Bridgeless multi-level rectifier with common direct current bus and control strategy

Abstract

The invention discloses a bridgeless multi-level rectifier with a common direct current bus and a control strategy, and belongs to an AC / DC conversion technology and a control technology thereof. A converter provides various main power circuits, each main power circuit is composed of expandable module units and used for forming a pair of public high-voltage direct-current buses, and the defect that high direct-current bus voltage cannot be generated due to voltage stress limitation of a power switch tube is overcome. According to the rectifier and the control strategy thereof provided by the invention, the number of required active power switch tubes is greatly reduced, the cost of the converter and the control complexity are greatly reduced, the balance control of the flying capacitor voltage can be conveniently realized on the basis of obtaining multi-level voltage output, and the expansion of any level number can be flexibly realized. The rectifier has an important application value in the fields of medium-high voltage direct current transmission, high-power medium-high voltage variable frequency speed regulation and the like.

Description

technical field [0001] The invention belongs to the technical field of medium and high voltage frequency conversion speed regulation, and in particular relates to a bridgeless multilevel rectifier with a common direct current bus and a system realization scheme of a control strategy. Background technique [0002] In recent years, "Multilevel Converter" (Multilevel Converter) has been more and more successful in the fields of high voltage and high power frequency conversion speed regulation, active power filtering, high voltage direct current (HVDC) transmission and power system reactive power compensation. Application. The basic circuit topology of traditional medium and high voltage multilevel converters can be roughly divided into clamping type and unit cascading type. At present, the diode clamping produced by Siemens or ABB is widely used in industry Type three-level medium and high voltage inverters, and cascaded H-bridge medium and high voltage inverters produced by Ro...

AI Technical Summary

Problems solved by technology

However, this type of converter also has obvious disadvantages, which are mainly manifested in: each phase N cascaded rectifier modules will generate N sets of DC output terminals, and because the input terminals are not isolated, the DC output terminals of these N sets of rectifier modules cannot be directly Series connection forms a pair of common high-voltage DC output buses, so it cannot be directly used for high-voltage DC transmission, nor can it be directly connected with multi-level inverter circuits for medium and high voltage frequency conversion speed regulation

In order to realize a common high-voltage DC output bus or realize flexible control of N groups of rectified output DC voltages, N groups of cascaded rectifier modules must be followed by N high-frequency isolated DC-DC conversion modules, resulting in the overall system topology and control mode Increased complexity and decreased productivity

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