Research on Combined Control Strategy of Three-Phase Photovoltaic Grid-Connected Inverter Based on Fuzzy PI Controller

Abstract

The control objective of three-phase photovoltaic (PV) grid-connected inverter is to generate high quality and stable AC sinusoidal output power with the same phase angle, frequency and amplitude compatible with the grid-connected voltage. To overcome the shortcoming of the normal current PWM control method and traditional PI algorithm, this paper researches a combined control strategy of three phase PV grid-connected inverter based on fuzzy PI controller. The combined control strategy switches different PWM current control method among the hysteretic PWM, SVPWM, hysteretic current SVPWM according to the error between command current and feedback current，and the d-axis command current is output of fuzzy PI controller of DC bus voltage. The simulation model of the combined control strategy for three phase PV grid-connected inverter based on normal PI controller is built with Matlab, simulation results verified the combination control strategy based on fuzzy PI controller has excellent performances.