Virtual Control-Based Sliding Mode Control of the Neutral Point of DC/AC Converters Connected to 3-Phase 4-Wire Grid*

This paper presents a study on the control of the neutral point of DC/AC converters connected to an unbalanced 3-phase 4-wire grid. The mathematical models of the converters, including an LCL filter, and the neutral line circuit in both balanced and unbalanced 3-phase 4-wire grids are developed. An active balancing method is employed to maintain the DC bus voltage's zero DC offset voltage. A virtual control technique is implemented in the controller design. Furthermore, a sliding mode control strategy is proposed to regulate the neutral point of DC/AC converters. The efficacy of the proposed approach is demonstrated through simulation results.