手电的灵魂——发光体

提到手电首先要说的就是发光体。它可以说是手电的核心部件了,现在的手电主要也是通过发光体来进行区分的。白炽灯发光效率太低,HID（氙气灯）要采用安定器,启动时需要预热时间,体积过于庞大。现在受关注程度最高。也最能够被接受的,就是基于LED发光方式的手电。这种发光方式也是未来照明领域的发展方向。本专题中．笔者主要讨论的就是LED手电。     

一种结合使能控制的采样钟同步实现方法

许多通信场景中调制信号不能完全满足过零特性,常用检测方法都不能直接应用,为了解决这个问题,采用了一种结合使能控制的采样钟同步方法。通过使能信号控制环路中的Gardner定时误差检测模块,达到环路收敛的目的。该方法既利用了通常的Gardner算法结构,具有低复杂度特性,又保证了环路可以可靠工作。在实验过程中给出了具体的工程实现流程,并通过仿真验证了该方法的有效性。     

OFDM系统的基带自适应预失真器设计

针对OFDM系统中功率放大器的非线性,设计了一种功放自适应预失真器,提出了基于内插环路的同步处理、RASCAL算法的自适应查询表预失真技术。增加同步误差判定模块以及查询表刷新判定模块,保证系统在同步误差波动情况下可靠工作,实现了系统的自适应处理。仿真表明该方法可以在同步误差波动情况下将OFDM系统发射机功率谱泄露改善约17 dB。     

基于功率检测自适应的前馈功放设计

分析了常用双环自适应前馈电路在屏蔽和宽带频率兼顾等地方的缺陷,设计了一个功率检测自适应电路。功率检测自适应应用于前馈系统第一极环路,通过MCU监控电压检测值,自动调节第一环路的移相、调幅矢量调节器,改变相位、幅度参数,以达到环路抵消最好,保证在功率与频率不断变化的情况下,误差信号提取时刻都保持最纯净。仿真结果显示,在输出125W的GSM前馈系统中,可使其IMD3小于-65dBc。     

一种适用于APSK信号的位定时误差检测改进算法

APSK调制在新一代卫星广播系统中得到广泛应用。本文研究了APSK信号的位定时恢复环路,提出将一种Gardner位定时误差检测改进算法应用于该环路,并仿真比较了采用传统DD-Gardner位定时误差检测算法与采用新的改进算法的位定时恢复环路的时钟捕获和跟踪性能。     

GSM手机功放输出功率控制方案

１概述ＧＳＭ手机功率放大器（ＰＡ）通常采用固定电流回路控制和固定功率回路控制方式对输出功率进行调节。固定电流回路控制方式通常利用误差放大器来检测功率放大器的电源电流 ,而用误差放大器的输出来控制功放的增益以使其电源电流与作用在控制环路的基带功率控制信号成比例，因此 ,它与电源电压无关。而固定功率回路控制则利用定向耦合器来将ＰＡ的部份输出功率耦合至检测回路。该电路可以是带温度补偿的肖特基二极管峰值检测器及其缓冲器（如ＬＴＣ５５０５-Ｘ），也可以采用对数放大器 ,如 (ＭＡＸ４０００-４００２)。控制环路输出…     

载波恢复相位检测技术及其仿真

载波恢复技术是无线电射频(RF)通信中相干解调接收机不可缺少的关键技术之一.载波恢复算法的优劣直接决定着接收机的性能.结合高速卫星通信的应用,文中首先对基于最大后验概率估计准则载波恢复环的结构模型进行了研究,然后对所采用的载波相位误差检测算法的特性进行了深入的分析,最后对载波恢复系统中尤其重要的环路鉴相特性进行了计算机仿真,给出了环路性能试验分析结果.结果表明,在低信噪比的情况下,这种载波恢复环路及其误差检测算法特别适合于高速卫星通信应用环境下的QPSK系统.     

