Modeling and Dynamic Analysis of Fractional-Order Buck Converter in Continuous Conduction Mode

According to the fact that the actual inductor and actual capacitor are fractional, the mathematical and state-space averaging models of fractional order Buck converters in continuous conduction mode(CCM) are constructed by using fractional calculus theory. Firstly, the parameter conditions that ensure that the converter working in CCM is given and transfer functions are derived. Also, the inductor current and the output voltage are analyzed. Then the difference between the mathematical model and the circuit model are analyzed, and the effect of fractional order is studied by comparing the integer order with fractional order model. Finally, the dynamic behavior of the current-controlled Buck converter is investigated. Simulation experiments are achieved via the use of Matlab/Simulink. The experimental results verify the correctness of theoretical analysis, the order should be taken as a significant parameter. When the order is taken as a bifurcation parameter, the dynamic behavior of the converter will be affected and bifurcation points will be changed as order varies.

Production of 48MnV-C non-heat treatment crankshaft steel by means of converter plus continuous casting and hot-rolling process

48MnV-C non-heat treatment crankshaft steel is specially used for making crankshafts of Cummings C engines.It mainly adopts the technology of V—N micro-alloying,at present,it has been successfully used in making crankshaft of heavy duty truck engines.BX STEEL made trial production by means of converter→secondary metallurgy(RH + LF)→rectangular slab caster→hot rolling process,and studied the T[O],T[N],[H]and non-metal inclusion in 48MnV - C steel under continuous casting process condition,the actual grain size and the slab quality.All the chemical compositions and test results met the needs of Cummings Crankshaft Steel Standard.In order to ensure the mechanical properties of the non-heat treatment steel,a certain amount of nitrogen is added to it,also a small amount of sulfur is added to improve the cutting property of the steel.This process route can make full use of the de-hydrogen function of RH,and during RH treatment,rough adjustment of alloy elements may be made while the adjustment of Nitride Manganese nitrogen pick up and adjusting Mn,as well as Ca treatment and S content adjustment may be done during LF treatment so as to ensure the requirement of high nitrogen,low hydrogen,low oxygen content in 48MnV-C steel.Magnetic marks are defects shown in magnetic powder testing after the steel was used to make finished crankshafts.The 48MnV - C non-heat treatment crankshaft steel produced by means of the above-mentioned process route has not only relatively high robust performance which meets the needs of truck crankshaft safety,but also high qualification rate and basically no "magnetic marks" are found after being made into finished crankshafts,which meets the crankshaft standard.Therefore,this steel has been widely used in domestic crankshaft industry.

Relative navigation for satellite formation flight using a continuous-discrete converted measurement Kalman filter

The present paper develops an approach of relative orbit determination for satellite formation flight.Inter-satellite measurements by the onboard devices of the satellite were chosen to perform this relative navigation,and the equations of relative motion expressed in the Earth Centered Inertial frame were used to eliminate the assumption of the circular reference orbit.The relative orbit estimation was achieved through a continuous-discrete converted measurement Kalman filter design,in which the measurements were transformed to the inertial frame to avoid the linearization error of the observation equation.In addition,the situation of the coarse measurement period(only microwave radar measurements are available)existing was analyzed.The numerical simulation results verify the validity of the navigation approach,and it has been proved that this approach can be applied to the formation with an elliptical reference orbit.

A Novel Approach to Practical Matrix Converter Motor Drive System With Reverse Blocking IGBT (To continue)

a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)

基于R-L分数阶定义的PCCM Boost变换器建模与分析

研究了基于R-L分数阶定义的电感电流伪连续PCCM(pseudo-continuous conduction mode)Boost变换器模型,并由此导出了变换器的状态平均模型,然后推导出升压比,直流静态工作点,电感电流波纹以及输出电压波纹的表达式。结果表明,与基于Caputo分数阶定义下的变换器模型相应表达式比较,R-L分数阶定义下的直流静态工作点和升压比不仅与占空比相关,而且还与电感和电容的阶数有关,输出电压波纹的表达式不仅与分数阶电感的阶数α有关,与分数阶电容的阶数β也相关。电感和电容的阶数对状态变量的直流分量和分数阶PCCM Boost的稳态特性有很大影响。最后,在MATLAB/SIMULINK中搭建了R-L分数阶PCCM Boost变换器数学模型和电路模型,仿真结果显示R-L分数阶PCCM Boost变换器模型的分析结果比其他PCCM Boost模型的分析结果更加稳定,误差更小。

