Energy feedback type power unit cascaded high voltage frequency converter

Abstract

The invention discloses an energy feedback type power unit cascaded high voltage frequency converter, which comprises a main transformer, reactors, power units, a master controller and the like, wherein the main transformer is a three-phase transformer with a plurality of secondary windings; the numbers of the secondary windings of each group are the same; each group of secondary windings comprises three identical paths of which each comprises three windings with the same number of turns; the three windings correspond to the three phases of the main transformer respectively; each winding is connected with the corresponding power unit by the corresponding reactor; the power units are equally divided into three groups corresponding to the three output phases of the high voltage frequency converter; the AC sides of inverter bridges of the power units of the same output phase are sequentially connected in series to obtain high voltage phase voltage; and one end of each of output links of the power units corresponding to each output phase of the high voltage frequency converter is connected, and the other ends of the output links of the power units corresponding to each output phase of the high voltage frequency converter serve as the output ends of each phase of the high voltage frequency converter respectively. The structure of the energy feedback type unit cascaded high voltage frequency converter can be simplified, the performance of the frequency converter can be improved, and the cost of the frequency converter can be reduced.

Description

technical field [0001] The invention relates to power electronics technology, in particular to an energy feedback type power unit series high-voltage frequency converter. Background technique [0002] In recent years, industrial energy saving and consumption reduction have gradually received widespread attention. As an important power-consuming equipment, high-voltage motors are also more and more adopted frequency conversion speed regulation to achieve economical operation. [0003] In the field of high-voltage inverters, since Peter W. Hammond proposed the unit-series high-voltage inverter in 1995, this method of realizing high-voltage power conversion through low-voltage power conversion technology is due to its good output voltage waveform, low input harmonic current, and low cost. Low cost and easy maintenance have become the mainstream technology of high-voltage inverters. Many high-voltage inverter manufacturers at home and abroad have launched products based on this...

AI Technical Summary

Problems solved by technology

[0007] In this unit series multilevel high-voltage frequency converter, each set of secondary windings (such as 12AU) of the phase-shifting main transformer 1 is a three-phase winding, including three non-phase-shifting windings 12BU, 12BV, and 12BW (each including 3 windings) and six phase-shifting windings 12AU, 12AV, 12AW, 12CU, 12CV, 12CW (each including 6 windings), so that the main transformer 1 includes 45 secondary windings, and the structure and process are quite complicated; each power The rectifier bridge 31' of the unit (such as 3AU) includes six solid-state switches 311-316, and the inverter bridge 33 includes four solid-state switches 331-334, so the whole frequency converter includes 90 solid-state switches in total, and the cost is high; the reactor (such as 2AU) are all three-phase reactors, which are bulky and heavy; in addition, since the rectifier bridge 31' of each power unit (such as 3AU) is individually controlled by the power unit, there are complex circuits, high costs, and Defects such as inability of the rectifier bridge 31' of each power unit (such as 3AU) to coordinate actions

The above is only for the series connection of three power units per phase. If there are more power units, the disadvantages will be more prominent

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