1/spl phi/ 3W grid-connection PV power inverter with partial active power filter

This paper presents a single-phase three-wire (1/spl phi/ 3W) grid-connection photovoltaic (PV) power inverter with a of partial active power filter (PAPF) feature, which can not only deal with PV power but filter current harmonics and improve power factor. Once the processed power exceeds the switch ratings, the inverter can reduce its output reactive power and harmonic power, while still supplying the maximum real power generated by the PV arrays. In the derivation of control laws, a limit circle is defined to confine the output power of the inverter. To determine the power that the inverter can process, the instantaneous reactive power of a 1/spl phi/ 3W system is defined and used to calculate reactive power, which can avoid complex detections of phase angle and magnitude of the fundamental component of a nonlinear load current. Simulation results and experimental measurements have verified the proposed algorithm and the feasibility of the inverter.     

Three-phase single-stage ac/dc boost integrated series resonant converter

A new ac/dc 3-/spl phi/ single-stage converter is proposed integrating a 3-/spl phi/ discontinuous current mode (DCM) boost with a dc/dc fixed frequency series resonant converter (SRC). This converter has the following features: natural power factor correction, soft switching, high-frequency (HF) transformer isolation with the series resonant tank operating in above resonance mode, etc. A new complementary gating control scheme is used for simultaneous control of boost converter and the SRC. Modes of operation are presented and analyzed. Based on the analysis, design curves are obtained. An optimum design is given and a design example is presented. Results obtained from SPICE simulation for the designed converter are given to verify the performance of the proposed converter for varying load as well as line voltage. Experimental results obtained from a laboratory prototype converter are presented to verify the theory.     

High-frequency AC power distribution in Space Station

A utility-type, 20-kHz, AC power distribution system for the space station employing resonant power-conversion techniques is presented. The system converts raw DC voltage from photovoltaic cells or three-phase, low-frequency AC voltage from a solar dynamic generator into a regulated, 20-G kHz AC voltage for distribution among various loads. Operations of the components of the system such as driver inverter, DC receiver, bidirectional receiver, and three-phase AC receiver are discussed. EASY5 computer modeling and simulations were performed to study the local and global performance of the system. Simulation results show that the system has fast response and good transient behavior. The AC bus voltage is effectively regulated using the phase-control scheme, which is demonstrated with both line and load variations. The feasibility of paralleling the outputs of driver modules is illustrated with the driver modules synchronized and sharing a common feedback loop. A high-frequency, sinusoidal AC voltage is generated in the three-phase, AC input case, when the driver modules are phased 120° away from one another and their outputs are connected in series     

Soft-switching single-stage AC-to-DC converter with low harmonic distortion

A 1 /spl phi/ high-frequency (HF) transformer isolated, soft-switching single-stage ac-dc converter with low line-current harmonic distortion is presented. Its operation is explained with equivalent circuits for the various intervals. The converter is analyzed and design curves are obtained. An optimization parameter is introduced and a systematic design procedure is illustrated with a design example. Detailed SPICE simulation and experimental results of a 500 W converter with load as well as line voltage variation are given to verify theory. The proposed converter employs a zero-voltage transition (ZVT) network to ensure zero-voltage switching (ZVS) at all loads, and natural power factor correction is ensured using a simple control circuit.     

Optimal number of phased array faces and signal processors for horizon surveillance

The problem of the optimal number of phased array faces for performing 360/spl deg/ horizon surveillance is considered. Assuming the detection performance is the same in all beam positions and the total number of T/R modules is constant, it is shown that the optimal number of array faces is three. This is true whether the arrays are operating simultaneously or sequentially. A parametric analysis is performed between the number of array faces operating simultaneously and the associated cost of simultaneous operation in terms of the size of the array.     

JBYQC软件设计关键问题

 <正> 1.问题的提出 JBYQC是卫星壳体结构优化设计人机交互式软件。软件适用机型为IBM-PC/AT或XT型微机,操作系统为DOS Version 3.00,该软件很适合在设计室中使用,并极易推广。 JBYQC是商品软件,对结构优化设计来讲,图文并茂的交互式屏幕是必须的,因此,交互式屏幕怎样设计,就成了第一个关键问题。     

Tests of a full-sized mechanically rechargeable zinc-air battery inan electric vehicle

A mechanically rechargeable zinc-air battery that has high power density and fast refueling capability is described. The battery is built from modules of 32 or 44 cells connected in series, and the modules can be arranged in any combination of series and parallel connections, and in practical quantity, according to the requirements of the vehicle, motor, and controller. The results of laboratory and in-vehicle tests of a zinc-air battery consisting of two 32-cell modules connected in series, with nominal voltage of 75 V and nominal capacity of 216 Ah, are presented     

程控三相中频电源的研制

全面分析了三相程控中频电源的原理,深入讨论了其信号源电路、功率放大电路以及接口控制电路的实现方法,提出了三相程控中频电源的详细设计方案.     

