Main part of that circuit are two H bridges. Bridges are switching 2 similar transformers which secondary sides are connected in series. H bridges are switching primary side of transformers and change polarity of the voltage accros the windings in each 10ms. Transistors in each bridge are switched with the same frequency but there is diference with phase about 15 percent. Switching causes changes in polarization of voltage across the primary windings in each 10 ms. Effect of that is the square wave on the output of each transformer. Transformers boost up the amplitudes of the square waves up to few hundrets of volts and phase shift beetwen square waves causes stairs-like shape of output voltage because voltages of secondary sides are suming together. Capacitor on the output smooths the shape of the voltage. There should be more hbridges to improve shape of output voltage. This info is written especialy for @hurz.
