Synchronous Adjustment of Modular Converter Based on Diode-Clamped Inverters with Multi-Zone PWM

Analysis of operation of multilevel converter consisting from transformer and triple diode-clamped inverters, adjusted by the specialized scheme of control (with the use of minimum number of voltage space vectors of inverter) and of synchronous modulation (providing continuous symmetry of voltage waveforms), has been executed in the paper. Scheme of synchronous space-vector modulation is based in this case on concept of multi-zone control, which includes continuous determination of boundary frequencies between control sub-zones (on the axis of the fundamental frequency of installation), and on alternative control correlations for determination of the pulse patterns. The system controlled by two basic versions of synchronous pulsewidth modulation (PWM) has been investigated. The analyzed control and modulation strategies have been verified by numerical simulations.