This paper presents the design and implementation of an energy management system (EMS) with fuzzy control for a DC micro-grid system. Modeling, analysis and control of distributed power sources and energy storage devices with MATLAB/Simulink are proposed, and the integrated monitoring energy management system (EMS) is implemented with LabVIEW. To improve the life cycle of the battery, fuzzy control manages the desired state of charge (SOC). The RS-485/ZigBee network has been designed to control the operating mode and to monitor the values of all subsystems in the DC micro-grid system.
In this article, we have proposed an accurate calibration method for measuring photodetector wideband response with optical heterodyne measurement technique. The experimental result ranging from 0 to 48.65 GHz indicates that the proposed calibration method can effectively remove the errors introduced by extra fixture as well as laser output fluctuations. Good agreement between the calibrated frequency response and the data provided by the manufacturer has been achieved. The proposed method can improve the accuracy for optical heterodyne measurement technique and reduce the requirements in both laser output stabilities and fixture frequency performance, which is suitable to characterize the photodetector frequency response in an ultrawide frequency range.
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In this paper, higher-dimensional periodic and chaotic oscillations for a parametrically excited viscoelastic moving belt with multiple internal resonances are investigated for the first time. The external damping and internal damping of the material for the viscoelastic moving belt are considered simultaneously. First, the nonlinear governing equation of planar motion for the viscoelastic moving belt with the external damping is given. Then, the transverse nonlinear oscillations of the viscoelastic moving belt are considered. The method of multiple scales and the Galerkin approach are applied directly to the governing partial differential equation of motion for the viscoelastic moving belt to obtain an eight-dimensional averaged equation for the case of 1:2:3:4 internal resonances for the first-, the second-, the third- and the fourth-order modes and primary parametric resonance of the first-order mode. Finally, numerical method is used to investigate higher-dimensional periodic and chaotic motions of the viscoelastic moving belt. The results of numerical simulation demonstrate that there exist the period, period 2, period 4, multiple period and chaotic motions of the viscoelastic moving belt. The multipulse chaotic motions of the viscoelastic moving belt are observed from numerical simulations.
Issues of global stabilization of a centrifugal compressor with spool dynamics are presented. Control schemes are designed for systems with and without system uncertainty. While activating only the close-coupled valve or the throttle as the single control input, backstepping tools are first used to achieve global stability of the working equilibrium for systems without uncertainty. The uncertainties in the spool dynamics and the compressor characteristic are known to be likely to happen in practical applications. Under such circumstances, the compressor torque and the close-coupled valve are then employed to achieve robust global stability of the working equilibrium via the Lyapunov redesign method. Numerical simulations are given to demonstrate the main results.
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