Digital Control Technologies for DC/DC Switching Converters

An overview of recent advances in digital control of low-to medium-power DC/DC switching converters is presented.Traditionally,analog electronics methods have dominated in controlling such DC/DC converters.However,with the steadily decreasing cost of ICs,the feasibility of digitally controlled DC/DC switching converters has increased sig-nificantly.This paper outlines a sample of digital solutions for DC/DC switching converters to enhance the performance of DC/DC switching converters.Furthermore,latest research activities pertaining to applications for steady-state and dy-namic performance improvement,such as efficiency optimization,controller auto tuning,and capacitor charge balance control,is discussed.These applications demonstrate the significant advantages and potentials of digital control.

A 1×4 Polymeric Digital Optical Switch Based on the Thermo-Optic Effect

We present a 1 × 4 Y-branch digital optical switch in which S-bend variable optical attenuators are integrated. The S-bend waveguides, which are always introduced to connect the switch and the standard fiber array, are made use of and designed as variable optical attenuators. A compact device with low crosstalk and larger branching-angle is obtained. The device is fabricated on the thermo-optic polymer materials,and the performance of the device is measured. With an applied driving power of less than 200mW, the device has a low crosstalk of less than - 35dB at a wavelength of 1.55 μm.

Design and implementation of digital switch for trunking system

Presents the application of such components as MT8980 and MT8924 in digital switch modules for trunking system, and design and implementation of digital switch modules, which can perform the functions of digital switch and conference call, and replace analog switch modules and maintain compatibility with analog systems so that the system can gradually and continuously updated to full digitization.

Investigation into the Independent Metering Control Performance of a Twin Spools Valve with Switching Technology-controlled Pilot Stage

In hydraulic area,independent metering control(IMC)technology is an effective approach to improve system efficiency and control flexibility.In addition,digital hydraulic technology(DHT)has been verified as a reasonable method to optimize system dynamic performance.Integrating these two technologies into one component can combine their advantages together.However,few works focused on it.In this paper,a twin spools valve with switching technologycontrolled pilot stage(TSVSP)is presented,which applied DHT into its pilot stage while appending IMC into its main stage.Based on this prototype valve,a series of numerical and experiment analysis of its IMC performance with both simulated load and excavator boom cylinder are carried out.Results showed fast and robust performance of pressure and flow compound control with acceptable fluctuation phenomenon caused by switching technology.Rising time of flow response in excavator cylinder can be controlled within 200 ms,meanwhile,the recovery time of rod chamber pressure under suddenly changed condition is optimized within 250 ms.IMC system based on TSVSP can improve both dynamic performance and robust characteristics of the target actuator so it is practical in valve-cylinder system and can be applied in mobile machineries.

Waveform digitization utilizing switched-capacitor arrays

Compared with traditional waveform digitization with flash-ADCs, waveform digitization with switched-capacitor arrays (SCAs) is able to achieve the sampling speed above 1 GS/s without degrading the analog to digital conversion precision significantly. In this paper, we present the implementation of a fast waveform digitization system with the use of SCAs, and evaluate its performance of waveform digitization and the waveform timing. At about 5 GS/s, the dynamic input range of the digitizer is about 66 dB, and its timing precision is about 20 ps (RMS).

Switching plasticity in compensated ferrimagnetic multilayers for neuromorphic computing

Current-induced multilevel magnetization switching in ferrimagnetic spintronic devices is highly pursued for the application in neuromorphic computing.In this work,we demonstrate the switching plasticity in Co/Gd ferrimagnetic multilayers where the binary states magnetization switching induced by spin–orbit toque can be tuned into a multistate one as decreasing the domain nucleation barrier.Therefore,the switching plasticity can be tuned by the perpendicular magnetic anisotropy of the multilayers and the in-plane magnetic field.Moreover,we used the switching plasticity of Co/Gd multilayers for demonstrating spike timing-dependent plasticity and sigmoid-like activation behavior.This work gives useful guidance to design multilevel spintronic devices which could be applied in high-performance neuromorphic computing.

