Sensorless operation of an Active Front End converter with LCL filter

In this paper sensorless control method fora an Active Front End (AFE) converter is presented. Developed algorithm is based on Voltage Oriented Control (VOC), extended by additional Voltage Dips Compensation (VDC) module. Moreover improved Virtual Flux (VF) estimator based on SOGI-QSG for LCL filter has been shown. This new sensorless control method can assure sinusoidal and balanced grid currents even during strong voltage dips. To avoid large current overshoots, new universal startup procedure has been developed. Operation relies on turning the zero vector on for a short time and measuring the currents growth. This allows to synchronize and soft starts with and without load connection at any grid voltage condition. Simulation and laboratory results illustrate operation of the developed control method in steady states and transients.