Optically Activated Charge Domain Model for High-Gain GaAs Photoconductive Switches

A model for theoretical analysis of nonlinear (or high gain) mode of photoconductive semiconductor switches (PCSS's) is proposed.The switching transition of high gain PCSS's can be described with an optically activated charge domain. The switching characteristics including rise time,delay and their relationship to electric field strength,optical trigger energies are discussed.The formation and radiation transit,accumulation of the charge domain are related with the triggering and sustaining phases of PCSS's,respectively.The results of the mathematical model on this mechanism agree with experimental results.

Control method based on DRFNN sliding mode for multifunctional flexible multistate switch

To address the low accuracy and stability when applying classical control theory in distribution networks with distributed generation,a control method involving flexible multistate switches(FMSs)is proposed in this study.This approach is based on an improved double-loop recursive fuzzy neural network(DRFNN)sliding mode,which is intended to stably achieve multiterminal power interaction and adaptive arc suppression for single-phase ground faults.First,an improved DRFNN sliding mode control(SMC)method is proposed to overcome the chattering and transient overshoot inherent in the classical SMC and reduce the reliance on a precise mathematical model of the control system.To improve the robustness of the system,an adaptive parameter-adjustment strategy for the DRFNN is designed,where its dynamic mapping capabilities are leveraged to improve the transient compensation control.Additionally,a quasi-continuous second-order sliding mode controller with a calculus-driven sliding mode surface is developed to improve the current monitoring accuracy and enhance the system stability.The stability of the proposed method and the convergence of the network parameters are verified using the Lyapunov theorem.A simulation model of the three-port FMS with its control system is constructed in MATLAB/Simulink.The simulation result confirms the feasibility and effectiveness of the proposed control strategy based on a comparative analysis.

High-speed Nonsingular Terminal Switched Sliding Mode Control of Robot Manipulators

This paper proposes a high-speed nonsingular terminal switched sliding mode control(HNT-SSMC) strategy for robot manipulators. The proposed approach enhances the control system performance by switching among appropriate sliding mode controllers according to different control demands in different regions of the state space. It is shown that the highspeed nonsingular terminal switched sliding mode(HNT-SSM)which is the representation of different control demands and enforced by the HNT-SSMC has the property of global highspeed convergence compared with the nonsingular fast terminal sliding mode(NFTSM), and provides the global non-singularity.The simulation study of an application example is carried out to validate the effectiveness of the proposed strategy.

Real-time State Monitoring During Switching Mode Transitions in High Power Three-level Inverters

大功率多电平逆变器近年来在实际工业生产中得到越来越广泛的应用。多电平逆变器由于结构复杂,采用元器件较多,因此在设计和实验中,实现各个工作状态下运行参数的同步监测和分析较为困难。本文针对大功率三电平逆变器,实现开关动态特性的在线测试,在此基础上,进一步研究三电平逆变器在开关状态变化时理论与实际负载运行工况下电路拓扑的转换变化规律。通过全电路电气参数和元器件状态的实时监测,发现在三电平逆变器非正常运行状态下开关转换时额外电应力,同时,深入研究在实际工况运行条件非正常状态下该额外电应力出现的机理和原因,为三电平逆变器的故障诊断提供了参考,对于设计高可靠性的多电平逆变器系统有一定的理论和现实意义。

SYNCHRONIZATION OF MASTER-SLAVE MARKOVIAN SWITCHING COMPLEX DYNAMICAL NETWORKS WITH TIME-VARYING DELAYS IN NONLINEAR FUNCTION VIA SLIDING MODE CONTROL

In this article, a synchronization problem for master-slave Markovian switching complex dynamical networks with time-varying delays in nonlinear function via sliding mode control is investigated. On the basis of the appropriate Lyapunov-Krasovskii functional, introducing some free weighting matrices, new synchronization criteria are derived in terms of linear matrix inequalities （LMIs）. Then, an integral sliding surface is designed to guarantee synchronization of master-slave Markovian switching complex dynamical networks, and the suitable controller is synthesized to ensure that the trajectory of the closed-loop error system can be driven onto the prescribed sliding mode surface. By using Dynkin＇s formula, we established the stochastic stablity of master-slave system. Finally, numerical example is provided to demonstrate the effectiveness of the obtained theoretical results.

A new four-dimensional chaotic system with first Lyapunov exponent of about 22,hyperbolic curve and circular paraboloid types of equilibria and its switching synchronization by an adaptive global integral sliding mode control

This paper presents a new four-dimensional（4 D） autonomous chaotic system which has first Lyapunov exponent of about 22 and is comparatively larger than many existing three-dimensional（3 D） and 4 D chaotic systems.The proposed system exhibits hyperbolic curve and circular paraboloid types of equilibria.The system has all zero eigenvalues for a particular case of an equilibrium point.The system has various dynamical behaviors like hyperchaotic,chaotic,periodic,and quasi-periodic.The system also exhibits coexistence of attractors.Dynamical behavior of the new system is validated using circuit implementation.Further an interesting switching synchronization phenomenon is proposed for the new chaotic system.An adaptive global integral sliding mode control is designed for the switching synchronization of the proposed system.In the switching synchronization,the synchronization is shown for the switching chaotic,stable,periodic,and hybrid synchronization behaviors.Performance of the controller designed in the paper is compared with an existing controller.

