Shunt active power filters have been introduced as a way to overcome the power quality problems caused by nonlinear and reactive loads [9, 14, 23]. These power electronics devices are designed with the goal of obtaining a power factor close to 1 and achieving current harmonics and reactive power compensation [5, 6, 15]. The usual approaches [5, 15] for the control of shunt active filters are based on two hierarchical control loops: an inner one that assures the desired current and an outer one in charge of determining its required shape and the appropriate power balance as well. The control structure followed in this Chapter is the one in [7], in which the current controller is composed of a feedforward action that provides very fast transient response, and also of a feedback loop which includes an odd-harmonic repetitive control that yields closed-loop stability and a very good harmonic correction performance. In turn, the outer control law is based on the appropriated computation of the amplitude of the sinusoidal current network and, aiming at a robustness improvement, this is combined with a feedback control law including an analytically tuned PI controller. However, although the control system performance is very good, it shows a dramatic performance decay when the network frequency value is not accurately known or changes in time. For a better assessment of this issue this Chapter shows the experimental behaviors under constant and varying network frequency. This performance degradation is also presented and analyzed in terms of the THD, PF and cosφ. The Chapter organization is as follows. Section 7.1 introduces the plant, the control objectives and the two hierarchical control loops. Section 7.2 shows the odd harmonic controller designed for constant network frequency, also analysing the performance degradation through the THD, PF and cosφ. Section 7.3 details the results for the varying sampling time repetitive controller including the stability analysis by means of robust control theory. It is worth to say that the stability analysis using the LMI approach introduced in Section 3.3 can not be applied in this implementation since the size of the resulting matrices makes the problem computationally unsolvable. Section 7.4 and Section 7.5 present the implementation of the adaptive pre-compensation scheme and the robust design respectively and, finally, a second order HORC is applied in Section 7.6.

关键词：控制器；并联有源；电力滤波器

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X-ray diffraction (XRD) is a powerful analysis method that allows researchers to noninvasively probe the crystalline structure of a material. This includes the ability to determine the crystalline phases present, quantify surface residual stresses, and measure the distribution of crystallographic orientations. The Structures and Materials Division at the NASA Glenn Research Center (GRC) heavily uses the on-site XRD lab to characterize advanced metal alloys, ceramics, and polymers. One of the x-ray diffractometers in the XRD lab (Bruker D8 Discover) uses three different x-ray tubes (Cu, Cr, and Mn) for optimal performance over numerous material types and various experimental techniques. This requires that the tubes be switched out and aligned between experiments. This alignment maximizes the x-ray tube s output through an iterative process involving four set screws. However, the output of the x-ray tube cannot be monitored during the adjustment process due to standard radiation safety engineering controls that prevent exposure to the x-ray beam when the diffractometer doors are open. Therefore, the adjustment process is a very tedious series of blind adjustments, each followed by measurement of the output beam using a PIN diode after the enclosure doors are shut. This process can take up to 4 hr to perform. This technical memorandum documents an in-house project to motorize this alignment process. Unlike a human, motors are not harmed by x-ray radiation of the energy range used in this instrument. Therefore, using motors to adjust the set screws will allow the researcher to monitor the x-ray tube s output while making interactive adjustments from outside the diffractometer. The motorized alignment system consists of four motors, a motor controller, and a hand-held user interface module. Our goal was to reduce the alignment time to less than 30 min. The time available was the 10-week span of the Lewis' Educational and Research Collaborative Internship Project (LERCIP) summer internship program and the budget goal was $1200. In this report, we will describe our motorization design and discuss the results of its implementation.

关键词：控制器；X射线衍射仪；机动光束对准

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Climate is a master controller of the structure, composition, and function of biotic communities, affecting them both directly, through physiological effects, and indirectly, by mediating biotic interactions and by influencing disturbance regimes. Sequoia and Kings Canyon National Parks (SEKIs) dramatic elevational changes in biotic communities -- from warm mediterranean to cold alpine -- are but one manifestation of climates overarching importance in shaping SEKIs landscape.

关键词：控制器；红杉和国王峡谷国家公园；自然资源条件评价

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This paper discusses the problem of robust H∞ control for a class of nonlinear uncertain singular systems with time delays.Considering the nonlinear disturbance link to uncertain singular systems with time delays effects,the design idea of robust H∞ controller is presented.Using Lyapunov stability theory and linear matrix inequality (LMI) method,a robust H∞ controller design example of such nonlinear uncertain singular systems with time delays both in state and output is given.Under nonlinear uncertain functions satisfying Lipschitz condition,a sufficient condition of such nonlinear uncertain singular systems which are asymptotically stable and satisfy the robust H∞ performance is obtained.Finally,a numerical example is given to show the applicability of the proposed method.

