Digital controller development for grid-tied photovoltaic inverter with model based technique

The main objective for a grid-tied photovoltaic (PV) inverter is to feed the harvested energy from PV panels to the grid with high efficiency and high power quality. A digital controller is the “heart” of the PV system: it calculates the maximum power point (MPP) and regulates the output current to meet the utility inter-connection standards. This paper introduced a new approach “model based design” to develop current controller for PV inverter. This design methodology filled the gap between computer simulation and hardware implementation of the digital controller and made an easy way for the implementation of complex and high level algorithm in a digital signal processor (DSP) [1]. The inverter's small signal model in D-Q rotating frame is derived and a double loop current controller is designed. The performance of the developed controller has been verified by both of the simulation in MATLAB and experimental results from a 2kW single phase PV inverter prototype.