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Low common mode vector modulation method and system for three-level SNPC inverter

A vector modulation and three-level technology, applied to electrical components, output power conversion devices, AC power input conversion to DC power output, etc., can solve the problem of space vector lack of medium vector, etc., to reduce electromagnetic interference and achieve balance , Improve the effect of modulation accuracy

Pending Publication Date: 2021-12-10
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Due to the coupled structure of the three-level SNPC inverter, the space vector of this inverter lacks the center vector, which brings challenges to the control and modulation methods of the topology

Method used

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  • Low common mode vector modulation method and system for three-level SNPC inverter

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Embodiment 1

[0037] In one or more embodiments, a low common-mode vector modulation method for a three-level SNPC inverter is disclosed. The method is aimed at a three-level SNPC inverter, combining figure 1 , the topological structure diagram of the three-level SNPC inverter, including the coupled part and the independent part. Four power switch tubes in the coupling part are connected in series, and the midpoints of the four switch tubes are connected to the neutral points of the two filter capacitors on the DC side. The independent module includes A-phase, B-phase and C-phase bridge arms, each phase bridge arm includes two power switch tubes, a total of six power switch tubes, and the midpoint of each phase bridge arm is connected to the AC load through a filter.

[0038] In this embodiment, the switch tube may be an IGBT tube.

[0039] The coupling part generates three levels through different switch combinations, but only two levels can be generated at the same time, and the three-ph...

Embodiment 2

[0094] In one or more implementations, a low common-mode vector modulation system for a three-level SNPC inverter is disclosed, including:

[0095] A module for sampling three-phase current, obtaining a reference voltage vector in the αβ coordinate system after current closed-loop control and coordinate transformation, and judging the sector where the reference voltage vector is located according to the value of its phase angle;

[0096] A module for selecting a small vector according to the sector where the reference voltage vector is located and the midpoint potential, and adjusting the action time of the small vector through a PI controller;

[0097] It is used to calculate the action time of the large vector, virtual medium vector and zero vector based on the modulation principle of synthesizing the reference voltage vector with the four vectors of large vector, virtual medium vector, small vector and zero vector; at the same time, design the three-level SNPC inverter The ...

Embodiment 3

[0100] In one or more embodiments, a terminal device is disclosed, including a server, the server includes a memory, a processor, and a computer program stored on the memory and operable on the processor, and the processor executes the The program realizes the low common mode vector modulation method of the three-level SNPC inverter in the first embodiment. For the sake of brevity, details are not repeated here.

[0101] It should be understood that in this embodiment, the processor can be a central processing unit CPU, and the processor can also be other general-purpose processors, digital signal processors DSP, application specific integrated circuits ASIC, off-the-shelf programmable gate array FPGA or other programmable logic devices , discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.

[0102] The memory may include read-only me...

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Abstract

The invention discloses a low common mode vector modulation method and system for a three-level SNPC inverter, and the method comprises the steps that a three-phase current is ssmpled, a reference voltage vector is obtained under an alpha-beta coordinate system, and a sector where the reference voltage vector is located is judged according to the value of a phase angle; a small vector is selected according to the sector where the reference voltage vector is located and the midpoint potential condition, and the action time of the small vector is adjusted through a PI controller; the action time of the large vector, the virtual medium vector and the zero vector is calculated; meanwhile, switch sequences of a coupling part and an independent part of the three-level SNPC inverter is separately designed, wherein the large vector, the small vector and the zero vector are low common mode vectors; and on-off of a power switch tube in the three-level SNPC inverter is controlled based on the action time and the switch sequence so as to control operation of the three-level inverter. According to the invention, the common-mode voltage is effectively suppressed, and the balance of the neutral-point potential is realized.

Description

technical field [0001] The invention relates to the technical field of three-level inverter vector modulation, in particular to a low common-mode vector modulation method and system for a three-level SNPC inverter. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] Three-level inverters have the advantages of output waveforms close to sine waves and small current harmonics, and are widely used in high-speed railways, new energy power generation, motor control and other fields, such as NPC inverters and cascaded inverters. The three-phase bridge arms of these three-level inverters are independent of each other, so at least 12 switches are required. The prior art proposes a new three-level SNPC inverter with four active switches shared by three phases. This coupling structure reduces the number of switches to 10, does not require the assistan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/5387H02M1/088H02M1/12
CPCH02M7/53871H02M1/088H02M1/12
Inventor 邢相洋景萌萌刘畅庞贤哲
Owner SHANDONG UNIV
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