新颖的软启动电路设计及其在蓝牙功放中的应用

为了有效控制蓝牙功率放大器的功率控制电路启动时所产生的浪涌电流,设计出了一个新颖的软启动电路.该电路可控制功率控制电路的浪涌电流上升斜率和峰值,使得功率控制电路的输出电流线性上升,并成功应用于蓝牙功率放大器电源管理中.基于TSMC 0.18μm工艺,Spectre仿真表明,浪涌电流的峰值被控制为520 mA,上升斜率被控制为40mA/μs,实现软启动.该电路并能根据不同应用系统的要求,方便地设置浪涌电流上升斜率和峰值.     

A variational principle for nonconservative power systems

Recent results for nonconservative dynamical systems involve a variational principle of the Hamilton type. In this approach the velocity of variation and the variation of velocity are not commutative as in the case of mechanics governing conservative dynamical systems. In this paper we adapt the above approach to power systems which include the effects of transfer conductances. For such power systems we show that if certain noncommutative rules (which are consistent with the ones used for the variation of velocities in nonconservative dynamical systems) are used, then it is possible to employ a variational principle of the Hamilton type to derive the classical model for power systems. Numerous simulations of specific postfault multimachine power systems have verified that the above noncommutative rules are indeed satisfied for the types of power systems which we consider.The present results give additional understanding for the types of energy functions that have recently been used in transient stability studies of power systems. In these works, several attributes of energy functions have been ascertained by means of simulations and heuristic reasoning, rather than analysis (e.g., path-dependent terms of energy functions have been approximated by making linear trajectory assumptions).The work of the first author was supported by the National Science Foundation under Grant No. ECS84-51091. The work of the second author was supported by the National Science Foundation under Grant No. ECS84-19918.     

A novel active power filter for reactive power compensation and harmonic suppression

A new single-phase active power filter for reactive power compensation and harmonic suppression is proposed. Besides the general performance of other active power filters, it also has the feature that it can maintain the mains current as a sine-wave and correct the displacement power factor close to unity even when the mains voltage is distorted. A prototype of this active power filter is developed and tested under rectifier load to verify its performance. The test results show that the proposed scheme can compensate the reactive power and suppress harmonics of the nonlinear load effectively.     

STC12C5412单片机及其在简易无功控制器中的应用

介绍了STC12C5412单片机及其特点,在此基础上,针对分散无功补偿的低成本要求,利用STC12C5412单片机设计一款简易无功控制器,论述了控制器的硬件结构、工作原理及软件设计.现场运行证实该控制器具有高可靠性低成本的优点,能够满足分散无功补偿的控制要求.     

A novel high power self-commutated static var compensator for load compensation

A novel high power self-commutated static var compensator for load compensation is proposed. The harmonics are eliminated by combining low frequency high power devices and high frequency low power devices. A modified control strategy is also proposed for applications involving high and faster rates of change in var demand. Detailed simulation studies for single phase and three phase topologies are presented.     

A novel current limitation principle basedon application of liquid metals

In this paper, a new current limiting principle based on the application of liquid metals is proposed. This principle takes advantage of the arcless commutation of currents to a gradually increasing parallel resistance and makes it possible to realize a current-controlled resistor for very high currents, which can be used to limit the fault currents in power networks. The conditions for the arcless current commutation are investigated theoretically and the optimum profile for the parallel resistor is derived. An experimental setup is constructed to investigate the behavior of the separating contacts under different current amplitudes, different current steepnesses, and different resistance profiles. The experimental results relating to the commutation phase are compared to the theoretical limits.     

Neural-network-based fuzzy model and its application to transientstability prediction in power systems

We present a general approach to deriving a new type of neural network-based fuzzy model for a complex system from numerical and/or linguistic information. To efficiently identify the structure and the parameters of the new fuzzy model, we first partition the output space instead of the input space. As a result, the input space itself induces corresponding partitions within each of which inputs would have similar outputs. Then we use a set of hyperrectangles to fit the partitions of the input space. Consequently, the premise of an implication in the new type of fuzzy rule is represented by a hyperrectangle and the consequence is represented by a fuzzy singleton. A novel two-layer fuzzy hyperrectangular composite neural network (FHRCNN) can be shown to be computationally equivalent to such a special fuzzy model. The process of presenting input data to each hidden node in a FHRCNN is equivalent to firing a fuzzy rule. An efficient learning algorithm was developed to adjust the weights of an FHRCNN. Finally, we apply FHRCNNs to provide real-time transient stability prediction for use with high-speed control in power systems. From simulation tests on the IEEE 39-bus system, it reveals that the proposed novel FHRCNN can yield a much better performance than that of conventional multilayer perceptrons (MLP's) in terms of computational burden and classification rate     

