Average Current Mode Control of a DC–DC Boost Converter to Reduce the Decoupling Capacitance at the PV Array Output

Abstract

Due to the full-wave AC–DC power conversion, second-order frequency oscillations of current and voltage are created in single-phase PV-grid-connected inverters. These oscillations propagate toward the input and adversely affect the PV power utilization ratio. Large power decoupling capacitors are the preliminary solution for coping with voltage ripples across PVs, and they decrease the lifetime of the overall system. This paper proposes the average current mode control (ACMC) of the input inductor in a DC–DC boost converter in a double-stage PV power conversion system. Through extensive explanations of the modeling and control of a DC–DC boost converter, it is shown that the ACMC reduces the propagation of the second-order frequency components (SOFCs) toward the input PV array. Two controllers—a proportional–integral controller and an integral single-lead controller—are considered to adjust the average value of the PV output current in a single-loop control structure. This control approach is simple to implement and exhibits high impedance to current oscillatory components, which, in turn, reduces the size of the required capacitance.

Keywords

• boost converter
• current control
• photovoltaic array
• power decoupling capacitor
• second-order oscillations
• utilization ratio