Design and performance of an EMI filter to reduce conducted EMI in an isolated full bridge buck converter power supply

EMI Filter Design and Performance for isolated full bridge buck converter is developed in this paper. In order to design a high performance EMI filter, many issues need to be considered beforehand. Some important issues including accurate model of converter components, parasitic elements, its effect on EMI noise and impedance mismatch are included in this paper. A numerical prediction of EMI/EMC has the potential to evaluate EMI performances at the design stage and before prototyping. It can also help reduce the post-prototype EMC cost by minimizing late redesign and modifications of a design implementation. Saber simulator is used to analyze the EMI noises and EMI filter’s performance. Conducted EMI noise measurement and EMI filter design of isolated full bridge buck converter has been achieved while successfully satisfying the FCC class B limits in the frequency range from 150 kHz to 30 MHz. Simulation results are compared with experimental data and the effectiveness of the EMI simulation approach is demonstrated.

A Design of High-precision High-Voltage Fiber-Optic Analog Signal Isolation Converter

This paper introduces a design of high-precision high-voltage fiber-optic analog sig-nal isolation converter based on the technology of Voltage-to-Frequency (V/F) and Frequency-to-Voltage (F/V) conversion. It describes the principle, system configuration and hardware design.

A Novel Topology of Single-Phase AC-DC Integrated Boost-SEPIC (IBS) Converter Using Common Part Sharing Method (CPSM) for High Step-Up Applications

A novel topology of Integrated Boost-SEPIC (IBS) AC-DC converter using common part sharing method (CPSM) has been proposed in this paper. Conventional boost converters with bridge rectifier configuration are inefficient due to limited voltage step-up ratio which may not be applicable for high step-up applications as in the case of micro generators. The proposed IBS topology is based on the common part sharing method capable of operating both for positive and negative half cycle of the input signal. Result and simulation were conducted using PSIM environment. The proposed AC-DC IBS topology eliminates the requirement of bridge rectifier achieving high efficiency (about 99%), improved power factor (0.75, leading) and lower THD (about 38.8%) which is within IEEE standard.

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。

Short-circuit fault analysis and isolation strategy for matrix converters

The behavior of matrix converter(MC) drive systems under the condition of MC short-circuit faults is comprehensively investigated. Two isolation strategies using semiconductors and high speed fuses(HSFs) for MC short-circuit faults are examined and their performances are compared. The behavior of MC drive systems during the fuse action time under different operating conditions is explored. The feasibility of fault-tolerant operation during the fuse action time is also studied. The basic selection laws for the HSFs and the requirements for the passive components of the MC drive system from the point view of short-circuit faults are also discussed. Simulation results are used to demonstrate the feasibility of the proposed isolation strategies.

Power Factor Improvement of AC-DC Converter Based on Separately Excited DC Motor Using Passive Filter

In industries DC motor drives are very essential due to their high performance applications such as its reliability, ease of control, low cost and simplicity. And speed control of these motors is very easy due to power electronic AC-DC converters. These power electronic converters are with prominent low power factor and higher Total Harmonic Distortion (THD). These converters operate only for short time resulting non-sinusoidal waveform. This problem of harmonic distortion can be mitigated by reshaping the non-sinusoidal waveform to pure sine wave. Different wave shaping techniques have been developed by using different filters among which one is tuned passive filter. This paper proposed power factor improvement and harmonic mitigation of AC-DC converters based on separately excited DC motor using tuned passive filter. In this context experimental model is designed and results are analyzed by power quality analyzer.

基于扩展移相的隔离型AC-DC变换器零矢量PWM调制策略

传统隔离型双向AC-DC变换器多为两级式结构,变换器效率低、控制系统复杂,现有的单级式解决方案通常依赖大量实时计算,难以兼具低电流应力、宽软开关范围和高功率传输能力特性。为此,该文设计基于双有源全桥的新型单级隔离型双向AC-DC谐振变换器,提出一种含有零矢量的复合频率调制策略。从高频开关周期入手,利用数学推导,证明所提方案在实现自动功率因数校正功能的同时,可降低开关器件的开关频率,免除附加吸收电路,实现交直流全桥的软开关,且几乎无功率回流,从而有效提升变换器的功率传输能力,所提单变量调节方法简化控制系统设计。最后,搭建额定功率为450W的仿真和实验平台,证明理论分析的正确性和调制策略的可行性。

Convexification of Hybrid AC-DC Optimal Power Flow with Line-Commutated Converters

Line-commutated converter (LCC)-based high-voltage DC (HVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OPF can be efficiently obtained from relaxed model.

