Direct control of 4-Leg 4-Level Flying Capacitor Converter for an Active Filtering Application

The quality of electrical energy in the distribution systems is a priority, from the producer of energy to the consumer. The increased consumption pushed both sides to seek solutions incorporating the cost of energy. Therefore, more and more 4-leg converters appears in order to control the neutral current appearing during unbalanced load operation on three-phase network connections. This structure of conversion is controlled by pulse width modulation techniques and more specifically by SVM (Space Vector Modulation). This work is therefore interested in the control of a 4-leg flying capacitor multilevel structure, using a direct control, with a geometrical approach to define adequate duty cycles for each calculation period. The control algorithm determines the status of switches providing balancing voltage capacitors and control of absorbed currents, with a large dynamic range adjustment from a SVM - 3D. The qualities of the algorithm are shown through simulation tests.