Estimating the clutch transmitting torque during HEV mode-switch based on the Kalman filter

A power train dynamics model of a coaxial parallel hybrid electric vehicle （HEV） was built for different clutch operating states. With the state vector constituted by the motor rotation speed and the clutch transmitting torque at two successive time steps, a discrete state space model for estimating the clutch transmitting torque was built, and the Kalman filtering algorithm was used to estimate the clutch transmitting torque. The Matlab/Simulink was employed to simulate the clutch transmitting torque for two mode-switch processes. Estimation errors were analyzed through compa- ring the estimated and simulated values of the clutch torque. Impact of the noise covariance and the sample time on clutch torque estimation errors were explored. The results show that the developed estimation method can be used to estimate the clutch transmitting torque for HEV with good accura- cy. The results are useful for torque direct control of automatic diaphragm clutches.

Multimode Design and Analysis of an Integrated Leg-Arm Quadruped Robot with Deployable Characteristics

To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.

Asynchronous Learning-Based Output Feedback Sliding Mode Control for Semi-Markov Jump Systems: A Descriptor Approach

This paper presents an asynchronous output-feed-back control strategy of semi-Markovian systems via sliding mode-based learning technique.Compared with most literature results that require exact prior knowledge of system state and mode information,an asynchronous output-feedback sliding sur-face is adopted in the case of incompletely available state and non-synchronization phenomenon.The holonomic dynamics of the sliding mode are characterized by a descriptor system in which the switching surface is regarded as the fast subsystem and the system dynamics are viewed as the slow subsystem.Based upon the co-occurrence of two subsystems,the sufficient stochastic admissibility criterion of the holonomic dynamics is derived by utilizing the characteristics of cumulative distribution functions.Furthermore,a recursive learning controller is formulated to guarantee the reachability of the sliding manifold and realize the chattering reduction of the asynchronous switching and sliding motion.Finally,the proposed theoretical method is substantia-ted through two numerical simulations with the practical contin-uous stirred tank reactor and F-404 aircraft engine model,respectively.

Throughput-based mode switching for MIMO ARQ systems in presence of transmit correlation

The mode switching between spatial multiplexing （SM） and space-time block code （STBC） diversity is investigated for the multiple-input multiple-output （MIMO） automatic repeat request （ARQ） system. Five important practical factors are considered in the proposed switching scheme： transmit correlation, ARQ technique, packet loss probability （PLP） constraint, discrete rate transmission （DRT） and channel coding. Under the spatially correlated channel, the distributions of the post signal-to-interference-plus- noise ratio （SiNR） for the SM mode and the STBC mode are obtained by using Gamma approximations. Then this paper derives the closed-form expressions of the PLP and the throughput for different modes when the ARQ technique is employed, based on which the mode switching algorithm is proposed to improve the spectral efficency. In the simulation, the correction of the expressions is first verified. Then, the significant gain observed by the proposed algorithm is presented. Since the switching point is the key parameter to implement the mode switching, this paper also shows how the switching point is affected by the practical factors considered.

DESIGN OF TERNARY CURRENT-MODE CMOS CIRCUITS BASED ON SWITCH-SIGNAL THEORY

By applying switch-signal theory, the interaction between MOS transmission switch-ing transistor and current signal in current-mode CMOS circuits is analyzed, and the theory oftransmission current-switches which is suitable to current-mode CMOS circuits is proposed. Thecircuits, such as ternary full-adder etc., designed by using this theory have simpler circuit struc-tures and correct logic functions. It is confirmed that this theory is efficient in guiding the logicdesign of current-mode CMOS circuits at switch level.

Robust H-infinity integral sliding mode control for a class of uncertain switched nonlinear systems

This paper develops a new method to deal with the robust H-infinity control problem for a class of uncertain switched nonlinear systems by using integral sliding mode control.A robust H-infinity integral sliding surface is constructed such that the sliding mode is robust stable with a prescribed disturbance attenuation level γ for a class of switching signals with average dwell time.Furthermore,variable structure controllers are designed to maintain the state of switched system on the sliding surface from the initial time.A numerical example is given to illustrate the effectiveness of the proposed method.

