This is my schematic design of a Pulse Width Modulator DC/AC inverter using the chip SG3524 .
I have built this design and using it as a backup to power up all my house when outages occur.
If you like my work and intend to build the circuit don't forget to give me the 5 satrs :D and subscribe to me by clicking on the "follow" button so I know how many people benefit from the design, Thanks
Notes:
>The schematic circuit design is for a 250 watt output, while the pics are of my 1500 watts inverter that i built, to increase the power of the circuit you have to add more of the Q7 and Q8 transistors in parallel, each pair you add will increase your power by 250 watts, ex: to get 750 watts of power from the inverter you need to add in parallel 2 of Q7 and 2 of Q8 to the original design.
>If you increase the power transistors you have to enlarge the T2 transformer to match the new needs, the circuit's transformer is rated 25 amps to handle 250 watts of 220v, for every 1 additional amp you need on the 220v side you have to increase 10 amps on the 12v side, of course there are limits to the thickness of the winding so if you need more than 750 watts i recommend that you use a 24VDC supply instead of 12 volts:
DC voltage and Transformer "T2" winding recommendation:
Power Supply Winding
750w 12VDC P:24V "12-0-12" / S:220V
1500w 24VDC P:48V "24-0-24" / S:220V
2250w 36VDC P:72V "36-0-36" / S:220V
3000w 48VDC P:96V "48-0-48" / S:220V
3750w 60VDC P:120V "60-0-60" / S:220V
4500w 72VDC P:144V "72-0-72" / S:220V
5250w 84VDC P:168V "84-0-84" / S:220V
*The transformer should be "center tapped" at the primary side.
**You can make the secondary 110v if needed.
***The transformer in the pic is a custom made (48V center tapped / 220v ) 2000 watts, weights like 10 kilos.
>R1 is to set the PWM duty cycle to 220v. Connect voltmeter to the output of your inverter and vary VR1 till the voltage reads 220V.
>R2 is to set the frequency to 50 or 60 Hz (R2 range is between 40Hz to 75Hz), so guys that do not have a frequency meter are advised to blindly put this variable resistor mid-way which should drop you in the range of 50~60 Hz.
If you want you can substitue the variable resistor with a fixed resistor using the following formula: F = 1.3 / (RxC)
in our case to get a 50Hz output we remove both the 100K and the variable 100K both from pin 6 and we put instead a 260K fixed resistor and we leave the 0.1uF (the 104 cap) as it is, this change should give out a fixed 50Hz as per the formula :
1.3 / (260,000 ohm x 0.0000001 farad) = 50Hz
But in reality it will not exactly give 50Hz because the 260K resistor has a specific error value margin so does the capacitor, that's why i recommend a variable resistor so that accurate calibration can be achieved.
>Use either tantalum or polyester film "as in pic" for the 104 caps, ceramic disc caps change value once hot and this in turn changes the frequency of the inverter so they are not recommended.
>Pin 10 of the SG3524 can be used to auto shut down the inverter, once a positive voltage is given instead of negative to pin10, the SG3524 will stop oscillating. This is useful for persons wanting to add some cosmetic makeup to their inverters like overload cutoff, low battery cutoff or overheating cutoff.
>Wiring connections on the power stage side should be thick enough to handle the huge amps drain from the batteries. I marked them with dark black on the schema also I included a pic so you see how thick those wires must be.
>The design does not include a battery charger since each person will be building a custom version of the inverter with specific power needs. If you are ordering a custom made transformer you can ask them to take out for you an additional output wire on the primary side to give 14v (between point 0 and this new wire) and use it to charge a 12v battery, of course this needs a seperate circuit to control charging auto cut-off. But anyway this is not advisable because it will shorten the life of the transformer itself since using it as a charger will toast the enamel coating layer of the copper wires over time. Anyway .. YES can be done to reduce cost.
