transformer must be rated lower than the battery voltage for getting optimum voltage at the output. if your battery is 24V you can use an 18-0-18V trafo.
Parts List
IC SG3525 Circuit
all resistors 1/4 watt 5% CFR unless otherwise specified
10K - 6nos
150K - 1no
470 ohm - 1no
presets 22K - 1no
preset 47K - 1no
Capacitors
0.1uF Ceramic - 1no
IC = SG3525
Mosfet/BJT Stage
All mosfets - IRF540 or any equivalent Gate resistors - 10 Ohms 1/4 watt (recommended)
All NPN BJTs are = BC547
All PNP BJTs are = BC557
Base Resistors are all 10K - 4nos
IC 555 PWM Stage
1K = 1no 100K pot - 1no
1N4148 Diode = 2nos
Capacitors 0.1uF Ceramic - 1no
10nF Ceramic - 1no
Miscellaneous IC 7812 - 1no
Battery - 12V 0r 24V 100AH Transformer as per specs.
A Simpler Alternative
With over 50,000 comments answered so far, this is the only electronics website dedicated to solving all your circuit-related problems. If you’re stuck on a circuit, please leave your question in the comment box, and I will try to solve it ASAP!
Sir I’ve finish building this project (the hand drawn one) but only get 22v athe output. What might be wrong?
Hello Andrews, It will be difficult for me to troubleshoot your circuit without checking it practically, so i would recommend to build and test it in a step wise manner. Please start with a basic SG3525 inverter using single MOSFETs as shown below:
If this works then we can proceed with the further upgradation.
Thank you very much. I’ve changed the transformer to 9v-0-9v to 230v transformer and now the output voltage is 230.
OK, good! Glad it is working now…
Merry Christmas sir, I am about to build a full h bridge low frequency sine wave inverter with SG3524 and lm324,
I have successfully built the two triangular generators separately using 2 lm324, the slow triangle is 50hz and the fast triangle is 450hz, these two triangular frequencies have been connected to lm358 to give me spwm signal.
The 2 outpts from the sg3524 are 50hz square wave giving a total output of 3 signals.Full h bridge circuit require 4 signals to trigger, my question is should I split the output of the lm 358 to two inorder to get the fourth signal?
Merry Christmas Richard!
I cannot figure out how you have configured the 3 phase from the IC SG3524.
Can you upload the schematic to this comment? Only then I would be able to provide a proper suggestion.
Also, for the slow triangle waves, you do not need a separate circuit, you can simply get it across the timing capacitor of the SG3524 IC.
I tried the pin ct on sg3524 for the slow triangle the voltage of the triangle was low that’s why I constructed another slow triangle using lm324 that gave the same width as the fast triangle
Please check the peak voltage of the Ct pin triangle waves using an oscilloscope, that will give you the exact peak value of this pinout. The triangle waves from the Ct pin is necessary for proper synchronization with the inverter frequency of 50 Hz.
Hello Sir Good day please I want to ask can I use the pwm or spwm circuit above to convert a square wave from ic sg3524 to a pure sine wave or do I need additional circuit
Good day Samuel,
The above SPWM concept can be used with any inverter oscillator IC to convert square waves to sine waves, so you can use it for SG3524 also…
Hello Sir. is it possible to run LEDs using the SG3525 outputs?
Hi Jedidiah, yes, it is possible, how exactly do you want to run the LEDs? But using this IC for lighting LEDs would be an overkill..
Alright Sir. I was thinking of a pulse generator that responds to a ceramic piezo sensor hence produce flashes. Its actually a door knock sensor that should respond visually to a vibration with flashes of light.
Thank you Jedidiah,
a door knock sensor that should respond visually to a vibration with flashes of light….for this we can simply use the IC 555 monostable circuit, the SG3525 is not required according to me.
How many MOSFETs do I need to add for 3000 watts? What should the transformer feature be?
You can use a 48V battery for the transformer and the MOSFET stages.
Parallel MOSFETs are not required, you can used single IRFP2907 MOSFETs.
Battery can be 48V 600 Ah lead acid battery.
Transformer can be 40-0-40V, 70 amps
Thank you Sir, from the hand drawn circuit I can see you’ve written “shutdown protection” between pin 10 and -VE, indicated 2v. Please am little bit confuse there, can you explain it to me?
