电压补偿型超导限流器在三相电网中的故障限流特性

基于电压补偿型超导故障限流器(SFCL)的单相电路结构和工作原理,提出了一种关于电压补偿型超导故障限流器的三相电路结构,并对其在三相电力系统发生不同故障时的运行特性进行了分析。利用Matlab/simulink建立仿真模型,仿真结果表明该电压补偿型SFCL的三相拓扑结构具有一定的可行性,对系统中发生不同短路故障时的短路电流都具有良好的限制作用。     

基于负离子的中性束注入器加速极逆变型高压电源控制策略

ITER中性束注入器加速极需要一套逆变型直流高压电源系统。该电源采用三相三电平(TPTL)直流变换器作为基本单元,通过占空比控制实现对输出电压的快速调节。针对三相三电平直流变换器在小占空比模式下输出电压纹波大的缺点,提出了一种全新的控制策略。该策略通过协调直流母线电压的大小和逆变器占空比的变化对输出电压进行调节。为了验证新的控制策略的性能,搭建了200 kV/60 A的MATLAB/Simulink仿真模型和400 V/6 A的原理样机。仿真结果和样机实验结果表明,新的控制策略可以实现逆变型高压电源在输出电压快速可调的情况下降低输出电压纹波。     

开关变换器斜坡补偿动力学机理研究

在反馈控制电路中引入适当的斜坡补偿电流,既可以有效拓宽电流控制开关DC-DC变换器稳定工作范围,实现混沌镇定控制,又可以使其工作模式从断续导电模式转移至连续导电模式,实现工作模式转移.以电流控制Buck-Boost变换器为例,通过建立含斜坡补偿的具有两个电感电流边界的二维离散时间模型和相应的Jacobi矩阵,深入研究了开关DC-DC变换器斜坡补偿的动力学机理.通过分析稳定性失稳和边界碰撞分岔的条件,讨论了斜坡补偿对开关DC-DC变换器稳定周期振荡和工作模式转移的影响,分别给出了相应的稳定性分界线和模式转移分界线.制作了实验电路,由实验结果说明了斜坡补偿对开关DC-DC变换器混沌镇定控制和工作模式转移的物理意义,并验证了理论分析的正确性.     

Precise design of integrated diffractive optical mode converter for fiber-to-waveguide coupling

Integrated diffractive optical mode converter, consisting of a diffractive optical element (DOE) and a slab waveguide, is used for fiber-to-waveguide coupling. The phase of the DOE is generally designed by optimization algorithm. In this paper, the precise design, a new method with one more restrictive way,is adopted to design the diffractive optical mode converter for fiber-to-waveguide coupling. Through this method, the intensity of any point on the output plane is fully filled with the required demand. Compared with what previously published, the coupling loss of the precise designed converter is lower.     

New electromagnetic ring balancer for active imbalance compensation of rotating machinery

New electromagnetic ring balancer for active mass imbalance compensation of rotating machinery is proposed in this paper. This type of active balancer maintains the balanced condition of machine by permanent magnets rather than clutch and external energy. Firstly, the imbalance compensation principle is presented, and then the balancer design is completed. For the proposed balancer, the actuation principle and operational process are presented in detail. Based on the finite element stable-state and transient calculations, the reasonable design parameters are obtained to direct the development of balancer prototype machine. The relative experimental tests are completed to validate the balancer design and fabrication. The proposed balancer has a simple structure, a wide range of balance capability, a stable and smooth operational process and a desirable vibration response. This study shows that the machine tool spindle integrated with active balancer indeed has an expected mass imbalance compensation function, and the mass–radius product of 6.03–38.55 g cm can eliminate the vibration of 0.0021–0.1076 gravitational acceleration.     

Digital measuring scheme for half-wave voltage of Y-tap multiple integrated optical circuit

A high-precision digital measuring scheme for half-wave voltage of Y-tap multiple integrated optical circuits is proposed. This scheme is based on Sagnac interferometer modulated with digital step waveform whose frequency is half of eigen frequency of the interferometer. The technology and measuring precision are discussed. An experimental setup is made and the temperature-dependences of half-wave voltage of two samples are studied. Analysis and experimental study prove that this scheme is convenient and accurate.     

Control of a unique active vibration isolator with a phase compensation technique and automatic on/off switching

This work examines the characteristics of a unique active vibration isolator and develops a control strategy for it. The proposed active vibration isolator is introduced and its dynamic model is presented. A characterization study is conducted to identify system parameters. It is shown that with a simple proportional feedback the closed-loop system has a very narrow stability margin due to the inherent dynamics of the actuator. To improve the stability of the closed-loop system and enhance the performance of vibration isolation, a phase compensator is incorporated in the control scheme. An optimization problem is formulated to determine the optimum controller parameters by minimizing the 2nd norm of the displacement transmissibility. Both absolute position feedback and relative position feedback are considered. In real time implementation, an automatic on/off switching strategy is devised to take full advantage of both the active isolator and passive isolator. The experimental results show that with the proposed control scheme, the isolator is capable of suppressing base excitations effectively.     

锂电池混合动力轮胎吊AFE变换器控制策略研究

针对传统采用不可控AC/DC变换器的混合动力轮胎式起重机系统,直流母线电压泵升导致的柴油发电机空转,造成能量浪费的问题。采用可控的有源前端变换器取代不可控的二极管整流,建立了AFE功率外环电流内环以及电压外环电流内环两种双环控制方法以实现柴油发电机输出功率的高效利用。运用matlab/simulink搭建了仿真模型,分别进行了锂电池混合动力RTG系统重载、轻载、空载下的动态仿真,仿真结果表明,两种双环控制方法均能实现锂电池混合动力RTG系统柴油发电机的恒功率输出,控制系统具有较好的动态性能。     

Control performance and robustness of an active noise control system for uncertain primary sound fields

In this work, the control performance and robustness of an active noise control system subjected to uncertain primary sound fields are investigated. For this purpose, the performance index, residual potential energy in a desired quiet zone, is derived as a function of sound field variables, quiet zone variables, and control system variables. In the presence of uncertainty, typical measures of the robustness and performance of a control system, maximum, minimum, mean, and variance of the performance index are derived theoretically. In addition, based on the least-squares orthogonality principle, the condition for implementing the best-oriented control system, which is robust and can maximize the control performance by using a given number of control sources and sensors, is investigated. Finally, numerical simulations are carried out to illustrate and verify the proposed theory.     

An all-optical integrated system for implementing arithmetic operation in 2’s complement method with the active participation of non-linear material based switches

Optics is regarded undoubtedly a potential and successful candidate in information and data processing because of its inherent parallelism. In last few decades several all-optical data processors, algebraic processors, arithmetic processors are proposed. Here in this communication the authors propose a completely new scheme for implementing binary data arithmetic in 2’s Complement method which is the most advantageous among all other established subtraction methods. To implement it we use non-linear material massively.