Grid-Connected Boost-Half-Bridge Photovoltaic Micro inverter System Using Repetitive Current Control and Maximum Power Point Tracking

This paper is a new grid - connected boost half-bridge photovoltaic (PV) micro inverter system and its control processes. A boost half bridge dc-dc converter using marginal devices is introduced and it is interfaced with the low voltage Photo voltaic module. By using this, it can achieve low cost, easy control, high efficiency and stable output. The grid gets synchronized sinusoidal current which is injected by a cascaded full bridge pulse width modulated inverter. For regulating the grid current, a plug-in repetitive current controller based on a fourth-order linear phase IIR filter is proposed. High power factor and very low total harmonic distortions are guaranteed under both heavy load and light load conditions. Dynamic stiffness is achieved when load or solar irradiance is changing rapidly. The dynamic behavior of the boost-half-bridge dc–dc converter is analyzed; maximum power point tracking (MPPT) method should be developed, so that it can generate a ramp-changed PV voltage reference. Variable step size is adopted such that fast tracking speed and high MPPT efficiency are both obtained. A 210W prototype was fabricated and tested processes. Simulation and experimental results, are provided to verify the validity and performance of current control, and the MPPT algorithm.