Design optimization of Aalborg-type transformerless PV inverters with focus on power quality

Abstract

Single-phase transformerless photovoltaic (PV) inverters are based on unconventional power circuit topologies and are required to achieve very high efficiency and power quality over their entire operating range. Optimization techniques applied to conventional converter topologies need to be extended to cover these requirements. This paper proposes a PV inverter design optimization method for Aalborg-type transformerless PV inverters which integrates simulations in an optimization algorithm to maximize the inverter European efficiency, while abiding by the power quality limits set by relevant standards. According to it, the entire PV system, including the PV array, the PV inverter with its controller, and the grid are simulated in MATLAB-Simulink to estimate the inverter losses and output current distortion for design alternatives devised by the optimization algorithm. Design results obtained on an Aalborg-type transformerless PV inverter, indicate that its European efficiency can be maximized under different sets of constraints, while maintaining permissible output current quality at all power levels.