127,806 research outputs found

    Analysis and Design of Hybrid Control Systems

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    Different aspects of hybrid control systems are treated: analysis, simulation, design and implementation. A systematic methodology using extended Lyapunov theory for design of hybrid systems is developed. The methodology is based on conventional control designs in separate regions together with a switching strategy. Dynamics are not well defined if the control design methods lead to fast mode switching. The dynamics depend on the salient features of the implementation of the mode switches. A theorem for the stability of second order switching together with the resulting dynamics is derived. The dynamics on an intersection of two sliding sets are defined for two relays working on different time scales. The current simulation packages have problems modeling and simulating hybrid systems. It is shown how fast mode switches can be found before or during simulation. The necessary analysis work is a very small overhead for a modern simulation tool. To get some experience from practical problems with hybrid control the switching strategy is implemented in two different software environments. In one of them a time-optimal controller is added to an existing PID controller on a commercial control system. Successful experiments with this hybrid controller shows the practical use of the method

    A Novel Control Approach to Hybrid Multilevel Inverter for High-Power Applications

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    This paper proposes a hybrid control scheme for a newly devised hybrid multilevel inverter (HMLI) topology. The circuit configuration of HMLI is comprised of a cascaded converter module (CCM), connected in series with an H-bridge converter. Initially, a finite set model predictive control (FS-MPC) is adopted as a control scheme, and theoretical analysis is carried out in MATLAB/Simulink. Later, in the real-time implementation of the HMLI topology, a hybrid control scheme which is a variant of the FS-MPC method has been proposed. The proposed control method is computationally efficient and therefore has been employed to the HMLI topology to mitigate the high-frequency switching limitation of the conventional MPC. Moreover, a comparative analysis is carried to illustrate the advantages of the proposed work that includes low switching losses, higher efficiency, and improved total harmonic distortion (THD) in output current. The inverter topology and stability of the proposed control method have been validated through simulation results in MATLAB/Simulink environment. Experimental results via low-voltage laboratory prototype have been added and compared to realize the study in practice.publishedVersio

    Design and Analysis of Hybrid Vessel Monitoring System Based on DTN and Internet Collaboration

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    In this paper, we propose hybrid Vessel Monitoring System (VMS) design as alternative for current VMS scheme by collaborating internet connection and Disruption-Tolerant-Networks (DTN). The hybrid solution combines offline VMS that use radio networks and online VMS that utilizing satellite-based internet. Hybrid VMS aims to provide a more flexible VMS design and able to speed up delivery process of offline vessel's data. The concept is both type of vessels must install a standard radio networks for data forwarding. The proposed method to speed up data delivery is by forwarding VMS data from one vessel to another using DTN forwarding scheme. Data can be forwarded to another offline vessel that will return to harbor earlier or to online vessels which have internet connection. Performance measurement is done through simulation analysis using ONE simulator. It aims to measure the speed up data delivery using hybrid VMS implementation compare to a pure offline VMS implementation. Simulation result show that hybrid VMS able to speed up data delivery for offline vessel data in 1.5 up to 2 times faster compare to a pure offline VMS implementation. Hybrid VMS also has advantages in flexible implementation by easily switching between online and offline VMS scheme, according to fisherman financial situation. Spray-and-Wait routing is the most suitable routing algorithm for hybrid VMS according to the efficiency ratio

    Design and Analysis of Hybrid Vessel Monitoring System based on DTN and Internet Collaboration

