变频器在空气压缩机恒压控制中的应用

以三菱FR-A700系列通用变频器为例,从控制原理、系统配置、变频器功能设置、系统工作特点及安装与使用等方面论述变频器的实际应用.对变频器的功能及其应用进行了研究.介绍了变频器应用于空气压缩机恒压供气控制中的控制方案、系统构成,并与传统控制方式进行了比较,分析说明了系统的优点.对使用中的关键问题进行了研究和分析,给出了行之有效的方法.     

高压变频器在LF炉除尘风机上的应用

分析了高压变频器在某炼钢厂LF炉除尘风机系统中的可行性应用,确定了控制方案.并对LF炉除尘风机系统改造前后实际运行的效果进行了分析对比,论证了高压变频器在电机系统节能工程中的重要作用.     

变频器自锁控制在工业现场中的应用

传统的PLC与变频器相结合的控制方式,并没有考虑到PLC故障时对变频系统所造成的影响,针对这些难点问题进行分析,给出了相应的解决方法.主要对ABB公司的变频器和AB公司的PLC进行分析,并介绍了变频器自锁控制在济钢2#1750泵房B泵组中的应用.     

PLC控制交流变频调速控制系统在电梯中的应用

以富士NB2-P90PLC控制安川616G5组成的控制系统为例,介绍了该系统在电梯中应用的硬件结构、PLC和变频器通讯的相关程序设计及变频器的参数设置。突出了变频器在电梯中的控制特点,为变频器在电梯控制中的应用提供了实际经验。     

基于双变量六脉波交-交变频器的变压变频控制方法研究

介绍了双变量控制基本原理,阐述了变压变频在双变量六脉波交-交变频器全范围调速系统中的应用;分析了传统变压变频的缺点,提出了采用对称余弦法对双变量六脉波交-交变频器的波形进行对称性改造的方法。仿真结果验证了双变量六脉波交-交变频器变压变频控制新方法的有效性。     

抽水蓄能机组静止变频起动系统控制策略研究

静止变频起动作为抽水蓄能机组的重要起动方式之一,其起动控制策略作为静止变频起动过程中的重点问题,需要深入分析。文章首先研究了静止变频起动系统基本工作原理,给出了变频器的控制要求。在此基础上,详细分析了静止变频器的脉冲换相、负载换相方式以及换相方式切换的控制策略,并对实际工程应用中的控制要求和参数优化问题进行了研究。最后通过RTDS试验对起动控制策略的有效性和准确性进行了验证。     

变频器在原油缓冲罐液位控制中的应用

介绍了变频器在液位控制系统中的实际应用。通过对液位控制回路的介绍,给出了一种利用变频器控制液位的设计方案,并结合实例介绍了改造后变频器控制液位的流程图和系统调试方法及原理。实践证明,改造后的系统稳定性好,抗干扰能力强,取得了较好的经济效益,为拓宽变频器的应用范围做了一次成功的尝试。     

基于Labview的变频器通讯技术

为了实现对变频器连续,动态的自动化控制,提高变频器参数设置的效率,设计了一种变频器监控系统。系统采用Labview作为软件开发平台,基于三菱变频器专用通讯协议和虚拟仪器技术中的VISA技术设计实现了PC机与三菱变频器 A700的串口通信,控制变频器的运行。实验证明,系统在主从模式下,能够同时对多台变频器进行参数设定和对变频器的工作状态进行监视。有效提高了变频器的控制效率,对伺服系统的维护也具有一定的参考意义。     

变频器在粉料干燥系统中的应用

以返料机、排料机和排烟机变频调速为例,介绍变频器在粉料干燥系统中的应用,突出了变频器在干燥系统中的自动控制。     

变频器控制单元和控制器件的比较研究

为了便于在工程实际中正确和合理地选择和应用变频器,特别是对变频器进行有效的控制,着重对变频器的控制单元和控制器件进行了深入的比较研究,为变频器和相关电子器件的应用提供借鉴。     

逆变电源并联系统的谐波环流抑制研究

针对逆变电源并联系统中的谐波环流问题,在分析了单个逆变电源谐波扰动数学模型及逆变电源并联系统中谐波环流产生原理的基础上,提出对逆变电源并联系统中的单个逆变电源模块采用电流内环、电压外环的双环控制方式,并在逆变电源输出端增加耦合电感的方法来抑制系统中的谐波环流。理论分析及仿真结果验证了该方法的有效性。     

基于空间矢量的能量回馈系统控制方法的研究

针对通用变频器无法很好地消除电动机在减速、制动时产生的泵生电压的问题,文章提出了一种变频器能量回馈系统的SVPWM控制方法。该控制方法应用于有源逆变电路,采用基于固定开关频率的SVPWM控制策略,可有效消除泵生电压,实现相位动态跟踪以及电流单位功率因数回馈,并可使通用变频器在四象限运行,具有电压利用率高、动态响应快的特点。仿真结果验证了该控制方法的正确性和有效性。     

10kV高压变频器在75t/h循环流化床锅炉引风机上的应用

本文主要介绍了Zinvert高压变频调速系统的工作原理和控制系统的组成,分析了广东溢达纺织有限公司热电厂目前引风机的现状和存在的不足。将高压变频器成功应用在了3台75t／h循环流化床锅炉引风机电机上,给电厂带来了较大的经济效益,更重要的是减少了环境污染,达到了节能减排的目的。     

Design and implementation of cascaded H-Bridge multilevel inverter using FPGA with multiple carrier phase disposition modulation scheme

The paper deals with design of Cascaded H-Bridge Multilevel Inverter (CHB-MLI) with separate DC source to each inverter using multiple carrier Phase Disposition PWM such as symmetric disposition, phase opposition disposition and alternative phase opposition disposition to reduce the Total Harmonic Distortion (THD) and to improve the power quality of the supply voltage and current. In early days, the multilevel inverters are controlled with high frequency PWM method. This is not suitable for high power applications due to the high switching losses. With the help of multiple carrier PWM switching losses in the inverter circuit are reduced, so it can be used for high switchi ng frequency applications. The simulation of proposed system is developed using MATLAB Simulink software. The Performance simulation results are validated through experimental test setup using SPARTAN - 6 FPGA. Simulation results and effectiveness of the proposed method is proved and validated by experimental data.     

