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New method for estimating flying capacitor voltages in stacked multicell and flying capacitor multicell converters

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Journal of Zhejiang University-Science C(computers and Electronics) 2010年第8期11卷 654-662页

作者： Arash KHOSHKBAR SADIGH Gevorg B.GHAREHPETIAN Seyed Hossein HOSSEINI Faculty of electrical & computer engineering University of Tabriz Department of electrical engineering Amirkabir University of Technology

Multicell converters are an interesting alternative for medium voltage and high power applications,because of the increased number of output voltage levels and apparent *** two most significant types of multicell converter are the flying capacitor multicell (FCM) converter and its derivative,stacked multicell (SM) *** flying capacitor voltages is an important constraint to the proper performance of FCM and SM ***,observation of the flying capacitor voltages used in active control is valuable,but using voltage sensors for observation increases cost and size of the *** paper deals with a new strategy to estimate the flying capacitor voltages of both FCM and SM *** proposed strategy is based on a discrete time model of the converter and uses only a load current *** circuit was simulated using PSCAD/EMTDC software and simulation results were presented to validate the effectiveness of the proposed estimation strategy in observing the flying capacitor *** is the most significant advantage of the proposed strategy,its performance being based on simple equations.

关键词： Flying capacitor multicell converter Stacked multicell converter Flying capacitor voltage Phase shifted sinusoidal pulse width modulation

An accurate analytical I-V model for sub-90-nm MOSFETs and its application to read static noise margin modeling

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Journal of Zhejiang University-Science C(computers and Electronics) 2012年第1期13卷 58-70页

作者： Behrouz AFZAL Behzad EBRAHIMI Ali AFZALI-KUSHA Massoud PEDRAM School of electrical and computer engineering University of Tehran Department of electrical engineering University of Southern California

We propose an accurate model to describe the I-V characteristics of a sub-90-nm metal-oxide-semiconductor field-effect transistor(MOSFET) in the linear and saturation regions for fast analytical calculation of the *** model is based on the BSIM3v3 *** of using constant threshold voltage and early voltage,as is assumed in the BSIM3v3 model,we define these voltages as functions of the gate-source *** accuracy of the model is verified by comparison with HSPICE for the 90-,65-,45-,and 32-nm CMOS *** model shows better accuracy than the nth-power and BSIM3v3 ***,we use the proposed I-V model to calculate the read static noise margin(SNM) of nano-scale conventional 6T static random-access memory(SRAM) cells with high *** calculate the read SNM by approximating the inverter transfer voltage characteristic of the cell in the regions where vertices of the maximum square of the butterfly curves are *** results for the SNM are also in excellent agreement with those of the HSPICE simulation for 90-,65-,45-,and 32-nm *** in the presence of process variations and negative bias temperature instability(NBTI) shows that the model can accurately predict the minimum supply voltage required for a target yield.

关键词： Modeling Nano-scale Process variation Read static noise margin(SNM) SRAM

Outperforming piezoelectric ultrasonics with highreliability single-membrane CMUT array elements

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Microsystems & Nanoengineering 2022年第3期8卷 61-75页

作者： Eric B.Dew Afshin Kashani llkhechi Mohammad Maadi Nathaniel J.M.Haven Roger J.Zemp Department of electrical and computer engineering niversty of AlbertaEdmontonCanada

It has long been hypothesized that capacitive micromachined ultrasound transducers(CMUTs)could potentially outperform piezoelectric ***,challenges with dielectric charging,operational hysteresis,and transmit sensitivity have stood as obstacles to these performance *** this paper,we introduce key architectural features to enable high-reliability CMUTs with enhanced ***,a CMUT element in an array is designed with an ensemble of smaller membranes oscillating together to transmit or detect ultrasound ***,this approach can lead to unreliable behavior and suboptimal transmit performance if these smaller membranes osilate out of phase or collapse at different *** this work,we designed CMUT array elements composed of a single long rectangular membrane,with the aim of improving the output pressure and electromechanical *** compare the performance of three different modifications of this architecture:traditional contiguous dielectric,isolated isolation post(P),and insulated electrode-post(EP)*** were designed to improve performance while also imparting robustness to charging and minimization of *** fabricate these devices,a wafer-bonding process was developed with near-100%bonding *** CMUT elements achieved electromechanical effciency values as high as 0.95,higher than values reported with either piezoelectric transducers or previous CMUT ***,all investigated CMUT architectures exhibited transmit effciency 2-3 times greater than published CMUT or piezoelectric transducer elements in the 1.5-2.0 MHz *** EP and lip CMUTs demonstrated considerable charging robustness,demonstrating minimal charging over 500,000 collapse-snap-back actuation cycles while also mitigating *** proposed approach offers significant promise for future ultrasonic applications.

