Multi-loop digital control of a line conditioner using DPLL

This article presents the study of an alternating voltage indirect conditioner, showing the main aspects of its digital control using multiple loop control to regulate and match the output voltage. The objective of this study was to verify the operation of a line conditioner when subjected disturbances, using a digital PLL to generate the reference. The generation of the sinusoidal reference for the output voltage control loop is discussed and digital PLL (DPLL) based on the three-phase instantaneous power theory is proposed. The advantage of the use of a PLL in this work, as a reference, is due to it being immune to variations and disturbances from the mains, being sensitive to the frequency variation that enables the fundamental component of the voltage to be monitored. The conditioner control is based on the concept of multi-loop, one being to control the output voltage RMS value and other for the pre-feeding of the input voltage. Simulation and experimental results obtained with a 3 kVA conditioner are presented.