Hi Andrews,
That is the shut-down input pin of the IC. If you configure a feedback system with this pinout, then if the feedback voltage increases above 2V, will cause the IC output to shut down or narrow the PWMs.
So can I leave the pin#10 of the SG3525 not connected?
No, it must be either configured with a feedback network or kept grounded.
please can I get the gerber file?
I don’t have the gerber files for this project unfortunately…
please I need your guide sir, I made 24v inverter using irfp 260 MOSFET(1pc) when I put on My CRT TV at night the MOSFET doesn’t blow, but another 60v inverter using psm50s20 MOSFET(1pc) it blows at night but not during the sunny day with solar.
although the TV has high starting surge
Hi Daniel, I could not find the datasheet of the psm50s20 MOSFET, so I cannot figure out why it is blowing up. However it is better to use standard MOSFETs like IRF540, IRFZ44 etc instead of any other untested variants.
Thanks sir, sorted out. Another issue is that on heavy load like freezer, it is not stable, please what can I do?
That’s good Daniel,
If the load is not stable then you must upgrade the transformer, MOSFETs and the battery according to the load. The output power must be much higher than the initial surge current intake of the freezer.
Sir, I want to build the Finalized SG3525 Pure Sine Wave Inverter Circuit. what are the voltage for the various capacitors?
Hello Kumah, all the capacitors can be rated at 25V.
Hi Swagatam,
Am a big fan of yours. Am a hobbyist ,electronics technician and electrician.
I first built your 3stage high current charger to perfection ,some 7years ago and an inverter using Sg3524 ic
.The circuit is from this site
.
it worked well for years till recently,it got damaged,I replaced MOSFETs with f1010e,but maintained the buffer transistors.
here is my challenge:
-sg3524 output reads 3v,
-mosfet overheat and blow above 150w ,
Am using 2 MOSFETs per channel.
I have a 7809 for the ic.
f1010e should work well,why the blowing, this inverter works,something is off.
I want to get running then use your 555 ideah to convert to pure sine wave.
it’s a 12v inverter,transformer is 1200va,900watts ,10-0-10 center tapped.
help please!
Thank you Ronnie,
If you are using 9V supply for the IC, then the peak voltage at the output pins of the IC should also around 9V.
So, you must confirm whether this is happening or not, and you will also need to check the frequency across the output pins, which must be 50Hz or 60Hz.
Without a minimum of 9V at their gates, the MOSFETs will not operate correctly and might keep blowing.
Do you have an oscilloscope, if yes then you can use it to confirm the above details across the IC output pins….
Hola ing. voy a proceder a armar este inversor se onda senoidal, seria necesario poner un regulador 7812 ?
You can add the 7812 IC after the diode D1 in the following diagram:
How could the design be if I want to increase 2 mosfets?
You can put any number of MOSFETs in parallel in the existing design without any changes in the circuit.
Thank you, another query would be necessary to add two more diodes 1n4148 at the exit of pin 6 in ic741 if I am going to add god mosphets more or just connect it to the diode 1n4148 x2 that are in the design?
If you want to add more number of parallel MOSFETs, just connect their gates, drains, and source terminals with each other, in common, in the existing setup, that’s all, no need to change anything else in the circuit design.
Hello all right ? about the sine inverter I found cool one thing I did not understand was the fact that the gate resistor is de1k something else and about the output stabilization part is not isolated I found it dangerous what I will suggest and use an optical coupler pc 817 with a TL431 to make the output control making more efficient and accurate.
Yes, the gate resistors are 1k, the high value is required for reducing loading of the op-amp.
The MOSFET gate discharge will not get affected by the high value 1k because of the reverse 1N4148 diodes.
Sure, you can make the feedback isolated using an opto-coupler.
Good day Engineer Swagatam, please what can I do to My efficient modified sine inverter, it could not power a brand of laptop charger, whereas the grid powers it, other brand laptop chargers are working with the inverter.
Hi Seun,
That specific brand could have been designed to work with pure sine wave AC only, that is why it might not be accepting a modified sine wave AC.
Thanks engineer, your guide article was amazing, I got a cleaner wave, but this pure sine wave consumes much more current than modified wave inverter, why is this so, sir.
