Asymmetric six-level rectifier and control method thereof

Abstract

The invention provides an asymmetric six-level rectifier and a control method thereof, the asymmetric six-level rectifier comprises three phases of bridge arms which are connected in parallel, and each phase of bridge arm comprises an H bridge circuit, a diode and an IGBT tube; the H-bridge circuit outputs three levels, the diode and the IGBT tube are matched with the direct current side capacitor to output two levels, and six levels are output through cascade connection of the two parts; a controller of the six-level rectifier determines a six-level space vector diagram based on a pre-constructed six-level switch state to realize six-level harmonic-free output; meanwhile, grid-connected current tracking and three-phase suspension capacitor voltage equality are realized by using a value function constructed based on the space vector diagram. According to the scheme, a direct-current side midpoint is not led out, so that a control scheme does not need to be designed to control direct-current side capacitor voltage balance; meanwhile, according to the scheme, only five IGBTs are adopted for each phase, multiple levels are achieved through fewer IGBTs, and cost is saved compared with other multi-level topologies.

Description

technical field [0001] The disclosure belongs to the technical field of rectifier control, and in particular relates to an asymmetric six-level rectifier and a control method thereof. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] As an efficient and convenient energy source, electric energy has been more and more utilized in the modern age of rapid industrial development. However, how to further optimize the power quality and improve the efficiency of power conversion needs to be solved urgently. [0004] Non-linear circuits such as traditional diode uncontrolled rectification and phase-controlled rectification, because the current waveform on the input side deviates from the sinusoidal curve seriously, will cause the current to contain large harmonic components, reduce the power factor of the rectifier, increase the total harmonic dis...

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Problems solved by technology

[0004] Non-linear circuits such as traditional diode uncontrolled rectification and phase-controlled rectification, because the current waveform on the input side deviates from the sinusoidal curve seriously, will cause the current to contain large harmonic components, reduce the power factor of the rectifier, increase the total harmonic distortion rate of the current, The circuit loss is large, causing harm to the operation safety of the power grid

[0005] Compared with traditional two-level and three-level converters, multilevel rectifiers reduce output voltage jumps, reduce harmonic content and current THD due to increased output levels, and increase the number of levels at the same time, improving The equivalent switching frequency of the power device is improved, and the efficiency is improved; however, the inventors found that the existing multilevel rectifier has the disadvantages of many level shifter switching devices and a complex overall structure

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