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A driving pulse edge modulation technique and its complex programming logic devices implementation

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Frontiers of Information Technology & Electronic engineering 2015年第12期16卷 1088-1098页

作者： Xiao CHEN Dong-chang QU Yong GUO Guo-zhu CHEN electrical engineering Department Zhejiang University school of automation and electrical engineering Zhejiang University of Science and Technology

With the continual increase in switching speed and rating of power semiconductors, the switching voltage spike becomes a serious problem. This paper describes a new technique of driving pulse edge modulation for insulated gate bipolar transistors(IGBTs). By modulating the density and width of the pulse trains, without regulating the hardware circuit, the slope of the gate driving voltage is controlled to change the switching speed. This technique is used in the driving circuit based on complex programmable logic devices(CPLDs), and the switching voltage spike of IGBTs can be restrained through software, which is easier and more flexible to adjust. Experimental results demonstrate the effectiveness and practicability of the proposed method.

关键词： Driving pulse edge modulation Switching voltage spike Complex programmable logic device(CPLD) Active gate drive

Fractional order modeling and control of dissimilar redundant actuating system used in large passenger aircraft

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Chinese Journal of Aeronautics 2018年第5期31卷 1141-1152页

作者： Salman IJAZ Lin YAN Mirza Tariq HAMAYUN school of automation and electrical engineering Beihang University Department of electrical engineering COMSAT Institute of Information Technology

In this paper, a methodology has been developed to address the issue of force fighting and to achieve precise position tracking of control surface driven by two dissimilar *** nonlinear dynamics of both actuators are first approximated as fractional order models. Based on the identified models, three fractional order controllers are proposed for the whole system. Two Fractional Order PID（FOPID） controllers are dedicated to improving transient response and are designed in a position feedback configuration. In order to synchronize the actuator dynamics, a third fractional order PI controller is designed, which feeds the force compensation signal in position feedback loop of both actuators. Nelder-Mead（N-M） optimization technique is employed in order to optimally tune controller parameters based on the proposed performance criteria. To test the proposed controllers according to real flight condition, an external disturbance of higher amplitude that acts as airload is applied directly on the control surface. In addition, a disturbance signal function of system states is applied to check the robustness of proposed controller. Simulation results on nonlinear system model validated the performance of the proposed scheme as compared to optimal PID and high gain PID controllers.

关键词： Aerospace Fractional order control Model identification Nelder-Mead optimization Robustness

Adaptive de-noising method based on wavelet and adaptive learning algorithm in on-line PD monitoring

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Journal of Harbin Institute of Technology(New Series) 2002年第4期9卷 359-362页

作者：王立欣诸定秋蔡惟铮 school of electrical engineering and automation

It is an important step in the online monitoring of partial discharge (PD) to extract PD pulses from various background noises. An adaptive de-noising method is introduced for adaptive noise reduction during detection of PD pulses. This method is based on Wavelet Transform (WT), and in the wavelet domain the noises decomposed at the levels are reduced by independent thresholds. Instead of the standard hard thresholding function, a new type of hard thresholding function with continuous derivative is employed by this method. For the selection of thresholds, an unsupervised learning algorithm based on gradient in a mean square error (MSE) is present to search for the optimal threshold for noise reduction, and the optimal threshold is selected when the minimum MSE is obtained. With the simulating signals and on-site experimental data processed by this method, it is shown that the background noises such as narrowband noises can be reduced efficiently. Furthermore, it is proved that in comparison with the conventional wavelet de-noising method the adaptive de-noising method has a better performance in keeping the pulses and is more adaptive when suppressing the background noises of PD signals.