Application of Automation and Intellectualization Technology in Steelmaking Plant

Steelmaking plant of Fujian San Gang min Guang Co.,Ltd.is keeping pace with the trend of the times.Under the new situation that the labor cost is rising day by day.Constantly introducing intelligent technology to improve the level of automation operation and reducing labor intensity of staff and workers.Especially under the support of MES information system.Advanced and practical technology is adopted in converter,refining and continuous casting process.In recent years,production management and control,energy management and control,material tracking,cost control and equipment operation and maintenance and reducing personnel to new achieve-ments in reducing personnel.

一种用于可再生能源的新型升降压变换器

针对可再生能源发电装置输出电压波动大、输出电能难以存储的情况,此处提出了一种输入、输出连续的新型升降压变换器,采用开关电感结构,实现了低电感电流纹波、宽电压转换比和低开关管电压应力。此处在连续导通模式(CCM)下对变换器进行了详细的工作原理分析和稳态特性推导。为验证所提变换器的可行性,搭建了一台输入12~80V,输出48V,功率100W的实验样机,在升压模式和降压模式下测得最大效率分别为92.62%,95.78%。

一种高速SRG功率变换器及其CCM风电控制

提出一种无主开关管的新型开关磁阻发电机(SRG)功率变换器拓扑,在高速运行和连续导通模式(CCM)下分析其励磁和发电两阶段工作过程,并与通过开关角控制的经典不对称半桥功率变换器进行对比,发现两者的励磁和发电工作过程基本相同。进一步通过仿真和实验,获得新型功率变换器在高速CCM时的相电压、相电流等结果与理论分析相吻合,并获得转速、励磁电压、发电电压、功率四者的约束关系,从而优化输出功率时可采用调节励磁电压和发电电压的方式,相比于不对称半桥功率变换器,两者的发电输出能力相当。最后,以变速风电应用为例,给出控制策略,无需转子位置检测和风速检测,基速以上无桨距角调节,证实了所提新型功率变换器及其控制策略在高速CCM运行时的有效性。

一种非隔离型软开关高增益准Z源DC-DC变换器

文中提出一种非隔离型软开关高增益准Z源DC-DC变换器。变换器具有输入电流连续、输入与输出供地、高电压增益以及开关器件应力小等优点。同时,变换器中所有开关管都工作在零电压开关(zero voltage switching,ZVS)条件下,所有二极管都工作在零电压零电流开关(zero-voltage zero-current switching,ZVZCS)条件下,可以减小开关管的开关损耗以及二极管的反向恢复损耗。通过引入三耦合绕组提高变换器电压增益,同时,有源钳位电路的加入减小了开关管两端的电压尖峰。较小感值的耦合电感相应的铜损小、体积小,进而提高了变换器的效率和功率密度。深入分析变换器的工作模态,推导变换器的电压增益以及元器件的电压、电流应力,进行稳态分析和参数设计。最后,搭建一台100 kHz、200 W、38~380 V的实验样机,变换器在额定功率的效率为96.13%,实验结果与理论分析相吻合,证明所提变换器的可行性。

钛微合金钢中氮含量控制技术研究与实践

介绍了莱钢银山型钢炼钢厂生产钛微合金钢Q355B不同生产环节氮含量变化情况,分析了生产流程各因素对钢中氮含量的影响,其中转炉终点碳氧含量、出钢温度,LF进站钢液温度、电极电耗、底吹氩气、埋弧效果,连铸保护浇注等对钢水增氮有较大影响。提出了相应的优化措施,通过转炉终点碳含量、出钢温度、精炼渣成分控制等措施,达到了稳定控制氮含量在40×10^(-6)以下的效果。

Embedded Control of LCL Resonant Converter Analysis, Design, Simulation and Experimental Results

