Design And Implementation Of Dual Buck Multilevel Inverter Based On Digital Control

At present, multi-level inverter is a research hot, how to simplify the topology and improve the reliability of circuit is one of the key issues. Based on bridge multi-level inverter, a lot of improvement measures have been proposed by scholars at home and abroad, and great achievements have been obtained. From another point of view, using dual buck circuit as the basic unit to build multilevel inverter, a novel dual buck five-level inverter has been designed and demonstrated in this paper, this inverter retains merits of dual buck half bridge inverter, and benefits to the simplification of clamp circuit and improvement of system stability.Firstly, overall scheme design of dual buck five-level inverter has been designed in this paper, which includes topology building, comparison and selection of closed-loop control strategy and modulation scheme; Secondly, working principle of the proposed inverter, such as switch working modes, closed-loop control strategy and voltage balance decoupling control has been concretely analyzed; Thirdly, according to overall scheme design, detail designs of the inverter have been carried out, including hardware designs such as main power circuits, sampling circuits, conditioning circuits, protection circuits, driving circuits, hardware parts of digital controller and PWM signal distribution unit circuits, and software designs such as realization of digital PI control strategy, algorithm for SPWM based on DSP and generation of partition control signals. Finally, system simulation using saber software and 1kW prototype of the presented inverter have been carried out.Results of simulation and experiment show that the design is reasonable and feasible, and the inverter gets a good performance, besides outputting five-level voltage, technical qualification, such as whole efficiency, THD of output waveform and so on, is satisfied with the requirements of the design.