This paper proposes multilevel topologies based on the concept of nested arrangement. Such topologies are called nested multilevel converters since the central point of the legs are connected at the same point, with the external legs involving the internal ones. Nested configurations present advantages as compared to the equivalent NPC topologies in terms of reduced number of diodes and consequently higher efficiency. In addition to proposing a new family of power electronics converters, this paper presents an optimized PWM strategy that allows synthesizing voltage waveforms with higher quality, a losses comparison with the NPC topology, and a general comparison with other topologies proposed in the technical literature. Simulated and experimental results are presented to validate the theoretical expectations. 0885-8993 (c)

This paper proposes a modification in both topology and operation algorithm for the existent 2/3 level converter. Such strategy reduces the effort of the algorithm calculation. Also a reduction in the number of components is introduced while maintaining the previous characteristics. The THD and losses of the two-level converter, the NPC three-level converter and the 2/3-level converter are compared, since the last topology has characteristics inherent to the other two. Simulated and experimental results demonstrate the validity of the proposed method and its advantages.

This paper presents a hybrid PWM strategy for Z-source NPC converter. The technique combines the space-vector PWM with the ease of implementation of a triangular-comparision PWM. Such strategy reduces the effort of the algorithm calculation. The introduction of the distribution ratio in this technique, allows the development of a systematic approach for implementation of either conventional or any modified vector strategies, even including the shoot-through inherent of Z-source inverter. Also, the paper proposes a simple software algorithm to generate the hybrid modulation for the Z-source NPC inverter. Simulated and experimental results demonstrate the validity of the proposed method.

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This paper investigates multilevel topologies based on the concept of nested arrangement. Such topologies are called nested multilevel converters since the central point of the legs are connected at the same point, with the external leg involving the internal one. The main contribution of this paper is to furnish a formal presentation of the nested multi-level configuration, including its generalization. This configuration presents advantages when compared to the equivalent NPC topology in terms of reduced number of diodes and consequently higher efficiency. The studied configurations can be considered as an interesting option for applications that demand a number of levels higher than or equal to four. Simulated and experimental results are presented to validate the theoretical expectations.