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.

Efficient Single-Stage Bridgeless AC to DC Converter Using Grey Wolf Optimization

Bridgeless single-stage converters are used for efficient(alternative current)AC-(direct current)DC conversion.These converters control generators,likeelectromagnetic meso-and micro-scale generators with low voltage.Power factorcorrection helps increase the factor of the power supply.The main advantage ofthe power factor is it shapes the input current for increasing the real power of theAC supply.In this paper,a two-switch bridgeless rectifier topology is designedwith a power factor correction capability.For the proposed converter topologyto have good power quality parameters,the closed loop scheme,which uses thegrey wolf optimization(GWO)algorithm,is implemented.The successes ofGWO encourage this research to implement GWO in the topology.The performanceof the proposed topology is analyzed under different load conditions.Simulation is carried out using the MATLAB/Simulink environment,and theresults are compared with those of conventional(proportional integral derivative)PID and(particle swarm optimization)PSO controllers.To validate the simulation results,a 350-W hardware prototype is implemented,and the voltage ripple,efficiency,and power factor under different load conditions are analyzed and tabulated.The comparative study clearly indicates that the proposed convertertopology with a closed loop control scheme using the GWO algorithm improves the power factor to 0.9732 and reduces the voltage ripple to 0.12%with a conversion efficiency of 98.25%.

New DCM Operated Single Phase Bridgeless Cuk Derived Converters for Power Factor Correction

This paper presents a power factor corrected (PFC) new bridgeless (BL) Cuk Topologies for low power applications. A BL configuration of Cuk converter is proposed which eliminates the usage of diode bridge rectifier at the front end of the PFC converter, thus reducing the switching and conduction losses coupled with it. This new BL Cuk converter has two semiconductors switches. The current flow during each switching cycle interval of the converter reduces the conduction losses compared to the conventional Cuk PFC converter. It also reduces the input current ripple and Electromagnetic Interference (EMI). The inrush current during the starting period is limited and the input, output currents of the converter are continuous with minimum current ripple. Hence it is preferred mostly compared to other PFC circuits. The proposed topology works in the Discontinuous Conduction Mode (DCM) with simple control circuitry to achieve almost a unity power factor with less distortion in the input AC current. The switching of the power switches is done under zero current. The proposed PFC topologies are theoretically investigated and performance comparisons are made with the conventional rectifiers. The proposed PFC converter is simulated in MATLAB/SIMULINK with Fuzzy Logic Controller (FLC) and results are demonstrated to evaluate the effectiveness of the controller.

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.

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.

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.

一类三电平伪图腾柱无桥PFC变换器

针对传统二极管钳位型三电平整流器在单相电源前级功率校正(power factor correction,PFC)电路应用场景下全控开关器件数量多的问题,该文基于3种传统无桥PFC电路进行三电平电路拓扑设计,提出一类三电平伪图腾柱PFC电路(single-phase three-level pseudo totem-pole PFC circuit,STPT-PFC),该类三电平PFC具有双电感支路桥臂,两者相互配合工作为输入电流提供路径,在正负半周两电感支路桥臂工作于不同模态可有效降低分别流过两电感的电流;基于该类PFC的一个代表性电路,从工作电流路径过程、关键波形和调制脉冲分配等方面对其进行工作原理分析,并对其它电路进行电路特性总结,推导桥臂对地电压电平特性与开关脉冲分配的数学关系式。另外,该类STPT-PFC共有5种结构,结合该类STPT-PFC结构特点,提出统一区间判断条件的双层载波调制技术,该类STPT-PFC具有相同开关器件不同拓扑结构可采用同一调制方案的特点,便于该类调制技术移植。最后,基于STPT-PFC-I电路设计1台额定功率1 kW、直流输出电压400 V的实验样机,从稳态及动态两方面进行实验分析,实验结果验证所提出一类三电平伪图腾柱PFC电路的可行性和三电平统一双层调制方法的有效性。

基于无源均流的谐振式无桥型Boost LED驱动电源

传统Boost功率因数校正变换器的输出电压必须大于输入电压,在一定程度上限制了其在LED驱动电源中的应用。同时,传统LED驱动电源因输入端整流桥的存在而限制了自身效率的进一步提升。基于谐振式Boost功率因数校正变换器拓扑提出了一种无源均流型无桥Boost LED驱动电源,通过引入谐振式电容均流网络,实现了多路均流输出;通过整流桥的去除,进一步提升了系统的效率。最后,搭建了一台效率可达93.64%的140 W实验样机,验证了理论分析的正确性与可行性。

