Research on ISOP Inverter System and Its Control Strategy that Can Work under Specific Loads

The input-series-output-parallel (ISOP) inverter system, which consists of standard DC/AC modules connected in series at the input side and in parallel at the output side, is very suitable for high input voltage as well as high output current applications. This paper points out under no-load conditions, the output power of the entire system is approximately zero. Due to differences between the various modules' losses, the existing control strategies fail, simply because the loss difference cannot be balanced by adjusting the output power of each module, resulting in input voltage of each module differs from each other a lot, which causes the system breaks down. This paper proposes adding an auxiliary input voltage sharing circuit, so that input voltage sharing can be achieved. Finally, the proposed control strategy under no-load conditions were simulated and experimented, the results show that the proposed control strategy is correct.