Photovoltaic Module-Integrated Stand-alone Single-Stage Switched Capacitor Inverter with Maximum Power Point Tracking

Abstract

A switched capacitor (SC) based inverter that tracks the maximum power point (MPP) of a photovoltaic (PV) source and generates a pure sine output is presented. To enable integration with the PV module, efficiency and compactness are maximized with a single-stage topology that tracks the MPP of the PV source, boosts the input dc voltage, and generates a regulated ac output in a stand-alone configuration with scope for grid-connected applications. The SC inverter is realized with multiple identical SC blocks controlled by sinusoidal pulsewidth modulation and load-dependent output capacitor adjustment. A detailed steady-state analysis is carried out, and a mathematical model is derived to understand the interdependence of various inverter parameters on each other and to optimally choose the inverter components. A hardware prototype of the stand-alone single-stage SC inverter that operates from a 60 V/70 W PV module and delivers a 110 Vrms, 50 Hz output is wired to demonstrate the functioning of the proposed MPP tracking inverter under different operating conditions. An inversion efficiency > 95%, a tracking efficiency > 97%, and a total harmonic distortion (THD) <; 4% have been practically achieved. All the details of this work are presented.