Current‐Fed Single‐Stage Converter With MPPT and Auto‐Voltage‐Sharing Integrated for MVDC Grids

ABSTRACT This paper proposes a current‐fed single‐stage input‐parallel‐output‐series (IPOS) modular converter for a large‐scale photovoltaic (PV) generation connected to MVDC grids, which can realize maximum power point tracking and auto‐voltage‐sharing by only sampling the PV voltage and current. The submodule (SM) is integrated by an interleaved parallel boost unit and a full‐bridge LC series resonant unit. The simple pulse width modulation is adopted, while the drivers of different SMs are interleaved but with the same duty cycle set. Because the full‐bridge LC series resonant unit operates as a DC transformer (DCX) with zero‐current switching realized for all rectifier diodes, the voltage gain of SM is only related to the duty cycle of the interleaved parallel boost unit for the boost inductor current is continuous. Hence, without any SM output voltage nor input current sensors, the SMs can automatically share the output voltage by using the same duty cycle set for each SM. Moreover, the zero‐voltage‐switching can be realized for switches. A 1.5‐kW prototype with three SMs is built to verify the converter characteristics and control strategy.