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A SAFE COMMUNICATION-SYSTEM FOR WHEELCHAIR-MOUNTED MEDICAL ROBOTS

COMPUTING & control ENGINEERING JOURNAL 1995年第5期6卷 216-221页

作者： DAVIES, B HIBBERD, R Dept. of Mech. Eng. Imperial Coll. of Sci. Technol. & Med. London UK

When a powered medical manipulator is added to a motorised electric wheelchair, the result is a system which can be safety critical for the user. When a number of other systems, such as environmental controllers, displays and navigation systems are incorporated into the overall systems, the complexity of central can further affect safety. The solution to these problems has resulted in the development of a new safe communication system for wheelchair mounted manipulator systems called Multiple-Master, Multiple-Slave (M3S). This work has been carried out as part of a consortium funded by the European TIDE programme.

关键词： manipulators safety-critical software wheelchair mounted manipulator systems Software engineering techniques control complexity environmental controllers medical computing motorised electric wheelchair Multiple-Master Multiple-Slave navigation systems wheelchair mounted medical robots safe communication system Biology and medical computing Manipulators M3S Health and safety aspects wheelchair-mounted medical robots safety critical control engineering computing powered medical manipulator biomedical equipment computerised control Biological and medical control systems

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Logarithmic droop-based decentralized control of parallel converters for accurate current sharing in islanded DC microgrid applications

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IET RENEWABLE POWER GENERATION 2021年第6期15卷 1240-1254页

作者： Monica, P. Kowsalya, M. Guerrero, Josep M. Vellore Inst Technol Sch Elect Engn Vellore 632001 Tamil Nadu India Vellore Inst Technol Dept Energy & Power Elect Vellore 632014 Tamil Nadu India Aalborg Univ Dept Energy Technol Aalborg Denmark

Remarkable progress in distributed power generation invigorated research into DC microgrids using a controllable DC-DC converter contingent to the functionalities therein. The study explores the circulating current issue in a parallel-connected DC-DC converter and its associated current-sharing capability. Despite, the conventional droop being a promising solution with less control complexity, the current sharing is achieved at an expense of voltage drop. The prime objective of this research work is to design a control strategy that guarantees a minimized circulating current with proper current sharing for a parallel-operated DC-DC converter. This paper puts forth a dual reference-based control to alleviate the droop and load effects of the system. The primary reference is generated by considering the effect of a marginal change in the input power of the converters. The virtual resistance-based droop technique utilizes the prime reference for secondary droop reference generation. A current sharing algorithm is designed to assimilate adaptability to the scheme running under a variable line and load parameters. The comprehensive approach to the proposed control strategy has the advantages of improved current sharing and voltage regulation. A parallel DC-DC converter with the proposed control mechanism was investigated using MATLAB/Simulink and validated experimentally.

关键词： virtual resistance-based droop technique power distribution control control mechanism accurate current sharing control of electric power systems Multivariable control systems islanded DC microgrid applications conventional droop minimized circulating current circulating current issue Distribution networks control strategy parallel-connected DC-DC converter parallel-operated DC-DC converter parallel converters DC microgrids Power system control power generation control Current control proper current sharing DC-DC power convertors current sharing algorithm power grids improved current sharing prime reference forth a dual reference-based control control complexity load effects electric current control decentralised control Power convertors and power supplies to apparatus Voltage control distributed power generation voltage regulators parallel DC-DC converter secondary droop reference generation associated current-sharing capability controllable DC-DC converter contingent Distributed power generation power system stability Power electronics, supply and supervisory circuits logarithmic droop-based decentralized control voltage control

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Analysis and design of split-capacitor resistive-inductive passive damping for LCL filters in grid-connected inverters

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IET POWER ELECTRONICS 2013年第9期6卷 1822-1832页

作者： Balasubramanian, Arun Karuppaswamy John, Vinod Indian Inst Sci Dept Elect Engn Bangalore 560012 Karnataka India

Grid-connected inverters require a third-order LCL filter to meet standards such as the IEEE Std. 519-1992 while being compact and cost-effective. LCL filter introduces resonance, which needs to be damped through active or passive methods. Passive damping schemes have less control complexity and are more reliable. This study explores the split-capacitor resistive-inductive (SC-RL) passive damping scheme. The SC-RL damped LCL filter is modelled using state space approach. Using this model, the power loss and damping are analysed. Based on the analysis, the SC-RL scheme is shown to have lower losses than other simpler passive damping methods. This makes the SC-RL scheme suitable for high power applications. A method for component selection that minimises the power loss in the damping resistors while keeping the system well damped is proposed. The design selection takes into account the influence of switching frequency, resonance frequency and the choice of inductance and capacitance values of the filter on the damping component selection. The use of normalised parameters makes it suitable for a wide range of design applications. Analytical results show the losses and quality factor to be in the range of 0.05-0.1% and 2.0-2.5, respectively, which are validated experimentally.

