一种新型的三电平逆变器中点电压平衡控制策略

本文首先论述了三电平逆变器SVPWM的原理，利用最近三角形合成规则，推导了三角形定点矢量的作用时间。在此基础上，提出了一种通过判断中点电容电位而合理选择和分配小矢量的无电流传感器的中点电位控制方法，并作了具体阐述。理论分析和实验结果证明了此方法的有效性。     

国产高压变频器在齐鲁石化供排水厂的应用

本文着重介绍了国产高压变频器在齐鲁石化供排水厂西夏配水站给水泵中的改造方案。应用情况表明，全达到了用户对水泵变频改造的目的，改造是成功的。     

高压变频器在大唐安阳发电厂引风机上的应用

本文扼要地介绍了高压变频调速装置的工作原理、大唐安阳发电厂引风机高压变频调速装置的应用以及技术和经济分析。     

Undeland缓冲电路在IGBT逆变桥中的应用

将Undeland缓冲电路用于IGBT逆变桥中,通过合理的归并元器件,提出了一种简单、实用的多桥臂逆变电路缓冲拓扑结构。并通过一个400 Hz逆变电路的仿真和实验波形得到验证。     

SINAMICS G120变频器在恒压供水系统中的应用

文章介绍了SINAMICS G120变频器调速技术在恒压供水中的应用,阐述了恒压供水的工作原理,变频器外部接线端子功能,工艺控制器参数设置及调试方法。     

A novel photovoltaic inverter topology based on common mode current suppression

ABSTRACT

Aiming at the problems of large leakage current and low efficiency of existing transformerless single-phase grid-connected photovoltaic inverters, a novel transformerless single-phase grid-connected photovoltaic inverter topology is proposed. In this topology, two freewheeling diodes are added to the single-phase full-bridge inverter, and the filter inductors are moved between the upper and lower bridge arms, so that the common mode voltage remains constant during the switching period and the common mode current is effectively suppressed. Finally, through simulation and the experimental platform of 3kW single-phase grid-connected photovoltaic inverter, it is verified that compared with the traditional full-bridge topology, the novel topology can effectively suppress the common mode current, while compared with the H5 and H6 topology, the novel topology reduces the system loss and improves the system efficiency.     

Two new impedance source network topologies for inverter applications

In the last decade, the impedance source networks have been vastly used in electrical power conversion such as in electric vehicles, industrial machines, medical systems and avionics, with considerable efficiency improvements. In this study, two new impedance source network topologies for inverter applications have been designed and tested. The first one is a one-cell switched inductor (SL), the second is a two-cell switched inductor (X-SL) combined with the classical Z-source inverter (ZSI). This novel combination allows the switched inductor to store the unused source energy in the interval when the source separates from the ZSI network during the shoot-through zero state. The design is generalised by adding multiple branches of series inductors and diodes which further improve the circuit performance. The National Instrument Multisim programme is used for the simulations of the new topologies. Both of the proposed topologies, SL combined with classical ZSI (SL&ZSI) and X-SL combined with classical ZSI (X-SL&ZSI), are tested with specific inductance and capacitance values. Major improvements are observed in the boost factor and the elimination of the start-up inrush current for both topologies, compared to the classical ZSI scheme. Furthermore, in both topologies, a significant reduction in the capacitor stress levels is obtained.     

Design of a quasi-optical mode conversion system with variable output beam size

The quasi-optical system consisting of a quasi-optical antenna and two parabolic mirrors can convert the TE₀₃ mode output (f = 301 GHz) of the Gyrotron FU IV into a well collimated, linearly polarized beam. This system offers the possibility of tuning the size of the beam produced from 5 mm up to 24 mm by rotating and moving the two parabolic mirrors.     

模糊控制技术在恒压供水系统中的应用

以8031单片机作为控制核心,嵌入模糊控制技术,设计出一个变频调速恒压供水系统.采用Fuzzy-PID控制,该系统不仅可以获得较好的动态性能,而且又可以获得较高的控制精度.文中介绍了该系统的组成、模糊控制算法、软硬件实现方法等.     

高压大功率变频器在转炉除尘风机中的应用

高压变频器在风机、水泵类的应用已经深入到各个行业，节能效果已经为大家所共识，其中炼钢厂转炉除尘风机就是一个很好的应用对象，本文以昆明三炼钢转炉除尘风机变频改造为实例，将其和液力耦合器进行一个详细的分析、比较，同时提出一点应用的体会。