This FB converter can supply 230 Vrms (DC +, DC-, or AC) to a resistive load through an inductive filter. The upper part of the schematic handles the different modulation strategies while the lower part contains the FB (H-bridge) and the power circuit. For conciseness, the diodes are omitted.
By default, control switches MOD 1 and MOD2 are set in the configuration \ / to enable PWM modulation. In this configuration, the control switch MOD3 can select between unipolar and bipolar modulation. Both PWM modes handle DC and AC conversion by the control of the modulation signal vm. While Bipolar mode drives leg A and B simultaneously when vm crosses the carrier signal vp, unipolar PWM shifts leg B by inverting the modulation signal.
Switching MOD 1 and 2 to their configuration / \ enables Square Wave modulation where the output voltage amplitude is controlled by the delay between vswA and vswB.
