A new control algorithm based on photovoltaic differential power processing architecture

To avoid mutual interference between the converter least power point tracking (CLPPT) algorithm and the photovoltaic maximum power point tracking (PMPPT) algorithm in the photovoltaic differential power processing (DPP) architecture, the converter-least-photovoltaic-maximum power point tracking (CL-PMPPT) algorithm is proposed in this paper. The proposed algorithm eliminates wrong response between CLPPT and PMPPT by using PMPPT as the control inner loop and CLPPT as the outer loop. Moreover, by adding the steady-state zero-oscillation algorithm and the approximate calculation of the optimal main string current, the proposed algorithm eliminates the steady-state three-level oscillation and improves the tracking speed. Compared with conventional DPP control algorithm, the proposed algorithm achieves faster tracking speed, better steady-state performance and higher efficiency. Followed by theoretical analysis, the simulation verifies the claimed advantages of the proposed CL-PMPPT algorithm.