This paper presents design and implementation of multiple maximum power point trackers (MPPTs) with wide input voltage variation for dc distribution systems. The topology of the proposed MPPT combines buck and boost c...
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ISBN:
(纸本)9781457712166
This paper presents design and implementation of multiple maximum power point trackers (MPPTs) with wide input voltage variation for dc distribution systems. The topology of the proposed MPPT combines buck and boost converters to accommodate PV input voltage from 0 V to 850 V. The control algorithm for tracking maximum power points is based on a "perturbation and observation" method. The proposed MPPT can on-line check the input configuration of PV-panel strings to determine the current for maximum power calculation. In the paper, operational principle, analysis and design of the proposed MPPT configuration and mode transition will be first presented. Flowcharts of the control algorithm include perturbation and observation method and on-line PV-panel string configuration check will be then explained. Experimental results obtained from three-string MPPTs with the maximum power of 10 kW have verified its performance and feasibility.
This paper investigates the optimal rate allocation problem with end-to-end delay constraints in multi-hop wireless networks. We introduce Virtual Link Capacity Margin (VLCM), which is the gap between the schedulable ...
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ISBN:
(纸本)9781457720536
This paper investigates the optimal rate allocation problem with end-to-end delay constraints in multi-hop wireless networks. We introduce Virtual Link Capacity Margin (VLCM), which is the gap between the schedulable link capacity and the maximum allowable flow rate over a link, for link delay control. We formulate the problem as a utility maximization framework with two sets of constraints: 1) capacity and schedulability constraints and 2) end-to-end delay constraints. By dual decomposition of the original optimization problem, we present a control algorithm that jointly tunes the flow rates and VLCMs, through a double-price scheme derived with regard to the constraints: the link congestion price reflecting the traffic load of a link, and the flow delay price reflecting the margin between the average packet delay and the delay requirement of a flow. We prove that the algorithm converges to a global optimum where the aggregate network utility defined over the flow rate set is maximized, while the delay constraints are satisfied. A key feature of our algorithm is it does not rely on a specific traffic model. The algorithm is implemented distributedly via joint wireless link scheduling and congestion control. Simulation results show that our algorithm outperforms heuristic rate allocation algorithms while satisfying the end-to-end delay constraints.
This paper presents a new tool designed to allow for rapid development and testing of different control algorithms for airborne spacing. This tool, Interval Management Modeling and Spacing Tool (IM MAST), is a fast-ti...
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ISBN:
(纸本)9781467317009
This paper presents a new tool designed to allow for rapid development and testing of different control algorithms for airborne spacing. This tool, Interval Management Modeling and Spacing Tool (IM MAST), is a fast-time, low-fidelity tool created to model the approach of aircraft to a runway, with a focus on their interactions with each other. Errors can be induced between pairs of aircraft by varying initial positions, winds, speed profiles, and altitude profiles. Results to-date show that only a few of the algorithms tested had poor behavior in the arrival and approach environment. The majority of the algorithms showed only minimal variation in performance under the test conditions. Trajectory-based algorithms showed high susceptibility to wind forecast errors, while performing marginally better than the other algorithms under other conditions. Trajectory-based algorithms have a sizable advantage, however, of being able to perform relative spacing operations between aircraft on different arrival routes and flight profiles without employing 'ghosting' methods. This comes at the higher cost of substantially increased complexity, however. Additionally, it was shown that earlier initiation of relative spacing operations provided more time for corrections to be made without any significant problems in the spacing operation itself. Initiating spacing farther out, however, would require more of the aircraft to begin spacing before they merge onto a common route.
The High Efficiency Video Coding (HEVC) standardization project mainly aims at improving the compression efficiency beyond the state-of-the-art H. 264/AVC standard for high and ultra high definition video contents. Th...
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ISBN:
(纸本)9781457720482
The High Efficiency Video Coding (HEVC) standardization project mainly aims at improving the compression efficiency beyond the state-of-the-art H. 264/AVC standard for high and ultra high definition video contents. The HEVC codec reference software, still under development, encodes video content using a fixed quantization step, thus leading to a variable bitrate stream which may not be suitable for the many multimedia applications where a constant bandwidth is required. Therefore, a rate control algorithm must be integrated in the HEVC codec taking into account that the novel coding tools further reduce the bitrate associated to texture data while increase the bitrate associated to the auxiliary information, e. g. motion vectors and coding modes. In this context, this paper studies the integration of a quadratic modeling rate control algorithm in the HEVC codec. Experimental results reveal that the rate control enabled HEVC codec provides a lower rate-distortion performance regarding a fixed quantization step HEVC codec, notably spending up to 20.12% more bitrate for the same objective quality. However, the integrated rate control algorithm offers lower bitrate fluctuations along the video contents than the HEVC codec with fixed quantization step.
The paper proposes a sensorless control strategy for long primary segmented permanent magnet linear synchronous motor(LPSPMLSM) used in electromagnetic catapult. Aiming at characteristics of parameter changes of LPSPM...
