12-Pulse Power Inverter with Fixed Switching Angle for Grid-connected PV Array

Abstract

A power converter interface that uses a simple boost converter (SBC) and a 12-pulse power inverter with maximum power point tracking (MPPT) for interfacing photo-voltaic (PV) array with utility grid is presented in this paper. Generally, PV array has a lower and changing dc voltage. It is boosted to a required level and is then converted to ac using the 12-pulse LCI. The LCI is operated at constant switching delay angle of 135°. As the switching angle and the grid voltage are constant, the voltage at dc link of the inverter is also constant. Hence, changes in PV power cause only the output current of the SBC to vary and not the output voltage. A power transformer is coupled to match the inverter voltage with that of the grid. MATLAB/ SIMULINK model of the proposed system have been constructed and simulated for 1 kW using 122 V, 8 A PV group feeding power to the 415 V local grid. The open-loop and closed-loop systems were tested for dynamically changing irradiations. Results gave a close agreement between analysis and simulation proving the effectiveness and practicality of the system.