I am trying to do a SPWM inverter I have issues with it though. testing the output from pin 8 and 9 I get 50hz but once the transformer is hooked up I get 640HZ I only have 1 6-0-6v transformer to test the circuit so I am not sure if the transformer is giving a bad reading.
Secondly the voltage slowly rise once power is applied to the circuit it takes over a minute for the voltage to reach maximum voltage.
A very poor post, I'm afraid. You should have learned more after 49 posts on the forum. Please read the "read this" post at the top of the forum section and then edit your post above and fix all the things that are wrong with it. These include but are not limited to: use of code tags; explanation of terms; including links to components used, a schematic or wiring diagram.
video link and code.
I hardly post here I have been trying to correct since i posted but this website takes for ever to allow someone to make a correction
[quote]
void setup(){
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
}
void loop(){
digitalWrite(8, HIGH);
delayMicroseconds(500);
digitalWrite(8, LOW);
delayMicroseconds(500);
digitalWrite(8, HIGH);
delayMicroseconds(750);
digitalWrite(8, LOW);
delayMicroseconds(500);
digitalWrite(8, HIGH);
delayMicroseconds(1250);
digitalWrite(8, LOW);
delayMicroseconds(500);
digitalWrite(8, HIGH);
delayMicroseconds(2000);
digitalWrite(8, LOW);
delayMicroseconds(500);
digitalWrite(8, HIGH);
delayMicroseconds(1250);
digitalWrite(8, LOW);
delayMicroseconds(500);
digitalWrite(8, HIGH);
delayMicroseconds(750);
digitalWrite(8, LOW);
delayMicroseconds(500);
digitalWrite(8, HIGH);
delayMicroseconds(500);
digitalWrite(8, LOW);
//......
digitalWrite(9, HIGH);
delayMicroseconds(500);
digitalWrite(9, LOW);
delayMicroseconds(500);
digitalWrite(9, HIGH);
delayMicroseconds(750);
digitalWrite(9, LOW);
delayMicroseconds(500);
digitalWrite(9, HIGH);
delayMicroseconds(1250);
digitalWrite(9, LOW);
delayMicroseconds(500);
digitalWrite(9, HIGH);
delayMicroseconds(2000);
digitalWrite(9, LOW);
delayMicroseconds(500);
digitalWrite(9, HIGH);
delayMicroseconds(1250);
digitalWrite(9, LOW);
delayMicroseconds(500);
digitalWrite(9, HIGH);
delayMicroseconds(750);
digitalWrite(9, LOW);
delayMicroseconds(500);
digitalWrite(9, HIGH);
delayMicroseconds(500);
digitalWrite(9, LOW);
}[/quote]
You used code tags correctly this time, but you failed to do or ignored all the other things. If you cannot understand, there are other forum sections where you can ask in other languages if that helps, but they will still need all the same information that you have not included.
Hi,
I can see by your code you are trying to modulate your PWM signal to produce a sinewave average voltage, first on one side of the low voltage winding then the other.
The problem you have is to do with the inductance of your transformer.
Sinewave Power Inverters use specially wound transformers to allow the high frequency use of PWM to modulate the DC input.
Your transformer is designed for 50Hz or 60Hz operation, try to use it with a higher frequency will not work.
This link may help with generating a sine-wave, but you need more research into the transformer application.
https://forum.arduino.cc/index.php?topic=446209.0
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Please include ALL components and their part numbers and labels on pins.
Thanks... Tom... 
I didnt do a circuit drawing I just attached 2 resistors from pin 8 and 9 o 2 Fets and then to the transformer.
I think your correct about the transformer though it came as a 12-0-12v and I modified it for 6-0-6v Ill have to buy a new one and test it on the same circuit.
the spwm wave form looks good so after proper filtering I think I should get a good waveform but the voltage takes its time to rise do you think the that the transformer is the cause of that also?
Hi,
enzyb:
I didnt do a circuit drawing I just attached 2 resistors from pin 8 and 9 o 2 Fets and then to the transformer.I think your correct about the transformer though it came as a 12-0-12v and I modified it for 6-0-6v Ill have to buy a new one and test it on the same circuit.
the spwm wave form looks good so after proper filtering I think I should get a good waveform but the voltage takes its time to rise do you think the that the transformer is the cause of that also?
Look on Ebay for "pulse transfomer". You may find one there that meets out needs. You are driving a transformer with a square wave which contains an infinite number of high frequencies, not just the fundamental switching rate.
Paul
Hi;
OPs Diagram
That circuit arrangement wont work at all for a Sine Wave Inverter.
You are feeding square waves into the transformer which will result in all manner of spurious output on the secondary based on the load.
Sine Wave Inverters generate the Sine Wave at the output voltage using a hi power hi frequency H bridge, followed by a low pass filter.
The normal approach is to use a hi power push pull Inverter driving a hi frequency ferrite transformer followed by a hi frequency rectifier producing a DC voltage equal to the peak voltage of the Sine Wave you wish to generate.
The high voltage DC is then fed to the H bridge which is driven by a hi frequency PWM signal which generates the Sine Wave.
These things are not easy to build, not easy to fault find when things go wrong, and extremely good at blowing up lots of Fets.
Do some more research before even thinking about trying to build one.
mauried:
That circuit arrangement wont work at all for a Sine Wave Inverter.
You are feeding square waves into the transformer which will result in all manner of spurious output on the secondary based on the load.
Sine Wave Inverters generate the Sine Wave at the output voltage using a hi power hi frequency H bridge, followed by a low pass filter.
The normal approach is to use a hi power push pull Inverter driving a hi frequency ferrite transformer followed by a hi frequency rectifier producing a DC voltage equal to the peak voltage of the Sine Wave you wish to generate.
The high voltage DC is then fed to the H bridge which is driven by a hi frequency PWM signal which generates the Sine Wave.
These things are not easy to build, not easy to fault find when things go wrong, and extremely good at blowing up lots of Fets.
Do some more research before even thinking about trying to build one.
The code produces a SPWM signal and I have already tested the spwm signal which is good just connecting the transformer wont produce a sine wave adding an appropriate filter to the output of the transformer should produce a sine-wave wave form.
Im aware of the high frequency design but im not that good at designing and those schematics dont seem to be free atleast not ones that work based on what I have seen
Paul_KD7HB:
Look on Ebay for "pulse transfomer". You may find one there that meets out needs. You are driving a transformer with a square wave which contains an infinite number of high frequencies, not just the fundamental switching rate.Paul
I have looked but I dont see anything that looks like I would use, could you send an example of what our talking about.
When persons normally do SPWM circuits dont they use the normal 50/60hz transformers just the same
