The Experts below are selected from a list of 2970 Experts worldwide ranked by ideXlab platform
O Vodyakho - One of the best experts on this subject based on the ideXlab platform.
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comparison of the space vector current controls for shunt active power filters
Iet Power Electronics, 2009Co-Authors: O Vodyakho, Taehyung Kim, Sangshin Kwak, Chris S EdringtonAbstract:A new space vector (SV) current control scheme for shunt active power filters (APFs) is introduced first, with a three-level neutral point-clamped voltage source inverter (VSI) as well as a standard two-level VSI. Then, the proposed control is compared with the other SV current control method to evaluate inherent advantages and drawbacks of the control schemes. The proposed control can selectively choose harmonic current components by using a real-time fast Fourier transform to generate the compensation current. The proposed current control utilises a Rotating Coordinate System, processing the information of the actual position of the grid-voltage SV, which is remarkably important in APF applications, and chooses switching states from the switching table implemented in a field programmable gate array. With the proposed control, the total harmonic distortion (THD) of the compensated grid current, the average switching frequency and switching power loss are significantly reduced. Different SV control strategies, including the proposed method, are compared via simulation and experiment, based on three-level and two-level VSIs.
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three level inverter based shunt active power filter in three phase three wire and four wire Systems
IEEE Transactions on Power Electronics, 2009Co-Authors: O Vodyakho, Chunting MiAbstract:This paper presents a direct current-space-vector control of an active power filter (APF) based on a three-level neutral-point-clamped (NPC) voltage-source inverter. The proposed method indirectly generates the compensation current reference by using an equivalent conductance of the fundamental component using APF's dc-link voltage control. The proposed control can selectively choose harmonic current components by real-time fast Fourier transform to generate the compensation current. The compensation current is represented in a Rotating Coordinate System with chosen switching states from a switching table implemented in a field-programmable gate array. In addition, a three-phase four-wire APF based on a three-level neutral-point-clamped inverter is also presented. The proposed APF eliminates harmonics in all three phases as well as the neutral current. A three-phase three-wire NPC inverter System can be used as a three-phase four-wire System since the split dc capacitors provide a neutral connection. To regulate and balance the split dc-capacitor voltages, a new control method using a sign cubical hysteresis controller is proposed. The characteristics of the APF System with an LCL-ripple filter are investigated and compared with traditional current control strategies to evaluate the inherent advantages. The simulation and experimental results validated the feasibility of the proposed APF.
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Comparison of the space vector current controls for shunt active power filters
2008 34th Annual Conference of IEEE Industrial Electronics, 2008Co-Authors: O Vodyakho, Taehyung Kim, Sangshin KwakAbstract:In this paper, a new space vector current control scheme for shunt active power filters is introduced with a three-level neutral point-clamped voltage source inverter as well as a standard two-level voltage source inverter. Then, the proposed control is compared with the other space vector current control method to evaluate inherent advantages and drawbacks of the control schemes. The proposed control can selectively choose harmonic current components by real time Fast Fourier Transform (FFT) to generate the compensation current. The proposed current control utilizes a Rotating Coordinate System processing the information of the actual position of the grid-voltage space vector which is remarkably important in active power filter application, and chooses switching states from the switching table implemented in a Field Programmable Gate Array (FPGA). With the proposed control, the total harmonic distortion of the compensated grid current, the average switching frequency, and switching power loss are significantly reduced.
Xuefeng Yang - One of the best experts on this subject based on the ideXlab platform.
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sensorless control of a shearer short range cutting interior permanent magnet synchronous motor based on a new sliding mode observer
IEEE Access, 2017Co-Authors: Lianchao Sheng, Yuqiao Wang, Mengbao Fan, Xuefeng YangAbstract:Considering the low reliability and poor adaptability of existing drum shear cutting parts, this paper presents a permanent magnet short-range cutting transmission System with a low-speed and high-torque interior permanent magnet synchronous motor (IPMSM) as the driving source and a sensorless control strategy based on a new sliding mode observer (SMO). To increase the robustness of the observer and reduce the error caused by chattering in the traditional SMO, the phase-locked loop technique is used instead of the traditional arc-tangent function estimation, and the sigmoid function is introduced to replace the traditional sign function; then, the sliding mode gain is adjusted through the fuzzy control algorithm in the new SMO. The scheme effectively improves the problems of the high failure rate caused by the long transmission chain of the shearer cutting section and the environmental impact for the mechanical sensor measurement results. Finally, the mathematical model of IPMSM based on the two-phase Rotating Coordinate System and end cutting load is established to verify the effectiveness and feasibility of the program. The results show that the new observer can accurately realize the speed and position estimation of the shearer cutting motor, and it has good dynamic response performance, observation accuracy, and robustness.
R S Johnson - One of the best experts on this subject based on the ideXlab platform.
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large scale oceanic currents as shallow water asymptotic solutions of the navier stokes equation in Rotating spherical Coordinates
Deep-sea Research Part Ii-topical Studies in Oceanography, 2019Co-Authors: Adrian Constantin, R S JohnsonAbstract:Abstract We show that a consistent shallow-water approximation of the incompressible Navier-Stokes equation written in a spherical, Rotating Coordinate System produces, at leading order in a suitable limiting process, a general linear theory for wind-induced ocean currents which goes beyond the limitations of the classical Ekman spiral. In particular, we obtain Ekman-type solutions which extend over large regions in both latitude and longitude; we present examples for constant and for variable eddy viscosities. We also show how an additional restriction on our solution recovers the classical Ekman solution (which is valid only locally).
