Dual inverters with synchronized PWM for grid-connected photovoltaic systems

The paper presents results of investigation of dual-inverter-based power conversion system with synchronized pulsewidth modulation (PWM) for photovoltaic application. This system topology includes two isolated strings of photovoltaic panels, feeding two standard three-phase inverters, connected to grid by a three-phase transformer with the open winding configuration on primary side. Algorithms of synchronized PWM provide in this case continuous voltage synchronization both in each inverter and in the load. In the case of fluctuation of the fundamental frequency of the grid, the proposed strategy of modulation also provides synchronization of the system output voltage with the grid voltage. Simulations show the behavior of dual-inverter systems with continuous and discontinuous schemes of synchronized PWM.