Recent advances in multilevel converter/inverter topologies and applications

TLDR: This paper focuses on the research advances in developing the cascade multilevel inverter topologies and their system configurations for power system applications from reviewing the traditional power conversion technology and the needs to eliminate zigzag transformers required in the traditional technology, to how to configure the cascade multi-level inverters to deal with unbalance and real-power (or active-power) flow.

Abstract: Multilevel converters and inverters have become the enabling power conversion technology for high voltage high power applications in today's power systems and large motor drives. Although the neutral-point clamped (NPC, a 3-level) inverter was invented in 1979, the multilevel concept was not formally established until the early 1990s when the diode-clamped multilevel inverter, the capacitor-clamped (or flying capacitor) multilevel inverter, and the cascade multilevel inverter were proposed and fully studied. In this paper, we will first focus on the research advances in developing the cascade multilevel inverter topologies and their system configurations for power system applications from reviewing the traditional power conversion technology and the needs to eliminate zigzag transformers required in the traditional technology, to how to configure the cascade multilevel inverters to deal with unbalance and real-power (or active-power) flow. These research breakthroughs have made the cascade multilevel inverters a perfect topology for power system applications such as FACTS devices. For example, the cascade multilevel inverter based 75 Mvar and 50 Mvar STATCOMs have been reported. Since the mid of 1990s, many contributors have made great effort in developing more multilevel inverter topologies because all the three multilevel topologies have certain limitations and are not operable in some applications. Then, we will review the generalized multilevel inverter topology, its topological advances to other multilevel inverters/ converters, and their potential applications. This paper also provides insights to how multilevel inverter topologies are related to each other and their pros and cons in practical applications.