A Star Cascaded Inverter Controlled Based on α′-β′ Coordinate System

Abstract

The invention discloses a star-shaped cascaded inverter controlled based on an α'-β' coordinate system. The three phases of the star-connected cascaded H-bridge inverter are connected in a star shape, and each phase is composed of 2n H bridges are cascaded; each H bridge includes 4 IGBTs; a star-connected cascaded H-bridge inverter is controlled using a space vector modulation method; the space vector modulation method is based on n H bridges in a star connection The space vector trajectory model of the bridge-cascaded multi-level inverter is derived; the unique space vector modulation method is used to make the controlled star-connected cascaded H-bridge inverter run more stably, the zero-sequence voltage is zero, and Easy to control.

Description

technical field The invention relates to the field of star cascaded multilevel inverters, in particular to a star cascaded inverter controlled based on an α'-β' coordinate system. Background technique The cascaded multi-level inverter technology is widely used in high-voltage and high-power converters. Its advantage is that it can use the cascade connection of power units to realize voltage division and effectively expand capacity. Bridge cascaded multilevel inverter (also known as H bridge cascaded multilevel inverter) and half bridge cascaded multilevel inverter (also known as modular multilevel inverter, MMC for short) ). There are two wiring modes of high-voltage and large-capacity H-bridge cascaded multilevel converters, star and delta. In the star-connection mode, the cascaded modules bear the phase voltage, so the cost can be reduced under the condition of low voltage. Therefore, the star-connection The cascaded multilevel inverter topology is widely used in medium ...

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Problems solved by technology

However, with the increase of the cascaded units in the space vector modulation method, the number of basic vectors increases greatly, and corresponding to one basic vector, there are multiple redundant switch state vectors. The selection of switch state vectors and the calculation of their action time are extremely complicated, resulting in The vector modulation method is difficult to implement, and makes the inverter difficult to control and poor in stability

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