Thanks Seun,
PWM sine wave should consume less current because it uses PWM technology, if it is consuming more current, then you must investigate why this is happening…
SIR, WHAT TO DO FOR PROTECTION OF IC3525 IN PARTICULAR CIRCUIT
Anil, you can supply 12V DC to the IC through a 7812 IC, and also the arrangement of C6, C7, R7, as shown in the first design.
Hi sir
I want to control duty cycle of dsp30f2010 plz help me also I have sent an email about project
Hi Azhar, sorry, i have not yet investigated this specific IC, so currently i have no idea regarding its working specifications…possibly I will try to study it and try to figure out your problem.
is there any other way to filter a square wave to sine wave using RC filter
Here’s an example of a sine wave inverter using RC filter:
Thanks for this, please what kind of capacitors are CX, cy, and please give a values to experiment with.
In the finalized sine wave design, CX must be adjusted to a value which generates triangles waves of around 300 Hz, you can try any online 555 calculator to find the value of this CX….where is CY, i cannot find it?
please what type of capacitors are they electrolytic or ceramic
It cannot be electrolytic because the value could be in nF or pF. So, you can use ceramic disc or PPC…
please sir, help out, will CX, cy be same values, please I can’t find any online calculator to calculate to get 300hz, the ones online are only astable.
Here’s the calculator you can use to find CX:
ohmslawcalculator.com/555-astable-calculator
I cannot find where is CY??
You’ve asked in Oct 14, 2024 about 2 experimental items (CX & CY) you drew on a picture
I was referring to this diagram:
Thanks, I checked it out.
However, I read you asked for the same item twice (above) when a person asked [Seun October 14, 2024 please sir, help out, will CX, CY be same values, (…) ], but that man never answered, and I felt compelled to fill in that blank, since you currently NEVER left and open question like that (unless a lazy person wanted you to do all the jobs).
I will visit that site often. That’s an electronic library, sir! I hope it never pass away (like me).
Thanks AJTH, for your kind words. I appreciate it very much…
If you are referring to the 4047 circuit, it is actually an RC series integrator circuit.
The best way to get the values of CX and CY is to find it through some trial and error and practical experimentation, because calculating it can be a lot difficult.
Hello sir, please can I use sg 3525 inverter circuit to invert 48v DC to 12v ac
Hi Daniel, yes, you can convert any voltage to any level as you like, using an inverter IC like SG3525 or any other similar IC. It simply depends on the transformer winding ratings…
please how can I embed WiFi network to monitor and automate sg3525 inverter design.
Daniel, Currently I do not have any circuit for monitoring an SG3525 inverter through Wifi network…
I discovered with 12v AC output, the transformer saturates causing damage. Please how will I do it?
Please explain your problem in detail, I cannot understand it.
I will to design an inverter with DC input 48v that will output 24v Ac, I am thinking if I make turns for primary and secondary windings with these it might saturate please guide.
Sure, for designing the transformer you can refer to the following article:
https://www.homemade-circuits.com/how-to-design-your-own-inverter/
I tried making a 20Khz inverter boost board I bought on Aliexpress to have adjustable output frequency range of 100Hz to 100Khz. It came with Ct=10nf, Rt=3.3kohm and Rd=100ohms. I replaced Rt with a variable pot of 100Kohm. The booster board stopped working consistently, sometimes draws high current from my source once I turn it on. And when it does not draw high current, there is no output. I have tried this for three boards, the same result. Please what can I do? Can I order a board for you to help me work on?
Please provide the IC number of the module, or provide the schematic diagram, only then I can help to solve the problem…
Thanks so much for your prompt reply!!
The IC number is SG3525AN (HLF 22A8).
Kind Regards
Hello ThankGod Amaechina, Changing the frequency is not recommended for any boost converter circuit, because the parts and the inductor values of all converters are calculated using a fixed frequency. Instead you must change the feedback to adjust the output voltage.
You can try the following designs to build your own boost converter using SG3525 IC.
https://www.homemade-circuits.com/dc-to-dc-converter-circuits-using-sg3524-buck-boost-designs/
I noticed that pure sine wave strained MOSFETs than modified sine wave, is this correct, sir?
