Open AccessAn improved hysteresis current control scheme during grid voltage zero‐crossing for grid‐connected three‐level inverters
Author(s) -
Wang Haifeng,
Wu Xinzhen,
Zheng Xiaoqin,
Yuan Xibo
Publication year - 2021
Publication title -
iet power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.637
H-Index - 77
eISSN - 1755-4543
pISSN - 1755-4535
DOI - 10.1049/pel2.12161
Subject(s) - control theory (sociology) , harmonics , frequency grid , hysteresis , grid , voltage , zero crossing , controller (irrigation) , automatic frequency control , computer science , sampling (signal processing) , compensation (psychology) , range (aeronautics) , control (management) , mathematics , engineering , filter (signal processing) , physics , telecommunications , electrical engineering , psychology , agronomy , geometry , quantum mechanics , artificial intelligence , psychoanalysis , computer vision , biology , aerospace engineering
For three‐level inverters, hysteresis current control (HCC) has been widely used in applications such as active power filters due to its fast‐dynamic response, and it does not need to control each frequency separately with multiple controllers, which makes it simpler. However, the large fluctuation range of switching frequency is a serious disadvantage of hysteresis current control. Especially, the switching frequency decreases significantly during grid voltage zero‐crossing. This frequency fluctuation will cause low‐frequency harmonics. The purpose of this paper is to propose a sampling compensation scheme, which can solve the problem of switching frequency fluctuation near the zero‐crossing of grid voltage. Based on the variable hysteresis band strategy, the virtual sampling and switching time prediction algorithm is designed, which does not need to increase the sampling frequency or add additional controller. Therefore, nearly fixed switching frequency can be achieved while maintaining the control performance. Both simulation and experimental tests have verified the efficacy of the proposed scheme.