Ti:LiNbO/sub 3/ digital optical switch matrices

Optical switch matrices were implemented using low drive voltage digital optical switches as switching elements. A drive voltage of 25 V for polarisation independent operation was achieved in a 4*4 switch. An 8*8 switch with low drive voltage could be achieved by assigning the proper lengths for switching elements.<>     

A novel CSI-fed induction motor drive

Current source inverter (CSI) fed drives are employed in high power applications. The conventional CSI drives suffer from drawbacks such as harmonic resonance, unstable operation at low speed ranges, and torque pulsation. This paper presents a novel CSI drive which overcomes all these drawbacks and results in sinusoidal motor voltage and current even with CSI switching at fundamental frequency. The proposed CSI drive uses a three-level inverter as an active filter across motor terminals replacing the bulky ac capacitors used in the conventional drive. A sensorless vector controlled CSI drive based on proposed configuration is developed. The simulation and experimental results are presented. Experimental results show that the proposed drive has stable operation even at low speeds. Comparative results show that the proposed CSI drive has improved torque ripple compared to the conventional configuration.     

四元组350MHz24V放大器AD8024

AD8024是美国模拟器公司（ADI）生产的一种四元组350MHZ的放大器，它具有低稳定时间，高速和高输出电压，且有低的电源电压，可驱动高电容性负载，主要在LCD驱动，高性能测试仪使用，外部不需要其它元件，本文详细介绍了该芯片的内部结构原理以及应用设计。     

A resonant MOSFET gate driver with efficient energy recovery

High frequency pulse-width modulation (PWM) converters generally suffer from excessive gate drive loss. This paper presents a resonant gate drive circuit that features efficient energy recovery at both charging and discharging transitions. Following a brief introduction of metal oxide semiconductor field effect transistor (MOSFET) gate drive loss, this paper discusses the gate drive requirements for high frequency PWM applications and common shortcomings of existing resonant gate drive techniques. To overcome the apparent disparity, a new resonant MOSFET gate drive circuit is then presented. The new circuit produces low gate drive loss, fast switching speed, clamped gate voltages, immunity to false trigger and has no limitation on the duty cycle. Experimental results further verify its functionality.     

Low Cost Gate Drive Circuit for MOSFETs and IGBTs

This work presents the design and implementation of a general purpose low cost drive circuit for insulated gate electronic power devices such as MOSFET and IGBT. The proposed drive circuit implementation is explained in detail and the results and waveforms obtained when the drive circuit is used in a chopper circuit with IGBT are presented.     

Low switching frequency and high dynamic pulsewidth modulationbased on field-orientation for high-power inverter drive

In megawatt-rated inverter-fed induction motor drive systems, the gate-turn-off switching losses account for a considerable amount of the total losses, hence, the switching frequency in such systems must be kept at a low value of only a few hundred hertz. To avoid undesired torque harmonics under such operating conditions, the pulse control of the inverter is made dependent on the orientation of the rotor flux of the drive machine. This method transfers a major portion of the unavoidable current distortions into the field axis where they have no influence on the machine torque. An optimal trajectory-oriented control is presented that achieves low switching frequency at low torque and current harmonics and exhibits a very fast dynamic response. The performance of this method is demonstrated by measured results from a 30-kW model drive     

Optical drive requirements for laser-activated semiconductor switches

Laser-activated semiconductor switch (LASS) devices of the thyristor type exhibit three regimes of operation. At low optical drive, optical triggering is obtained with delay time before conduction and relatively low current rise rates. At intermediate drive levels, fast switching is obtained with no appreciable delay time and fast current rise rates (greater than 10⁹A/s) but with substantial power lost in the switch element. At higher optical drives, saturated switching is observed with the rise rate and power loss relatively independent of the optical drive level. LASS thyristors of 1- and 4-kV operating voltage ratings have been characterized in the lossy fast switching regime. For pulses of 100-ns duration, the devices act as resistive elements. The magnitude of the resistance varies inversely with the optical drive, and can be understood as conductivity modulation of the conduction path by the photogenerated carriers. Such characterization allows switch system design tradeoff between the required optical drive level and the tolerable power loss in the switch elements.     

Sensorlose Drehzahl- und Lageregelung von Permanentmagnet-Synchronmaschinen auf Basis des INFORM-Verfahrens

This paper deals with the operation of permanent magnet synchronous motors without speed- and position sensors in speed- and position-controlled drive applications. Starting from classical field-oriented control methods, a speed-sensorless drive is presented. The basic idea is to estimate the actual speed and position of the drive by means of the INFORM method (low speed and standstill) and EMF-based models (high speed). Measurements on a position-controlled industrial system verify the high quality of the sensorless system which reduces the hardware costs of the drive and increases the reliability by eliminating mechanical components.     

基于PMOS自适应输入输出低压白光LED驱动

白光LED是最被看好的新兴光源产品,其在照明市场的发展潜力值得期待。白光LED具有体积小、发热量低、耗电量小、寿命长、反应速度快、环保、可平面封装易开发成轻薄短小产品等优点。在小功率白光LED驱动电路中,电池（一节电池）供电已经成为一种趋势。在基于标准CMOS工艺条件下,设计了一个可以使用一节电池供电、外围器件极少、无需输出电容、脉冲驱动的白光LED驱动电路,并可以随输入电压不同自适应调节工作状态,适合中小电流条件下白光LED背光照明应用中。     

电荷驱动在高速压电致动平台中的应用

一个高速压电驱动平台的性能经常被支撑结构的低谐振频率所限制。采用一种非对称致动器可消除传到基座上的惯性力,但传统的电压驱动方法会引起严重的率相关迟滞,惯性力补偿效果不佳。该文提出采用电荷驱动法来消除非对称致动器产生的惯性力。实验表明,在激励电压峰-峰值为20V时,采用电荷驱动法,在110Hz~10kHz内惯性力基本消除,补偿效果比电压驱动方法好。     

