An efficiency optimization strategy of PV/DC modular integrated structure under power mismatch condition

Conventional parallel connected dc-dc converter of photovoltaic (PV) system is widely used. However, the output voltage of PV integrated converter is relatively low. In some practical application, the converters need to be connected in series to create a high and suitable dc-bus voltage. So series connected dc-dc converters are getting more and more concerned recently. To obtain higher performance, series PV/DC modular integrated structure is becoming of higher interest. In series PV/DC modular integrated structure, the serial output current is forced to be equal, which will obviously decrease the system efficiency under some special imbalance cases. This paper proposes an optimization approach that utilizes a power diversion circuit to decouple the output current, which overcomes the mutual influence among the mismatch PV modules and the normal ones. Simulation and experiment results indicate that the proposed optimization strategy operates well with efficiency improvement of 13.02% under a special mismatch case.