Estudo e implementação de topologias multiníveis com indutores acoplados e número reduzido de componentes.

Abstract

This work studies the reduction of the total number of components in four multilevel converters structures. This enables the simplification of modulation strategy used to control the switches, reducing the cost of these converters, besides contributing to the reduction of total electrical losses. They are discussed a total of eight single-phase multilevel inverters, four of these are already known in the literature, called conventional and the other four are proposed with the reduction of the conventional switches, using inductors magnetically coupled between unidirectional complementary legs. For each proposed converter it is discussed the operation and modulation strategy employed. In quantitative terms, the inverters using the inductive coupling obtained better relationship between the number of levels of the output voltage and the number of topology switches, better harmonic performance and lower level of electrical losses in semiconductors. Moreover, for the correct operation of these converters, it was necessary to add a offset reference voltage in each leg so that the diodes in the legs could conduct when a complementary switch is turned off. Also, it should be noted that the reduction of semiconductors and magnetic element added in a multilevel converter is only valid when any of the parameters of weight, volume and/or total cost of converter is lower than the traditional multilevel converters and the relevance of these parameters must be specified in converter design, according to its specific application. To validate the proposed converters it’s presented the obtained simulation results and some of the experimental tests performed in the Laboratory of Industrial Electronics and Machinery Drive (LEIAM) belonging to the Federal University of Campina Grande (UFCG).