Stabilization of a class of discrete-time switched systems via observer-based output feedback

In this paper, observer-based static output feedback control problem for discrete-time uncertain switched systems is investigated under an arbitrary switching rule. The main method used in this note is combining switched Lyapunov function （SLF） method with Finsler＇s Lemma. Based on linear matrix inequality （LMI） a less conservative stability condition is established and this condition allows extra degree of freedom for stability analysis. Finally, a simulation example is given to illustrate the efficiency of the result.

Output Feedback Based Admissible Control of Switched Linear Singular Systems

The admissibility analysis and robust admissible control problem of the uncertain discrete-time switched linear singular (SLS) systems for arbitrary switching laws are investigated. Based on linear matrix inequalities, some sufficient conditions are given for: A) the existence of generalized common Lyapunov solution and the admissibility of the SLS systems for arbitrary switching laws, B) the existence of static output feedback control laws ensuring the admissibility of the closed-loop SLS systems for arbitrary switching laws and norm-bounded uncertainties.

Reducing the minimum output power of soft-switching inverter arc welding power supplies

The full-bridge zero-voltage and zero-current switching inverter, which can adjust the output power by keeping the duty-cycle of lagging arm constant, changing the duty-cycle of leading arm, is a common circuit topology of soft-switching inverter arc welding power supplies. However, the output power still remains a certain value when the duty-cycle of leading arm decreases to zero. The working-mode of soft-switching inverter and the waveforms of major parameters with the condition of duty-cycle of leading arm being zero are studied in this paper. U-1 characteristic experiments prove that the minimum output power of soft-switching circuit, which depends on the charged voltage of capacitors in parallel with leading arm, can be decreased by reducing the duty-cycle of lagging arm. By switching working-modes between half-bridge and full-bridge, the output power can swing from zero to the power rating.

Output Feedback Controller Design for Discrete-time Switched Singular Systems

This paper is concerned with the problems of robust admissibility and static output feedback( SOF)stabilization for a class of discrete-time switched singular systems with norm-bounded parametric uncertainties.The objective is to design a suitable robust SOF controller guaranteeing the regularity,causality and asymptotic stability of the resulting closed-loop system under arbitrary switching laws. Based on the basic matrix inequality sufficient condition for checking the admissibility of switched singular systems,together with some matrix inequality convexifying techniques,the SOF controller synthesis is developed for the underlying systems. It is shown that the controller gains can be obtained by solving a set of strict linear matrix inequalities( LMIs). A simulation example is given to show the effectiveness of the proposed method.

PERFORMANCE ANALYSIS OF ATM SWITCH FABRIC WITH COMBINED-INPUT/OUTPUT BUFFERING

This paper analyses the performance of the ATM switch fabric with Combined-Input/ Output Buffering(C-IOB) under two different service principles for the cells at the head of line (HOL) positions of input buffers: First Come First Service (FCFS)/Random Service(RS) for the set of HOL cells addressed to a given output port with different/same "age" (the waiting time at the HOL position) and Pure Random Service(PRS) for all HOL cells addressed to a given output port regardless of their "ages" while the Queue Loss (QL) transfer scheme is adopted for interaction between input and output buffers in the ATM switch fabric. The results obtained show that the C-IOB ATM switch fabric with PRS service policy and the QL transfer scheme is better than other buffering ATM switch fabrics.

定频PWM控制混合桥双LLC谐振变换器研究

针对宽输出电压应用中传统频率控制LLC谐振变换器工作频率范围宽且存在较大循环电流的问题,提出1种定频PWM控制混合桥双LLC谐振变换器。根据原边侧结构的不同,所提变换器有3种拓扑结构形式,分别为半桥-半桥双LLC谐振变换器、半桥-全桥双LLC谐振变换器、全桥-全桥双LLC谐振变换器。其中,原边侧结构并联输入,2个变压器二次侧串联输出。相较于传统频率控制LLC变换器,3种拓扑形态始终在谐振频率点工作,缩小了开关频率范围;在PWM控制策略下,可以分别实现2倍电压增益、3倍电压增益和4倍电压增益以适应宽电压场合;电路中循环电流损耗低,软开关性能良好。Simulink仿真和实验结果验证了所提方案的可行性。

基于能量模型的临界导通模式Boost变换器软开关方法

在变换器高频化发展的趋势中,功率器件的软开关实现对变换效率的影响更加突出。无辅助电路的临界导通工作模式下,Boost变换器主开关管在特定增益下无法实现软开关。为此,该文提出一种能量模型及相应的软开关实现方法。首先,建立死区前后储能元件能量变化的数学模型。然后,结合死区起止时刻的能量平衡方程,研究软开关无法实现的电路机理。在此基础上,考虑开关管输出电容非线性特征,提出软开关实现方法,避免了复杂谐振过程的时域精确建模,提高软开关实现的准确性。最后,搭建500W实验样机进行实验,结果表明,相较于对谐振过程建模的传统时域模型,所提方法将实际开通电压降低47%,使峰值变换效率提升0.4%,进而验证了其有效性。