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some problems in physical oceanography including the use of Rotating spherical Coordinates treated as exercises in classical fluid mechanics methods and examples
Deep-sea Research Part Ii-topical Studies in Oceanography, 2019Co-Authors: R S JohnsonAbstract:Abstract The ideas and methods typically associated with classical fluid mechanics are briefly introduced and then applied to some problems in physical oceanography. The main thrust is to show that this approach is surprisingly successful, avoiding the need to invoke any modelling (based, for example, on physical principles without an accompanying derivation) or to implement numerical methods. The governing equations in a spherical, Rotating Coordinate System are presented, together with a suitable non-dimensionalisation, leading to a discussion of the available asymptotic approximations. The tangent plane, and f- and β-plane approximations, are also mentioned. A number of examples (inviscid), taken from the recent literature, are described, with the emphasis on the formulation and methods employed. The first, used as an introduction to the ideas, is based on the β-plane approximation and describes the slow evolution of the flow along the Pacific Equator (the EUC); a fully three-dimensional, nonlinear flow structure is constructed. The next pair of examples (which are quite closely related) are exact solutions of the full set of governing equations; one relates to the velocity profile typical of the EUC, and the other to the jet-like flow structures that contribute to the Antarctic Circumpolar Current. The final example shows how a theory for (nonlinear) large gyres, Rotating in the thin ocean layer on the surface of a sphere, can be constructed. A few general comments and observations are made in conclusion.
Kyoungchul Kong - One of the best experts on this subject based on the ideXlab platform.
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Two-Degree-of-Freedom Control of a Two-Link Manipulator in the Rotating Coordinate System
IEEE Transactions on Industrial Electronics, 2015Co-Authors: Kyoungchul KongAbstract:As applications and tasks of robotic manipulators become more diverse and complicated, the desired motions of the robots also become more sophisticated and complicated. In spite of this diversity of tasks, the Coordinate System to describe the tasks has not been changed much; the conventional Cartesian Coordinate System is still the most widely used Coordinate System. It is found in this paper that the Rotating Coordinate System significantly simplifies the kinematics of a two-link robotic manipulator with the biarticular actuation coordination, which is inspired from human muscles that can generate torques at adjoining two joints simultaneously. Taking the advantage of this simple kinematic relationship by the Rotating Coordinate System and the biarticular actuator coordination, the dynamics of the two-link manipulator is analyzed, and a disturbance observer (DOB) is designed based on the derived dynamics to nominalize the actual dynamics and to reject undesired disturbances. The proposed DOB-based control algorithm can achieve better control performance in the Rotating Coordinate System, and comparative experiments verify the effectiveness of the proposed Coordinate System and control methods.
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design of a biarticular robotic manipulator and its control in the Rotating Coordinate System
International Conference on Advanced Intelligent Mechatronics, 2014Co-Authors: Hyunjin Choi, Kyoungchul KongAbstract:In human-interacting applications of the robotic manipulators, it is important for the robotic manipulators to emulate the dynamic characteristics and performance of human motions. To this end, a biarticular actuation mechanism is introduced to solve the kinematics and dynamics of a two-link manipulator in this paper. For an effective and convenient expression of the equation of motion from inspiration of the human musculoskeletal structure, the kinematics and dynamics are analyzed in the Rotating Coordinate System, which enables the sophisticated and intuitive control of an end-effector. In order to provide a general platform for designing control algorithms and state observers, the dynamic equation is formalized into a state-space equation. A feedback controller is designed (1) to reject undesired dynamic couplings caused by the inherent mechanical structure and (2) to realize the desired dynamic characteristics to achieve position control of the end-effector. The proposed methods are verified by experimental results in this paper.
Lianchao Sheng - One of the best experts on this subject based on the ideXlab platform.
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sensorless control of a shearer short range cutting interior permanent magnet synchronous motor based on a new sliding mode observer
IEEE Access, 2017Co-Authors: Lianchao Sheng, Yuqiao Wang, Mengbao Fan, Xuefeng YangAbstract:Considering the low reliability and poor adaptability of existing drum shear cutting parts, this paper presents a permanent magnet short-range cutting transmission System with a low-speed and high-torque interior permanent magnet synchronous motor (IPMSM) as the driving source and a sensorless control strategy based on a new sliding mode observer (SMO). To increase the robustness of the observer and reduce the error caused by chattering in the traditional SMO, the phase-locked loop technique is used instead of the traditional arc-tangent function estimation, and the sigmoid function is introduced to replace the traditional sign function; then, the sliding mode gain is adjusted through the fuzzy control algorithm in the new SMO. The scheme effectively improves the problems of the high failure rate caused by the long transmission chain of the shearer cutting section and the environmental impact for the mechanical sensor measurement results. Finally, the mathematical model of IPMSM based on the two-phase Rotating Coordinate System and end cutting load is established to verify the effectiveness and feasibility of the program. The results show that the new observer can accurately realize the speed and position estimation of the shearer cutting motor, and it has good dynamic response performance, observation accuracy, and robustness.