关键词： IEEE standards invertors Q-factor state-space methods split-capacitor resistive-inductive passive damping grid-connected inverters third-order LCL filter IEEE Std 519-1992 active method passive method control complexity SC-RL damped LCL filter state space approach power loss damping resistors switching frequency resonance frequency inductance values capacitance values damping component selection quality factor

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Improved control strategy for Cuk converter assisted wind-driven SEIG for DC nanogrid

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IET ELECTRIC POWER APPLICATIONS 2020年第10期14卷 1906-1917页

作者： Kumar, Saurabh Mukkapati, Ashok Bhupathi Kumar Krishnasamy, Vijayakumar Kaur, Rajvir Chitti Babu, B. Malaviya Natl Inst Technol Elect Engn Dept Jaipur Rajasthan India IIITDM Dept Elect & Commun Engn Kancheepuram Tamil Nadu India Singapore Univ Technol & Design ISTD Singapore Singapore

In this study, the current mode control strategy for a Cuk converter assisted self-excited induction generator-based wind energy conversion system (WECS) for DC nanogrid is proposed. The sliding mode controller (SMC) is a non-linear controller and, is preferred because of good static and dynamic response for input -output disturbance rejections. However, the knowledge of all the state variables is required, which increases the number of sensors and control complexity. To reduce the number of sensors, reduced-order SMC (ROSMC) can be implemented. Conventionally design of the voltage loop in ROSMC does not consider the uncertainty of the control parameter. However, the accuracy of the control signal generated by the ROSMC also depends on how accurately the reference current is generated. Therefore, a genetic algorithm tuned PI controller is proposed to generate the ripple-free reference current. Artificial intelligence assisted ROSMC (AIROSMC) is proposed because of its advantages over SMC, which are a reduced number of sensors, improved dynamic response and easy implementation. The extensive simulation study is carried in MATLAB\Simulink for comparative analysis of fixed frequency SMC, two variable SMC, ROSMC, and AIROSMC. The harmonic spectrum analysis is carried out to justify the selection of DBR instead of the controlled rectifier.

关键词： wind power plants voltage control electric current control nonlinear control systems genetic algorithms voltage regulators PI control power convertors DC-DC power convertors dynamic response variable structure systems power generation control voltage loop ROSMC PI controller ripple-free reference current AIROSMC extensive simulation study fixed frequency SMC variable SMC diode bridge rectifier-based SEIG topology WECS controlled rectifier Cuk converter assisted wind-driven SEIG power management voltage regulation power balance interfacing converter multiobjective control time-variant control current mode control strategy Cuk converter assisted self-excited induction generator sliding mode controller nonlinear controller DC nanogrid application static response input-output disturbance rejections state variables control complexity reduced-order SMC dynamic response DC nanogrid MATLAB Simulink harmonic spectrum analysis diode bridge rectifier SEIG topology wind energy conversion system

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Four-port solid-state transformer based on hybrid MMC with enhanced dual half-bridge submodules

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IET POWER ELECTRONICS 2020年第12期13卷 2432-2441页

作者： Li, Dongye Ji, Zhendong Sun, Yichao Zhao, Jianfeng Zhang, Chi Nanjing Inst Technol Sch Elect Power Engn 1 Hongjing Ave Nanjing 211167 Peoples R China Nanjing Univ Sci & Technol Sch Automat 200 Xiaolingwei St Nanjing 210094 Peoples R China Nanjing Normal Univ Sch Elect & Automat Engn 1 Wenyuan Rd Nanjing 210023 Peoples R China Southeast Univ Sch Elect Engn 2 Sipailou Nanjing 210096 Peoples R China

This study presents a novel solid-state transformer (SST) with four ports that can connect the medium-voltage (MV) DC bus, the MV AC bus, the low-voltage (LV) DC bus, and the LV AC bus, respectively. This SST is suitable for application in the hybrid AC/DC power grid that functions as an energy router between AC and DC systems. Furthermore, the SST submodule is enhanced with two types of dual-half bridge converters, namely DHSM1 or DHSM2, depending on if an additional active switch is used to block the possible short circuit. Thanks to the designed structure of the proposed SST that combines DHSM1 and DHSM2 as the front-end stage, it achieves reduced hardware complexity with the remaining capability to handle the DC short-circuit fault that may occur at the medium- or high-level voltage DC grid. In addition, an optimised overall control strategy that can reduce the measurement demand and control complexity is proposed, with the possible power flow path inside the SST fully analysed. Simulation and experimental results validate the feasibility of the proposed SST and the effectiveness of the overall control scheme with the DC fault handle capability.

