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T-type five-level NNPC converter and modulation method applicable to converter

A converter, five-level technology, applied in the direction of converting AC power input to DC power output, electrical components, single-network parallel feeding arrangement, etc., can solve the problems of increasing algorithm complexity and uncertainty, and achieve universal Strong performance and applicability, simplified algorithm, and the effect of reverse withstand voltage equalization

Pending Publication Date: 2021-08-10
SHANDONG JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] However, since each phase in the three-phase NNPC topology uses a flying capacitor as a quarter-level output, and three of the five levels will affect the voltage of the flying capacitor, the cost function in the MPC algorithm The choice of λ should consider the interaction between the flying capacitor and the output level, and the value of the weight factor λ needs to be repeatedly debugged, which significantly increases the complexity and uncertainty of the algorithm

Method used

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  • T-type five-level NNPC converter and modulation method applicable to converter
  • T-type five-level NNPC converter and modulation method applicable to converter
  • T-type five-level NNPC converter and modulation method applicable to converter

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Embodiment 1

[0047] This embodiment discloses a T-type five-level NNPC converter, which includes three-phase bridge arms connected in parallel, each phase bridge arm includes four IGBT tubes connected in series, and two IGBT tubes in different directions are connected in series on one side of the midpoint of the phase bridge arm. After these two tubes, connect two flying capacitors to the upper and lower connections of the four IGBT tubes in series. The voltage of the flying capacitor should be maintained at Vdc / 4, and the other side of the midpoint of the bridge arm is connected to the resistor through a filter; in parallel The input terminals of each bridge arm are connected to a voltage source; each IGBT tube is driven by a control circuit, and the filter is a single-L filter circuit. The converter has fewer switching devices, and can realize five-level output by using only six switching tubes for each phase, and has low cost, high reliability, and small volume and weight.

[0048] The ...

Embodiment 2

[0054] The purpose of this embodiment is to provide a modulation method for a T-type five-level NNPC converter, including:

[0055] Firstly, the mathematical model of the T-type NNPC five-level converter is established, and the mathematical model of the T-type NNPC five-level grid-connected inverter is obtained through the Clarke transformation with constant voltage amplitude, and the system is discretized by the backward Euler method Thus, the state value at time k is obtained. Since the sampling frequency is much greater than the operating frequency, the value at the next k+1 time is usually obtained by Lagrangian interpolation and extrapolation, and the demand vector and five-level vector diagram at the next time are thus obtained. The minimum error vector is selected by comparing the zero-synthesized vectors in , and the calculated vectors are converted into all switch states. Among them, the voltage vector corresponds to one or more switch states, and its impact on the fly...

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Abstract

The invention provides a T-type five-level NNPC converter and a modulation method suitable for the converter. According to the invention, working signals of a converter are collected, the optimal vector of the converter is calculated in real time through a cost function, the redundant switch states under the optimal vector are all extracted and sent to the next level, the switch state with the minimum influence is selected by comparing the influences of the redundant switch states on the voltage of a flying capacitor, the switch state is modified, and the modified switch state is sent to a switching tube to realize control so as to realize the control of the flying capacitor voltage. The method effectively controls the capacitor voltage, enables the reverse withstand voltage of each switching device to be balanced, improves the system stability, and reduces the overall cost of the system.

Description

technical field [0001] The disclosure belongs to the technical field of converter voltage control, and in particular relates to a T-type five-level NNPC converter and a modulation method applicable to the converter. 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] Compared with two-level and three-level converters, the comprehensive performance of multi-level converters has been improved, and it has been used more and more in industrial applications such as renewable energy conversion, motor drive, reactive power compensation, and transportation. s concern. The multilevel converter can significantly reduce the total harmonic distortion (Total Harmonic Distortion, THD) of the AC output, reduce the switching loss, reduce the voltage stress (dv / dt) of the switch tube, increase the input voltage range of the converter, reduce the overall volu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M7/5387H02M7/5395H02M1/44H02M1/12H02M1/088H02J3/38
CPCH02M7/483H02M7/53871H02M7/5395H02M1/44H02M1/126H02M1/088H02J3/38
Inventor 裴文卉戴向阳
Owner SHANDONG JIAOTONG UNIV
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