    Get PDF
    In this paper, we propose hybrid Vessel Monitoring System (VMS) design as alternative for current VMS scheme by collaborating internet connection and Disruption-Tolerant-Networks (DTN). The hybrid solution combines offline VMS that use radio networks and online VMS that utilizing satellite-based internet. Hybrid VMS aims to provide a more flexible VMS design and able to speed up delivery process of offline vessel’s data. The concept is both type of vessels must install a standard radio networks for data forwarding. The proposed method to speed up data delivery is by forwarding VMS data from one vessel to another using DTN forwarding scheme. Data can be forwarded to another offline vessel that will return to harbor earlier or to online vessels which have internet connection. Performance measurement is done through simulation analysis using ONE simulator. It aims to measure the speed up data delivery using hybrid VMS implementation compare to a pure offline VMS implementation. Simulation result show that hybrid VMS able to speed up data delivery for offline vessel data in 1.5 up to 2 times faster compare to a pure offline VMS implementation. Hybrid VMS also has advantages in flexible implementation by easily switching between online and offline VMS scheme, according to fisherman financial situation. Spray-and-Wait routing is the most suitable routing algorithm for hybrid VMS according to the efficiency ratio

    Control Based Soft Switching Three-phase Micro-inverter: Efficiency And Power Density Optimization

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    In the field of renewable energy, solar photovoltaic is growing exponentially. Grid-tied PV micro-inverters have become the trend for future PV system development because of their remarkable advantages such as enhanced energy production due to MPPT implementation for each PV panel, high reliability due to redundant and distributed system architecture, and simple design, installation, and management due to its plug-and-play feature. Conventional approaches for the PV micro-inverters are mainly in the form of single-phase grid connected and they aim at the residential and commercial rooftop applications. It would be advantageous to extend the micro-inverter concept to large size PV installations such as MW-class solar farms where threephase AC connections are used. The relatively high cost of the three-phase micro-inverter is the biggest barrier to its large scale deployment. Increasing the switching frequency may be the best way to reduce cost by shrinking the size of reactive components and heat-sink. However, this approach could cause conversion efficiency to drop dramatically without employing soft switching techniques or using costly new devices. This dissertation presents a new zero voltage switching control method that is suitable for low power applications such as three-phase micro-inverters. The proposed hybrid boundary conduction mode (BCM) current control method increases the efficiency and power density of the micro-inverters and features both reduced number of components and easy digital implementation. Zero voltage switching is achieved by controlling the inductor current bidirectional in every switching cycle and results in lower switching losses, higher operating frequency, and reduced size and cost of passive components, especially magnetic cores. Some iv practical aspects of hybrid control implementation such as dead-time insertion can degrade the performance of the micro-inverter. A dead-time compensation method that improves the performance of hybrid BCM current control by decreasing the output current THD and reducing the zero crossing distortion is presented. Different BCM ZVS current control modulation schemes are compared based on power losses breakdown, switching frequency range, and current quality. Compared to continuous conduction mode (CCM) current control, BCM ZVS control decreases MOSFET switching losses and filter inductor conduction losses but increases MOSFET conduction losses and inductor core losses. Based on the loss analysis, a dual-mode current modulation method combining ZVS and zero current switching (ZCS) schemes is proposed to improve the efficiency of the micro-inverter. Finally, a method of maintaining high power conversion efficiency across the entire load range of the three-phase micro-inverter is proposed. The proposed control method substantially increases the conversion efficiency at light loads by minimizing switching losses of semiconductor devices as well as core losses of magnetic components. This is accomplished by entering a phase skipping operating mode wherein two phases of an inverter are disabled and three inverters are combined to form a new three-phase system with minimal grid imbalance. A 400W prototype of a three-phase micro-inverter and its hybrid control system have been designed and tested under different conditions to verify the effectiveness of the proposed controller, current modulation scheme, and light load efficiency enhancement method

    Issues in the design of switched linear systems : a benchmark study

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    In this paper we present a tutorial overview of some of the issues that arise in the design of switched linear control systems. Particular emphasis is given to issues relating to stability and control system realisation. A benchmark regulation problem is then presented. This problem is most naturally solved by means of a switched control design. The challenge to the community is to design a control system that meets the required performance specifications and permits the application of rigorous analysis techniques. A simple design solution is presented and the limitations of currently available analysis techniques are illustrated with reference to this example
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