变母线电压的LLC高压电容充电电源设计

提出了一种两级式可变母线电压的高压电容充电电源技术方案,该拓扑在半桥LLC谐振电路的基础上增加了一级图腾柱无桥功率因数校正(PFC)电路,通过改变母线电压来解决传统LLC谐振电源在输出更高电压时,工作频率变化范围过大带来的充电效率下滑的问题。由于图腾柱电路本身具备功率因数校正的功能,该电源设计还拥有能够直接从电网取电而不影响电网电能质量的优势。首先介绍了本电源设计中两部分的电路拓扑和工作原理,采用等效电阻法分析了电容负载下的电源输出特性。针对前级图腾柱电路设计了双环控制器以实现对母线电压和功率因数的控制,针对后级LLC电路提出了比例积分(PI)加低通滤波的恒流控制器以降低高频噪声带来的不利影响。最后通过模型构建与仿真分析,研究了高压电容充电电源3000 V/1 A时的充电特性,验证了本电源技术方案、设计和控制策略的可行性。

单相无桥功率因数校正变换器拓扑族推演回顾与性能分类总结

随着多种节能标准与低碳政策的实施,单相无桥功率因数校正(power factor correction,PFC)拓扑受到更多关注。目前,虽然多种无桥拓扑已被提出并被应用于不同应用场合,但尚未有文献系统地概述这类无桥PFC拓扑结构特点并开展拓扑性能分析。该文通过将双变换单元进行输入并联输出并联(input-parallel output-parallel,IPOP)、输入并联输出串联(input-parallel output-series,IPOS),提出无桥拓扑族系统推演方法以及无桥拓扑IPOP与IPOS的分类。同时,以6种变换单元为例,推演28种无桥拓扑并作相关拓扑概述,说明无桥拓扑族系统推演方法的普适性。其次,通过对称性与对偶性,进一步简化无桥拓扑族的器件数量。然后,筛选出12种主要无桥拓扑与传统有桥拓扑比较,并分别介绍12种无桥拓扑性能特点。最后,基于性能对比结果,归纳IPOS与IPOP两类拓扑的优缺点与适用场景。

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.

基于三端口无桥PFC的两级式隔离型双输出AC-DC变换器

提出基于三端口无桥功率因数校正器(powerfactor corrector,PFC)的隔离双输出AC-DC变换器及其控制方法。利用三端口无桥PFC同时提供电压稳定的直流母线和电压宽幅变化的直流母线,实现了中间直流母线电压与直流输出电压的自适应匹配,大大降低了后级直流变换器的电压增益变化范围,为后级LLC谐振变换器的高效设计与实现提供了有利条件。文中给出三端口无桥PFC与双输入LLC谐振变换器的新型组合结构,详细分析三端口无桥PFC的工作原理,提出相应的调制策略和控制方法。实验结果表明,所提出的解决方案能够实现更高的效率。

Three-phase AC-DC Converter for Direct-drive PMSG-based Wind Energy Conversion System

In this paper,a wind energy conversion system(WECS)is presented for the electrification of rural areas with wind energy availability.A three-phase AC-DC converter based on a bridgeless Cuk converter is used for power extraction from the permanent magnet synchronous generator(PMSG).The bridgeless topology enables the elimination of the front-end diode bridge rectifier(DBR).Moreover,the converter has fewer components,simple control,and high efficiency,making it suitable for a small-scale WECS.A squirrel cage induction motor(SCIM)is used to emulate a MOD-2 wind turbine to implement the PMSG-based WECS.A direct-drive eight-pole PMSG is used in this study;thus,a low-input-voltage system is designed.The converter is designed to operate in the discontinuous inductor current mode(DICM)for inherent power factor correction(PFC)and the maximum power point tracking(MPPT)is achieved through the tip-speed ratio(TSR)following.The performance of the developed system is analyzed through simulation,and a 500 W hardware prototype is developed and tested in different wind speed conditions.

单相有源AC-DC变换器的统一算法及其应用(英文)

This paper discusses a novel boost single-phase active AC-DC converters, named low-end semi-controlled bridge AC-DC converter. By analysis, its topology and principle can be derived from the conventional single-phase power factor corrector （ PFC）. But it has also some differences, such as power device positions, inductor type, input voltage waveform detection and induction current detection, so its design is also different. The converter is implemented by employing two current detection approaches, i.e., current transformer detection and shunt resistor detection. Consequently, it can provide a steady DC output voltage with a low voltage ripple, approximately unitary input power factor and 2.5 kW output power. The experimental results show validity of the theoretical analysis.

