Hybrid multi-level inverter for permanent magnet traction system and control method thereof

Abstract

The invention discloses a hybrid multi-level inverter and a control method thereof, and a high-speed rail permanent magnet traction system. The inverter comprises at least one single-phase bridge armand a direct-current input circuit for providing a direct-current voltage for the at least one single-phase bridge arm. Each single-phase bridge arm comprises a high-voltage low-frequency unit and a low-voltage high-frequency unit which are cascaded; each high-voltage low-frequency unit comprises a two-level upper bridge arm and a two-level lower bridge arm which are coupled in series; the power switching devices in the two-level upper bridge arm and the two-level lower bridge arm are operated in a fundamental frequency mode; each low-voltage high-frequency unit comprises an intermediate connection unit and at least one T-shaped three-level unit which are sequentially cascaded, the intermediate connection unit is composed of two complementary power switching devices, and the last T-shapedthree-level unit of each low-voltage high-frequency unit is connected with an independent output; the intermediate connection unit is in cascade connection with the midpoints of the two-level upper bridge arm and the two-level lower bridge arm; and the power switching devices of the intermediate connection units and the T-shaped three-level units are operated in a high-frequency switching mode.

Description

technical field [0001] The invention relates to a traction system in a high-speed rail, in particular to a hybrid multilevel inverter, a control method thereof, and a permanent magnet traction system for a high-speed rail. Background technique [0002] The traction system is the "heart" of a high-speed train, and its performance determines the starting, braking and maximum speed of the train. The traction system of high-speed trains has undergone a transformation from DC motors to AC asynchronous motor drives. Compared with induction motor drives, permanent magnet synchronous motors have low loss, high efficiency, high power density, good starting characteristics, and strong acceleration performance. With significant advantages such as low noise, it has the technical potential to gradually replace AC induction motors. [0003] The permanent magnet traction system mainly includes traction transformer, traction converter (rectifier, inverter and intermediate DC link), permane...

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Problems solved by technology

[0005] Aiming at the above-mentioned deficiencies in the prior art, a hybrid multilevel inverter and its control method and high-speed rail permanent magnet traction system provided by the present invention solve the problems of low switching frequency, large volume and weight, and fault tolerance of the existing inverter. bad question

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