Control Strategy for Input-series and Output-parallel Connected Inverter System

Input-series and output-parallel (ISOP) inverter system is very suitable for high input-voltage and high output-current power conversion applications. Input voltage sharing (IVS) and output current sharing (OCS) among the constitutional modules of the ISOP inverter system are required for its proper work. A control strategy with load current controlled was proposed for ISOP inverter system to achieve IVS and OCS. The output current magnitudes were regulated based on the error of the input voltages of the modules,i.e.,increasing the output current of the module with higher input voltage and decreasing the output current of the module with lower input voltage. Compared with the control strategy with output filter inductor current controlled,the unmatched filter capacitors have no influence on the OCS with the proposed control strategy. Meanwhile,the relationship between the IVS loop and output voltage loop was analyzed and their design guidelines were also given. A 2 kVA two-module ISOP inverter system prototype was fabricated and tested in the lab and the experimental results verify the proposed control strategy.