定频移相控制六开关双谐振变换器研究

针对传统频率控制的LLC谐振变换器在宽电压应用中电压调节性能差且循环电流较大的问题,设计一种六开关双谐振LLC变换器。该变换器由2个全桥LLC谐振变换器共用1个桥臂混合组成。相较于传统的频率控制,该变换器采用定频移相控制调节输出电压,减小开关频率范围。根据2个变压器连接方式的不同,变换器有2种拓扑形态。当2个变压器顺极性串联时,变换器的增益范围为0~1,可以实现超宽输出电压;当2个变压器反极性串联时,变换器的增益范围为1~2,在工作过程中具有较小的环流损耗。2种拓扑形态下,原边开关管和副边二极管分别实现ZVS开通和ZCS关断。最后,通过Simulink仿真和实验验证了研究内容的有效性。

Controlling the output power of soft switching arc welding inverter by two-stage continuous PWM method

The full bridge zero voltage zero current switching （ FB-ZVZCS ） , which could adjust the output power by keeping the duty ratio of lagging leg constant and changing the duty ratio of leading leg, was a common circuit of soft switching arc welding inverter power source. However, when the duty ratio of leading leg was reduced to zero, the output power stayed the constant value instead of becoming zero. The working status and waveforms of some major parameters were studied in this paper while the duty ratio of leading leg was zero. It was concluded that the minimum output power of soft switching inverter was related to the charging voltage of paraUel capacitors, and the output power also could be reduced by reducing the duty ratio of lagging leg. A novel two-stage continuous PWM control method that could switch working-mode between full bridge and half bridge was put forward in this paper. This kind of control method could further reduce the output power of soft switching inverter in order to meet the requirement of low heat input of sheet metal welding.

一款28nm电路的同步开关输出噪声的仿真与设计

同步开关输出噪声是影响芯片信号完整性的主要噪声之一,较大的噪声有可能导致数字系统中元件的错误翻转。本文首先简要介绍了同步开关输出噪声的产生及特点,然后通过电路模型仿真,得到了与噪声相关的因素。最后结合实际电路,根据仿真的结果得到了控制同步开关输出噪声的方案。

一种具有连续输出电流的单开关改进二次型Buck-Boost变换器

针对太阳能光伏发电、燃料电池等需要高增益直流电源的特点,引出了具有连续输出电流的高增益改进二次型Buck-Boost变换器。介绍了该改进变换器的工作原理及稳态特性,另外在多个方面将改进变换器与其他变换器进行了比较,由比较参数显示了改进变换器的优良特性。最后利用PSIM仿真软件建立了改进变换器仿真模型,从降压和升压的角度对改进变换器进行了仿真实验分析,从实验分析的结果来看,改进变换器性能较好,验证了其理论分析的正确性。

具有混合控制策略的宽输出双全桥LLC谐振变换器

针对宽输出电压范围应用中传统频率控制的LLC型谐振变换器存在开关频率调节范围宽、循环电流大及难实现高效运行等问题,提出1种具有定频移相-定频PWM混合控制策略的双全桥LLC型谐振变换器,以适用于较宽输出电压范围。其由2个全桥LLC型谐振变换器共用1个桥臂组合而成,输出电压通过定频移相-定频PWM混合控制进行调节,使该谐振变换器实现4倍电压增益范围以获得较宽输出电压,同时解决传统频率控制中循环电流过大及在移相控制移相角小时的软开关不能实现问题,提升系统效率。该转换器开关频率工作在谐振频率点,电压增益与负载无关且有助于磁性元件设计,在全负载范围内实现软开关。最后给出详细的电路工作原理分析并通过仿真进行验证,搭建实验平台验证了所提变换器的可行性和有效性。

基于SWIPT的无小区大规模MIMO-NOMA系统能量效率研究

无小区大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)与非正交多址接入(Non-Orthogonal Multiple Access,NOMA)都是未来6G的使能技术。无线携能通信(Simultaneous Wireless Information and Power Transfer,SWIPT)技术在进行信息解码的同时收集能量,与无小区大规模MIMO-NOMA优势互补。文中基于SWIPT研究无小区大规模MIMO-NOMA系统中的能量效率问题,通过联合优化功率分配系数和SWIPT的时隙切换(Time Switching,TS)系数,提高系统的能量效率。为了最大化能量效率,采用布谷鸟算法设计功率分配系数。考虑一种特殊情况,将所有终端的TS系数设置相同,进而推导了最佳TS系数的封闭表达式。仿真结果表明,相较于几种已有方案,文中提出的优化方案可以显著提升系统的能量效率。

直流稳压电源的设计

随着人类的生活水平和科学技术的进步,电力系统在人们的生活中的作用日益突出。当今社会电子设备的应用越来越广泛,对其电源的使用要求越来越高。通过开关电源、线性电源和反激式电源的基本原理,分析了DC/DC变换器中的调制方法,从电源在便携式设备中的应用需求出发,在总结分析现有技术的基础上,通过系统设计、电路原理图设计和PCB布局设计,进行电路板的性能验证,结果表明所设计的直流电源适应于便携式设备,性能稳定,满足设计要求,为同类产品的设计提供参考。

