Research on the Stability of Photovoltaic Power System Based on Dual Buck Inverter

The stability of photovoltaic power system based on dual buck inverter is researched in this paper. Dual buck inverter overcomes the shootthrough problem in the traditional inverters, and this topology has development potential and research value because of its high reliability. Since the circuit works in half-bridge input mode, the input voltage is un-balanced, the instability caused by the un-balanced voltage limits the development and promotion of the circuit. The theoretical value of the un-balanced voltage is analyzed and the minimum input capacitance value of DBI is deduced. A three-loop control strategy is proposed. This strategy will feed forward the un-balanced voltage of input capacitors into the traditional double-loop control system to control the capacitor voltage deviation, which can solve the problem of un-balanced voltage effectively and reduce the minimum input capacitance value. The theoretical analysis result and the three-loop control strategy are verified by the simulation and experimental results. The experiment of 1 kW photovoltaic system based on dual buck inverter verifies the three-loop control strategy can effectively improve the system stability.