Comparison and combination of digital controls for single-phase boost PFC converters in avionic power systems

摘要

Achieving a low harmonic current distortion (THDi) along with a unit power factor (PF) in single-phase boost AC-DC converters with power factor correction (PFC) using classical controls requires a high current control bandwidth, which usually implies a high switching frequency, yielding high switching losses. This is a major problem in applications with a high value of the grid frequency, e.g., avionic power systems with a line frequency up to 800 Hz. Over the years, several control techniques have been proposed to improve the shape of the line current without increasing the switching frequency of the converter. This paper studies the viability of adding adaptive filters based on the second order generalized integrator (SOGI) structure in the current loop to maintain a switching frequency lower than 100 kHz with the same purpose. A notch filter based on SOGIs is also applied to the output voltage regulation loop in this study, in order to increase its regulation speed without degrading the reference current waveform, which would distort the line current. A comparison between the method based on SOGI filters and other control methods is shown. Finally, the combination of several methods is studied. Simulation results have been obtained by means of PSIM software.