A Digital Interconnected Bus Providing Voltage Synchronization for the Modular Series-Connected Inverters

The input port or the output port series-connected system is very suitable for medium- or high-voltage applications. For the output series-connected modular inverter system, the important issue is to guarantee that the phase angle of the different modules are exactly the same, otherwise, the total output voltage cannot meet the requirement. This letter proposes a digital synchronization strategy, which adopts a digital interconnected bus to provide the common reference signal for the composed modules. The operation principle, circuit schematic, and control design of the proposed strategy are explained in detail in this letter, and finally, the performance of the strategy is verified on a three-module series-connected inverter system.