无桥DBPFC变换器的虚拟超局部优化控制策略

针对传统平均电流控制的无桥Dual-Boost功率因数校正(DBPFC)变换器存在功率因数低、总谐波失真大、动态响应速度慢以及输出电压纹波较高等不足,文章提出一种虚拟超局部优化控制策略。通过坐标变换的方法建立了变换器在虚拟dq模式下的工作模型,实现对电流的无静差跟踪,并在此基础上设计了一种超局部优化控制策略,改善了基于数学模型设计的电流控制器对参数变化及内、外部扰动敏感的缺陷,克服控制器对参数的依赖。仿真和实验结果表明,文章所提虚拟超局部优化控制的无桥DBPFC变换器的功率因数可达0.996,总谐波失真为4.93%,且具有良好的动态响应能力和较高的电能质量水平。

一种有源钳位隔离型无桥SEPIC PFC变换器

传统隔离型SEPIC功率因数校正(Power factor correction, PFC)变换器的开关管电压应力大,且因输入端整流桥的存在,自身效率难以进一步提升。使用无桥PFC和有源钳位技术对SEPICPFC变换器进行改进,提出了一种有源钳位隔离型无桥SEPIC PFC变换器,通过使用开关管和快恢复二极管替代整流桥,改善了变换器效率;通过运用有源钳位技术,实现了开关管的软开关,降低了开关管的电压应力,并进一步提高了变换器效率。最后,设计了一台输出功率为70W的应用于飞机座椅电源的试验样机,仅使用一级变换器就实现了高功率因数、高效率和输入输出的隔离,验证了理论分析的正确性。

Optimized Power Factor Correction for High Speed Switched Reluctance Motor

The Power Factor Correction(PFC)in Switched Reluctance(SR)motor is discussed in this article.The SR motors are applicable for multiple applications like electric vehicles,wind mills,machineries etc.The doubly salient structure of SR motor causes the occurrence of torque ripples,which affects the power factor of the motor.To improve the power quality,the power factor has to be corrected and the ripples have to be minimized.In order to achieve these objectives,a novel power factor correction(PFC)method is proposed in this work.Here,the conventional Diode Bridge Rectifier(DBR)is replaced by a Bridgeless Hybrid Resonant(HR)converter,which assists in improvising the output in a wider range.The converter is chosen because of having variety of beneficial measures including high gain.The converter’s output is fed to the SR motor by means of an asymmetric Bridge Resonant(BR)converter.The proposed converter operates in continuous mode of conduction with the switching frequency of 10 KHz.A hysteresis current controller and Proportional Integral(PI)controller are utilized for reducing the harmonics in the source current along with the regulation of output voltage.In addition,the speed control of SR motor is accomplished by means of the Whale Optimization Algorithm(WOA)assisted PI controller.The proposed methodology is effective for the control of unity power factor,torque and current ripples.The Total Harmonic Distortion(THD)of the source current is also minimized,which suits the standard of International Electrotechnical Comission IEC 61000-3-2.By this methodology,the power factor of 0.99 is achieved with 97%efficiency and 3.92%THD.The proposed methodology is validated in simulation by MATLAB and in hardware by FPGA Spartan 6E.

Adaptive Nonlinear Sliding Mode Control for DC Power Distribution in Commercial Buildings

The developing populace and industrialization power demand prompted the requirement for power generation from elective sources.The desire for this pursuit is solid due to the ever-present common assets of petroleum deri-vatives and their predominant ecological issues.It is generally acknowledged that sustainable power sources are one of the best answers for the energy emergency.Among these,Photovoltaic(PV)sources have many benefits to bestow a very promising future.If integrated into the existing power distribution infrastructure,the solar source will be more successful,requiring efficient Direct Current(DC)-Alternating Current(AC)conversion.This paper mainly aims to improve control-lers’performance between AC/DC Energy sources and the DC loads using the Adaptive Nonlinear Sliding Mode(ANSM)control method.The proposed ANSM method efficiently controls power quality issues,such as transient response,powerflow reliability and Total Harmonics Distortion(THD).The proposed con-troller is applied for both AC/DC and DC/DC converters and the performance of the proposed controller is validated through simulation checking the above para-meters.The simulation results confirm ANSM configuration is more reliable and efficient than the existing fuzzy and sliding mode control methods.

A Novel 5-level Flying Capacitor Bridgeless PFC Converter Based on Cost-effective Low-voltage eGaN FETs

In this study,a type of multilevel flying capacitor bridgeless PFC converter is proposed that permits the use of economical and efficient 100 V GaN transistors.Compared with the popular two-level totem-pole bridgeless PFC converters achieved using the much more expensive 650 V GaN devices,this new design has several distinct advantages:lower component costs,lower dv/dt,lower power losses,and reduced concerns about device reliability.A 1.6 kW,5-level PFC converter prototype is designed and fabricated with an efficiency of 99.18%and a power factor of 0.99,which are experimentally demonstrated.The operation principle,design considerations,control strategy and experimental results are discussed.