Digital controller design for PV inverter with model based technique

The digital controller is the “heart” of the PV system: it will track 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 digital 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). With the model based technique, a double loop current controller is designed based on inverter's small signal model in D-Q rotating frame. Also a Perturbation & Observation (P&O) algorithm is implemented for maximum power point tracking (MPPT). The digital controller model has been verified by simulation in MATLAB. Then the controller has been implemented with a TI's DSP TMS320F28335 and tested on a PV inverter prototype with solar panels.