Acting as an interface between the grid and many energy systems, the active front-end (AFE)
has been widely used in a large variety of industrial applications. In this paper, in order to ensure the
fast dynamic performance and good disturbance rejection ability of the AFE, a high-gain observer
(HGO) plus adaptive super-twisting algorithm (STA) for the three-level neutral-point-clamped (NPC)
converter is proposed. Comparing with the conventional PI control strategy, the proposed controller
implements the adaptive STA in the voltage regulator to provide a faster transient response. The gains
of the adaptive STA keep varying according to the rules being reduced in steady state but increasing in
transient conditions. Therefore, the chattering phenomenon is mitigated and the dynamic response is
guaranteed. Additionally, to undermine the impact of external disturbances on the dc-link voltage, a
high-efficiency HGO is designed in the voltage regulation loop to reject it. Experimental results based
on a three-level NPC prototype are given and compared with the conventional PI method to validate
the fast dynamic performance and high disturbance rejection ability of the proposed approach.National Key R&D Program of China SQ2019YFB130028National Natural Science Foundation of China 61525303National Natural Science Foundation of China 41772377National Natural Science Foundation of China 61673130Self-Planned Task of State Key Laboratory of Robotics and System (HIT) SKLRS201806BMinisterio de Economía y Competitividad TEC2016-78430-RJunta de Andalucía P18-RT-1340Fondo de Investigación Nacional de Qatar NPRP 9-310-2-13