Can Digital Village Construction Help Upgrade Rural Household Consumption?An Empirical Examination Based on China’s Rural Household Survey Data

Digital village construction opens a new vista for fulfilling consumption capabilities and optimizing consumption patterns in rural areas.For this research,we used the microdata on rural households from the 2019 China Household Finance Survey(CHFS)to conduct an empirical examination of the impact of digital village construction on the upgrading of rural household consumption and its possible influence mechanisms in the endogenous switching regression(ESR)model.Our research findings can be summarized in three points.First,digital village construction has significantly contributed positive contributions to the improvements and upgrading of rural household consumption.Second,digital village construction can help upgrade rural household consumption by increasing their participation in online shopping and expanding online shopping channels.Third,digital village construction means different things to rural households at different levels of risk exposure,with its facilitation to consumption upgrades in proportion to income risks facing rural households.Our research findings,which came from an extensive,in-depth exploration of the factors influencing rural household consumption,are of practical significance and policy value to the stimulating and fulfilling of consumption potentials among rural households.

A digital controlled alternating electromagnetic stirring generator based on dual inverter structure

A digital controlled alternating electromagnetic stirring generator is proposed in this paper. The main circuit of the generator makes use of dual inverter structure among which the former inverter uses full bridge zero voltage switching topology and the latter inverter uses full bridge inverter circuit. To improve the dynamic response performance, the inverting frequency of the former inverter is as high us 100 kHz. The Cortex-M3 kernel based ARM microcontroller LM3S818 is adopted as the cybernetics core of the digital control system to achieve accurate, stable and flexible control of the generator. All the PWM signals for the former and latter inverters are generated by the LM3S818 directly. The constant current characteristic of the former inverter is obtained through current close-loop feedback control, and can ensure the operation safety when the output current waveform is at zero crossing point. Both simulation and experiment results show that the proposed generator is with such advantages as wide soft-switching range, perfect control accuracy and flexible waveform modulation, and can fulfill the requirements of electromagnetic stirring process.

Digital control system for pulsed MIG welding power based on STM32

Digital control system for pulsed MIG welding power based on STM32 is set up with 32-bit STM32FlO3ZET6 directing against the pulse waveform modulation of pulsed MIG welding. High-frequency inverter and medium-low frequency pulse waveform modulation of pulsed MIG welding are realized by using the integrated PWM module within STM32 to generate PWM signals of phase-shifted full-bridge soft-switching and constant-current control of output current is achieved by means of anti-windup PI control algorithm to improve the stability and reliability of control system. Experimental results demonstrate that the designed digital control system based on STM32 can achieve pegrect pulsed MIG welding technique with stable welding process and good weld appearance, fully demonstrating the advantages of digital control based on STM32.

Design and Experimentation of FPGA-Based Soft-Switched Interleaved Boost Converter for Telecommunication System

This paper proposes the design and experimentation of digital control of soft-switched interleaved boost converter using FPGA for Telecommunication System. The switching devices in the proposed converter are turned on and off with Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) respectively. The circuit is operated in Continuous Conduction Mode (CCM) with various load ranges having duty cycle of more than 50%. The proposed converter is studied by developing the simulation module in MATLAB/SIMULINK. A PI controller is designed and implemented in FPGA to obtain a regulated DC output for line and load variations. Simulation and experimentation results are verified with a prototype development of the proposed converter. The results indicate that the converter performance is enhanced with closed loop control.