关键词： piezoelectric elements bonding

A Sliding Mode Approach to Enhance the Power Quality of Wind Turbines Under Unbalanced Voltage Conditions

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IEEE/CAA Journal of Automatica Sinica 2019年第2期6卷 566-574页

作者： Mohammad Javad Morshed Afef Fekih IEEE the Department of electrical and computer engineering University of Louisiana at Lafayette

An integral terminal sliding mode-based control design is proposed in this paper to enhance the power quality of wind turbines under unbalanced voltage conditions. The design combines the robustness, fast response, and high quality transient characteristics of the integral terminal sliding mode control with the estimation properties of disturbance observers. The controller gains were auto-tuned using a fuzzy logic *** effectiveness of the proposed design was assessed under deep voltage sag conditions and parameter variations. Its dynamic response was also compared to that of a standard SMC *** performance analysis and simulation results confirmed the ability of the proposed approach to maintain the active power,currents, DC-link voltage and electromagnetic torque within their acceptable ranges even under the most severe unbalanced voltage conditions. It was also shown to be robust to uncertainties and parameter variations, while effectively mitigating chattering in comparison with the standard SMC.

关键词： Doubly fed induction generators(DFIG) fuzzy approach integral terminal sliding mode control(ITSMC) observer power quality voltage unbalances wind turbines

A Data-driven Motion Control Approach for a Robotic Fish

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Journal of Bionic engineering 2015年第3期12卷 382-394页

作者： Qinyuan Ren Jianxin Xu Xuefang Li Department of electrical and computer engineering National University of Singapore Singapore

In this paper we propose a data-driven motion control approach for a biomimetic robotic fish. The task of the motion control is to achieve desired motion by means of controlling the fish-like swimming gaits of the robot. Due to the complexity of hydrodynamics, it is impossible to derive an analytic model that can precisely describe the interaction between the robotic fish and surrounding water during motion. To address the lack of the robotic model, we explore data-based modeling and control design methods. First, through biomimetic learning from real fish motion data, a General Internal Model （GIM） is established. GIM translates fish undulatory body motion into robotic joint movement; associates the fish gait patterns, such as cruise and turning, with corresponding joint coordination; and adjusts the robotic velocity by GIM parameters. Second, by collecting robotic motion data at a set of operating points, we obtain the quantitative mapping from GIM tuning parameters to robotic speed. Third, applying the quantitative mapping and using GIM parameters as manipulating variables, a feedforward control is computed according to the desired speed, which greatly expedites the initial movement of the robotic fish. Fourth, Proportional-Integral-Derivative （PID） is employed as feedback control, together with an inverse mapping that compensates for the nonlinearity appeared in the quantitative mapping. Fifth, modified Iterative Feedback Tuning OFT） is developed as an appro-priate data-driven tuning approach to determine controller gains. By switching between feedforward and feedback, the motion performance is improved. Finally, real-time control of robotic fish is implemented on a two-joint platform, and two representative swimming gaits, namely ＂cruise＂ and ＂cruise in turning＂, are achieved.

