基于PWM技术蓄电池充放电与检测系统设计

为解决传统蓄电池充放电装置功率因数低、高谐波污染等不足,针对电力机车用15kVA蓄电池,设计了基于PWM整流逆变技术的蓄电池充放电装置与检测监控系统。装置用作充电电源时,采用电流双闭环控制系统,实现分阶段恒流模式或恒压模式充电;用作蓄电池放电试验的负载时,将能量回馈电网。通过SPWM调制可实现放电功率的灵活调控。试验及检测结果表明该装置具有能量双向流动、网侧电流正弦化、功率因数高、功率灵活调控的特点。     

基于空间矢量调制三相电压型PWM整流系统的仿真

正弦脉冲宽度调制(SPWM)技术应用于传统的电压型PWM整流中,SPWM的控制波形可由相间解耦得到。然而,这个过程复杂且直流电压利用率很低。本文提出了一种在同步参考坐标下的三相电压模型的控制策略,空间矢量脉冲宽度调制(SVPWM)。整流器具有高质量的直流侧电压和功率因数。文章提供了MATLAB/SIMULINK的仿真模型。结果证实了模型的正确性及其控制方法。仿真结果表明,与传统的SPWM方法相比,这种方法能明显提高系统的动态性能。     

基于DSP的空间电压矢量PWM和线电压PWM的对比研究

叙述了空间电压矢量肪冲宽度调制（SVPWM）和线电压肪冲宽度调制（LVPWM）的基本原理，介绍了用数字信号处理器（DSP）TMS320F240生成LVPWM的方法以及分别用硬件和软件方式实现SVPWM，并对二者进行了对比性的研究。     

开关电源的PWM-PFM控制电路

本文比较了开关电源中的三种控制方式脉宽调制(PWM)、脉频调制(PFM)、调宽调频(PWM-PFM),并简要介绍了一种新型开关电源,对其新颖、实用的PWM-PFM电路的工作原理作了较详细的分析.实验证明,此电路对输入电压波动较大的工业环境具有很好的适应性.     

基于FPGA的SVPWM系统研究及Simulink仿真

本文深入研究SVPWM控制算法的原理,在MATLAB仿真环境下,对SVPWM算法和优化策略进行了仿真,通过Verilog硬件描述语言分别对常规模式和优化模式下的设计进行编译仿真,将在QUARTUSⅡ环境下硬件设计的编译仿真结果与MATLAB下的SVPWM仿真结果对比,验证了硬件设计方案是正确可行的     

使用PWAM光纤传输技术的红外检测系统(英文)

分析使用了一种PWAM(二级脉冲幅度调制以及脉冲宽度调制)光纤传输技术作为红外探测系统中的信号传输手段,用以取代传统的电缆传输方式。传输系统的主要指标设定在模拟信号的信噪比不小于50dB,数字信号的误码率不低于10-9。PWAM系统的接收机灵敏度作为主要的参数进行了分析。计算机仿真表明了PWAM光纤传输技术在红外探测系统中应用的良好性能。     

基于双重调制技术的可见光通信系统研究

LED调制带宽制约着可见光通信(VLC) 系统的数据传输速率。为此,提出一种基于双重调制技术COB(chip on board)封装 的LED灯具,通过实现16级脉冲振幅 调制(PAM),将系统数据传输速率提升4倍;结合脉冲宽度调制(PWM)技术 进行调光,同时兼顾室内的照明及通信。采用Matlab软件模拟仿真视频传输试 验。结果表明,在相同信噪比(SNR)的情况下,基于双重 调制技术的VLC系统的误码率(BER)比传统使用开关键控(OOK)调控技术系 统的BER更低。本文系统在不增加器件带宽前提下,成倍提高了无线通信的 质量与 数据传输速率;从照明与通信的角度优化了VLC系统的信源,具有广阔的 应用前景。     

LCD驱动中调制算法的应用与实现研究

讨论了脉冲宽度调制方式与帧速率调制方式应用在LCD driver(液晶显示驱动)中的优劣,探讨了混合使用两种算法的改进方案,结果表明混合使用脉冲宽度调制方式与帧速率调制方式,能够在显示效果及功耗方面达到最优。     

无三次谐波电压输出的空间矢量脉冲宽度调制技术

本文针对空间矢量脉冲宽度调制(SVPWM)技术使得电压源型逆变器(VSI)输出电压中含有三次谐波的问题,提出一种新的方法,使得输出电压中不再含有三次谐波。首先分析了SVPWM存在三次谐波的原因是每个载波周期中三个输出端电压的平均值不为零。在此基础上,本文提出一种新的开关管开通和关断时间的计算方法,使得每个载波周期三个输出端电压的平均值为零,从而确保输出电压中没有三次谐波。最后通过仿真,验证了本文所提方法的有效性。     

脉冲宽度调制直流变换器的应用

本文详细介绍了Ｍａｘｉｍ公司脉冲宽度调制直流变换器ＭＡＸ７２４／７２６的原理和应用,包括降压变换器、升压变换器、逆向变换器。提供了典型应用电路图、设计公式以及关键事项。     

直流母线供电的抽油机群控系统智能保护装置的开发

共直流母线变频抽油系统具有节能、方便控制、易于操作等优点,适合应用于油田采油等生产领域.但对于油田直流供电配置的抽油机变频群控系统,由于负载的变化,会引起同步运行的抽油机冲程的冲次差异以及能耗的变化.这会造成电网电压跌落等问题,影响电能质量.本文提出了一种智能保护装置,实时检测直流母线电压的变化,调整输出端频率,控制抽油机的工作状态,提高了抽油机的运行可靠性和效率,在油田应用中取得了良好的应用效果.     

