Phase-independent control of a three-phase four-leg inverter

Electrical grid faces many challenges such as the integration of the increasing renewable energy, the management of electrical vehicle, storage systems, etc. These factors can damage the stability of the grid and condition the availability and quality of the electrical supply. Furthermore, in distribution lines different loads and generators are connected in each phase which increment the unbalance between the phases and, thus, the quality of the power supply for each phase. A bidirectional power flow in unbalanced systems is managed in several papers but in which the power flow is the same in all the phases. In this paper, a new control strategy for a three-phase four-leg inverter is proposed based on an individual control per-phase that permits different power flows in each phase simultaneously. The proposed system includes a battery connected to the DC bus that helps maintaining balanced voltages in the grid despite of load changes and an optimal modulation technique is selected. Simulations results validate the viability of the proposed control system.