基于Buck变换器的新型滑模控制策略

为获得比较理想的直流输出电压,优化变换器的动态性能,基于Buck变换器采用新型滑模变结构控制策略,阐述其工作原理,并结合状态方程,推导出滑模面的存在条件和到达条件,然后对电路参数及控制系数进行设计.仿真结果表明采用这种新型滑模控制策略的Buck变换器对系统扰动和负载变化具有很强的鲁棒性,系统具有良好的动态响应.     

Simulation modelling and analysis of modular cascaded multilevel converter based shunt hybrid active power filter for large scale photovoltaic system interconnection

Modular multilevel inverters are promising candidates for next generation of efficient, robust and reliable inverters in large scale photovoltaic system. A modular cascaded multilevel inverter based shunt hybrid active power filter (SHAPF) for three phase grid-connected large scale PV systems is represented in this paper. The main contribution of this paper is to model and control of grid interfaced large scale photovoltaic system with embedded hybrid active power filter functions. In proposed system, the features of hybrid active power filter have been amalgamated in the control circuit of the voltage controlled voltage source inverter interfacing the photovoltaic system to the grid. As a result, the same inverter part of SHAPF is utilized to inject power generated from photovoltaic source to the grid and also to act as hybrid active power filter to compensate harmonics and reactive power demand. With using compensation ability, the grid currents are sinusoidal and in phase with grid voltages. The whole system is modeled in PSCAD/EMTDC. The simulation results are demonstrated to verify the operation and the control system of the proposed system.     

Improved three-vector based dead-beat model predictive direct power control strategy for grid-connected inverters

Since only one inverter voltage vector is applied during each duty cycle, traditional model predictive direct power control (MPDPC) for grid-connected inverters (GCIs) results in serious harmonics in current and power. Moreover, a high sampling frequency is needed to ensure satisfactory steady-state performance, which is contradictory to its long execution time due to the iterative prediction calculations. To solve these problems, a novel dead-beat MPDPC strategy is proposed, using two active inverter voltage vectors and one zero inverter voltage vector during each duty cycle. Adoption of three inverter vectors ensures a constant switching frequency. Thus, smooth steady-state performance of both current and power can be obtained. Unlike the traditional three-vector based MPDPC strategy, the proposed three vectors are selected based on the power errors rather than the sector where the grid voltage vector is located, which ensures that the duration times of the selected vectors are positive all the time. Iterative calculations of the cost function in traditional predictive control are also removed, which makes the proposed strategy easy to implement on digital signal processors (DSPs) for industrial applications. Results of experiments based on a 1 kW inverter setup validate the feasibility of the proposed three-vector based dead-beat MPDPC strategy.     

Stable reactive power balancing strategies of grid‐connected photovoltaic inverter network

In this paper, a distributed reactive power control based on balancing strategies is proposed for a grid‐connected photovoltaic (PV) inverter network. Grid‐connected PV inverters can transfer active power at the maximum power point and generate a certain amount reactive power as well. Because of the limited apparent power transfer capability of a single PV inverter, multiple PV inverters usually work together. The communication modules of PV inverters formulate a PV inverter network that allows reactive power to be cooperatively supplied by all the PV inverters. Hence, reactive power distributions emerge in the grid‐connected PV inverter network. Uniform reactive power distributions and optimal reactive power distributions are considered here. Reactive power balancing strategies are presented for both desired distributions. Invariant sets are defined to denote the desired reactive power distributions. Then, stability analysis is conducted for the invariant sets by using Lyapunov stability theory. In order to validate the proposed reactive power balancing strategies, a case study is performed on a large‐scale grid‐connected PV system considering different conditions. Copyright © 2015 John Wiley & Sons, Ltd.     

基于DSP控制的逆变器并联技术研究

对基于DSP控制的逆变器并联技术进行了应用基础研究。首先从理论上分析了多台逆变器输出功率不均衡的原因，得出两逆变器模块输出电压相位差会产生输出有功功率不均衡，而两逆变器模块输出电压幅值差将引起输出无功功率不均衡。因而可通过分离检测各模块输出的有功功率差和无功功率差，并利用DSP控制电路来控制每模块的基准相位和电压幅值，使各模块输出功率保持均衡。经两台小功率逆变器并联实验，结果表明该方法具有良好的控制并联模块输出功率均衡的能力，同时能保证各模块可独立运行，适合热插拔功能的应用，为实现不中断逆变器代电奠定了一定的基础。     

级联式多电平逆变器三角载波移相控制的研究

级联式多电平逆变器因其具有众多的优点,在高压变频调速领域中得到广泛应用.三角载波移相控制是级联式多电平逆变器常用的控制算法,在介绍级联式多电平逆变器的基础上,详细分析了三角载波移相控制方法的原理,在Matlab/Simulink仿真环境下对级联式多电平逆变器进行了仿真,并给出了TMS320C2812 DSP实现逆变系统的数字化控制方案,利用FPGA与DSP结合的方式实现多路SPWM脉冲对功率单元级联式逆变器进行控制.仿真和实验结果论证了FPGA与主控制器结合实时产生多路脉冲的可行性,验证了基于_二角载波水平移相级联式多电平逆变器具有优良的输出特性.