>A cooling fan will be needed to reduce heat off the heat sinks and transformer, i recommend getting a 220v fan and connecting it to the output T2 transformer, when you power up the circuit the fan will start this will always give you a simple way to know that 220v is present and everything is OK.. You can use a computer's old power supply fan if you like.
Note that the fan must suck air out from the inverter case and NOT blow inside, so install it the correct way or it will be useless.
Also note how I fixed both the heat sinks and where the fan is, in a way that the fan sucks hot air from like a channel between the 2 heatsinks.
>2 circuit breakers are recommended instead of fuses, one on the DC side and one on the AC side, depending on your design
Ex: for a 24vDC ( 1500 watts design ) put a 60Amp breaker on the DC side and a 6Amp on the AC side.
For every 1amp of 220vAC you will be draining like 8 to 10 Amps from the 12v battery, make your calculations !
> The 2 Heat sinks should be big enough to cool the transistors, they are separate and should NOT touch each other. "see the pics"
>Important: If you're building a big design that uses more than 24VDC as power source, make sure not to supply the driver circuit with more than 24v maximum. (EX: If you have 4 batteries 4x12 = 48v , connect the v+ supply of the driver circuit to the second battery's (+) terminal with a thin 1 mm wire which is more than enough. this supplies the driver circuit with +24v while supplies the power transformer with +48v)
> "Optional" : Deep Cycle batteries are your best choice, consider them for best results .. read more
> Be cautious when building this circuit it involves high voltage which is lethal, any part you touch when the circuit is ON could give you a nasty painful jolt, specially the heat-sinks, never touch them when the circuit is on to see if the transistors are hot !! I ate it several times :)
> The optional "Low voltage warning" is already embedded in the PCB layout, you can disregard it and not install it's components if you do not needed. It does not affect the functionality of the main circuit.
> The Motorola 2N6277 is a heavy duty power transistor, it is used in many US tanks for it's reliability but unfortunately it is a very hard to find part, instead you can substitute each 2N6277 with 2 x 2N3773 or any equivalent.
> I've included an optional "Battery level indicator" circuit diagram that has 4 LEDs, you can see it installed on the front panel of my inverter pic, it is functioning great and shows precisely how much juice the batteries still have. I have included a small relay that is powered by the last LED to auto shutoff the inverter once last LED is off.
>Also included an optional "Overload circuit", it is very easy to build and can be calibrated to the desired overload current threshold cutoff point through the potentiometer VR1.
R1 is rated 5watts for inverters upto 1000 watts. For bigger versions of the inverter like 1000 to 3000 watts inverters, replace R1 (1 ohm, 5watts) with (1 ohm, 17watts) which should handle loads upto 10 VA.
Make sure you install a proper relay to handle big current drains.
>Please guys take your time to read and understand my notes, browse and read the posts and questions asked by others because there are many useful information listed in replies. The main reason for me not answering your question is because it has already been asked before and answered upon.
> It would be nice and inspiring for others if you take some photos and show us how you built your version, any additions to the circuit are mostly welcomed to be listed here, we can all benefit from them.
I have built this design and using it as a backup to power up all my house when outages occur.
If you like my work and intend to build the circuit don't forget to give me the 5 satrs :D and subscribe to me by clicking on the "follow" button so I know how many people benefit from the design, Thanks
Notes:
>The schematic circuit design is for a 250 watt output, while the pics are of my 1500 watts inverter that i built, to increase the power of the circuit you have to add more of the Q7 and Q8 transistors in parallel, each pair you add will increase your power by 250 watts, ex: to get 750 watts of power from the inverter you need to add in parallel 2 of Q7 and 2 of Q8 to the original design.
