A Flying Capacitor Based Neutral Voltage Balancing System for Three Phase Four Wire Inverter with State Feedback Control

This paper addresses the important problem of the neutral point voltage equalisation in three-phase four-wire standalone inverters employing a state feedback control technique. The neutral voltage balancer functions independently, and state feedback gains can be obtained utilising optimal controller design methodologies. The suggested state feedback control approach is immune to parameter changes and keeps the neutral voltage very close to zero under diverse dynamic loading scenarios. This paper also proposes a flying capacitor-based switch network that significantly reduces the neutral link inductor current ripple. A MATLAB-based simulation analysis is performed to illustrate the efficacy of the suggested method in providing balanced neutral voltage distribution with reduced oscillations, hence improving the overall stability and performance of the inverter system. Simulation results shows the neutral voltage equalisation with balanced and unbalanced DC link capacitors. This work, using a state feedback control method and a flying capacitor-based switch network, provides a potential choice for enhancing the robustness of stand-alone inverter systems under unbalanced loading conditions.