Power electronic controller with time sharing switching strategy for grid connected PV systems

摘要

The design and implementation of a high-efficiency two-stage power electronic controller for feeding power from a photovoltaic (PV) array to the load/utility grid is proposed. The PV array is connected to the load/utility grid through a boost converter and an inverter. The boost converter is controlled by sinusoidal pulse width modulation (SPWM) pulses so as to get a clamped quasi-sinusoidal waveform at the DC link. The inverter converts the clamped quasi-DC voltage into AC voltage using the SPWM controller. At any time only one switch operates at high frequency, thus yielding reduction in the switching losses of the converters. The controller used for the inverter takes care of both the maximum power point tracking (MPPT) at unity power factor (UPF) and grid synchronization. The power electronic controller has been constructed using IGBT switches. The complete system has been modeled with MATLAB/Simulink software and simulation results are compared with experimental results. Experiments have been conducted at varying irradiations for both stand-alone (110 W) and grid-connected (110 V, 50 Hz) systems with a PV array of 130.2 V and 4.5 A employing the dSPACE DS1103 controller. The steady-state and dynamic responses of the proposed system are presented.