MOSFETs are built to handle high frequencies in the MHz range, so an SPWM with a few 100 Hz frequency can have no adverse impact on the MOSFETs, according to me…
please I found out that the 18k resistor for the fast wave is getting very hot, I don’t know what went wrong/
There’s no way the 18k resistor should become hot? Even if you connect the 18k directly across the 12V DC supply still it cannot become hot?….how much DC supply are you using for powering the 555 and the SG3525 circuit?
I will try to update the complete schematic of the SG3525 sine wave inverter soon…
please before upgrading to spwm, the output frequency was 50Hz , but after it became 150hz, please assist
Please add a 3uF/400V PPC capacitor across the AC output of the transformer and check the frequency again, it should be 50Hz.
Hello sir, I noticed when I connect the spwm complete circuit, it works but after 10-15secs, it stops working. I restart again, same thing.
I now found out that the step down voltage regulator IC for 12v supply is getting hot when the spwm circuit was connected. but when I remove it, the regulator is not hot.
please kindly assist.
Hello Daniel, which schematic are you using exactly?
Good morning Sir
Thanks for the great work you are doing.
Sir I am interested in the last circuit. The 5000Watts square wave. And have two concerns
1) Can just those 4 MOSFETs 3205 be able to support 5000Watts?
2) please for the Circuit of a pure sine wave version of the 5000Watts Inverter.
thanks
Hello Ngang,
Sorry for the confusion, actually single 3205 MOSFETs cannot handle 5000 watts, especially when the voltage is 12v.
You would require at least 5 MOSFETs in parallel on each of the channels.
I would actually recommend IRFP2907 MOSFETs instead, which are even more powerful than 3205.
Okay Sir. Thanks very much for the clarification.
Sir, I need a 5000Watts pure sine wave inverter circuit diagram
Thank you NGANG, I think you can first complete the square wave 5000 watt inverter circuit and confirm the results then we can convert it to a sine wave inverter.
Sir, I made an inverter with 2 stages, my circuit was normal but for some reason an explosion occurred. now I’m fixing this circuit. stage 1 with sg3525 and stage 2 with egs002. My stage 2 is probably normal but for stage 1 it doesn’t seem like it. I did a load test after the transformer (before the stage 2 circuit) there was a drop in the power supply voltage/source voltage from 12v to 8v. I wonder, is my IC 3525 the problem or my HFT? inverter spec 1000watt 12v to 220 pure sine wave EE55 transformer
Hi Kwk,
I am not sure how a SG3525 can be used with EGS002? It is simply not required, because EGS002 by itself is a full-fledged inverter module and does not require any external oscillator IC? Let me know your opinion on this.
pls send me a full diagram of pure sine wave inverter with part label using sg352 4 or 4047ic
You can go through the following article, this may help you to learn the details:
https://www.homemade-circuits.com/designing-a-sine-wave-inverter-circuit-from-the-scratch-tutorial/
Hello sir, please I want to build an inverter with 60v input, please how I keep the battery well managed, not to have imbalance state. Thanks Engineer Swagatam
Hello Grace, If you are using many batteries in series, then you will need a balance charger circuit to keep proper balance across the batteries.
I have a balancer circuit, but it is not tested by me yet:
https://www.homemade-circuits.com/lipo-battery-balance-charger-circuit/
Hello Swagatam, I constructed the Basic modified sinewave inverter in design number one. But when i power the circuit the wires connected to the MOSFETS is burning out, I presume is because the current carrying capacity of the jumper wires are not good enough. So, I am changing the wires now to thicker once. My question is, without loading the circuit is the current flowing through the mosfet supposed to be that high to burn off the wires?
Hello Collins,
If your MOSFETs are burning that means there’s some serious fault in your circuit.
In that case please remove the MOSFETs and first confirm whether your IC outputs are generating the required frequency or not?
If you IC does not oscillate and produce the intended frequencies at the MOSFET gates then your MOSFETs and the transformer both might burn.
So, please disconnect the MOSFETs and confirm if the IC is oscillating or not.
Hello Swagatam,
Thank you for your response. I will do that and keep you posted.
No problem Collins, all the best to you.
Hello sir, will the Spwm generator link to in4148 or BC 547 for the bjt buffer stage, please which one is better?