基于声光频移器反馈控制的397.5 nm紫外激光功率稳定研究

基于声光频移器设计的反馈环路,对397.5 nm紫外激光功率起伏进行反馈抑制。整套系统通过比例积分电路得到的误差信号来改变声光频移器的射频功率,利用声光频移器的布拉格衍射方式对激光功率进行控制,从而实现激光功率的长时间稳定。另外还对通过倍频产生的紫外激光特性进行了分析。最后,通过反馈系统在时域上实现了紫外激光功率的相对起伏,由±11.739%降至±0.053%,稳定度改善约220倍;在频域1～8000 Hz范围内,其功率谱密度得到明显的降低;在5 kHz频率处,功率谱密度由9.6×10~(-5) dBV·Hz~(-1/2)改善为1.9×10~(-6) dBV·Hz~(-1/2)。     

脉冲干扰旁瓣对消器的响应

本文所讨论的是对脉冲串干扰的旁瓣对消器的响应。这种干扰是由于人为干扰或其它雷达辐射而产生的。解析了影响对消器的控制加权的微分方程,而解法与对消器的几个工作参数如环路滤波器的时间常数、环路增益、干扰功率,重复周期、脉冲的占空系数等有关。基于这里获得的结果,为了对消,可以选择最佳环路增益和时间常数来满足所给定的条件。     

一种复合伪随机码跟踪环路设计及误差分析

该文针对当存在较大的载波相位跟踪误差时可能导致传统的复合码相干型跟踪环路失效的问题提出一种复合码非相干型跟踪环路。通过给出基于二进制偏移载波(BOC)调制的复合码的构造和相关特性分析,设计了具有非相干型鉴别器的跟踪环路,并分析了环路的跟踪误差。分析和仿真结果表明该环路解决了在存在较大载波相位误差时跟踪环路失效的问题,且具有良好的跟踪性能。     

Design and analysis of automotive high intensity discharge lamp ballast using micro controller unit

A new scheme of the automotive high intensity discharge (HID) lamp ballast systems is proposed. The proposed scheme is consisted of the high frequency DC-DC converter and the low frequency DC-AC inverter as same as conventional HID ballast system. However this system separates the input voltage of the ignitor from DC link voltage using auxiliary winding, which results in the use of the lower voltage rating power devices for HID lamp ballast system compared with conventional system. As a result, proposed system has a lower cost or a higher efficiency. For the improvement of the efficiency, the proposed ballast controller using micro-controller unit (MCU), controls the frequency to operate the DC-DC converter in critical conduction mode. This paper presents the design and analysis of the proposed ballast and some experimental results.     

Novel Automotive High Intensity Discharge(HID) Lamps with Electronic Ballasts

A new scheme of automotive high intensity discharge(HID) lamps with electronic ballasts is proposed. The design of the proposed ballast and some experimental results are presented. The proposed scheme is consisted of the high frequency DC-DC converter and the low frequency DC-AC inverter. This system separates the input voltage of the ignitor from DC link voltage using auxiliary winding, then it could use the lower voltage rating power devices for HID lamp ballast system and reduce the size of HID lamp ballast. The proposed ballast controller using micro-controller unit(MCU) controls the frequency to operate the DC-DC converter in critical conduction mode, which reduces the noise of the circuit and improves the efficiency by 2%~4%.     

Acoustic-resonance-free electronic ballast for automotive HID lamps

A novel cost-effective and acoustic-resonance-free electronic ballast used to drive automotive high intensity discharging (HID) lamps that utilise a constant lamp power control scheme is proposed. The presented ballast is comprised of a buck-boost flyback converter to provide negative DC voltages and a half-bridge-type inverter to supply the lamp with low-frequency, square-wave AC voltage/ current. Owing to its low-frequency operation, no acoustic resonance occurs on the automotive HID lamps. Design guidelines and experimental results are demonstrated for a 35 Wautomotive HID lamp prototype ballast operating at 400 Hz switching frequency with battery input DC voltage of 12 V.     

