Fixed Voltage Based P&O Method for Battery Charging from Partial Shaded PV String

A photovoltaic (PV) system under partial shading conditions (PSCs) exhibits multiple local power peaks (LPPs) and a single global maximum power peak (GMPP) in its powervoltage ($\mathbf{P}-\mathbf{V}$) characteristics. Conventional maximum power point tracking (MPPT) methods are ineffective in such conditions, as they may track an LPP instead of the GMPP. Therefore, it is necessary to track GMPP accurately for the battery charging application from the partially shaded PV string. In this paper, a novel fixed voltage based perturb and observe (FVPO) method is proposed to track the GMPP for battery charging under PSCs. The proposed method calculates ‘ n ‘ fixed voltage points using a new hyperbolic approximation approach and measures power at these points in an $n \times 1 \mathrm{PV}$ string. The calculated power values are then compared, and the duty cycle corresponding to the maximum power is fed to the converter. This initializes the perturb and observe method to track the GMPP accurately. Hence, the proposed method is simple, easy to implement, and quickly tracks the GMPP without the need to detect partial shading or scan the entire P-V curve. Furthermore, the effectiveness of the proposed FVPO method is validated for a PV string with three modules under various PSCs using the MATLAB platform for battery charging applications. It tracks the GMPP within 0.36 s under the most complex shading condition. The energy loss ranges from 5.61 to 20.14 J, enabling efficient real-time PV battery charging.