Multilevel voltage source converters and systems

摘要

Nested neutral point clamped (NNPC) multilevel power converter stages and systems are presented, in which the converter stage includes an NPC inverter core circuit with a flying (switched) capacitor nesting circuit, with the switches of the NPC core and the switched capacitor circuit being gated using selected redundant switching states to control the voltage of the switched capacitors to achieve a multilevel output voltage having equally spaced voltage step values. Multiple inverter stages can meet cascaded or connected in various configurations to implement single or multiphase power conversion systems, and higher output voltages can be achieved by forming to converter stages into an H-bridge configuration, and connecting multiple H-bridge stages in series with one another.

主权项

1. A multilevel power converter, comprising:
an inverter circuit, comprising:
an inverter switching circuit including: a plurality of inverter switching devices connected in series with one another between first and second inverter circuit input nodes, and an inverter output node connecting two of the plurality of inverter switching devices, anda clamping circuit including first and second clamping elements connected in series with one another between first and second internal nodes of the inverter switching circuit, and a third internal node joining the first and second clamping elements; a switched capacitor circuit, comprising:
switched capacitor circuit switching devices individually connected between a corresponding DC input and a corresponding inverter circuit input node, andfirst and second capacitors individually connected between a corresponding one of the inverter circuit input nodes and the third internal node; and a controller providing switching control signals to the plurality of inverter switching devices and to the switched capacitor circuit switching devices to provide a multilevel output voltage at the inverter output node at one of a plurality of distinct levels; wherein the controller selects from among a plurality of redundant switching states for at least one of the distinct output voltage levels in providing the switching control signals to control charging and discharging of the first and second capacitors to regulate corresponding first and second capacitor voltages to one third of a DC input voltage between the first and second DC inputs.