Design of Repetitive Controller and Input Filter for Active Front-End Rectifier in Solid-State Transformer Under Finite Harmonics and Source Impedance

This paper investigates the effects of low frequency harmonics and source impedance on active front-end rectifier in modular solid-state transformer. The topology for analysis was selected to three-level boost (TLB) converter which is widely used for power factor correction. Harmonic contents of input source cause periodic distortions in input current, degrading THD factor. In the presence of finite source impedance, performance of properly designed current controller can be deteriorated in terms of phase margin and system instability. In this paper, those external effects are studied with equivalent single module TLB. Repetitive controller and input filter designs are presented to compensate periodic distortion and overlapped impedance interaction in frequency domain, respectively. Simulation and experimental results are provided to verify the analysis.