限制调频范围的不对称多模式宽输出LLC变换器

频率控制的传统LLC谐振变换器往往受限于开关频率的有效调节范围,难以实现宽输出电压范围,为此,研究了一种限制调频范围的不对称多模式宽输出LLC谐振变换器。采用双谐振腔且对应两变压器变比不同的不对称结构,能够根据原边开关组合的不同,使得双谐振腔分别工作在单半桥、双半桥和半桥+全桥3种不同的模式,从而获得3种不同的电压增益,并且保证每种模式之间归一化增益调节范围不超过1.5,可以在窄开关频率范围内实现宽输出电压范围。建立300 W的实验样机,验证了所提变换器可实现1~3倍的宽输出电压范围,并且实现了原边开关管的零电压开通和副边二极管的零电流关断,具有良好的软开关性能,验证了变换器的可行性。

切换拓扑下异构多智能体系统自适应输出一致性

针对通信拓扑突变的不确定异构多智能体系统,将拓扑突变等效为切换拓扑问题,进而设计一种基于领导者-模型-跟随者匹配的分布式自适应协同控制方法,实现领导者-跟随者输出一致性.首先,提出局部输出跟踪误差概念,将领导者-跟随者输出一致性问题转化为相邻智能体局部输出一致性问题;然后,针对系统参数已知的情况,进行分布式标称协同控制器设计,实现参考模型-领导者匹配和跟随者-参考模型匹配,以保证通信拓扑突变下领导者-跟随者输出一致性;进而,针对系统参数未知的情况,进行分布式自适应协同控制器设计,实现通信拓扑突变下跟随者输出对领导者输出的渐近跟踪.所设计的控制方法不依靠全局信息即可保证所有智能体系统闭环稳定及跟随者对领导者的输出一致性.最后,通过一个仿真案例验证了所设计的控制方案的有效性.

一种CC/CV平滑切换的宽输出电压充电电路

目前多种动力蓄电池凭借着能量密度高、续航里程长和可循环使用等优势,在新能源汽车领域得到了广泛应用。针对当前以谐振电路为基础构建复合变换器应用于蓄电池充电存在输出电压范围、模式间切换、效率等不同问题,提出了一种四开关Buck-Boost与电容钳位LLC级联复用式变换器作为充电电路。该电路增益曲线的容性区和感性区均可工作,宽调频范围的容性区具有恒流特性,感性区的最佳谐振点具有恒压特性,利于实现蓄电池恒流恒压充电控制。频率与占空比的解耦控制拓宽了变换器的输出电压范围,且负载阻抗连续变化下电压增益连续,利于实现蓄电池恒流恒压平滑切换及满足不同电池充电控制方案,宽增益下的宽调控范围可减少输出纹波。拥有桥臂间移相软开关、复用桥臂增强软开关能力和降低通态电流、变压器低磁链及最终移动于最佳谐振点工作等电路特性,利于实现电能高效传输。仿真与实验结果验证了充电电路全程满足ZVS、ZCS的恒流恒压控制及充电模式间平滑切换特性。

双路输出的反激式变换器拓扑及特性研究

此处提出了一种双路输出的反激式变换器拓扑,该拓扑只需要一个输出绕组就可以实现双路输出,相比传统的通过多个绕组实现多路输出的方式,节省了绕组数量,节约了重量、体积和成本,同时还能实现初级开关管的零电压开关(ZVS),降低开关损耗。此处首先对所提变换器拓扑实现双路输出和初级开关管ZVS的过程进行模态分析和必要的数学推导,然后对关键参数进行设计,并且对变换器拓扑进行特性分析。最后在Matlab的Simulink中进行仿真验证,并设计制作了一台15 W的样机,验证了所提拓扑的可行性。

基于DPA-Switch的反激式开关电源设计

DPA-Switch是高集成度DC/DC转换芯片,集PWM控制器和MOSFET于一体,其电路简单,性能优异。文中利用DPA-Switch设计了一个单端反激式多路输出开关电源,简要介绍了变压器的绕制。实验结果表明该电源运行可靠,输出稳定。

继电保护测试仪自动检测系统设计

继电保护测试仪是对继电保护装置调试和检验的重要仪器。为了进一步提高继电保护测试仪的检测精度、稳定性和检测效率,设计了基于LabVIEW的继电保护测试仪自动检测系统。该系统采用LabVIEW模块化的编程思想,实现继电保护测试仪的自动检测、手动检测、保存报告等功能。为了解决继电保护测试仪的输出为三相,而万用表和示波器仅支持单相测试的问题,设计了输出转换装置。基于转换装置,可以在测试开始前一次性完成所有接线,并在测试过程中根据不同校准项目进行测试回路自动切换。功能测试结果表明,该系统能满足检验标准化、报告标准化和闭环自动测试要求。该系统对其他二次测量设备的自动检测校准有一定的借鉴意义。