不平衡电网下AC-DC矩阵变换器的新型模型预测控制

为降低AC-DC矩阵变换器在输入不平衡条件下网侧有功功率波动,以及离散型模型预测控制中开关频率不固定的问题,提出一种新型模型预测控制方法。通过根据电网电流相位角选择有效矢量,避免了传统模型预测控制评估价值函数计算的负担。提出了一种二阶扩展复数卡尔曼滤波器,计算精度可以达到泰勒级数展开的二阶项,新型模型预测控制能够在不平衡电网系统中应用。仿真结果表明:所提控制策略在输入电压不平衡工况下,能够有效抑制网侧电流谐波,稳定系统输出的有功功率,并且表现出良好的性能。

AC/DC通信电源模块远场电磁辐射发射预测研究

AC/DC通信电源产生的电磁辐射易超过限值,对其电磁辐射机理和预测方法开展研究有助于改善电磁兼容性设计。首先,在分析AC/DC通信电源模块共模电磁噪声的形成源头和传播路径后,提出其远场电磁辐射可分解为由“输入端口”、“输出端口”共模电压驱动的2类辐射。然后,提出将共模电压驱动源与寄生辐射体的辐射传递函数相结合,进行远场电磁辐射预测的新方法;设计频谱分析仪+电阻衰减器,实现各共模电压驱动源的频谱测量;采用FEKO电磁仿真软件,通过数值计算得到各寄生辐射体的辐射传递函数。最后,实现了4 kW AC/DC通信电源模块辐射预测,并实测验证了其有效性。

隔离型双向AC-DC矩阵变换器闭环控制方法研究

根据隔离型双向AC-DC矩阵变换器(Isolated AC-DC Matrix Converter,IAMC)没有中间电容缓冲环节,输入和输出变换器控制之间存在耦合,研究提出了IAMC两级功率变换器的控制方法。通过对全桥变换器进行闭环控制进而实现对直流侧输出电流和功率的直接控制;三相-单相矩阵变换器实现对有功和无功功率的独立控制,以满足网侧功率因数的高精度控制。所提控制策略有效降低了两级变换器的耦合强度,保证了系统的良好性能。在MATLAB中进行仿真,结果表明,所提出的控制方法在使系统电能质量得到提高的同时,可以实现单位功率因数可调,验证了所提控制策略的正确性和有效性。

高效单片AC/DC电源管理集成电路设计

随着科技快速发展,电子产品的复杂程度不断升级,日益向小型化、智能化、高效能方向迈进。电源管理系统作为电子产品中的重要系统之一,其重要作用逐渐凸显。本研究设计了一种单片AC/DC开关电源集成电路,该电路具有效率高、体积小、可靠性高等优点。因此,本文基于高效的单片AC/DC电源管理集成电路构成,对其进行了优化设计,希望能够为我国电源管理系统设计行业的相关工作提供参考和借鉴。

Model Predictive Control Strategy of Multi-Port Interline DC Power Flow Controller

There are issues with flexible DC transmission system such as a lack of control freedom over power flow.In order to tackle these issues,a DC power flow controller(DCPFC)is incorporated into a multi-terminal,flexible DC power grid.In recent years,a multi-port DC power flow controller based on a modular multi-level converter has become a focal point of research due to its simple structure and robust scalability.This work proposes a model predictive control(MPC)strategy for multi-port interline DC power flow controllers in order to improve their steady-state dynamic performance.Initially,the mathematical model of a multi-terminal DC power grid with a multi-port interline DC power flow controller is developed,and the relationship between each regulated variable and control variable is determined;The power flow controller is then discretized,and the cost function and weight factor are built with numerous control objectives.Sub module sorting method and nearest level approximation modulation regulate the power flow controller;Lastly,theMATLAB/Simulink simulation platformis used to verify the correctness of the establishedmathematicalmodel and the control performance of the suggestedMPC strategy.Finally,it is demonstrated that the control strategy possesses the benefits of robust dynamic performance,multiobjective control,and a simple structure.

一种高效率半桥LLC型的AC/DC变换器设计

AC/DC开关电源是电力系统的主要动力来源,其发展趋势是:容量大、功率密度大、效率高、功率因数低、谐波含量低。但现有的数字电源仍存在着一些普遍问题:抗干扰能力差、结构功能简单、无法满足电厂和变电站等相关场所使用需求。设计了一种基于芯片控制的半桥开关电源,对其主电路进行了理论分析,并对EMI整流滤波电路、PFC功率因数校正电路、LLC半桥电路等电路进行了详细的设计。实验测试结果表明,该设计合理,具有大容量、高效率、高功率因数、低纹波等特点,能够充分满足目前的市场需求。

