Research On Distributed Control Of The Single-Phase Cascaded Inverter

Power electronics converters usually adopt centralized control that means all the functions are implemented by a main controller. This contro model requires high hardware resource, makes the circuit complex and has a large number of long driving wires which is easily interfered by power circuit so it has a low reliability. To resolve the disadvantages of centralized control, distributed control based on single phase cascaded inverter is researched in this paper.At first the filter structure of cascaded inverter is studied. Conventional cascaded inverter is connected by H-bridges in series and then uses a centralized filter and has its major loop connected by switches in series. When unexpected open circuit occurs in one or more switches the inverter will stop working. A structure of cascaded inverter using separated filters is proposed in this paper, its major loop can be connected by the filter capacitor when open circuit occurs thus the fault tolerant ability is enhanced and it can be further modularized. In this paper, a distributed control scheme for single phase cascaded inverter using separated filters is proposed. The CPS-SPWM technology and a multi-loop closed control strategy, which is the voltage effective value feedback, voltage instantaneous value feedback and inductance current feedback, is adopted. The distributed control scheme can be divides into two levels: the higher level is application manager and the lower level is hardware manager. The function of distributed control scheme is the same as which of centralized control scheme, but their approachs to implement the function is different. At last, simulation and experiment results are presented to validate it.