关键词： partial discharge wavelet transform adaptive noise reduction mean square error (MSE)

Asynchronous control for 2-D Markov jump cyber-physical systems against aperiodic denial-of-service attacks

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Science China(Information Sciences) 2023年第7期66卷 195-209页

作者： Peng CHENG Di WU Shuping HE Weidong ZHANG Department of automation Shanghai Jiao Tong University school of electrical engineering and automation Anhui University

This work focuses on the asynchronous controller design for two-dimensional Markov jump cyberphysical systems against denial-of-service attacks. Firstly, due to the openness of the network, it is vulnerable to cyber-attacks, resulting in the control input signal may not being sent to the designated location. Meanwhile, considering the influence of transmission delays and unavoidable packet dropout, a hidden Markov model can help to deal with the unavoidable asynchronous phenomenon between the plant mode and the controller mode. Then, by introducing the concepts of time instants and global states into two-dimensional systems, an asynchronous control scheme for two-dimensional Markov jump cyber-physical systems is successfully formulated. Subsequently, recurring to the multi-Lyapunov function method and iterative technology,sufficient conditions are achieved to make sure that the dynamic hidden two-dimensional Markov jump cyberphysical systems are asymptotically mean-square stable. To conclude, an application example related to the metal rolling process is provided to illustrate the feasibility and effectiveness of the presented asynchronous control scheme under aperiodic denial-of-service attacks.

关键词： asynchronous two-dimensional Markov jump cyber-physical systems denial-of-service attacks hidden Markov model

Power system transient stability simulation based on module bi-directional iteration

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Science China(Technological Sciences) 2005年第5期48卷 585-600页

作者： FANG Dazhong YANG Xiaodong school of electrical engineering & automation Tianjin University Tianjin 300072 China School of Electrical Engineering & Automation Tianjin University Tianjin 300072 China

A new simultaneous solution method using module bi-directional iteration is proposed for power system transient stability simulation. In this method, power network is partitioned into a tree hierarchy; computation modules are established for decomposed power networks and various power system components respectively. Through representing every computation module by a computation node, a computation tree is constructed by connecting the nodes together according to their electrical relations in power systems. A tree-traversing procedure called forward reduction and backward evaluation is performed to calculate correction factors of the variables in Newton iterations. This high-efficiency simulation method is feasible to be applied in parallel computation for large interconnected systems. Simulation tests are conducted on the New England 10-generator test power system and the North China-Northeast interconnected system, and the results are compared with those of the commercial software BPA to validate the effectiveness and correctness of this method.

关键词： power system transient stability simulation, bi-directional iteration, simultaneous solution.

An adaptive locomotion controller for a hexapod robot: CPG, kinematics and force feedback

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Science China(Information Sciences) 2014年第11期57卷 223-240页

作者： CHEN WeiHai REN GuanJiao WANG JianHua LIU Dong school of automation Science and electrical engineering Beihang University

Insects can perform versatile locomotion behaviors such as multiple gaits, adapting to different terrains, fast escaping, etc. However, most of the existing bio-inspired legged robots do not possess such walking ability, especially when they walk on irregular terrains. To tackle this challenge, a central pattern generator(CPG)-based locomotion control methodology is proposed, integrated with a contact force feedback function. In this approach, multiple gaits are produced by the CPG module. After passing through a post-processing circuit and a delay-line, the control signal is fed into six trajectory generators to generate predefined feet trajectories for the six legs. Then, force feedback is employed to adjust these trajectories so as to adapt the robot to rough terrains. Finally the regulated trajectories are sent to inverse kinematics modules such that the position control instructions are generated to control the actuators. In both simulations and real robot experiments, we consistently show that the robot can perform sophisticated walking patterns. What is more, the robot can use the force feedback mechanism to deal with the irregularity in rough terrain. With this mechanism, the stability and adaptability of the robot are enhanced. In conclusion, the CPG-base control is an effective approach for legged robots and the force feedback approach is able to improve walking ability of the robots, especially when they walk on irregular terrains.