多泵切换对数字液压传动风力机工作特性影响的分析

多泵数字液压传动风力机可根据风速大小使相应排量液压泵参与工作,使液压风力机在整个工作风速范围内始终保持高效。但不同排量液压泵参与工作的切换会造成风力机液压传动系统流量发生突变并产生压力冲击,影响风力机工作特性和风轮对风能的吸收。在分析多泵数字液压传动风力机工作原理的基础上,对5 MW级多泵数字液压传动风力机的方案进行设计和AMESim仿真建模;进行恒定风速和变风速条件下液压泵工作切换的仿真研究,得到多泵切换时液压风力机的风能利用系数、液压系统流量、压力等工作特性的变化规律;搭建了5 kW风能能量多泵数字液压传递半实物仿真实验平台对仿真结果进行实验验证;研究结果为多泵数字液压传动风力机风能高效利用和稳定运行提供理论依据和技术参考。

基于GaAs E/D PHEMT工艺的Ku波段双通道幅相控制多功能芯片

基于GaAs增强/耗尽型赝配高电子迁移率晶体管(E/D PHEMT)工艺设计了一款14~18 GHz的双通道多功能芯片。芯片集成了单刀双掷(SPDT)开关、6 bit数控移相器、4 bit数控衰减器和增益补偿放大器。采用正压控制开关以减小控制位数;优化移相、衰减和放大等电路拓扑结构,以获得良好的幅相特性;采用紧凑布局、双通道对称的版图设计,以实现小尺寸和高性能。测试结果表明,+5 V电压下,接收通道增益大于3 dB,1 dB压缩点输出功率大于8 dBm;发射通道增益大于1 dB,1 dB压缩点输出功率大于2 dBm;64态移相均方根误差小于2.5°,16态衰减均方根误差小于0.3 dB,芯片尺寸为3.90 mm×2.25 mm。该多功能芯片可实现对射频信号幅度和相位的高精度控制,可广泛应用于微波收发模块。

数字平台个人数据可携带政策的竞争效应

个人数据可携带政策是应对数字平台日益突出的数据垄断问题的重要反垄断监管政策,但是对于个人数据可携带政策的竞争效应,现有理论研究并没有给出明确的答案。构建在位者-进入者动态博弈模型来分析个人数据可携带政策的竞争效应,结果显示:个人数据可携带政策总体上可以降低消费者转换成本,削弱在位平台的数据垄断势力,促进市场竞争并提高消费者总福利和社会总福利。但个人数据可携带政策的竞争促进效应具有明显的场景差异,在消费者面临网络关注转换成本情况下,其具有明显的竞争促进效应;在消费者面临个性化服务转换成本情况下,个人数据可携带政策虽然能在一定程度上缓解竞争扭曲,但无法根本改变在位平台的垄断化趋势。总体来说,个人数据可携带政策是应对数据垄断的可行反垄断政策选择,但政策实施要区分不同场景进行精准设计,以有效实现维护市场可竞争性的目标。

基于Links-RT的数字液压风力机半实物仿真系统设计

数字液压风力机可根据风速大小使相应排量液压泵参与工作,使液压风力机在整个工作风速范围内始终保持高效。由于大型风力机不具备开展实验研究的条件,且风力机中的液压系统具有较强的非线性,为了准确研究数字液压风力机多泵切换时系统工作特性的变化规律,提出了一种基于Links-RT的数字液压风力机半实物仿真系统,并对数字液压风力机风轮特性模拟和最大功率跟踪控制进行设计。通过风速阶跃变化、恒定风速时多泵切换、渐变风速多泵切换3种工况下数字液压风力机工作特性的实时仿真测试,验证了数字液压风力机半实物仿真系统的正确有效性,为数字液压风力机的稳定运行和风能高效利用提供理论依据和技术参考。

一种高速高精度电流舵DAC的设计

针对电流舵DAC高频下因时钟馈通而导致动态性能指标降低的缺点,提出了一种自适应开关限幅单元,通过对摆幅进行限制从而减少了馈通效应,并且结合开关驱动电路改变了栅极控制信号交叉点的位置,降低开关翻转引入的毛刺,提高了无杂散动态范围。采用了CMOS 0.18μm工艺,结合四项开关等其他结构,设计了一种16位1.5 GSPS的电流舵DAC,并对DAC的性能进行了仿真和测试。测试结果表明DAC拥有良好的线性度,在1.5 GSPS采样率和70 MHz输入频率的情况下,无杂散动态范围(SFDR)为78.59 dB,动态性能良好。

