A New Discrete Four Quadrant Control Technique for Grid-Connected Full-Bridge AC–DC Converters

This paper presents a new control technique for grid-connected full-bridge AC–DC converters. The proposed control scheme is based on one-cycle control approach and enables the converter to process power in all four quadrants. In the proposed method, switching pulses are generated using a discrete control law with a superimposed fictitious reactive current term. 

This term enables seamless four-quadrant operation of the converter. Implementation of the discrete controller includes estimation of the current ripple based on measured values of the input current and voltages, sampled at the beginning of each switching cycle. The estimated current ripple is then used for a carrier-less implementation of the proposed control technique. A detailed controller stability analysis using Lyapunov theory is also presented. Theoretical analysis, simulation results, and experimental results show fast dynamic response for the grid current.

Index Terms—AC–DC Converters, One-Cycle Control (OCC), Predictive-Digital Control, Reactive Power Control, Power Factor (PF).