关键词： hexapod robot locomotion control central pattern generator(CPG) kinematics force feedback

Effect of Degree-of-Symmetry on Kinetostatic Characteristics of Flexure Mechanisms:A Comparative Case Study

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Chinese Journal of Mechanical engineering 2018年第2期31卷 54-65页

作者： Xiao-Bing He Jing-Jun Yu Wan-Wan Zhang Guang-Bo Hao school of Mechanical engineering and automation Beihang University school of engineering-electrical and Electronic engineering University College Cork

The current research of kinetostatic characteristics in flexure mechanisms mainly focus on the improvement of accuracy. To reduce or eliminate the parasitic motion is considered as an approach by using the common knowledge of symmetry. However, there is no study on designing the flexure mechanisms with symmetrical features as many as possible for better kinetostatic performance, when considering the resulting cost by the symmetry. In this paper, the concept of degree of symmetry(DoS) is proposed for the first time, which is committed to symmetry design in the phase of conceptual design. A class of flexure mechanisms with 0?DoS, 1?DoS, 2?DoS and 3?DoS are synthesized respectively based on the Freedom and Constraint Topology method. Their overall compliance matrices in an analytical form formulated within the framework of the screw theory are used to analyze and compare the effect of different number of DoS on the kinetostatic characteristics for flexure mechanisms. The finite element analysis(FEA) simulations are implemented to verify the analytical results. These results show that the higher the DoS is, the smaller the parasitic motion error will be. The flexure model with 3?DoS is optimized according to the overall compliance matrix and then tested by using the FEA simulation. The testing result shows that with the best combination parameters, the parasitic motion error for 3?DoS mechanism is almost eliminated. This research introduces a design principle which can alleviate the unwanted parasitic motion for better accuracy.

关键词： Flexure mechanism Symmetry Kinetostatic characteristics FEA simulation

Multi-objective energy management system for DC microgrids based on maximum membership degree principle

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Journal of Modern Power Systems and Clean Energy 2018年第4期6卷 668-678页

作者： Panbao WANG Wei WANG Nina MENG Dianguo XU school of electrical engineering and automation Harbin Institute of Technology

With the increasing quantity of DC electrical equipment, DC microgrids have been paid more and more attention. This paper proposes an approach to multi-objective optimisation of an energy management system(EMS) for a DC microgrid that includes a hybrid energy storage system(HESS). The operating and maintenance cost and the loss of power supply probability(LPSP) of the system are used as optimisation targets. The power flows of all distributed generators(DGs) in the DC microgrid during operating period are optimized. Based on the improved differential evolution(DE) algorithm, and by using the multi-objective non-dominated sorting method and the maximum membership degree principle(MMDP) of fuzzy control, the overall satisfaction degree of Pareto solutions to power flow optimization can be obtained. Simulation results verify the effectiveness of the proposed EMS optimization scheme, which is able to achieve an effective trade-off between the economy and the reliability of microgrid operation.

关键词： DC microgrids Energy management system Multi-objective optimization Differential evolution algorithm Maximum membership degree

Normalized estimation of fundamental frequency and measurement of harmonics/interharmonics

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控制理论与应用（英文版） 2013年第1期11卷 10-17页

作者： Zhaobi CHU Ming DING Shaowu DU Xueping DONG school of electrical engineering and automation Hefei University of Technology

An adaptive notch filter is presented to estimate the fundamental frequency and measure both harmonics and interharmonics of an almost periodic signal with unknown time-variant fundamental frequency, which has the ro- bustness that the convergence speed is determined by neither amplitude nor frequency of fundamental component. The algorithm forms a one-dimensional slow adaptive integral manifold whose existence and stability are proved by averaging method and Lyapunov stability theorem. The local exponential stability and the ultimate boundedness of fundamental fre- quency estimation are proved. The local exponential stability makes sure that the fundamental frequency, the harmonic and interharmonic components can be all fast tracked. The principle for adjusting the parameters with their influences on tran- sient and steady-state performance is investigated and decreasing parameters can improve noise characteristic. The validity is verified by simulation results.

关键词： Normalized fundamental frequency estimator Harmonic analysis Adaptive notch filter Stability analysis