Implementation of nondeterministic pulsewidth modulation forinverter drives

A single-phase power factor preregulator to improve the power quality in the input side of an ac/dc/ac converter and a random pulsewidth modulation (PWM) to reduce the emitted noise energy and the mechanical vibration for an induction motor drive is proposed. The hysteresis current control (HCC) technique for a voltage source switching mode rectifier (SMR) is adopted. A control scheme is presented such that the line current is driven to follow the reference current which is derived from the dc bus voltage regulator and the output power estimator. A random pulse position technique for a three-phase voltage source inverter system to reduce the noise energy and resonant vibration from ac machine drive is described. By randomly varying the instantaneous pulse position in each switching frequency, the frequency distribution of harmonics is spread in a wide frequency range which results in reduction of torque pulsations in the ac motor drive systems. To investigate the proposed control scheme, experimental tests based on a laboratory prototype were implemented to show the nearly unity power factor at the SMR and reduce the noise energy concentrated at the specific tones     

Optimizing Murty's ranked assignment method

We describe an implementation of an algorithm due to Murty for determining a ranked set of solutions to assignment problems. The intended use of the algorithm is in the context of multitarget tracking, where it has been shown that real-time multitarget tracking is feasible for some problems, but many other uses of the algorithm are also possible. The following three optimizations are discussed: (1) inheriting dual variables and partial solutions during partitioning, (2) sorting subproblems by lower cost bounds before solving, and (3) partitioning in an optimized order. When used to find the 100 best solutions to random 100/spl times/100 assignment problems, these optimizations produce a speedup of over a factor of 20, finding all 100 solutions in about 0.6 s. For a random cost matrix, the average time complexity for finding k solutions to random N/spl times/N problems appears to be nearly linear in both k and N, for sufficiently large k.     

Transient Analysis of the Rectified Superconducting Alternator

A set of five differential equations is derived to describe the transient electrical behavior of a three-phase superconducting alternator connected to a full-wave thyristor bridge. The approximation of constant flux linkages for the rotor circuits is utilized to reduce the number of numerical integrations from five to two. This produces a very efficient algorithm that is quite useful for studies requiring a large number of simulations. Numerical results based on the parameters of a 10-MVA superconducting machine are included.     

Nullifying ACF grating lobes in stepped-frequency train of LFM pulses

An effective way to increase the bandwidth of a coherent pulse-train is to add a frequency step /spl Delta/f between consecutive pulses. A large /spl Delta/f implies a large total bandwidth, hence improved range resolution. However, when the product of the frequency step times the pulse-duration t/sub p/, is larger than one (t/sub p/ /spl Delta/f > 1), the autocorrelation function (ACF) of the stepped-frequency pulse-train suffers from ambiguous peaks, known as "grating lobes." It is well known that replacing the fixed-frequency pulses with linear FM (LFM) pulses of bandwidth B can reduce those grating lobes. We present a simple analytic expression for the ambiguity function (AF) and ACF of such a signal and derive from it very simple relationships between /spl Delta/f, B, and t/sub p/ that will place s exactly where the grating lobes are located, and thus remove them completely.     

Modified Costas signal

A modification to the Costas signal is suggested. It involves an increase of the frequency separation /spl Delta/f beyond the inverse of the subpulse duration t/sub b/ combined with adding linear FM (LFM) with bandwidth B, in each subpulse. Specific relationships between /spl Delta/f and B will prevent autocorrelation grating lobes, that would normally appear when t/sub b//spl Delta/f>1.     

Explicit formulas for two state Kalman, H/sub 2/ and H/sub /spl infin// target tracking filters

The continuous time, two state, target tracking problem is considered from the Kalman, H/sub 2/, and H/sub /spl infin// filter viewpoint. While previous treatments were numerical in nature, analytic transient responses and infinite horizon solutions with analytic performance expressions are presented here. Tracking indices, involving the maneuver and measurement uncertainties, are shown to have a role for both the steady state and transient responses. In addition, the H/sub /spl infin// tracker has a sensor index involving the performance bound and measurement uncertainty, which, along with the tracking index, plays a significant role in the H/sub /spl infin// tracker expressions. Analytical expressions for the probability of target escape, the probability that the target position will be outside the radar beamwidth (BW), are developed not only to compare the performance of various trackers, but also as a design tool to meet tracking specifications. Examples illustrate the performance of the target trackers as a function of the error gain upper bound.     

Mixed H/sub 2//H/sub /spl infin// filtering for uncertain systems with regional pole assignment

The mixed H/sub 2//H/sub /spl infin// filtering problem for uncertain linear continuous-time systems with regional pole assignment is considered. The purpose of the problem is to design an uncertainty-independent filter such that, for all admissible parameter uncertainties, the following filtering requirements are simultaneously satisfied: 1) the filtering process is asymptotically stable; 2) the poles of the filtering matrix are located inside a prescribed region that compasses the vertical strips, horizontal strips, disks, or conic sectors; 3) both the H/sub 2/ norm and the H/sub /spl infin// norm on the respective transfer functions are not more than the specified upper bound constraints. We establish a general framework to solve the addressed multiobjective filtering problem completely. In particular, we derive necessary and sufficient conditions for the solvability of the problem in terms of a set of feasible linear matrix inequalities (LMIs). An illustrative example is given to illustrate the design procedures and performances of the proposed method.     

