True Maximum Power Extraction in Photovoltaic Systems using High Gain Energy Efficient DC-DC Converter

Abstract

High-gain DC-DC converters are used as impedance matching networks in Photovoltaic (PV) systems to implement Maximum Power Point Tracking (MPPT). The ripple current drawn by the DC-DC converter creates oscillation of the operating point around the Maximum Power Point (MPP) at switching frequency. This deteriorates the power extracted from the PV modules and affects the performance of MPPT algorithms. In a PV system employing a high gain DC-DC converter, the system efficiency and hence power delivered to the load can be increased by tracking the output power instead of tracking the power extracted from the PV module/s. Here, shifting the placement of the current sense resistor from input to the output does the trick. This paper proposes a high-gain energy-efficient DC-DC converter (HGDC) to minimize the ripple current drawn from the PV module/s. The performance of HGDC is studied for different irradiance levels and is compared with similar high-gain converters reported in the literature. The results demonstrate the superior performance of HGDC in terms of reduction in ripple current drawn, reduced power oscillations, and hence operation close to true MPP. Besides, the HGDC has higher energy efficiency, operates close to true MPP with different types of MPPT algorithms, shares common ground between input and outputs minimizing the EMI and safety risks.