关键词： power transmission faults power grids AC-DC power convertors power convertors DC-DC power convertors power transformers load flow control bridge circuits switching convertors SST submodule dual-half bridge converters DHSM1 DHSM2 additional active switch possible short circuit DC short-circuit fault high-level voltage DC grid measurement demand control complexity possible power flow path DC fault handle capability port solid-state transformer hybrid MMC enhanced dual half-bridge submodules novel solid-state transformer medium-voltage DC bus MV AC bus low-voltage DC bus LV AC bus

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Robust predictive current control of PWM rectifiers with LCL filters under unbalanced and distorted network conditions

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IET POWER ELECTRONICS 2022年第3期15卷 226-236页

作者： Liu, Xiang Zhang, Yongchang Yang, Haitao Rodriguez, Jose North China Elect Power Univ Sch Elect & Elect Engn Beijing 102206 Peoples R China North China Univ Technol Inverter Technol Engn Res Ctr Beijing Beijing Peoples R China Univ Andres Bello Santiago Chile

Pulse-width modulation (PWM) rectifiers with LCL filters can achieve better filtering and have lower total inductance than its counterpart of L filters. However, the control complexity is also increased due to the higher system order. Furthermore, the performance may deteriorate significantly when the inductance used in the controller deviates from its actual value due to saturation, temperature, and so on. This paper proposes a robust predictive current control (RPCC) scheme based on the ultra-local model for LCL-filtered PWM rectifiers. Excluding the converter voltage related term, the other part of the system F including the disturbance caused by parameter mismatches and other dynamic process, can be estimated using differential algebra (DA) or an extended state observer (ESO). After obtaining F, the reference voltage vector can be calculated based on the principle of deadbeat current control. The proposed RPCC is extended to an unbalanced and distorted grid by modifying the grid current reference;thus, the three-phase grid currents are balanced and sinusoidal. The proposed RPCC based on DA and ESO is compared to the conventional model-based predictive current control (MPCC), and the experimental results confirm its robustness and effectiveness under mismatched parameters and network disturbances.

关键词： Algebra ultra-local model Optimal control LCL-filtered PWM rectifiers deadbeat current control extended state observer Current control robust control control of electric power systems power system control Stability in control theory pulse-width modulation rectifiers unbalanced grid differential algebra three-phase grid currents distorted grid power grids Power system control converter voltage related term RPCC predictive control model-based predictive current control grid current reference robust predictive current control mismatched parameters reference voltage vector unbalanced network conditions electric current control PWM rectifiers control complexity observers distorted network conditions differential algebraic equations

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In-depth study of direct power control strategies for power converters

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IET POWER ELECTRONICS 2014年第7期7卷 1810-1820页

作者： Hu, Jiefeng Zhu, Jianguo Dorrell, David G. Univ Technol Sydney Fac Engn & Informat Technol Sydney NSW 2007 Australia

Direct power control (DPC) has received a significant amount of research attention because of its benefits such as simplicity, robustness and excellent dynamic response. In the last few years DPC has been widely used in power electronics and electric drives. Recently, because of the rapid increase in the penetration of distributed generation sources connected to the local AC and/or DC common buses through power electronic converters, further development of DPC strategies is highly required. In addition, given the fact that the requirements of the system performance vary in different applications, it is very useful to provide an in-depth analysis so as to select the suitable control approach. This study presents an investigation of DPC of power converters. The theoretical principles are analysed and studied. The performance of each control method is then validated by experimental tests on a laboratory power converter system. The evaluated characteristics include the power ripple, line current total harmonic distortion (THD), switching behaviour, control complexity, etc. The reported results provide engineers and researchers on the subject with valuable insights into the features and implementation constraints of the DPC strategies in power and energy systems.