Hello Daniel,
1N4148 is the better option, so please use iN4148 diodes for feeding the SPWM to the buffer BJT bases.
Thanks sir, please the direction of the diode will block current
Daniel, the diode direction is correct, it is supposed to be reverse biased…it is positioned to conduct during the off pulses from the the op amp output…
Is it in order in the article
Yes…
Hello Mr Swagatam, thank you for your informative lessons on electronics, it has been beneficial.
How can I synchronise Sg3525 IC to make 3-phase inverter?
Hello Seun,
I don’t think SG3525 ICs can be used to generate sequential 120 degree phase signals for operating MOSFETs in 3 phase configuration.
please sir, I need sg3524 inverter circuit with well controlled pin 9 to give constant output 220v AC irrespective the battery voltage. thanks
Daniel, the feedback can produce a constant voltage only as long as the battery voltage is above normal. If it drops below normal then the feedback cannot help.
Thanks, I agree with this, a colleague argues it remains constant, irrespective of the voltage
If the battery is low or if there’s an overload, the feedback cannot raise the voltage, the output voltage will drop. Please ask your colleague how to do it.
please how can I put a soft start to the inverter circuit
Capacitor at pin#8 of the SG3525 IC decides the soft start.
Thanks for your reply, I am working with Sg3524 IC, how will I add soft start, and value. Thanks.
For SG3524 IC soft start, connect a 1N4148 diode at pin#9, anode to pin#9, then connect its cathode to the positive of a 4.7uF capacitor, negative of the capacitor to ground.
Thanks Swagatam,I appreciate you. I already has 4.7uf and 1k resistor connected in series into pin 9 and ground. How should I add the diode then, sir?
Daniel, then i think you must replace the 1k with the diode, and check the response.
Thanks sir, how will I test it’s response.
2. if I want to incorporate your guide for Ana’s 3kva inverter using 555 timer only, will I adjust anything.
With the slow-start added, the output voltage will not rise quickly to 220V, rather after a second or two.
If you want to add soft-start to Ana’s circuit, you can do it by adding a capacitor between pin#8 and ground, no other changes would be required.
Sorry sir, I meant to make it pure sine wave for Anas circuit, is there anything, I will modify in the 555 timer. Thanks Swagatam.
For making a pure sine wave inverter, you will have to employ the opamp technique, using fast and slow triangle waves.
Hello sir, My breaker used to trip off when the MOSFET blows, but because My batteries a weaker, it doesn’t anymore, putting more stress on the battery.
Please can I get a trip off signal from the sg35xx IC to off the relay if I use relay instead of breaker. Thanks Swagatam.
Daniel, getting a trip off signal to turn OFF a relay may not possible, or may be complicated, however you can initiate an instant shut down of the inverter and prevent the MOSFFETs from blowing, by appropriately configuring the shut down feature of the IC.
hi swagatam
it seems 555 doesn’t provide perfect triangle instead provide sawtooth , is it not a problem?
second thing voltage level from ct pin of sg352x is lower than that from 555 pin2 (fast tringle ) lead opamp to not trigger
, using lm358 in place of ua741 is correct?
Hi Abu,
Yes, the triangle waves are not perfect but still we can get a reasonably good sine wave output. The sine output will be much better than a modified output. Actually the slow triangle wave must be a sine wave ideally.
What are the peak values of the two triangle waves, did you measure them, please specify if possible??
LM358 can be used, or a comparator IC can be also used with appropriate modifications.
peak voltage of slow triangle is about 5v and that of fast is about 11v
Even with this difference in peak voltage, spwm will be generated at the output of the opamp, because fast triangle waves would be comfortably intersecting the slow triangle waves.
Sir, from this comment, can I still 741 IC for processing the spwm, because Abu reported that there was no trigger from the slow and fast wave
Daniel, IC 741 can be used, please see my reply to Abu.
Thanks sir, you advised We use a Trafo 9-0-9 v, @ 9v the MOSFET blew but worked well without blowing @10v, can I still use the Trafo for the PSW
Daniel, At 9V the MOSFET should never blow, there could be some other hidden issues, for example mosfet not rated as per trafo current.
Hello sir, please why is the amperage readings from the clamp meter is confusing. When I plug the electric stove it reads 2.35amps and battery drains fast. But with other loads without the stove it reads 4.25amps but the battery last longer.