关键词： robotic fish motion control data-driven IFT

An online maximum power point capturing technique for highefficiency power generation of solar photovoltaic systems

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 357-368页

作者： Lijun ZHANG Samson Shenglong YU Tyrone FERNANDO Herbert Ho-Ching IU Kit Po WONG Department of electrical Electronic and Computer Engineering University of Western Australia

This paper proposes a novel high-efficiency generation technique for photovoltaic(PV) system,named maximum power point capturing(MPPC) technique. This is an aperiodic perturbation MPPC technique compared to the conventional periodic perturbation maximum power point tracking technique. Firstly, under a closed-loop circuit and an open-loop circuit,the complete I-V curves and P-V curves are defined. Secondly, the proposed MPPC technique is based on the complete I-V curves and a practical model of solar PV *** proposed method realizes that maximum power point(MPP) is captured online, and its control strategy is designed to set a steady operating area around MPP. The duty cycle keeps constant when the operating point is within the steady operating area, i.e., aperiodic perturbation, and when the operating point is outside the steady operating area, MPPC is triggered to capture a new MPP with an updated steady operating area. Simulation results demonstrate that no oscillations exist in steady-state;dynamic performances are improved;and only two perturbations are required to capture the new MPP. Using the proposed MPPC method,low voltage ride through and high voltage ride through can be prevented.

关键词： Photovoltaic systems Maximum power point tracking(MPPT) Maximum power point capturing(MPPC) Complete I–V curves

Power Flow Based Volt/var Optimization Under Uncertainty

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Journal of Modern Power Systems and Clean Energy 2021年第5期9卷 1000-1006页

作者： Rabih A.Jabr electrical and computer engineering American University of BeirutBeirutLebano

Volt/var optimization(VVO)is a control function that is employed in distribution systems to keep the load voltages within the standard limits,and it includes secondary objectives such as loss *** power flow based VVO is the way of choice in practical applications because it can handle a variety of objective functions and provides a solution even for large-scale network *** paper extends the power flow based VVO to account for uncertainty in both the load values and the power generation from photovoltaic *** proposed method employs circular arithmetic in complex variables to compute VVO settings that guard against load uncertainty and an optimized linear decision rule that modulates the reactive power of photovoltaic inverter in function of its active ***,the proposed method is tested on distribution networks with up to 3146 nodes and is shown to produce optimal solutions that are robust against power variations.

关键词： Circular arithmetic optimization method reactive power control voltage control Wirtinger calculus

Operation and Flexibility Contribution of Natural Gas Tanks in Multi-carrier Energy Systems

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CSEE Journal of Power and Energy Systems 2021年第3期7卷 622-631页

作者： Alireza Hamedi Ali Reza Seifi Dariush Keihan Asl School of electrical and computer engineering Shiraz UniversityShirazIran

Energy storage systems(ESSs)have an assistive role in the operation of multi-carrier energy *** paper presents a type of natural gas(NG)ESS called NG tank and studies the operation and flexibility contributions of this ESS in the *** tank modeling and formulation are unified the same as the electrical *** NG tank and the electrical ESS models are implemented on a large-scale multi-carrier energy network and the impressive effects of utilizing these units are investigated in the operational planning of the energy *** optimal operational problem is solved utilizing the teaching learning based optimization(TLBO)algorithm to minimize the operational cost of the system.

关键词： electrical ESS multi-carrier energy system NG tank optimal operation

Hybrid silicon modulators

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Chinese Optics Letters 2009年第4期7卷 280-285页

作者： J.E.Bowers Department of electrical and computer engineering University of California Santa Barbara

A number of active elements have been demonstrated using the hybrid silicon evanescent platform, including lasers, amplifiers, and detectors. In this letter, two types of hybrid silicon modulators, flflfilling the building blocks in optical communication on this platform, are presented. A hybrid silicon electroabsorp- tion modulator, suitable for high speed interconnects, with 10-dB extinction ratio at -5 V and 16-GHz modulation bandwidth is demonstrated. In addition, a hybrid silicon Mach-Zehnder modulator utilizing carrier depletion in multiple quantum wells is proved with 2 *** voltage-length product, 150-nm optical bandwidth, and a large signal modulation up to 10 Gb/s.

关键词： Bandwidth Electroabsorption modulators Modulation Modulators Optical communication Quantum well lasers Semiconducting indium compounds Semiconductor quantum wells Silicon Silicon detectors