A moving pole-placement compensation design method to increase the bandwidth of RC-damper-based dual “Buck-Boost” AC/DC converter

摘要

Recently, an LCL-filter-based dual “Buck-Boost” AC/DC converter for DC Nano-grid with three terminal outputs was proposed. Since it is a high order filter based single-phase converter, a RC damper is adopted to keep the system stable. This converter has two work modes: “Boost” and “Buck”. During the “Buck” mode, the control-to-grid current transfer function of this dual “Buck-Boost” AC/DC converter has a movable zero, which is related to the input power and the output DC voltage. When the input power increases, the movable zero will slide to the lower frequency range. And then, the gain between the cut-off frequency point and the resonant frequency of LCL filter will swell up, resulting in reduced amplitude margin and suppressed bandwidth of system. Based on the theoretical analysis, a new dynamic pole placement compensation control design method is proposed for this dual AC/DC converter with an RC damper. The effectivity is verified through simulation and experimental results on an 110V/ 1000 W prototype.