An improved hysteresis current control scheme during grid voltage zero?crossing for grid?connected three?level inverters

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 each frequency separately with multiple controllers, which makes simpler. However, the large fluctuation range of switching is a serious disadvantage control. Especially, decreases significantly during grid voltage zero-crossing. This will cause low-frequency harmonics. The purpose this paper propose sampling compensation scheme, can solve problem near zero-crossing voltage. Based on variable band strategy, virtual time prediction algorithm designed, increase or add additional controller. Therefore, nearly fixed be achieved while maintaining performance. Both simulation experimental tests have verified efficacy proposed scheme.