>If you increase the power transistors you have to enlarge the T2 transformer to match the new needs, the circuit's transformer is rated 25 amps to handle 250 watts of 220v, for every 1 additional amp you need on the 220v side you have to increase 10 amps on the 12v side, of course there are limits to the thickness of the winding so if you need more than 750 watts i recommend that you use a 24VDC supply instead of 12 volts:
DC voltage and Transformer "T2" winding recommendation:
Power Supply Winding
750w 12VDC P:24V "12-0-12" / S:220V
1500w 24VDC P:48V "24-0-24" / S:220V
2250w 36VDC P:72V "36-0-36" / S:220V
3000w 48VDC P:96V "48-0-48" / S:220V
3750w 60VDC P:120V "60-0-60" / S:220V
4500w 72VDC P:144V "72-0-72" / S:220V
5250w 84VDC P:168V "84-0-84" / S:220V
*The transformer should be "center tapped" at the primary side.
**You can make the secondary 110v if needed.
***The transformer in the pic is a custom made (48V center tapped / 220v ) 2000 watts, weights like 10 kilos.
>R1 is to set the PWM duty cycle to 220v. Connect voltmeter to the output of your inverter and vary VR1 till the voltage reads 220V.
>R2 is to set the frequency to 50 or 60 Hz (R2 range is between 40Hz to 75Hz), so guys that do not have a frequency meter are advised to blindly put this variable resistor mid-way which should drop you in the range of 50~60 Hz.
If you want you can substitue the variable resistor with a fixed resistor using the following formula: F = 1.3 / (RxC)
in our case to get a 50Hz output we remove both the 100K and the variable 100K both from pin 6 and we put instead a 260K fixed resistor and we leave the 0.1uF (the 104 cap) as it is, this change should give out a fixed 50Hz as per the formula :
1.3 / (260,000 ohm x 0.0000001 farad) = 50Hz
But in reality it will not exactly give 50Hz because the 260K resistor has a specific error value margin so does the capacitor, that's why i recommend a variable resistor so that accurate calibration can be achieved.
>Use either tantalum or polyester film "as in pic" for the 104 caps, ceramic disc caps change value once hot and this in turn changes the frequency of the inverter so they are not recommended.
>Pin 10 of the SG3524 can be used to auto shut down the inverter, once a positive voltage is given instead of negative to pin10, the SG3524 will stop oscillating. This is useful for persons wanting to add some cosmetic makeup to their inverters like overload cutoff, low battery cutoff or overheating cutoff.
>Wiring connections on the power stage side should be thick enough to handle the huge amps drain from the batteries. I marked them with dark black on the schema also I included a pic so you see how thick those wires must be.
>The design does not include a battery charger since each person will be building a custom version of the inverter with specific power needs. If you are ordering a custom made transformer you can ask them to take out for you an additional output wire on the primary side to give 14v (between point 0 and this new wire) and use it to charge a 12v battery, of course this needs a seperate circuit to control charging auto cut-off. But anyway this is not advisable because it will shorten the life of the transformer itself since using it as a charger will toast the enamel coating layer of the copper wires over time. Anyway .. YES can be done to reduce cost.
>A cooling fan will be needed to reduce heat off the heat sinks and transformer, i recommend getting a 220v fan and connecting it to the output T2 transformer, when you power up the circuit the fan will start this will always give you a simple way to know that 220v is present and everything is OK.. You can use a computer's old power supply fan if you like.
Note that the fan must suck air out from the inverter case and NOT blow inside, so install it the correct way or it will be useless.
Also note how I fixed both the heat sinks and where the fan is, in a way that the fan sucks hot air from like a channel between the 2 heatsinks.
>2 circuit breakers are recommended instead of fuses, one on the DC side and one on the AC side, depending on your design
Ex: for a 24vDC ( 1500 watts design ) put a 60Amp breaker on the DC side and a 6Amp on the AC side.
For every 1amp of 220vAC you will be draining like 8 to 10 Amps from the 12v battery, make your calculations !