The Objective of this paper is to give more insight into CCM Operation of the LCL Converter to obtain op-timum design using state-space analysis and to verify the results using PSPICE Simulation for wide variation in loading conditions. LCL Resonant Full Bridge Converter (RFB) is a new, high performance DC-DC con-verter. High frequency dc-dc resonant converters are widely used in many space and radar power supplies owing to their small size and lightweight. The limitations of two element resonant topologies can be over-come by adding a third reactive element termed as modified series resonant converter (SRC). A three ele-ment resonant converter capable of driving voltage type load with load independent operation is presented. We have used embedded based triggering circuit and the embedded ‘C’ Program is checked in Keil Software and also triggering circuit is simulated in PSPICE Software. To compare the simulated results with hardware results and designed resonant converter is 200W and the switching frequency is 50 KHz.

Investigation of the Mechanism of Tangent Bifurcation in Current Mode Controlled Boost Converter

Tangent bifurcation is a special bifurcation in nonlinear dynamic systems. The investigation of the mechanism of the tangent bifurcation in current mode controlled boost converters operating in continuous conduction mode (CCM) is performed. The one-dimensional discrete iterative map of the boost converter is derived. Based on the tangent bifurcation theorem, the conditions of producing the tangent bifurcation in CCM boost converters are deduced mathematically. The mechanism of the tangent bifurcation in CCM boost is exposed from the viewpoint of nonlinear dynamic systems. The tangent bifurcation in the boost converter is verified by numerical simulations such as discrete iterative maps, bifurcation map and Lyapunov exponent. The simulation results are in agreement with the theoretical analysis, thus validating the correctness of the theory.

Design and Experimentation of FPGA-Based Soft-Switched Interleaved Boost Converter for Telecommunication System

This paper proposes the design and experimentation of digital control of soft-switched interleaved boost converter using FPGA for Telecommunication System. The switching devices in the proposed converter are turned on and off with Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) respectively. The circuit is operated in Continuous Conduction Mode (CCM) with various load ranges having duty cycle of more than 50%. The proposed converter is studied by developing the simulation module in MATLAB/SIMULINK. A PI controller is designed and implemented in FPGA to obtain a regulated DC output for line and load variations. Simulation and experimentation results are verified with a prototype development of the proposed converter. The results indicate that the converter performance is enhanced with closed loop control.

单端初级电感变换器的分数阶建模与仿真分析

出于电感和电容本质上是分数阶的实际情况考虑,针对单端初级电感变换器(Single ended primary inductor converter,SEPIC)的分数阶建模问题进行研究,建立了更准确的分数阶模型。在分数阶微积分的理论基础上,使用状态空间平均法,建立了电流连续模式下SEPIC的分数阶数学模型,推导了分数阶模型的静态工作点、电感电流纹波、电容电压纹波和传递函数表达式。采用分抗电路拟合的方法,实现0.9阶电感和0.9阶电容,用它们替换变换器中的整数阶元件,得到了SEPIC的分数阶电路模型。在MATLAB/Simulink仿真软件中,对SEPIC的分数阶数学模型和电路模型进行了仿真,并与理论计算值进行比较,仿真结果与理论计算基本一致,充分验证了分数阶模型的正确性。对比了分数阶模型与整数阶模型的差异,分数阶模型会产生更大的纹波,但具有更好的动态性能:响应速度更快,超调量更小,到达稳态的时间更短。

基于连续潮流模型的直流配电网负荷裕度分析

直流配电网由于能灵活接纳分布式电源和直流负荷,是未来智能配电网的发展趋势。随着直流配电网中负荷需求的不断增加,系统会由于静态电压失稳而崩溃。因此,研究直流配电网的负荷裕度对保障系统安全可靠运行至关重要。文中建立直流配电网的潮流模型,并将含双有源桥DC-DC变换器的潮流模型嵌入到直流配电网潮流模型中,提出了基于连续潮流法的直流配电网负荷裕度计算方法。通过两类典型的拓扑结构的直流配电网仿真,结果表明直流配电网在减小网络损耗和提高供电能力方面明显优于交流配电网,而且DC-DC变换器变比增加有助于负荷裕度提升。

