question on inverter

[erchiu]

while I repaired an inverter, I found one thing That I did not understand and ask for an explanation To you.
It is an 12v 220v modified sine wave
Internally there are four transformers each driven by two mosfet IRF3205.
the integrated oscillator is an TL494 and by its outputs (pins 9 and pin 10) drives alternately the mosfets with a pair of NPN / PNP (s8050 / s8550).
In practice, on the pin 9 there are a pair of transistors,from These leave from 4 resistors of 10 ohm and four IRF3205.
same thing for the pin10.
I 4 Transformers are in parallel.
Because with a single transformer and two mosfets the voltage is 90 V, while if connect them all arrive at 320volts after the bridge rectifier after the transformer.
I hope I Explained myself.
Sorry if the Talked at length.
Thanks in advance
erchiu

 

[erchiu]

Hi everyone.
Today i removed the 4 fast diodes of the rectifier bridge and i seen as are connected the 4 transformers.
The outputs are connected all in series.
In this way is as a single transformer.
I thought that the four transformer served for have more ampere, but i wrong.