20-08-2013, 04:51 PM
Grid-Connected Boost-Half-Bridge Photovoltaic Micro inverter System Using Repetitive Current Control and Maximum Power Point Tracking
Grid-Connected Boost-Half.docx (Size: 11.29 KB / Downloads: 20)
Abstract
This paper presents a novel grid-connected boost- half-bridge photovoltaic (PV) micro inverter system and its control implementations. In order to achieve low cost, easy control, high efficiency, and high reliability, a boost-half-bridge dc–dc converter using minimal devices is introduced to interface the low-voltage PV module. A full-bridge pulse width-modulated inverter is cascaded and injects synchronized sinusoidal current to the grid. More over, a plug-in repetitive current controller based on a fourth – order linear – phase IIR filter is proposed to regulate the grid current. High power factor and very low total harmonic distortions are guaranteed un- der both heavy load and light load conditions. Dynamic stiffness is achieved when load or solar irradiance is changing rapidly. In addition, the dynamic behavior of the boost-half-bridge dc–dc con- verter is analyzed; a customized maximum power point tracking (MPPT) method, which generates a ramp-changed PV voltage ref- erence is developed accordingly. Variable step size is adopted such that fast tracking speed and high MPPT efficiency are both ob- tained. A 210W prototype was fabricated and tested. Simulation and experimental results are provided to verify the validity and performance of the circuit operations, current control, and MPPT algorithm.