基于拓展型双曲正切函数的全桥LLC变换器大信号建模方法

连续模型的准确性对于电力电子变换器的特性分析与实时仿真十分重要。由于独特的谐振腔结构,LLC变换器在不同工作频率区间分别以连续电流模式和断续电流模式运行,故而传统方法很难以连续模型实现其多种运行模式的统一描述。为此,该文提出一种基于拓展型双曲正切函数的全桥LLC变换器大信号建模方法。首先,分析各工作频率区间全桥LLC变换器特性,建立一种大信号非连续模型,该模型能够实现LLC变换器多种运行模式的统一描述。然后,构建含陡度因子/脉冲系数的拓展型双曲正切函数,利用其将上述大信号模型连续化,从而建立了全桥LLC变换器的大信号连续模型。基于此模型,连续系统的方法可以被直接应用以实现对变换器特性分析、实时仿真和控制器设计。同时,相比于现有LLC变换器大信号连续模型,该模型具有较低的阶数和更高的精确度。此外,该模型在时域中能够提供次级侧功率器件高准确性的开关信息,便于作为同步整流设计的参考。最后,仿真和实验结果验证了该模型的准确性和有效性。

输入电流低纹波的超高增益非隔离DC-DC变换器

高电压增益DC-DC变换器广泛应用于清洁能源发电系统。输入电流低纹波有利于延长可再生能源模块和变换器的使用寿命。提出一种集成三绕组耦合电感和倍压电路的超高增益DC-DC变换器。变换器拥有输入电流连续、电压增益高、开关管电压应力小、无源钳位及输入输出共地等优点,特别适合作为并网电路前级DC-DC变换器,应用于清洁能源发电系统。独特的三绕组耦合电感和倍压电路构成的升压结构,使变换器在较小的耦合电感总匝比和合适的占空比下实现了很高的电压增益。和相同电压增益的基于两绕组耦合电感的变换器相比较,增加的降压绕组(n_(2)<1)不但没有增加耦合电感的感量和磁芯体积,反而减少了耦合电感的总电感和磁芯大小。因此在实现相同的升压比时,所提变换器比现有相近结构的变换器耦合电感总感量小,磁芯体积小,相应的耦合电感损耗小,功率密度高。开关管和钳位二极管的低电压应力为选择低导通损耗的开关器件和超快恢复二极管提供了便利,减小了开关管导通损耗和二极管反向恢复损耗。论文详细分析变换器的工作模态、稳态性能、各元器件的电压和电流应力,提出变换器的元器件设计指导准则,最后用实验室样机进行验证,实验结果和理论分析非常契合。

连续三态模式开关前置型准Z源高增益Boost变换器的特性

为了全面了解开关前置型准Z源Boost变换器的性能,对其在连续三态模式(continuous triple-state mode, CTSM)下的工作原理和稳态特性进行了深入分析。相比于传统的电流连续导通模式(continuous conduction mode, CCM)和连续双向导通模式(continuous bidirectional conduction mode, CBCM),CTSM下该变换器保留了功率管电压应力相等且约为输出电压一半的优点,但是具有更高的电压增益;此外,电感L2的体积大幅度减小,开关管实现了零电流开通,且所有二极管能自然关断。通过一台280 W/100 kHz实验样机验证了理论分析的正确性。实验表明,输出电压400 V条件下,在全负载范围内CTSM都具有显著的效率优势,其最大效率为97.1%。

分布式储能型MMC电池荷电状态均衡优化控制策略

为提高电池的能量利用率和解决电池因制造工艺、循环充放电次数不同以及老化程度不一致等因素导致的荷电状态(SOC)极度不均衡问题,提出一种兼顾电流波动抑制的分布式储能型模块化多电平换流器的电池SOC均衡优化控制策略。为准确控制充放电功率,采用双环控制:外环针对相间、桥臂间和子模块间电池SOC差异,建立离散时域预测功率模型,通过负反馈控制生成动态电流参考值;内环设计了模型预测优化控制策略,准确追踪动态电流参考值,实现电池SOC均衡、提高电池能量利用率,并提高系统的动态响应能力以及抑制电池电流纹波,延长电池使用寿命。最后通过在PSCAD/EMTDC中构建仿真模型对所提出的控制器性能进行验证。