Thyristor-Based Four-Quadrant Multilevel Current Source Converter with Main Circuit

Abstract

The invention relates to alternating-current to direct-current conversion of electric energy, discloses a four-quadrant multilevel current-source converter with a main circuit based on a thyristor and belongs to improvement to the fact that reactive power compensation is needed to be performed additionally caused by the fact that phase current is restricted and phase voltage is delayed due to a phase shift range of a trigger angle ranging from 0 to 180 when two groups of three-phase bridge-paralleled twelve-pulse thyristor circuits are utilized in high-power places. The converter is characterized in that a paralleling reactor in the topology is replaced by a multilevel injection circuit to enable each group of the three-phase bridges to output stepped multilevel pulse direct current and provide zero-current phase-commutation conditions for the thyristor. The multilevel injection circuit consists of multiple units with the same structure, each unit consists of two components with inverse resistant characteristics and a reactor, and cathodes or anodes of the components are connected with a terminal of the reactor to enable each group to structurally be a three-port unit. Consequently, the multilevel injection circuit and the main circuit are coordinated for controlling to provide the zero-current phase-commutation conditions for a main bridge thyristor, so that controlled turn-off of the thyristor is realized, and the whole circuit can possess four-quadrant operating capability.

Description

technical field

[0001] The invention relates to the field of electric energy AC-DC conversion, in particular to the topology of a thyristor-based current source switching converter in a main circuit. Background technique

[0002] Since thyristors have the highest power level in the family of power semiconductor devices, and the driving circuit is relatively simple, thyristor three-phase bridge circuits are widely used in high-voltage and high-power applications. However, since thyristors are semi-controlled devices, the gate trigger pulse can only Control its opening, so that the trigger angle phase shift range of the three-phase bridge is only 0~180°, which restricts its phase current to always lag behind the phase voltage, so the current source converter using the traditional thyristor three-phase bridge needs to be equipped with a considerable capacity The capacitor is used as a reactive power compensation device, which not only leads to an increase in the size of the dev...

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