PCM/FM aeronautical telemetry in frequency selective multipath interference

The performance of PCM/FM using a delay-line detector in multipath interference is analyzed. In aeronautical telemetry applications, the multipath interference causes a in the signal spectrum which is web modeled by a channel composed of a line-of-sight signal and a strong specular reflection with magnitude /spl Gamma/ and excess delay less than a bit time. Analysis shows that the bit error probability is strongly dependent on the location of the within the spectrum. The bit error probability averaged over the location is also analyzed. For the case of no predetection filtering, the average bit error probability is dependent on the depth of the but not on the width. The loss in performance (relative to the AWGN environment) is bounded by (1-/spl Gamma/)/sup -2/ which is the depth of the . For the case of predetection filtering, the average bit error probability is dependent on both the width and depth of the . The performance loss is bounded by (1-/spl Gamma/)/sup -2/spl Gamma// which is less than that for the case of no predetection filtering.     

Hybrid discriminative/class-specific classifiers for narrowband signals

The class-specific (CS) method of signal classification operates by computing low-dimensional feature sets defined for each signal class of interest. By computing separate feature sets tailored to each class, i.e., CS features, the CS method avoids estimating probability distributions in a high-dimension feature space common to all classes. Building a CS classifier amounts to designing feature extraction modules for each class of interest. In this paper we present the design of three CS modules used to form a CS classifier for narrowband signals of finite duration. A general module for narrowband signals based on a narrowband tracker is described. The only assumptions this module makes regarding the time evolution of the signal spectrum are: (1) one or more narrowband lines are present, and (2) the lines wandered either not at all, e.g., CW signal, or with a purpose, e.g., swept FM signal. The other two modules are suited for specific classes of waveforms and assume some a priori knowledge of the signal is available from training data. For in situ training, the tracker-based module can be used to detect as yet unobserved waveforms and classify them into general categories, for example short CW, long CW, fast FM, slow FM, etc. Waveform-specific class-models can then be designed using these waveforms for training. Classification results are presented comparing the performance of a probabilistic conventional classifier with that of a CS classifier built from general modules and a CS classifier built from waveform-specific modules. Results are also presented for hybrid discriminative/generative versions of the classifiers to illustrate the performance gains attainable in using a hybrid over a generative classifier alone.     

Surveillance system based on data fusion from image and acousticarray sensors

The present publication shows a model of a monitoring system of high benefit, based on two complementary sensorial systems (image+acoustics), which allows the information received to fuse, and to prioritize the computational resources toward the zones with considerable risk. The application uses components such as: active acoustic radar based on a phase array of microphones, with techniques of beamforming, and multibeam detection schemes; efficient compression algorithms and video transmission in real time. The system is composed of an arbitrary number of sensors (monitoring probes), distributed by the monitoring space, a data network and a central server (monitoring manager). The sensors consist of a microprocessor, with its memory and three main modules: (1) acoustic radar; (2) video capture card; and (3) network card. The flexibility of the system allows new modules to be added such as: personal detector card; sound card; cards for telecontrol; etc. The sensor microprocessor preprocesses the information received by the modules, packs and transmits it to the central server through a data network. The system uses IP protocol, and SNMPv2 for management     

可重构模块化机器人的构形设计

本文对模块机器人的结构进行了研究。并归纳出6种模块，其中包括3种关节模块。2种连杆模块和1种基座模块，同时还对3个自由度模块机器人的结构进行了设计。     

An alternative to traditional software rehosting

This paper describes one alternative to rehosting TPS software to newer computer platforms. It describes the solution that Southwest Research Institute (SwRI) used to solve a problem with re-engineering legacy software into a modern object-oriented language. The advantages gained by this method are more advanced instruction to the operator (such as pictures and movies), flexible reporting scheme to diagnose system problems, and ease of software maintenance. This solution uses commercially available products including National Instruments/spl trade/ TestStand/spl trade/ and LabVIEW/spl trade/ and Microsoft/spl reg/ Visual Basic/spl reg/. The system is a four-tiered architecture to drive all test execution. The user interface is written in Visual Basic and allows the user to interact with the test execution when needed. This user interface in turn calls tests that are written in TestStand, and finally the individual tests call driver functions written in LabVIEW. A database serves as a repository for all test results, displays, and test limits. The use of this database allows for easy querying of measurement data to analyze trends in failures that help diagnose specific problems. By using this database, all test limits and test displays are contained in one central location that enables engineers to change these displays and limits on the fly without needing to change or even understand any test code. One other benefit of this data containment is that all Government classified data is separated out of the code and stored as one file, instead of in various locations as it was in the original source code.