> The 2 Heat sinks should be big enough to cool the transistors, they are separate and should NOT touch each other. "see the pics"
>Important: If you're building a big design that uses more than 24VDC as power source, make sure not to supply the driver circuit with more than 24v maximum. (EX: If you have 4 batteries 4x12 = 48v , connect the v+ supply of the driver circuit to the second battery's (+) terminal with a thin 1 mm wire which is more than enough. this supplies the driver circuit with +24v while supplies the power transformer with +48v)
> "Optional" : Deep Cycle batteries are your best choice, consider them for best results .. read more
> Be cautious when building this circuit it involves high voltage which is lethal, any part you touch when the circuit is ON could give you a nasty painful jolt, specially the heat-sinks, never touch them when the circuit is on to see if the transistors are hot !! I ate it several times :)
> The optional "Low voltage warning" is already embedded in the PCB layout, you can disregard it and not install it's components if you do not needed. It does not affect the functionality of the main circuit.
> The Motorola 2N6277 is a heavy duty power transistor, it is used in many US tanks for it's reliability but unfortunately it is a very hard to find part, instead you can substitute each 2N6277 with 2 x 2N3773 or any equivalent.
> I've included an optional "Battery level indicator" circuit diagram that has 4 LEDs, you can see it installed on the front panel of my inverter pic, it is functioning great and shows precisely how much juice the batteries still have. I have included a small relay that is powered by the last LED to auto shutoff the inverter once last LED is off.
>Also included an optional "Overload circuit", it is very easy to build and can be calibrated to the desired overload current threshold cutoff point through the potentiometer VR1.
R1 is rated 5watts for inverters upto 1000 watts. For bigger versions of the inverter like 1000 to 3000 watts inverters, replace R1 (1 ohm, 5watts) with (1 ohm, 17watts) which should handle loads upto 10 VA.
Make sure you install a proper relay to handle big current drains.
>Please guys take your time to read and understand my notes, browse and read the posts and questions asked by others because there are many useful information listed in replies. The main reason for me not answering your question is because it has already been asked before and answered upon.
> It would be nice and inspiring for others if you take some photos and show us how you built your version, any additions to the circuit are mostly welcomed to be listed here, we can all benefit from them.
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OK. so we draw a new schematics with 72V input and IGBT's.
Please take a look so we can continue on developing.
Thank you in advance.
Photo:
http://oi43.tinypic.com/2wg62hg.jpg
Ex: the 2n6277 is a 250w transistor. if you are building a 750w inverter then you'll need 3 transistors on each side this means 6 in total for both sides. Since the inverter works as a push-pull this means that if one side of the power stage is conducting the other side must be off, so when one side is conducting it must deliver the full required 750 watts, that's why we need 3.
Search for your FET data sheet and see the power rating of it.
Ex: the 2n6277 is a 250w transistor. if you are building a 750w inverter then you'll need 3 transistors on each side this means 6 in total for both sides. Since the inverter works as a push-pull this means that if one side of the power stage is conducting the other side must be off, so when one side is conducting it must deliver the full required 750 watts, that's why we need 3.
Search for your FET data sheet and see the power rating of it.
sir im going mad of this problem i tried all best i can but it didn't succeed i put my volter meter and i set the two variable,out put 164v out put why is there any thing i left or put in?pls i need your assist pls.
Please check all your wiring connections again, this should not happen. Usualy if one side is heating up this is because the other side is not oscillating at all. Check the driving voltage on the gates of the fets.
It will be impossible to send you a trans. from another country due to it's heavy weight, it will cost probably more than the value of the transformer itself to ship it abroad.
As I said earlier in many replies, I do not suggest building your own transformer by hand because it requires experience and involves many hidden tricks and many calculations.
Anyway the # of turns formula is :
Vo = Vi x (# of Sec. Turns) / (# of Primary Turns)
EX: 24 x 100 / 11 = 218v
so primary is 11 turns and secondary is 100 turns
Your only solution is to find a place where they rewind motors and transformers and they'll do it for you "this is what i did myself".
A good start would be to ask a tech guy that repairs washing machines, those guys usualy know where to re-wind the burned motors of washing machines.