车载AC-DC变换器的模糊无差拍控制策略

针对车载充电机前级AC-DC变换器工作时,网侧电流存在严重畸变以及系统的动态响应性能不足的问题,提出了一种模糊控制和无差拍控制相结合的功率因数校正控制策略。在小信号建模的基础上,对传统PI平均电流控制进行分析,将其电压环改用模糊PI控制,以增强直流侧电压的动态响应性能;将电流环改用无差拍控制,以提高交流侧电流质量、减小谐波损耗。同时对无差拍控制进行了改进,通过预测第k+2时刻采样电流和第k+1时刻参考电流,改善了实际系统的时间延时和相位滞后问题。采用MATLAB/Simulink进行仿真,结果表明该控制策略有效地减小了网侧电流的总谐波失真,并提升了输出侧的动态响应指标。

一种新型单级隔离型AC-DC变换器研究

文中提出一种新型单级式隔离AC-DC变换器及控制方案。所提结构在不改变图腾柱无桥功率因数校正(totem pole bridge-free power factor correction,TP-PFC)和双向全桥(dual active bridge,DAB)两级式AC-DC变换器特性的前提下,将TP-PFC高频桥臂和DAB原边侧第一个桥臂进行开关复用,减小了开关器件数目。同时,相较于TP-PFC和DAB两级式AC-DC变换器,取消了直流母线电解电容并且抑制了交流电感电流尖峰。利用其拓扑特点及所提出的控制方案,实现了拓扑开关器件的全范围软开关。首先详细分析所提拓扑结构的工作特性,包括工作模态、拓扑优点、功率特性及软开关特性;其次基于对拓扑的分析,提出控制简单的控制策略;最后,对所提拓扑结构及控制方案进行实验验证。

基于移相和调频的单级双向AC-DC变换器临界电流调制策略

传统双有源桥单级AC-DC变换器的移相调制难以实现全范围软开关,开关管损耗大,效率难以进一步提高。针对此问题,该文提出一种基于临界电流模式(BCM)的调制策略,将移相和调频相结合,实现所有开关管的零电压开通,从而有效地降低了开通损耗。该文分析单级式双向AC-DC变换器的临界电流调制基本原理和软开关实现条件,并推导出软开关条件下的移相和频率数学表达式。搭建DC 48 V、AC 220 V、500 W实验样机,最高效率达到94%,通过实验验证该调制策略的有效性和正确性。

基于单级AC/DC脉冲激励源的电容式无线输电系统

电容式无线输电(CPT)系统的原边激励源通常是由工频整流器和高频逆变器组成的级联变换器,使用的半导体和无源元件数量较多,导通损耗也较高。该文提出了一种新型的单级AC/DC变换器,与传统的变换器相比,该变换器只使用2个开关管和2个二极管,可以将工频交流电变换成CPT系统所需的直流脉冲激励源。该文介绍了该变换器的工作原理,提出了实现高功率因数、软开关的设计方法。最后,通过硬件实验证明了该变换器在电容式无线输电系统中的可行性,实现了开关管的零电压导通,具有高输入功率因数。

Research on power electronic transformer applied in AC/DC hybrid distribution networks

The AC/DC hybrid distribution network is one of the trends in distribution network development, which poses great challenges to the traditional distribution transformer. In this paper, a new topology suitable for AC/DC hybrid distribution network is put forward according to the demands of power grid, with advantages of accepting DG and DC loads, while clearing DC fault by blocking the clamping double sub-module(CDSM) of input stage. Then, this paper shows the typical structure of AC/DC distribution network that is hand in hand. Based on the new topology, this paper designs the control and modulation strategies of each stage, where the outer loop controller of input stage is emphasized for its twocontrol mode. At last, the rationality of new topology and the validity of control strategies are verified by the steady and dynamic state simulation. At the same time, the simulation results highlight the role of PET in energy regulation.

Novel Double-Damped Tuned AC Filters in HVDC Systems

This paper presents a performance analysis of novel doubledampedtuned alternating current (AC) filters in high voltage direct current(HVDC) systems. The proposed double-damped tuned AC filters offer theadvantages of improved performance of HVDC systems in terms of betterpower quality, high power factor, and lower total harmonic distortion (THD).The system under analysis consists of an 878 km long HVDC transmissionline connecting converter stations at Matiari and Lahore, two major cities inPakistan. The main focus of this research is to design a novel AC filter usingthe equivalent impedance method of two single-tuned and double-dampedtuned AC filters. Additionally, the impact of the damping resistor on the ACchannel is examined. TheTHDof theHVDCsystem with and without currentAC filters was also compared in this research and a double-damped tuned ACfilter was proposed. The results of the simulation represent that the proposeddouble-damped tuned AC filter is far smaller in size, offers better powerquality, and has a much lower THD compared to the AC filters currently inplace in the converter station. The simulation analysis was carried out utilizingpower systems computer-aided design (PSCAD) software.