关键词：控制器；时滞；非线性；奇异系统

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Genetic Algorithm (GA) has been used in this chapter for a new approach of sub-optimal model reduction in the Nyquist plane and optimal time domain tuning of PID and fractional order (FO) PI~λD~μ controllers. Simulation studies show that the Nyquist based new model reduction technique outperforms the conventional H_2 norm based reduced parameter modeling technique. With the tuned controller parameters and reduced order model parameter data-set, optimum tuning rules have been developed with a test-bench of higher order processes via Genetic Programming (GP). The GP performs a symbolic regression on the reduced process parameters to evolve a tuning rule which provides the best analytical expression to map the data. The tuning rules are developed for a minimum time domain integral performance index described by weighted sum of error index and controller effort. From the reported Pareto optimal front of GP based optimal rule extraction technique a trade-off can be made between the complexity of the tuning formulae and the control performance. The efficacy of the single-gene and multi-gene GP based tuning rules has been compared with original GA based control performance for the PID and PI~λD~μ controllers, handling four different class of representative higher order processes. These rules are very useful for process control engineers as they inherit the power of the GA based tuning methodology, but can be easily calculated without the requirement for running the computationally intensive GA every time. Three dimensional plots of the required variation in PID/FOPID controller parameters with reduced process parameters have been shown as a guideline for the operator. Parametric robustness of the reported GP based tuning rules has also been shown with credible simulation examples.

关键词：控制器；模型降阶；进化算法；规则提取

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In many real world scenarios, the model of the controlled process changes over time. Clearly in such situations the parameters of the controller need to be adjusted to give an acceptable level of control system performance. Many adaptive control techniques exist to cope with such changes in system dynamics. Traditionally since PID controllers have been extensively used in industrial processes, the adaptation laws looked at changing the proportional, integral and derivative gains of the controllers. With the use of Fractional order PID controllers, both the gains and the differentiation and integration orders may be fine-tuned online, to achieve a better system performance. This chapter looks at integration of computational intelligence paradigms with fractional order adaptive control and the various advantages that this synergism can offer.

关键词：控制器；分数阶；增益调度；整序

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Solid-State Drives (SSDs) offer significant performance improvements over hard disk drives (HDD) on a number of workloads. The frequency of garbage collection (GC) activity is directly correlated with the pattern, frequency, and volume of write requests, and scheduling of GC is controlled by logic internal to the SSD. SSDs can exhibit significant performance degradations when garbage collection (GC) conflicts with an ongoing I/O request stream. When using SSDs in a RAID array, the lack of coordination of the local GC processes amplifies these performance degradations. No RAID controller or SSD available today has the technology to overcome this limitation. This paper presents Harmonia, a Global Garbage Collection (GGC) mechanism to improve response times and reduce performance variability for a RAID array of SSDs. Our proposal includes a high-level design of SSD-aware RAID controller and GGC-capable SSD devices, as well as algorithms to coordinate the global GC cycles. Our simulations show that this design improves response time and reduces performance variability for a wide variety of enterprise workloads. For bursty, write dominant workloads response time was improved by 69while performance variability was reduced by 71.

关键词：控制器；全球协调；垃圾收集器；固态硬盘阵列

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A novel double-loop control approach for reducing excess torque of the servo loading system based on disturbance observer is proposed.The mathematical model of the loading system is established by mechanism theory and the reasons causing the excess torque are analyzed,the nominal model and disturbance weighting function are determined based on an approximate method.Disturbance observer based the inner loop controller is designed by H∞ mixed sensitivity method and the external-loop controller is designed as the classical PID controller.Both the simulation and experiments results show that disturbance observer is feasible and effective to eliminate the excess torque,accuracy of the loading system is improved.

关键词：控制器；干扰观测器；电动伺服加载系统

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In this paper, the methodology for the design of fuzzy controllers for softcore processors, such as the Xilinx Microblaze embedded in the VIRTEX5 FPGA, is proposed to regulate the angular position of the axes of an experimental platform. The platform uses servomotors to control the rotational movements of the X-Y-Z axes, this with respect to the earth horizon. The angular position is feedback using three inclinometers sensors based on MEMS technology with SPI interface. The desired position is regulated using three independent fuzzy PD+I controllers, which use the error and change of error as input signals. The proposed methodology consists in the design and evaluation of the fuzzy controllers using the Fuzzy Logic Toolbox of Matlab.

关键词：控制器；FPGA；软核；模糊逻辑控制器

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A brushless DC (BLDC) motor achieves higher energy efficiency and endures less wear and tear than a traditional brushed DC motor due to the lack of friction between current coils and motor brushes; it requires additional control logic, however, often implemented using a microcontroller, to perform motor commutation. Standard drive circuitry consists of a rail voltage applied to a three-phase inverter and a pulse width modulated (PWM) signal applied to MOSFET gates in accordance with the commutation pattern. Typically, motor speed control is achieved by varying the pulse width applied to the gates while maintaining a fixed rail voltage. We implemented a proportional-integral (PI) feedback system to control motor speed while varying rail voltage. Using this PI controller, we examined the relationship between steady-state power consumption and rail voltage for a fixed reference, as well as the effect of variable rail voltage on transient controller response and total transient power consumption.

关键词：控制器；无刷直流电机；可变电压轨

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