Diode end-pumped self-Q-switched and mode-locked Nd,Cr：YAG /KTP green laser

We first experimentally demonstrate a laser-diode end-pumped self-Q-switched and mode-locked Nd,Cr：YAG green laser with a KTP crystal as the intra-cavity frequency doubler. The device produces an average output power of 680 mW at 532 nm. The corresponding pulse width of the Q-switched envelope of the green laser is 170 ＋ 20 ns. The mode-locked pulses have a repetition rate of approximately 183 MHz and the average pulse duration is estimated to be around sub-nanosecond. It is found that the intra-cavity frequency doubling greatly improves the modulation depth and stability of the mode-locked pulses within the Q-switched envelope.

The Effect of Injected Energy on Low Energy Single Longitudinal Mode Pre-Lase Q-Switched Pr:YLF Laser

In this paper, the effect of injected energy on low energy single longitudinal mode (SLM) pre-lase Q-switched is analyzed and the optimization procedure is shown in detail. Here, taking the Pr:YLF laser as an example of low energy laser, and the parameters of Pr:YLF laser by using pre-lase have been shown. Compared with normal Q-switched laser, the single pulse energy reaches 60.16% and the pulse width exceeds 39.73% when the same maximum energy is injected and SLM is achieved in pre-lase. The analysis results show that pre-lase is suitable for low energy laser to obtain SLM and there be an optimal performance to achieve the optimal energy output.

Robust pre-specified time synchronization of chaotic systems by employing time-varying switching surfaces in the sliding mode control scheme

In the conventional chaos synchronization methods, the time at which two chaotic systems are synchronized, is usually unknown and depends on initial conditions. In this work based on Lyapunov stability theory a sliding mode controller with time-varying switching surfaces is proposed to achieve chaos synchronization at a pre-specified time for the first time. The proposed controller is able to synchronize chaotic systems precisely at any time when we want. Moreover, by choosing the time-varying switching surfaces in a way that the reaching phase is eliminated, the synchronization becomes robust to uncertainties and exogenous disturbances. Simulation results are presented to show the effectiveness of the proposed method of stabilizing and synchronizing chaotic systems with complete robustness to uncertainty and disturbances exactly at a pre-specified time.

Air-Water Cooling System for Switch-Mode Power Supplies

The results are presented of an experimental investigation of heat transfer in an air-liquid cooling system for a Switch-Mode Power Supply (SMPS) for TV digital power amplifiers. Since these SMPSs are characterized by high power and high compactness, thereby making the standard cooling techniques difficult to be used, a new cooling system is developed, using water and air as the cooling media. The active components (MOSFETs) are cooled with a liquid cold-plate, the passive ones (condensers, transformers, coils) with an air flow, in turn cooled by the cold-plate. By inserting the cooling system in an experimental tool where it is possible to control the cooling water, measurements are made of temperature in the significant points of the SMPS. The electric efficiency is also measured. The evaluation of the thermal performance of this cooling system is useful in order to limit its maximum operational temperature. The efficacy of the cooling system is demonstrated;the trends of efficiency and power dissipation are evidenced.

A switching-based backstepping sliding mode control for space manipulator in presence of gravity variation

A novel switching-based backstepping sliding mode control(SBSMC) scheme is devised for the space manipulator exposed to different gravity.With a view to distinct differences in dynamics properties when the operating conclition of space manipulator changer,the space manipulator can be thought of as a system composed of two subsystems,the ground subsystem and the space subsystem.Two different types of backstepping sliding mode(BSM) controllers are designed,one is suited for the ground subsystem and the other is for the space one.The switching between two subsystems can be implemented automatically when the switching mechanism is triggered,and the controllers for their subsystems experience synchronous switching.In this way,the space manipulator always has good behaviors in trajectory tracking.Moreover,multi-Lyapunov functions are introduced to prove the stability of this switching approach.According to simulation results,the method constructed in this research has better performance in control precision and adaptability compared with proportional-derivative(PD) control.

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。

基于TOPSwitch-GX系列单片开关电源应用设计

介绍了美国PowerIntegrations公司最新研制的开关电源集成芯片TOPSwitch-GX系列的主要特点,设计了一款基于此系列芯片的多路输出单端反激式开关电源,阐述了设计的主要步骤,给出了设计注意事项及试验结果。此电源具有低成本、高效率、小尺寸、全密封式的特点。

基于TinySwitch-Ⅱ的双路隔离输出开关电源设计

在某些特定电路场合,需要提供多路的隔离直流电源。对于多路隔离输出的开关电源,不能采用多路共地输出开关电源的常用方法来提高其交叉调整率,而隔离式的方法却设计复杂。文中设计了一种基于TinySwitch-Ⅱ芯片TNY264的小功率双路隔离输出的开关电源,采用线性稳压芯片对辅助回路进行稳压的方法,设计简单易行,并给出了高频变压器的详细设计过程。设计结果测试表明,设计的开关电源具有很好的电压调整率和负载调整率。