Hello Seun, I think your meter is malfunctioning, because it’s showing the wrong results.
Thanks for the reply. Please how can I make My inverter efficient so that the standby current consumption will be 0.95A like factory made inverter rather than 2.24Amps.
You can add an ON/OFF switch in series with the positive line which connects with the transformer. If the supply to the transformer or MOSFETs is switched OFF the standby current will reduce drastically.
Thanks for this advice, won’t the inverter be totally shut off, also, will the switch handle the current when it is on load, please kindly advise what to do to make it seamless
Only the load and the transformer would be switched OFF, the IC and the MOSFETs would remain operational and in a standby mode. You must use a switch that is appropriately rated, to handle the load cuurrent.
I put a circuit breaker as the switch but shut off the inverter. What is the difference between a switch and the breaker
There’s no difference unless your circuit breaker has an automatic turn OFF system.
I don’t understand automatic off, because it doesn’t trip off by itself. I put it off by myself.
In that case it is same as the switch, no difference.
To reduce the standby current from your inverter like that of the redimade ones, you need an inductor in series with the positive lead from the battery to the transformer centre tap (that is for push-pull configuration). Or you connect an inductor in series with one terminal of the transformer before it reaches the H-bridge MOSFET’s connection (that is for H-bridge configuration/ non center tap transformer).
The inductor must be wound on a ferrite ring core and big enough to handle the current require from the inverter also it should be 8turns to 12turns. Then the thickness of the wire must be specified with the current needed in the inverter.
Dear Mr. Swagatam,
If an inverter with 100 KW power output at 50 kHZ is to be built what core would you be using? Can you please specify a core?
Thanks and kind regards,
Job Thykkoottathil.
Hi Job,
For 50kHz only a ferrite core is suitable, so you can use a ferrite core transformer.
Dear Mr. Swagatam,
I was thinking of a ferrite core with permeability 1300G. But not sure what the effective area and other dimensions should be. Just wondered whether you could help.
Kind regards,
Job.
Dear Job,
I think you will have to calculate the parameters accurately. I have posted an article on this, you can refer to this for more info.
https://www.homemade-circuits.com/how-to-design-and-calculate-ferrite-core-transformers-for-inverters/
THANK YOU SO MUCH MR SWAGATAM FOR THE QUICK RESPONSE, I REALLY APPRECIATE.
You are welcome Godspower!
SIR, PLEASE CONVERTION TO SINE WAVE IN THE ABOVE CIRCUIT, WILL IT ALSO WORK FOR SG3524. THAT WHAT AM HAVING IN MY LOCATION NOW.
Yes, it will work for SG3524 also.
GOOD DAY MR SWAGATAM, PLEASE MY QUESTION IS TAKEN FROM THE CIRCUIT DIAGRAM OF MR ANAS, WHERE YOU REPLIED TO HIS CIRCUIT MY ADDING PWM AND THE BJT TO CHOP THE SIGNAL FROM PIN 11 AND 14.
Hi Godspower,
If the voltage to the ICs are regulated using a 7812 ic, or a 7809 ic then the pwm will be stable, and the output voltage will also be stable and there won’t be any need of using a feed back.
The 741 ic circuit is universal.
Hi. I am reading this article very closely and I am confused with circuit design #1 wherein a small sensing transformer TR2 is used. The article states that the rectified output of TR2 is fed to Pin 2 (non-inverting input) of the SG3525S IC. However, looking at the circuit schematic, it seems that this rectified output is actually fed to Pin 1 (inverting input). Can you please clarify. Thank you very much.
Hi,
Sorry for the confusion. Yes, the feedback from the sensing transformer goes to Pin#1 and not Pin#2. Pin#2 is the reference pinout clamped with 5.1V reference value. I have corrected the typo accordingly now.
Hi, Mr. Swagatam, I had been following you r articles here in the Philippines. If I may, can you send me a complete detailed drawing for the PSW circuit you designed and inserted/incorporated to the basic 5kva 24vdc 220v output inverter by Mr. ANAS HAMAS.. Can you help me to have a PCB layout of that 5kva PSW inverter circuit? I am not a professional tech but only a newbie but can follow instructions.