Time delay compensation in power controlled cellular radio systems

Transmission power control is an important means to manage the radio resources in wireless communications. The performance, however may be reduced due to time delays as in any controlled system. Most controllers to date are designed without considering time delays, which may result in oscillatory or unstable systems. To overcome these problems, time delay compensation (TDC) is introduced. The main idea is to adjust the measurements [e.g., signal-to-interference ratio (SIR)] to include the effects of issued but not yet applied power control commands. TDC thereby improves the stability and performance of an arbitrary power control algorithm. The benefits are illustrated by simulations using some popular power control algorithms     

A novel digital compensation technique for current bias without additional power consumption

A new digital compensation technique is proposed for current reference. The current variations induced by deviations of temperature and process are calibrated through a digital method. The circuit structure is simplified, and the problem of instability in conventional analog current bias can be overcome since the digital part cut off the closed compensation loop. Designed with 0.18 μm CMOS technology, the output current can be calibrated to 100 μA with a maximum error of ±0.3 μA under all the process corners, no matter how the temperature changes in an ultra-wide range of ?116 to 160 °C. In addition, the current precision can be maintained as the load voltage varies in the range of 0.31–1.04 V, and the load sensitivity is about 8,000 ppm/V. The digital part can be shut down after the calibration phase, so no additional power will be consumed except the bias itself.     

A novel active power filter based on the least compensation currentcontrol method

A new least compensation current technique to detect the harmonic and reactive current for active power filters is presented in this paper. With the technique, a novel active power filter based on the least compensated current control is proposed, in which the measurement of harmonic and reactive current and the generation of compensated current are completed in the same closed-loop. Compared with the existing control methods of active power filter, the proposed method has simpler structure, quicker dynamic, higher reliability and better compensation performance. Simulating and experimental results are provided that verified theoretical predictions and demonstrate the effectiveness of the proposed control method and circuit configuration     

Instantaneous power compensation in three-phase systems by using p-q-r theory

This paper proposes a novel power compensation algorithm in three-phase four-wire systems by using p-q-r theory. The p-q-r theory is compared with two previous instantaneous power theories, p-q theory and cross vector theory. The p-q-r theory provides two-degrees of freedom to control the system currents by only compensating the instantaneous imaginary power without using any energy storage element. The definition of powers maintains power conservation, and agrees well with the general understanding of power. Simulation results show the superiority of p-q-r theory both in definition and compensation.     

数据流的技术原理及其在电视台的应用

介绍了数据流的工作原理,相对应的压缩格式及传输协议,数据流网络系统的优异性能和目前的市场状况,并以深圳电视台为实例,阐述了构建电视台数据流一体化网络系统的解决方案。     

A new image flux conduction model and its application to selectiveimage smoothing

A discrete image flux conduction equation which is completely new in this field is proposed. The new approach starts with formulating a discrete image flux conduction equation based on the concept of heat conduction theory. Based on this discrete equation, the status change at a time point can be directly computed from its spatial neighborhood. To more accurately estimate an image flux, we have used an orthogonal wavelet basis to approximate the gradient of the intensity at each point. Since the proposed approach is discrete by nature, it is not necessary to formulate a continuous PDE to fit the discrete image data set. Furthermore, introduction of different numerical methods to solve the PDE can also be avoided. Since the proposed approach does not require that a PDE be solved, it is therefore more efficient and accurate than the conventional methods. Experimental results obtained using both synthetic signals and real images have demonstrated that the proposed model could effectively handle the selective image smoothing problem.     

