Input-Series and Output-Parallel Connected Inverter System for High Input Voltage Applications

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) between the modules of the ISOP inverter system are required for its proper work. A control strategy with load current controlled is proposed for ISOP inverter system in the paper to achieve IVS and OCS. The output current magnitudes are regulated based on the error of input voltages, increasing the output current with higher input voltage and decreasing the output current 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 is analyzed and their design guide lines are also given. A 2 kVA two-module ISOP inverter system prototype is fabricated and tested in the lab and the experimental results verify the proposed control strategy.