If the re-winding guy does not have accessories to build you a big trans, like the E metals etc.. I suggest that you find some old or probably buy a new 110/220v big transformer and tell him to take it apart and re-wind it to your desire. (according to my table).
please help me:
I created inverter : by microcontroller and made PWM wave with frequency : 5 Khz.
But, When I run : department, it appeared : similar beep sound intermittent, so I measured : voltages outside : found the limits of 50 to 60 volts and not fixed , in this case: suddenly the mosfet burned : ... This is my map and I want to help:
http://store2.up-00.com/Apr13/JsK48244.jpg
2
http://store2.up-00.com/Apr13/lof42769.jpg
3
http://store2.up-00.com/Apr13/sH642769.jpg
I'm found that mosfets with it aluminum plate was their heat it too high in one side .... while the other side the Mosfets were not elevated their heat and does not appear that it was never Operated !
If the transformer raise one hand or from one side of the mosfet ,Does this lead to burn mosfets with?
pleasehelp me?
1- Your T2 transformer is very small just as I expected. It is rated at 2 amps (48 watts) ! and since it is a chinese ready made trans then expect at least -25% from what it written on it, this makes it even less (36 watts).
You can't put a load on such a small trans. Did you see the notes and the pic of my transformer?
Did you look at the transformer table size?
(1500w 24VDC P:48V "24-0-24" / S:220V)
(***The transformer in the pic is a custom made (48V center tapped / 220v ) 2000 watts, weights like 10 kilos).
2- I notice that you mounted your MOSFETS on a board, where is the big heat sink gonna fit? even your blue and black power wires are not thick enough. The power transistors or MOSFETS should be mounted directly on the heatsinks, see the pics and also see how thick the cable connections should be.
Great to hear that u built a working unit !
The soft start is a built in functionality inside the IC itself and protects the power transistors "mosfets in your case" from burning due to sudden high loads when starting the inverter, great that u noticed that, this was one of the reasons i chose this specific IC for the design !
I suggest that you setup the frequency correctly with a frequency meter, u don't have to buy one, any repair shop, maintanace guy or anyone else that u might know.. just take the circuit "without the power transistors and the transformer" and a little 9v battery to power it up, u will need 1 min only to set the freq.
Battery charging circuits are everywhere on the internet, they differ depending on the kind of batteries u want to charge so that was the main reason for me not getting into those details since this topic is wide (gel , lead acide, sealed...etc..)
Auto switching can be achieved by simply adding a 220v multi pole relay and powering it from the mains, once the mains electricity goes out the relay immediatley flips and powers the inverter on "this is my way".
N.B. be carefull how to connect that relay in a way that 220v electricity from the inverter does not power the relay again or else the inverter will enter an ON-OFF never ending loop :)
Best Regards
Nick
or rather can you help me get a standard smart SLA battery charger circuit that uses simp;le components.
how do you calculate the filter capacitor values?
thanks alot for the response
sir i tried all my effort still, the problem is that i build the circuit with irfp250 it work but when i switch on the circuit out put is 203v but if there is load like 220v fan it jump up to 220 to 221v (24dc car battery)T2 is 220v 2000ma (12v) sir please whats do you suggest? kindly help me im looking forward to hear from you sir thanx you,
I build it with a modifications. I tell you, my house is iluminated with solar panel system (made myself all the sistem except the batterys) I don´t need much power so i made a transformer 11+11 in primary, 222 in sec, and a coil for 12V for PWM control. One transformer, no two.
The circuit driver an power transistor are like they are in the picture. Driver BC 338 (NPN) and BC 328, (PNP), Power: Mosfet IRF540 with an internal dumper diode, not need transformer diode.
This mosfets can drive 15 amps (with dissipation) I use it with 80 Wattl load, so its a 8 amps an their are cool with 30º ambient.
Less component, more cheap, more easy, less dissipation (less energy burn)
Well, thank you again.
Really thank´s Nick.
Greetings from the beatiful land of Argentina.
Sebastián.