Analysis of Non-Sinusoidal Steady Electric Field of ±500 kV Converter Transformer

The line side winding is under the fundamental frequency AC voltage, while the valve side winding contains not only fundamental AC voltage component, but also the DC voltage component, fundamental AC voltage component, and higher harmonic voltage components when the converter transformer is at its normal operating condition, and the electric field of converter transformer is a non-sinusoidal steady one. To analyze the non-sinusoidal steady electric field containing the DC component, fundamental AC and higher harmonic components, the voltage spectrum of the valve winding in a ±500 kV converter transformer is firstly analyzed, and the non-sinusoidal periodic steady electric field is obtained by the fast discrete Fourier transform. Different resistivity of the oil and oil-immersed paper is adopted to simulate the aging of oil paper insulation at operation, and get the non-sinusoidal steady electric field.

三相隔离型AC-DC-DC电源自适应线性自抗扰控制方法及纹波抑制补偿策略

三相隔离型AC-DC-DC电源因其具有功率密度大、电气隔离等优点,在工业上应用广泛。但在一些负荷频繁投切的特殊应用场景下,如电泳、电镀等,基于传统PI控制的电源存在输出电压响应速度慢及纹波大的问题。为了提升电源的输出电压响应速度,该文在分析线性自抗扰控制中关键带宽参数与输出量之间关系的基础上,提出一种控制器带宽参数自适应调节的线性自抗扰控制(A-LADRC)方法以实现输出电压在负荷突变下的快速调节。而针对系统前级不控整流环节中电压六脉动分量对后级系统带来的输出电压纹波增大问题,设计一种根据系统输出电压反馈值,自适应调整变换器占空比补偿量的控制策略,以实现减小电压纹波的目的。最后通过一台400 V/50 A的实验样机对所提方法进行了验证,结果表明所提方法能够有效提升系统输出电压响应速度并减小电压纹波,具有较好的实际工程应用价值.

High-temperature characteristics of SiC module and 100 kW SiC AC–DC converter at a junction temperature of 180 ℃

High-temperature,high-power converters have gained importance in industrial applications given their ability to operate in adverse environments,such as in petroleum exploration,multi-electric aircrafts,and electric vehicles.SiC metaloxide-semiconductor field-effect transistor(MOSFET),a new,wide bandgap,high-temperature device,is the key component of these converters.In this study,the static and dynamic characteristics of the SiC MOSFET,half-bridge module,are investigated at the junction temperature of 180℃.A simplified experimental method is then proposed pertaining to the power operation of the SiC module at 180℃.This method is based on the use of a thermal resistance test platform and is proven convenient for the study of heat dissipation characteristics.The high-temperature characteristics of the module are verified based on the conducted experiments.Accordingly,a 100 kW high-temperature converter is built,and the test results show that the SiC converter can operate at a junction temperature of 180℃in a stable manner in compliance with the requirements of high-temperature,high-power applications.

A Review of Isolated Bidirectional DC-DC Converters for Data Centers

In today’s fast-paced,information-driven world,data centers can offer high-speed,intricate capabilities on a larger scale owing to the ever-growing demand for networks and information systems.Because data centers process and transmit information,stability and reliability are important.Data center power supply architectures rely heavily on isolated bidirectional DC-DC converters to ensure safety and stability.For the smooth operation of a data center,the power supply must be reliable and uninterrupted.In this study,we summarize the basic principle,topology,switch conversion strategy,and control technology of the existing isolated bidirectional DC-DC converters.Subsequently,existing research results and problems with isolated bidirectional DC-DC converters are reviewed.Finally,future trends in the development of isolated bidirectional DC-DC converters for data centers are presented,which offer valuable insights for solving engineering obstacles and future research directions in the field.

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。

固态变压器中隔离双向DC/DC变换器扩展移相下虚拟电流控制策略

该文以固态变压器后级隔离双向DC/DC变换器为重点研究对象,提出一种扩展移相下虚拟电流控制策略。通过分析后级变换器在扩展移相传输功率下相移量关系以获得最小电流应力最优解来提高变换器的传输效率,减少器件损耗。同时通过虚拟电流控制思想在线估算传输功率来提高系统动态响应性能,减少电流传感器使用。最后,对该文所提出的扩展移相下虚拟电流控制与扩展移相控制进行实验对比分析,验证了扩展移相下虚拟电流控制策略具有降低电流应力,显著提高变换器的动态响应的优点。

