Optimum sizing of components for photovoltaic maximum power point tracking buck converter

Abstract

A photovoltaic (PV) maximum power point tracking (MPPT) converter consists of MPPT algorithm and converter. Although there has been a lot of improvement for MPPT algorithm, there is still much to improve for the converter. This paper proposed optimum sizing for the ideal PV MPPT buck converter with resistive and battery loads. The optimum sizing ensures the MPPT converter operates in the continuous current mode (CCM) operation and within the defined output voltage ripple for the specified range of irradiance. These conditions are achieved by deriving the equations of the inductances and capacitances required for the MPPT buck converter. The CCM operation is designed to be closed to the DCM to ensure a small inductance value. The specified output voltage ripple ensures the quality of the output of the MPPT buck converter. The verification of the derivation is done using MATLAB/Simulink circuit simulation. The conventional single diode PV model and perturb and observe (PnO) MPPT is used in the system. The result shows that the range of output resistance is highly affecting the duty cycle range, which leads to MPPT failure if the output resistance is not calculated properly. The converters for both resistive and battery loads can operate in the CCM and close to the DCM operation based on the proposed design. These converters also maintain output voltage ripple factor at 1% or lower, which the proposed derivation follows the specification. In conclusion, the proposed derivation of the MPPT buck converter is accurate.