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ISBN:
(纸本)9781467303057;9781467303064
The paper proposes a sensorless control strategy for long primary segmented permanent magnet linear synchronous motor(LPSPMLSM) used in electromagnetic catapult. Aiming at characteristics of parameter changes of LPSPMLSM, researchers mean to establish mathematical models of the motor. In accordance with the analysis of mathematical models of the motor, this paper presents an ameliorated sliding mode observer to acquire smooth observed back electromotive force (EMF). Besides, the method of two segments' observation of back EMF and Synchronization solves the both speed and position observation problem when movers move in single stator or transgress two stators. In that way, speed closed-loop control which has high dynamic response ability can be achievable by the sensorless algorithm. Ultimately, through the verification of Simulation testing, segmented motor can satisfy the demand of EML field by using control algorithm mentioned above.
The paper introduces an active variable stiffness exoskeleton robotic system (AVSER) with the active variable stiffness elastic actuator (AVSEA), which improves the safety for human-robot interaction and produces uniq...
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ISBN:
(纸本)9781467325769
The paper introduces an active variable stiffness exoskeleton robotic system (AVSER) with the active variable stiffness elastic actuator (AVSEA), which improves the safety for human-robot interaction and produces unique adjustable stiffness capacity to meet the demand for safe active-passive elbow rehabilitation. The AVSEA consists of two DC-motors. One is used to control the position of the joint, and the other is used to adjust the stiffness of the system. The stiffness is generated by a leaf spring. By shortening the effective length of the leaf spring, the AVSEA is able to reduce the stiffness automatically, which makes the AVSER from active (assistive) motion to passive (resistance) rehabilitation during the process of therapy. In the paper, the mechanical design, modeling, and control algorithms are described in details. The capacity of the proposed AVSER with electromyogram (EMG) signal feedback is verified by rehabilitation exercise experiments for the subject to demonstrate the efficacy of the developed system.
In this paper, a finite control set predictive control in cascade with PI controller is presented for a three-phase neural point clamped boost rectifier. The control algorithm consists of a finite control set predicti...
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ISBN:
(纸本)9781922107633
In this paper, a finite control set predictive control in cascade with PI controller is presented for a three-phase neural point clamped boost rectifier. The control algorithm consists of a finite control set predictive control for inner current loop in synchronous reference frame and a PI voltage control for the outer-loop system. There are two reference signals for this cascade controller, one being the de link voltage reference and the other q-axis current reference, which are used to regulate the de link voltage and achieve an unity power factor. A physical model is used for the design of finite control set predictive controller in the inner-loop and an empirical model is used for the design of PI controller for the outer-loop. Simulation results show the satisfactory closed-loop control performance for the de-link and the q-axis current regulation.
This paper analyzes the generalized hysteresis current control algorithm for three level inverter topologies. The inverter topologies considered are H-bridge, diode clamped and capacitor clamped three level inverters....
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ISBN:
(纸本)9781467301589
This paper analyzes the generalized hysteresis current control algorithm for three level inverter topologies. The inverter topologies considered are H-bridge, diode clamped and capacitor clamped three level inverters. It is shown that the switching frequency for the proposed hysteresis algorithm can be estimated using an empirical relation. The algorithm can be directly implemented for the H-bridge and diode clamped three-level inverter, however a pre-charged capacitor is required for the inner capacitor in case of the capacitor clamped three-level inverter. The averaged modulator dynamics of the proposed controller has been derived that is used to analyze the performance of the current control loop. The results are verified using PSCAD/EMTDC simulation studies. Experimental results are obtained for the H-bridge inverter to validate the proposed control algorithm and its performance.
Robot and Functional Electrical Stimulation (FES) techniques have been widely used in upper limb rehabilitation training. In this work, we developed a hybrid interactive robotic system with FES for hand training. The ...
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ISBN:
(纸本)9781467311427
Robot and Functional Electrical Stimulation (FES) techniques have been widely used in upper limb rehabilitation training. In this work, we developed a hybrid interactive robotic system with FES for hand training. The preliminary system evaluation was achieved via a finger tracking task. The results showed that 1) the hybrid system could be successfully driven by EMG with interactive control algorithms;2) the combined system could improve the tracking performance with adequate assistance combination from robot part and FES part. This combined system may have the potential to be used for hand rehabilitation.
Considering the strong nonlinearity and coupling of electromagnetic formation, this paper established the relative orbit dynamics in which the currents generating EM force were direct control variables (current-node m...
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ISBN:
(纸本)9780877035879
Considering the strong nonlinearity and coupling of electromagnetic formation, this paper established the relative orbit dynamics in which the currents generating EM force were direct control variables (current-node model). An electromagnetic formation relative position control method based on switched strategy and variable parameters' sliding mode control algorithm was proposed to deal with the deviation of orbital eccentricity, EM force model's uncertainty and control input matrix's peak problem. Applying the knowledge of system uncertainty, we obtained reasonable control parameters of the sliding mode control algorithm with variable parameters;and the input matrix's peak problem due to the setting of free electromagnetic dipoles was solved by switched control strategy.
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