基于SEPIC的新型高增益DC-DC变换器及衍生拓扑分析

针对光伏并网系统中单开关升压变换器(如SEPIC、Boost、准Z源、二次型)电压增益低和半导体器件电压应力大的问题,提出1种基于SEPIC的外部升压型高增益DC-DC变换器。首先对所提变换器在电感电流连续导通模式和断续导通模式下的工作原理和稳态特性进行详细分析,并与其他新型拓扑进行性能对比。在此基础上,给出了基于外部升压网络的衍生拓扑。最后,通过搭建1台400 V/200 W的实验样机证明了理论分析的准确性。所提变换器利用阻抗网络和开关电容单元构成的外部升压网络提升了SEPIC变换器的电压增益,并改善了半导体器件电压应力大的缺点。

矩阵式隔离型双向AC-DC变换器控制策略

针对矩阵式隔离型双向AC-DC变换器,提出一种控制策略,即前级矩阵变换电路和后级全桥电路的调制策略以及矩阵变换器双向开关的换流方法。其中,前级矩阵变换电路的调制基于双线电压调制思路,对扇区进行重新划分,调整和优化开关状态选择,以满足简化换流需求,后级全桥电路根据前级矩阵变换电路的调制策略,配合前级调节脉冲宽度进行协调控制,双向开关换流采用基于交流电压相对大小的两步换流方法。仿真和实验结果表明,在整流和逆变模式下,矩阵式隔离型双向AC-DC变换器均能保证网侧电流正弦,功率因数接近于1,输出电压电流可以保持恒定。由此证明,提出的控制策略,可实现变换器能量双向变换,且输入输出性能优良。

Composite Converter Combined APFC with Switched-capacitor Converter

To reduce switch numbers and voltage stress in semiconductor devices,this paper proposes a novel single-phase converter combined Active Power Factor Correction(APFC)with switched-capacitor converter.In addition,dynamic voltage regulation and voltage gain are improved by integrating the boost converter and switching capacitor cells.The interstage bulk capacitor is no longer needed.An average current control with redistribution of voltage in cells is proposed to obtain voltage lift ability of the switching capacitor cells and maintain a high-power factor.To study and verify the proposed converter preliminarily,theoretical analysis and simulation are presented in the paper.Furthermore,a 50o W prototype with two different configurations is built for experimental verification.The proposed converter can reach 95.62%of maximum efficiency,0.99 of power factor,and 3.55%of THD with 600 V output voltage,simultaneously.

输入不平衡下隔离型AC-DC矩阵变换器控制策略研究

为降低隔离型AC-DC矩阵变换器(Isolated AC-DC matrix converter,IAMC)在输入不平衡下网侧有功功率波动,以及抑制网侧LC滤波器的谐振,提出一种基于有源阻尼的无差拍直接功率控制策略。该策略利用网侧电流及其延迟分量来计算IAMC输入侧滤波器电容电压,省去了传统有源阻尼控制的高精度电压传感器,降低了硬件成本损耗,且无需进行旋转坐标变换以及锁相环,运算量较小。仿真结果表明:所提控制策略在输入电压不平衡工况下可有效抑制网侧电流谐波,降低系统无功功率直流分量,稳定系统输出的有功功率,且具有较好的动态性能。

适用于直流微网系统的新型双向三端口变换器及其控制策略

在传统分布式新能源并网接口中增加储能装置作为第三端口,可有效改善因分布式新能源强不确定性和随机性等特征引发的输出功率波动问题。为此提出并研究了一种适用于高升降压比直流微网系统的新型非隔离双向三端口变换器及其控制方法。通过集成双有源半桥变换器和非隔离双向Buck/Boost变换器,实现了三个端口中任意两个端口之间功率的双向传输。详细分析了所提新型变换器的工作原理、变换器输出特性以及控制策略,通过移相+脉宽调制控制方法,实现了宽范围的电压调节和各端口间功率的平滑切换。搭建了一台1 kW的试验样机,验证了所提出的新型三端口变换器及其控制方法的可行性和有效性。研究结果对于提高分布式新能源接入稳定性具有理论指导与工程实践借鉴意义。

一种高增益非隔离型耦合电感Boost变换器

这里提出一种高增益非隔离型耦合电感Boost变换器。该变换器利用耦合电感匝数比可调的特性,使占空比拥有更宽余度的同时实现较高的电压增益。此外,采用无源箝位结构,回收漏感能量,抑制开关管的电压尖峰,从而选取低导通电阻的开关器件,提高变换器的效率。在连续导通模式(CCM)下,详细分析了所提变换器的工作原理和稳态特性。为了验证所提变换器的可行性,搭建了一台输入电压20 V,输出电压200 V,功率100 W的实验样机,测得其最大效率和满载效率分别为95.4%和94.2%。