A new high-performance AC/DC power factor correction switching converter based on one-cycle control technology and active floating-charge technology

A new family of converters,high-performance AC/DC power factor correction(PFC) switching converters with one-cycle control technology and active floating-charge technology,was derived and experimentally verified.The topology of a single-phase CCM and DCM Boost-PFC switching converter was also analyzed.Its operating prniciples and control methods were expounded.Based on these,a new type of AC/DC switching converter circuits for PFC combined with one-cycle control technology was presented herein.The proposed AC/DC switching converter significantly helps improve the converter efficiency and its power factor value.

面向低压大容量直流供电的混合型AC/DC接口变流器解耦控制

为解决传统基于电流源型整流器(currentsourcerectifier,CSR)的两级式高降压比电力电子变换设备中存在的多控制目标之间的耦合问题,在所提出的相控电流源型整流器和输入串联输出并联LLC-DC/DC变换器相结合的混合型拓扑结构基础上,通过建立考虑系统直流环节电感电容的小信号模型,提出了一种在较低自由度下可同时实现交流侧功率因数和输出直流电压调节的解耦控制方法。通过绘制系统的根轨迹,分析了系统解耦前后控制参数对系统稳定性的影响。最后,通过RT-Lab半实物仿真验证了所提方法的有效性。

双向隔离型AC-DC矩阵变换器的双极性SVM调制分析

首先介绍双向隔离型AC-DC矩阵变换器工作原理及能量流动方向的影响因素,然后详细分析双极性电流空间矢量调制方法的实现原理,最后设计了PI直接功率控制器用于调节充电电流。实现了单位功率因数控制和电网电流低谐波失真率,并通过仿真验证了设计的正确性。

基于改进MFAC的交直流微电网分布式二次控制

针对现有交直流微电网分布式二次控制(distributed secondarycontrol,DSC)受分布式电源一次控制参数影响较大、通信拓扑结构复杂、二次控制参数难以整定等问题,提出基于改进MFAC的交直流微电网DSC(MFAC-DSC),利用分布式电源的历史采样数据在线估计其动态线性化参数,解决了传统方法受一次控制参数影响较大的问题;通过优化DSC的通信结构和控制策略,避免了互联变流器参与二次控制通信,解决了互联变流器通信失效影响DSC的问题;推导了MFAC-DSC系统收敛性,给出了稳定收敛条件。基于交直流微电网实验平台在多种工况下验证了MFAC-DSC的可行性,与传统的DSC策略的对比结果表明:MFAC-DSC方法有效减少分布式电源下垂系数变化带来的功率波动,保证下垂系数有更大的调节范围,同时解决了互联变流器通信失效造成的控制失效和母线电压偏移等问题。

一种大功率宽输入范围AC/DC开关电源设计

随着全球对能源问题的越来越重视,电子产品的耗能问题将愈来愈突出,如何降低功耗,提高供电效率成为一个亟待解决的问题。传统的线性稳压电源效率低、体积大、耗能大。开关电源具有效率高、体积小、重量轻等优点。正因为如此,开关电源被誉为高效、节能型电源,代表着稳压电源的发展方向,并已广泛应用于各种电力电子设备中。

Investigation on some key problems of large power AC-DC-AC converter

China is an important country in iron and steel industry.Power electronics converters are widely used.For the cold rolling mills of high speed,AC-DC-AC converters should be used.In the paper,the design and the control system of the large power three-level AC - DC - AC converter with IGCTs is investigated,and a back-to-back large power three-level AC - DC - AC converter with IGCTs has been got. With a series experiments,the performance of the converter is examined.The experiment result indicates the converter reaches the design requirement and it shows excellent performance.The converter system has been put into use safely.It is estimated that the AC - DC - AC converter system will be used in the drive systems for rolling mills in the near future.

Solving Optimal Power Flow Using Modified Bacterial Foraging Algorithm Considering FACTS Devices

In this paper, a new Modified Bacterial Foraging Algorithm (MBFA) method is developed to incorporate FACTS devices in optimal power flow (OPF) problem. This method can provide an enhanced economic solution with the use of controllable FACTS devices. Two types of FACTS devices, thyristor controlled series compensators (TCSC) and Static VAR Compensator (SVC) are considered in this method. The basic bacterial foraging algorithm (BFA) is an evolutionary optimization technique inspired by the foraging behavior of the E. coli bacteria. The strategy of the OPF problem is decomposed in two sub-problems, the first sub-problem related to active power planning to minimize the fuel cost function, and the second sub-problem designed to make corrections to the voltage deviation and reactive power violation based in an efficient reactive power planning of multi Static VAR Compensator (SVC). The specified power flow control constraints due to the use of FACTS devices are included in the OPF problem. The proposed method decomposes the solution of such modified OPF problem into two sub problems’ iteration. The first sub problem is a power flow control problem and the second sub problem is a modified Bacterial foraging algorithm (MBFA) OPF problem. The two sub problems are solved iteratively until convergence. Case studies are presented to show the effectiveness of the proposed method.