Thank you for this opportunity to connect with you.
Egay Diolola
Thank you Edgardo, glad to meet you.
I understand you want to build the 5kva PSW inverter, however designing the PCB can be extremely time consuming so it won’t be possible for me to provide the PCB design.
That said, you should not build the whole 5kva circuit at once, you must first build a basic 100 watt version, then integrate the sine PWM and check the results, if everything works correctly, only then you must upgrade the MOSFFETs and the transformer for building the 5kva version.
Also, this design is very complex and will require testing and confirming the stages through an oscilloscope, therefore it may not be recommended for any newcomer, please proceed with caution.
Pls if we can get a pure sine wave using the ic sg3525 used above, i will also be happy because i undertand the schematics above more. I’m new to this, please be simple in explanations, i will appreciate that so much sir. thanks, waiting for yor reply.
Hi, In the above article I have explained elaborately regarding how to implement the pure sine wave feature in a SG3525 inverter circuit. You will read it carefully to understand all the steps.
Thank you very much, I appreciate this response and how fast it came through.
Hello,
First, I want to say thanks for your sharing of this knowledge of yours in this simple way, though not all that simple for me. my question is that I’m working on a pure sine wave inverter and I’m working with a cd4047, can you help me witth a more suitable schematics or guide on that, i have been seeing people working with CD4047 but they always have theri oscillator pin 13 left out, they don’t seem to have the explanations on why they did that, leaving the pin empty. I’m expecting your reply sir, thanks again.
For a 4047 pure sine wave inverter you can refer to the following post:
https://www.homemade-circuits.com/pure-sine-wave-inverter-circuit-using/
Regarding the output pinouts suppose your 4047 IC is set to produce 50 Hz frequency, then the pin#10 and pin#11 will alternately generate 50 Hz frequency while the pin#13 will generate a 100 Hz frequency.
Ok, thanks.
Bonjour chers techniciens merci pour cette matière
You are welcome Richard!
Is it necessary to include the error voltage circuit powered by 0-12volts transformer through the 2.2K pot as part in the Pure Sinewave Inverter Circuit, OR it’s unnecessary?
I am unable to find any circuit with 2.2K pot, please given more details about which circuit design you are referring to?
Hello. About the Pure Sinewave Inverter Circuit, should I use two 15v zener diodes or two 1N 4148 in the PWM circuit?
Secondly, what should I incorporate/consider as most important circuit, Short circuit/overload current protection OR Low battery & overload protection?
Hello, You will have to use 1N4148 diodes as shown in the diagram.
All those can be considered important. For the protections you may incorporate suitable feedback networks, as explained in the following article:
https://www.homemade-circuits.com/inverter-circuit-with-feedback-control/
I need circuit idea for High frequency plastic welding (dielectric heating)
old circuit all are using vacuum tubes such like 833a. 7t85 rb.7t69rb
but I need igbt based circuit
out put capacity is 5kw frequency 27mhz
Sorry, I do not have this circuit with me right now.
Can use sg3524 circuit to replace the sg3525 circuit
Yes you can do it.
Can I use this circuit to power twenty mosfets
Sure, you can put as many MOSFETs as you want.
Hello Sir Swagatam!
Hello Laszlo!
Thank You! Commenten My Easun Inverter pure sine 3000 w distroed modul ,diy replacement
Sorry, an exact DIY replacement module may not be possible for your specific inverter, you will have to contact the manufacturer for the module board.
Hello, sir,
Is there an error in the last diagram “A simpler alternative”? the resistor connected to the seventh leg goes to minus, but should go from the 7th leg to the resistor and to the 5th leg of the microcircuit;
Thank you
Hello Danil, You are absolutely correct, thank you! I have added the correction message just under the image.
Hello sir,
Can I use BD139/BD140 in place of BC547/BC557.
Thanks
Hello Olusegun,
Yes, you can use them, but that will be unnecessarily costlier and bulkier.
Thanks for your quick response all the time. I have them at my disposal. That’s why I’m asking.
No problem! You can use them.
Sir, can I get a pure sine wave non transformer based inverter circuit diagram
Hi George, you can refer to the following article:
https://www.homemade-circuits.com/5kva-transformerless-inverter-circuit/