A medium and high voltage inverter DC capacitor pre-charging device

Abstract

The invention discloses a DC capacitor precharging device for medium and high voltage frequency converters, comprising a low voltage control circuit, a single-phase three-winding isolation transformer, a first voltage doubler circuit, a second voltage doubler circuit and a DC reverse resistance circuit; the low voltage control circuit is mainly By adjusting the input voltage of the primary side of the transformer, the purpose of suppressing the pre-charging current is achieved; the transformer is mainly used for voltage conversion and high-low voltage isolation; the function of the voltage doubler circuit is to realize the AC conversion of the secondary side of the transformer to DC; After the charging is completed, the capacitor energy is prevented from being released to the low voltage side. The device of the invention solves the problem of single-phase 220V charging DC high-voltage capacitors, adds a bidirectional thyristor to limit the input current, adopts a voltage doubler circuit to reduce the number of rectifying diodes, and achieves the purpose of reducing costs.

Description

technical field [0001] The invention belongs to the technical field of electric drive, and in particular relates to a DC capacitor precharging device for medium and high voltage frequency converters. Background technique [0002] In today's world, energy has become the pillar of national economic development, and energy conservation and environmental protection have become common concerns of both developed and developing countries. Energy saving, in the final analysis, is mainly the saving of electric energy. At present, medium and high voltage AC-DC-AC inverters are widely used in power transmission and power conversion equipment, and have shown significant energy-saving effects. Every time the medium and high voltage inverter starts, it needs to precharge the DC capacitor to reduce the impact on the power grid and protect the power electronic devices. [0003] At present, the DC pre-charging devices of medium and high-voltage inverters that have been relatively successfu...

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Problems solved by technology

[0003] At present, the DC pre-charging devices of medium and high-voltage inverters that have been relatively successful in research mostly use the topology of a three-phase three-winding step-up transformer and a twelve-pulse rectifier: this topology circuit is connected to a three-phase 380V circuit, through a step-up transformer and six High-voltage current-limiting resistors and twelve-pulse rectifiers can obtain the required DC voltage. Due to the large number of current-limiting resistors and diodes, the volume and cost of the inverter are greatly increased.

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