Planar MESFET grid oscillators using gate feedback

A method for quasi-optically combining the output power of MESFETs in which drain and source leads couple directly to the radiated field is introduced. The design consists of a planar grid of devices placed in a Fabry-Perot cavity. Capacitive feedback is provided to the gate, allowing oscillation at much higher frequencies than previous grids. The oscillation frequency is dependent on the device characteristics, the resonator cavity, and the symmetries of the grid. A transmission-line model for the grid is discussed and used to design two oscillator arrays. A 16-element grid has produced 335 mW of power at 11.6 GHz with a DC-to-RF conversion efficiency of 20%. This design was scaled to produce a 36-element grid oscillator with output power of 235 mW at 17 GHz. These results represent a significant improvement in the performance of planar grid oscillators. The planar configuration of the grid is very convenient for monolithic integration and is easily scalable to millimeter-wave frequencies     

基于能带调制模型的高压增强型AlGaN/GaN HFET器件

提出了一种能带调制模型,通过在异质结界面处引入负离子电荷(如氟离子)调制异质结处的局部能带分布,实现了对异质结界面处的高密度2DEG的改变。基于能带调制模型,提出了一种复合调制沟道AlGaN/GaNHFET器件。通过在增强型沟道调制区和RESURF调制区分别引入不同剂量的负离子,不仅实现了增强型器件,而且可以降低尖峰电场,优化异质结电场分布,提高器件击穿电压。通过器件仿真软件对其器件工作原理进行了模拟分析,并通过实验结果表明,其器件品质因子FOM由传统器件的4.8MW.cm-2提高到26.7MW.cm-2。     

Tunable infrared modulator and switch using Stark shift in stepquantum wells

A tunable infrared modulator and/or switch using intersubband Stark shift in a step quantum well is discussed. The device utilizes the intersubband absorption and the large change of separation between energy levels in the step quantum well under an applied electric field. The incident infrared beam on the device is either absorbed or transmitted depending on the energy separation of the levels, and thus the modulation can be achieved by adjusting the energy levels with an applied electric field. The extremely short lifetime of the intersubband transition makes this modulator suitable for application in high-speed long-wavelength optical communications     

一种用于电磁炉老化的能馈型电子负载

针对电磁炉老化中的应用,本文提出一种可能量回馈的电磁炉老化装置 能馈型电子负载.通过对电子负载在老化中的应用,设计了逆变模块的控制策略,并把上述方案设计2kW电子负载实验样机.实验结果表明,该方案简单易行,可实现模拟电磁炉的负载并能量回馈电网.     

A design tool to study the impact of mission-profile on the reliability of SiC-based PV-inverter devices

This paper introduces a reliability-oriented design tool for a new generation of grid connected PV-inverters. The proposed design tool consists of a real field mission profile model (for one year operation in USA-Arizona), a PV-panel model, a grid connected PV-inverter model, an electro-thermal model and the lifetime model of the power semiconductor devices. A simulation model able to consider one year real field operation conditions (solar irradiance and ambient temperature) is developed. Thus, one year estimation of the converter devices thermal loading distribution is achieved and is further used as an input to a lifetime model. The proposed reliability oriented design tool is used to study the impact of MP and device degradation (aging) in the PV-inverter lifetime. The obtained results indicate that the MP of the field where the PV-inverter is operating has an important impact in the converter lifetime expectation, and it should be considered in the design stage to better optimize the converter design margin. In order to improve the accuracy of the lifetime estimation it is crucial to consider also the device degradation feedback (in the simulation model) which has an impact of 30% in the precision of the lifetime estimation in the studied case.     

无线LED照明驱动系统方案设计

本文主要提出以电磁耦合与电磁共振的方式,为LED提供无线驱动电能。采用高精度的正激变换恒流源驱动LED,并利用光电池进行光照强度采集反馈调整恒流源电流以控制LED发光强度,保证光照恒定。此外该系统还在电网输入端增加有源电力滤波器（Active Power Filter,APF）,以减少该装置作为非线性负载而引入电网的高次谐波。本文所述方案能有效地提高LED照明分布的灵活性,解决电力线布线的繁琐,同时在高效管理光照能耗的情况下不影响电网电能质量,因此其具有深厚的实用价值和应用潜力。     

具有纯频率调制和啁啾抑制的幅度调制的三电极DFB LD

二电极和三电极(多电极或多节)分布反馈激光器是超长传输距离和超大传输容量光纤通信系统的关键器件。本文详细地讨论了三电极分布反缋(DFB)激光器的重要特性,其中包括调谐理论、频率调制响应以及纯频率调制和啁啾抑制的辐度调制。     

A simple method for predicting the forward blocking gain of gridded field effect devices with rectangular grids

In this paper an algorithm is presented which greatly simplifies field calculations on gridded field effect devices. By using this algorithm to make calculations on devices with rectangular grid elements it is shown that for a given grid aspect ratio, the forward blocking gain is a unique function of a normalized grid reverse bias. The normalization factor is the grid bias at zero blocking gain. By knowing this voltage, the blocking gain can then be calculated for any device regardless of semiconductor material type, substrate doping, and details of the grid geometry. These methods are successfully tested by comparing with measured results on a variety of devices. Finally an empirical relation is presented which can be used to approximately predict the forward blocking gain for a device with arbitrary aspect ratio and grid bias.