关键词： power control power convertors dynamic response harmonic distortion direct power control strategy dynamic response electric drives distributed generation sources local AC common bus local DC common bus power electronic converters DPC strategy power ripple line current total harmonic distortion line current THD switching behaviour control complexity

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Model predictive control of induction motor based on amplitude-phase motion equation

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IET POWER ELECTRONICS 2019年第9期12卷 2400-2406页

作者： Lu, Ziguang Zhang, Ruilin Hu, Likun Gan, Lin Lin, Jingyu Gong, Pingping Guangxi Univ Sch Elect Engn Nanning Peoples R China

Tedious adjustment of the weighting factor restricts the wide application of conventional model predictive torque control (MPTC) for induction motors (IMs) in practice. To solve this problem, this study introduces a new variable R (reactive torque) to control the flux of IM, which is the dual of torque T, with radial orientation and in relation to reactive power. Then, a novel MPTC strategy based on variable R and torque T is proposed and named RT-MPC. Compared with conventional MPTC, RT-MPC uses a pair of variables with the same dimensions and time scales instead of the torque and flux amplitude in MPTC. This approach eliminates the weighting factor of the cost function, unifies the time scales of control variables, and avoids prediction of rotor flux at the (k+2) instant. Simulation and experimental results show that RT-MPC can avoid the weighting factor, reduce switching frequency, and reduce control complexity. RT-MPC can also maintain excellent dynamic and steady-state performance similar to conventional MPTC. Hence, the proposed method is expected to be more practical.

关键词： conventional model predictive torque control Optimal control control variables amplitude–phase motion equation control of electric power systems predictive control Mechanical variables control RT-MPC reactive torque time scales wide application machine control tedious adjustment Drives radial orientation flux amplitude torque control induction motors control complexity rotor flux r induction motor model predictive control weighting factor conventional MPTC novel MPTC strategy Asynchronous machines IMs induction motor drives

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AN EMPIRICAL-STUDY OF SOFTWARE METRICS

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1987年第6期13卷 697-708页

作者： LI, HF CHEUNG, WK UNIV HONG KONG DEPT ELECT ENGNHONG KONGHONG KONG

Software metrics are computed for the purpose of evaluating certain characteristics of the software developed. A Fortran static source code analyzer, FORTRANAL, was developed to study 31 metrics, including a new hybrid metric introduced in this paper, and applied to a database of 255 programs, all of which were student assignments. Comparisons among these metrics are performed. Their cross-correlation confirms the internal consistency of some of these metrics which belong to the same class. To remedy the incompleteness of most of these metrics, the proposed metric incorporates context sensitivity to structural attributes extracted from a flow graph. It is also concluded that many volume metrics have similar performance while some control metrics surprisingly correlate well with typical volume metrics in the test samples used. A flexible class of hybrid metric can incorporate both volume and control attributes in assessing software complexity.

关键词： Software Metric control complexity Cross Correlation Empirical Study Halsteads Software Science Hybrid Metrics

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A Modular Modulation Decoupling Algorithm for Multiple Active Bridge Based Multiport EV Charger

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IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS 2024年第4期12卷 3637-3649页

作者： Cai, Yicong Li, Jing Gu, Chunyang Yang, Jiajun Guenter, Sandro Buticchi, Giampaolo Zhang, He Univ Nottingham Ningbo China Dept Elect & Elect Engn Key Lab More Elect Aircraft Technol Zhejiang Prov Ningbo 315100 Peoples R China Yongjiang Lab Adv Elect Machine Drive Res Ctr Ningbo 315202 Peoples R China Univ Nottingham Ningbo China China Beacons Inst Ningbo 315100 Peoples R China

To enhance the power density and increase the efficiency of electrical power distribution systems (EPDSs), the concept of multiple active bridge (MAB) converters has been developed. The conventional MAB control method utilizes proportional and integral (PI) voltage controllers for each dc port without decoupling, facing the drawbacks of slow dynamic responses and limited power transfer capability. This article proposes a Newton iteration-based decoupling algorithm combined with a current decoupling control algorithm to realize the voltage controls for the multiport electric vehicles (EV) charger applications. This control strategy composes of the dc reference current generators and the current to phase shifts decoupling algorithm, which divides the MAB converter with n ports, into n-1 virtual dual active bridge (DAB) subbranches. Generalized phase shift(GPS) modulation was utilized in the decoupling algorithm to quantitatively characterize the relationship between the phase shift and the port average current, aiming at achieving the "modular" switching of the fundamental modulations. The complexity and accuracy of the proposed online offline Newton decoupling (O2ND) algorithm have been evaluated and compared with Newton decoupling (ND) algorithm and simplified Newton decoupling algorithm (SND). The effectiveness and flexibility of the O2ND algorithm and the performance of the O2ND current decoupling control are verified through a comparative assessment by means of simulation and experimental results.

关键词： Voltage control Bridge circuits Topology Phase modulation control systems complexity theory Global Positioning System control complexity electric vehicles (EV) charging generalized current partial derivatives multiple active bridge (MAB) Newton iteration power decoupling

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