Large-Signal Stability Improvement of DC-DC Converters in DC Microgrid

• Published in: IEEE transactions on energy conversion Vol. 36; no. 3; pp. 2534 - 2544
• Main Authors: Gui, Yonghao, Han, Renke, M. Guerrero, Josep, C. Vasquez, Juan, Wei, Baoze, Kim, Wonhee
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: constant power load; Controllers; Damping; DC microgrid; DC-DC power converters; DC–DC converter; Distributed generation; disturbance observer; Disturbance observers; Electrical loads; exponentially stable; Feedback control; Load modeling; Microgrids; PI control; Singular perturbation; Stability; Stability analysis; Transient response; Voltage control; Voltage converters (DC to DC)
• ISSN: 0885-8969; 1558-0059
• DOI: 10.1109/TEC.2021.3057130

In DC microgrids, constant power loads (CPLs) reduce the effective damping of the DC-DC converter and may induce destabilizing effects into the DC-DC converter. To overcome such problems regarding CPL and ensure large-signal stability of DC-DC converters in DC microgrids, some feedforward terms are added to <inline-formula><tex-math notation="LaTeX">V</tex-math></inline-formula>-<inline-formula><tex-math notation="LaTeX">I</tex-math></inline-formula> droop-based dual-loop controller for a DC-DC converter based on the large-signal model. It is proven that the feedforward terms can not only improve the transient response but also guarantee the exponential stability of the closed-loop system in the whole operating range in regards to a large-signal manner, which is verified by using a singular perturbation model. Moreover, a disturbance observer is designed to estimate the output current, thereby enabling the removal of the current measurement sensor. The proposed technique can be easily plugged into a pre-defined <inline-formula><tex-math notation="LaTeX">V</tex-math></inline-formula>-<inline-formula><tex-math notation="LaTeX">I</tex-math></inline-formula> droop-based dual-loop controller without an additional sensor being required. Ultimately, both simulation and experimental tests verify the effectiveness of the proposed method.