农户数字信息选择对绿色生产风险影响及机制研究——基于小麦种植户调研数据分析

农户绿色生产风险的规避与防范是粮食产业绿色高质量发展的重要保障。基于河北与河南省912份小麦种植户微观调研数据,运用内生转换Probit模型和反事实分析法,探讨农户数字信息选择对绿色生产风险的影响效应及作用机制。结果表明:43.42%的小麦种植户面临较高的绿色生产风险;数字信息选择能显著降低小麦种植户绿色生产风险,选择数字信息的农户若未选择数字信息,其高绿色生产风险的概率会增加22.48%;数字信息的选择通过信息获取、生产监测、市场分析三个中介路径显著降低农户绿色生产风险。因此,政府应夯实网络基础设施建设,强化数字信息供给的精准性;提高种粮大户的政策性补贴力度,促进小麦种植户规模化产业化经营。

Digital switched hydraulics

This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems （SIHSs）. The performance of SIHSs is presented in brief with a discussion of several possible configurations and control strategies. The soft switching technology and high-speed switching valve design techniques are discussed. Challenges and recommendations are given based on the current research achievements.

数字乡村参与促进了农村居民创业选择吗?——基于内生转换Probit模型的实证分析

创业是解决农村居民就业、实现共同富裕的有力举措。文章基于数字乡村参与微观视角,运用SOR模型构建“情境刺激—内部动机—行为反应”过程机制,理论分析数字乡村参与与农村居民创业选择的关系,并进一步通过CFPS微观调查数据、内生转换Probit模型,实证检验经济、治理、生活三种不同应用场景下数字乡村参与对农村居民创业选择的影响。研究发现,农村居民数字乡村及各维度参与均显著促进农村居民创业选择。异质性分析表明,数字乡村参与对高教育、高收入水平的农村群体的创业效应更大,且在粮食主产区和东部、中部地区更为突出。因此,要积极鼓励农村居民参与数字乡村实践,同时也要重视数字乡村各领域发展的包容性和公平性。

一种具有1~128倍可变增益放大器的低功耗Sigma⁃Delta ADC

为满足传感器应用的低功耗需求,设计并实现了一种低功耗Sigma⁃Delta模数转换器(ADC)芯片。该ADC采用一阶全差分开关电容Sigma⁃Delta调制器,且集成了可编程增益放大器(PGA)和Bandgap;使用1.5 bit量化结构,相较于1 bit量化结构减小了3 dB的量化误差;使用优化的反馈电路,减小了电容失配引入的误差;PGA采用轨到轨的运放电路拓扑,增大了整个芯片的电压适应范围。基于180 nm CMOS工艺对该ADC进行了设计和流片。测试结果表明:该Sigma⁃Delta ADC在采样频率512 kHz、过采样率(OSR)为256时,峰值信噪谐波失真比(SNDR)和有效位数(ENOB)分别为75.29 dB和12.21 bit,芯片功耗仅为0.92 mW。芯片能在2.3~5.5 V宽电源电压范围内正常工作,可实现最大128 V/V的增益。适用于小型传感器的信号测量应用,可以满足小型传感器低功耗、高精度的需求。

广电数字微波传输网络业务交换机ISF技术应用与常见故障分析

业务交换机是数字微波传输网络的核心设备,是广播电视提供优质播出信源的重要保证。围绕广电数字微波传输网络业务交换机中智能堆叠框架(Intelligent Stacking Framework,ISF)这一关键技术的应用情况展开研究,详细论证ISF技术应用涉及的物理端口连接、拓扑信息采集、成员设备定位等方式方法,并针对ISF业务交换机常见故障进行分析,给出合理且可行的故障处置建议,为技术人员开展相关技术应用和系统运维等工作提供参考。