A Novel Constant Power Control Circuit for HID Electronic Ballast

This paper presents a constant power control circuit for a three-stage high-intensity discharge (HID) electronic ballast. The three-stage electronic ballast is composed of a boost pre-regulator to achieve a high power factor, a DC/DC buck converter to regulate lamp current with constant lamp power, and a full-bridge inverter to drive the HID lamp with a low-frequency ac squarewave current. The buck converter operating in current mode utilizes current sense level-shift technique to achieve constant power output. The proposed constant power control circuit is easily designed and implemented for the three-stage HID electronic ballast. Finally, a laboratory prototype of a 70 W HID electronic ballast is implemented. The measured results show that the proposed ballast can be applied for various HID lamps with low lamp power variation (less than 0.6%).     

Analysis and Improvement of Automotive High Intensity Discharge Lamp Ballast Based on Microcontroller Unit

The superior performance of high intensity discharge（HID） headlamp is clearly shown for luxury sedans, and the lamp luminescence properties are analyzed. The principle of its ballast technology is analyzed in detail. For against the disadvantage of current ballast technology for sedans lamp, a novel type of electronic ballast for HID is designed based on programmable intelligent computer（PIC） microcontroller unit（MCU） and S1A2410M inverter and it provides guidance and can be easily used in control configuration selection and design. The feasibility and superiority of the system are proved.     

Novel Design of HID Lamp Electronic Ballast for Automotive Systems

This paper presents a high intensity discharge（HID） lamp for automotive illumination. A novel type of ballast for HID is proposed without an acoustic resonance. The system consists of high frequency DC/DC converter,DC/AC inverter（SLA2403M）, high voltage igniter and a microcontroller unit（MCU）. The proposed ballast controls the complex start-up process and constant power process by programming on the rnicrocontroller. It is verified that experimental results agree well with the calculated ones. The ballast features such functions as failure protection, line under-voltage, line over-voltage, output short circuit and disconnection protections.     

一种数字控制HID灯电子镇流器的研制

介绍了一种单片机数字控制车用前照明高强度气体放电灯（high intensity discharge，HID）电子镇流器。镇流器系统主要由高频DC／DC开关电源、DC／AC逆变器、高压启动电路和单片机控制电路组成。它通过单片机软件编程，实现精确的数字控制，确保HID灯启动复杂的时序控制和恒功率控制过程，而且可以很好地处理各种故障模式，具有输入过压／欠压保护，输入反接保护，输出短路、开路保护等功能。     

Low-cost high power-density electronic ballast for automotive HIDlamp

A low-cost high-efficiency high power-density electronic ballast for 35 W automotive high intensity discharge (HID) is presented along with the results of theoretical computations and experimental tests. The ballast circuits is based on a 100 kHz resonant inverter, a half-wave rectifier and a 400 Hz operated square-wave inverter. The converter operates at zero turn on losses, nearly zero turn off losses, and at a reduced electromagnetic interference level. The ballast circuit is designed to prevent inappropriate operations due to the acoustic resonances. The lamp voltage waveform has limited dv/dt and no DC component contributing to a long operating life of the lamp. A breadboard of the electronic ballast was designed and experimentally tested on a 35 W lamp, for a DC input voltage ranging from 9 V to 16 V. The electronic ballast performs all the features required to turn-on, warm-up and drive at the steady state a 35 W HID lamp and operates at a maximum steady state efficiency η=84%,     

35 W集成控制型HID镇流器的设计

设计了一种基于集成芯片控制的HID灯镇流器。该镇流器集成了对恒功率、电流采样、温度补偿、斜坡补偿部分的控制,同时改进了采样电路,有效提高了调制信号的占空比。镇流器电路拓扑结构简单,降低了成本,效率达到80.3%,可靠性高,无声谐振现象。     

Development of a distributive control scheme for fluorescent lighting based on LonWorks technology

In this paper, a new distributive control system for indoor fluorescent lighting based on LonWorks technology is presented. The system features the following elements: microprocessor-controlled fluorescent lamp electronic ballast, communication system using the power line as communication media, and control software for Windows 95 environment. The electronic ballast has been especially designed to be operated under the proposed distributive control system. Thus, it features high-input power factor, high-frequency lamp supply, lamp power regulation against line voltage variations, dimming capability, and lamp failure detection. With this scheme, a low-cost distributive control system for lighting applications has been achieved, allowing energy and maintenance savings and increase in the reliability of the fluorescent lighting systems.