Active Voltage Balancing Control of A 7-Level Hybrid Multilevel Converter Topology

The series connection of a standard 3-level active neutral-point-clamped (ANPC) inverter and two cascaded H-bridge (CHB) modules comprising the flyingcapacitors (FCs) instead of the isolated dc-voltage sources forms a 7-level hybrid topology that is referred to as improved ANPC (I-ANPC) converter. This paper proposes an active voltage balancing technique for control of this hybrid multilevel inverter. The suggested method is based on a set of effortless logic-equations that aim to stabilize the FC voltages within the CHB modules at their requisite reference values as well as to control the output voltage of the overall hybrid converter based on the phase-shiftedcarrier pulse-width-modulation (PSC-PWM) strategy. The experimental results obtained from a single-phase I-ANPC inverter's prototype are presented to validate the proposed control technique and its simple logic-equations.