High-speed bulk InGaAsP-InP electroabsorption modulators withbandwidth in excess of 20 GHz

Bulk InGaAsP-InP electroabsorption optical modulators with high extinction ratio, low drive voltage, and high modulation bandwidth at λ=1.3 μm are reported. The devices have a tapered-fiber-to-modulator-to-tapered-fiber extinction ratio greater than 20 dB at a drive voltage of <5 V. Very low capacitance modulators (<0.2 pF) were fabricated using SiO₂ bonding pad isolation, resulting in a measured electrical modulation bandwidth in excess of 20 GHz     

基于路测数据的TD-SCDMA网络室外传播模型校正研究

无线传播模型是用来对无线电波的传播特性进行预测的一种模型。传播特性的预测是无线网络规划的基础,其准确性影响到网络规划的准确性和质量。本文针对连续波测试传播模型校正方法所存在的低效率和低准确性等问题,提出了一种利用现网路测数据进行传播模型校正的方法,从理论上证明了路测信号可以替代连续波测试信号用于传播模型校正。本文使用校正的传播模型是SPM模型。     

一种低功耗三相无刷电机驱动控制器的设计

介绍了一种基于数字信号逻辑运算理论的低功耗三相无刷电机驱动控制器。调速PWM信号、换向逻辑、霍尔位置信号等输入信号经运算处理后,产生6路与电机换相顺序相对应的控制信号,用来控制三相全桥驱动电机负载。该驱动控制器具有静态电流小、输出电流大、抗干扰能力强、集成过流保护等特点,可广泛应用于三相电机控制、伺服电机驱动、万向节控制等领域。     

基于反电势线性拟合的无霍尔BLDC驱动方法

对于以反电势过零点判断来控制无感直流无刷电机的方案,在驱动的低速阶段,由于反电动势值过小,难以准确地检测过零点,针对该问题,提出一种新的低速反电势过零检测方法。该方法在低速采用线性拟合代替硬件判断反电势过零点,并在PWM_OFF时刻进行反电势采样,提高了低速阶段的控制性能,通过Matlab的Simulink仿真证明该方案切实可行。     

1.3-μ m InGaAlAs Short-Cavity DBR Lasers for Uncooled 10-Gb/s Operation With Low Drive Current

We present a novel 1.3-mum laser, a short-cavity distributed-Bragg-reflector (DBR) laser that enables uncooled, 10-Gb/s operation with low drive currents. The laser consists of a short InGaAlAs multiple-quantum-well active region butt-jointed to an InGaAsP-DBR region. A fabricated laser with a 75-mum active region demonstrated 100 degC, 10-Gb/s operation at a record low drive current of 14-mA peak-to-peak (mA_p-p) with an average output power of -3 dBm     

An Ultrahigh-Speed, Low Power Electrical Drive System

New emerging applications in the areas of portable power generation, small turbocompressors and spindles require the development of ultrahigh-speed, low power electrical drives. A 500 000 r/min, 100 W electrical drive system is presented. Because of the ultrahigh-speed requirements, standard machine design and power electronic topology choices no longer apply and the complete drive system has to be considered. A permanent magnet machine with a slotless litz-wire winding is used, which results in a low motor inductance and a high fundamental machine frequency. Three different combinations of power electronic topologies and commutation strategies have been experimentally investigated. A voltage source inverter with block commutation and an additional dc-dc converter is selected as the most optimal choice for the power electronics interface as it results in the lowest volume of the entire drive system due to lower switching losses, no heat sink cooling required, a small number of semiconductor devices, and relatively simple control implementation in a low cost digital signal processor.     

迫弹激光引信用脉冲半导体激光电源的设计与应用

设计了适应于迫弹激光近炸引信的小体积、低电压、窄脉宽、高功率的脉冲半导体激光电源.采用电容充放电的模式,选用高速大功率MOSFET管作为开关,设计了相应的高速开关控制电路.激光电源模块的重复频率高达50kHz,常规热电池供电电压条件下的输出脉冲激光峰值功率为9W,光脉冲上升沿为4.2 ns,光脉宽为10 ns,为有效提...     

一种低压驱动TFT液晶显示屏的方法

介绍了一种低压驱动 Ｔ Ｆ Ｔ 液晶屏的方法。它是通过变化每行的公共电压来实现的。数据驱动器的输出电压最高只须 ５ Ｖ, 从而使 Ｌ Ｓ Ｉ数据驱动器的尺寸可以做得更小, 功耗也更低。     

Steady-state and transient performance evaluation of a DTC schemein the low speed range

In this paper, a direct flux and torque control scheme for industrial application is analyzed in order to emphasis the drive performance at standstill and in the low speed range. The control strategy utilizes the torque and rotor flux commands to determine the reference value of the stator flux. In order to improve the low speed performance a closed loop estimator is employed to evaluate the rotor flux. The validity of the control scheme is verified by simulations and experimental tests of an induction motor drive system     

角锥棱镜相干合成激光器的自适应驱动方法

针对高功率激光器合成效率低、能量不集中的问题,构建基于角锥棱镜腔的相干合成激光器,分析远场合成效率不高的原因,提出光—电闭环的自适应驱动方法,通过反馈调节,克服因线路、器件以及其他电磁干扰等因素造成的不同步问题,提高相干合成效率。实验结果表明,经过自适应驱动的激光器,能显著提高相干合成效率,避免人工调整参数带来的误差,提高了激光器的稳定性和工作效率。