A novel detection criterion for weak m-ary signals and its application to ultrawideband multiple access systems

In this paper, we propose a novel criterion for the detection of weak m-ary signals. In the sense of minimizing the error probability, the proposed criterion is optimal when the signal strength approaches zero. Based on the proposed criterion, a detection scheme for ultrawideband multiple access systems is proposed and analyzed in the presence of impulsive interference. Numerical results show that the proposed detector requires less complexity than, and possesses almost the same performance as, the maximum likelihood detector. In impulsive interference, the proposed detector also offers significant performance improvement over the detector optimized for a Gaussian environment.     

A novel circuit for dead angle compensation in the DC-to-DCconverter controlled by a magnetic amplifier

A novel circuit for compensating the dead angle in the DC-to-DC converter controlled by a magnetic amplifier is presented. The proposed circuit suppresses the dead angle so that the core loss may be reduced. The behavior of this circuit is explained analytically and a condition for compensation is derived theoretically. By adding this compensation circuit, excellent control characteristics of the converter are obtained without spoiling the current surge suppression characteristics of the magnetic amplifier     

串行A/D转换器MAX186原理及其应用

介绍了MAXIM公司的12位串行A/D模数转换器MAX18×系列的原理。给出了MAX186同8051单片机的接口及相应的软件程序及其在烟气分析仪中的应用。     

Analysis of power losses for instantaneous compensation of three-phase four-wire systems

This paper deals with the effect that the instantaneous compensation in three-phase four-wire systems, including or not the compensation of the neutral current, has on the supply line power losses. Thus, for three-phase circuits, the instantaneous compensation criterion has been established based on the instantaneous power theory. According to the instantaneous value concept the noninstantaneous power current is reduced, without altering the instantaneous active power. Two approaches are marked in this paper for instantaneous compensation: the first one is for eliminating the total noninstantaneous power current but the neutral current can still flow. The second one for eliminating the modified noninstantaneous power current, thus the neutral current component is compensated. It demonstrates that, in common situations of medium and low relative-values of the zero-sequence voltage, the total losses (line and neutral losses) obtained with the second approach are lower than those obtained with the first approach. The same results are obtained when a criterion based on the average value concept is used. Simulated and experimental results are obtained to confirm the theoretical properties and to show the compensator performance.     

OFDM在长距离光传输系统色散补偿中的应用

为了降低光纤长距离传输中电域色散补偿(EDC,Electronic Dispersion Compensation)的实现复杂度,采用正交频分复用技术(OFDM,Orthogonal Frequency Division Multiplexing)与光单边带调制(OSSB,Optical Single Sideband),可有效实现光纤的色散补偿。文章介绍了基于光直接检测(DD,Direct-Detection)的OFDM系统,重点对系统色散补偿的实现进行了具体的数学分析,并进行了数字仿真,就系统误码率(BER)与传统光传输系统(NRZ,Non-Return-to-Zero)进行了比较。结果表明,较传统光传输中电域色散补偿,基于光直接检测的OFDM系统色散补偿实现简单,系统复杂度降低,同时也提高了系统性能。     

Interval-analysis techniques in linear systems: An application in power systems

In this paper we apply the technique of interval analysis to get bounds on the initial value response of a linearized single machine infinite bus problem when a parameter is varied. It is generally believed that responses for parameter variations in an interval should lie within the responses for the extremums of the parameter variations. This is not generally true and our example demonstrates this. The interval-analysis technique permits getting the overall bound on the response. Further experimentation also revealed that the method has some limitations particularly involving lightly damped long-term dynamics.The technique is useful in finding the robustness of a particular design such as the power system stabilizer for parameter variations.The work of M. A. Pai and C. Kulig was supported by NSF Grant ECS 87-19055 and NSF Grant ECS 87-19055 REU, respectively. The work of A. N. Michel and H. F. Sun was supported by NSF Grant ECS 88-02924.     

DSP应用系统的电源设计

本文主要介绍了TI公司TMS320C6000系列芯片的供电系统设计。整个系统采用单5V电源供电,用高效率的同步电压转换芯片提供稳定的DSP内核电压(1.9V)和周边I/O接口电压(3.3V),同时巧妙地解决了两种供电的顺序问题,并增设了电源监控和复位电路,可以同时监测5V、3.3V和1.9V,确保供电系统稳定、高效地工作。