Capacitor Voltage Balancing of a Grid-Tied, Cascaded Multilevel Converter with Binary Asymmetric Voltage Levels Using an Optimal One-Step-Ahead Switching-State Combination Approach

This paper presents a novel capacitor voltage balancing control approach for cascaded multilevel inverters with an arbitrary number of series-connected H-Bridge modules (floating modules) asymmetric voltages, tiered by factor two (binary asymmetric). Using nearest-level reference waveform, the uses one-step-ahead to find optimal switching-state combination among all redundant combinations balance voltages as quickly possible. Moreover, using Lyapunov function candidate and considering LaSalle’s invariance principle, it is shown that offline calculated trajectory each discrete output level can be used operate (asymptotically stable) inverter without measuring any achieving sensorless well. To verify stability its variant, demonstrator 33 levels operated in grid-tied mode. For chosen 33-level converter, NPC main-stage individual H-bridge are switching frequency about 1 kHz 2 kHz, respectively. The slightly reduced dynamic system response and, furthermore, current THD operating point was increased from 3.28 4.58 comparison feedback.