光伏系统DC/DC变换器设计与仿真

本次研修主要针对整个光伏发电系统前端的DC/DC转换器部分进行研究、设计和仿真。此部分不仅要根据设计要求设计选择合理的占空比和元件参数,完成DC/DC变换,还需要考虑最大能量跟踪控制,以保证最大可能的利用能源,提高系统效率。     

准谐振正激变换器零电压开关设计

准谐振有源箝位正激变换器的有源箝位电路与常规的有源箝位正激变换器的结构类似,但实际工作过程存在许多差异。通过分析准谐振有源箝位正激变换器的工作过程,研究了准谐振有源箝位正激变换器的开关管零电压导通的边界条件,并进行了仿真和实验验证。     

基于ATE的8位超高速ADC动态参数测试

提出了一种采用Advantest 93000型自动测试设备,配合外挂高性能信号源SMA 100A,对8位1.5 GS/s超高速ADC进行动态参数测试的方案。该方案使用外挂信号源,提供采样时钟和模拟输入信号,解决了93000与外部信号源之间输入信号不同步,以及两者频率差异导致的采样不稳定问题,有效提升了93000测试超高速ADC动态参数的能力,可广泛应用于超高速ADC量产测试。     

基于C8051f040单片机的光离子化气体浓度检测电路设计

对光离子化气体浓度的测量,本质上是对其产生的微电流的测量。为此以C8051f040单片机为核心器件,采用内部ADC、信号采集单元设计一种测量系统,可以对0~200×10-6量程范围内的待测气体浓度实时检测并用数码管显示。该系统通过金属屏蔽信号采集单元和在软件编程中采用过采样、数字滤波相结合的方法来提高系统的信噪比。在计算机自动配气系统中测试了二甲醚的气体浓度,误差范围≤0.07×10-6,响应速度快、工作可靠、可作为实际应用。     

A low-distortion multi-bit sigma–delta ADC with mismatch-shaping DACs for WLAN applications

A low-distortion feed-forward MASH2_4b-2_4b sigma–delta analog-to-digital converter (ADC) for wireless local area network (WLAN) applications was presented. The converter exhibits improved performances than the ADCs which have been presented to date by adding a feedback factor in the second stage and employing a 2nd-order noise-shaping dynamic element matching (DEM) scheme. The feedback factor induces a zero in the noise transfer function (NTF) and therefore improves the in-band signal to noise and distortion ratio (SNDR) of the modulator. The mismatch-shaping DEM was introduced and applied to the 4-bit DACs in this paper to improve the resolution and linearity of the ADC. Fabricated in a 0.18 μm CMOS process with single 1.8 V supply voltage, the converter achieves a peak SNDR of 85.4 dB over a 10 MHz bandwidth which implies an effective number of bits (ENOB) of 13.90-bit. The spurious free dynamic range (SFDR) is –94 dB for a 1.25 MHz@–6dBFS input signal at 160 MHz sampling frequency. The occupied area is 0.44 mm² and dissipation power 23.4 mW.     

All-digital controlled boost DC–DC converter with all-digital DLL-based calibration

Traditional digital controls mostly use digital–analog converters to convert input and output voltages into digital coding to achieve control. This paper proposes the use of two digital ramps with two different frequencies to replace a digital–analog converter. This approach can produce seven bit resolution for the DPMW signal. In addition, we use an all-digital DLL phase correction concept to further enhance the resolution of the DPWM signal by an additional three bits, resulting in 10-bit DPWM signal resolution. The proposed circuit uses 0.35 μm CMOS processes, with a core area of 0.987 mm², a system switching frequency of 500 KHz, an input voltage range of 3.3–4.2 V, and an output voltage range of 5 V. Output voltage measurement accuracy reaches 99%, while the system reaches efficiency of 91% with output loads of up to 500 mA.     

稀疏多带信号的压缩采样技术的研究

实现宽带压缩采样的结构有多种类型,在分析调制宽带转换器的采样结构的原理的基础上,针对稀疏多带信号的压缩采样,搭建了四通道的宽带压缩采样系统的原型系统平台,其中,混频调制信号是现场可编程门阵列硬件电路产生的序列。采用稀疏多频带信号作为系统的输入测试信号,并且利用另一已知的稀疏多带信号作为系统的同步信号,对宽带压缩采样原型系统进行系统仿真。该系统中的混频调制信号容易生成、实现结构简单、参数设置灵活。软件仿真及硬件测试,验证了该宽带压缩采样系统的硬件平台的正确性和可行性。     

Ground copper slag as a supplementary cementing material and its influence on the fresh properties of self-consolidating concrete

This paper reports on an experimental programme to investigate the effect of using ground copper slag (GCS) as a replacement of cement on the fresh properties of self-consolidating concrete (SCC). Totally, seven self-compacting ground copper slag concrete (SCGCSC) mixtures were made with a fixed water–powder ratio of 0.51 in which a portion of the cement was replaced by GCS in weight ratios of 0%, 5%, 10%, 15%, 20%, 25% and 30%. The fresh properties were investigated by slump-flow, visual stability index, V-funnel, J-ring, L-box, air content, screen stability and setting time tests. The SCGCSCs were designed to give a constant slump flow of 680 ± 30 mm which was achieved by using the super-plasticiser at varying amounts. This allowed us to have a reasonable comparison of the obtained results. Totally, it has been concluded that using GCS significantly increased the workability of SCC mixtures. As the GCS increased, the slump flow is also increased at a constant amount of water and super-plasticiser, but the time required to flow is decreased. The results showed that it is possible to successfully produce SCC with GCS as cement replacement.     

电梯用超级电容器节能与应急平层装置的研究*

介绍电梯用超级电容器节能装置的组成,给出其节能的基本原理以及本项目研究的关键技术和项目创新点。运用零电流谐振式DC-DC转换器以及动态均衡电路提高电能回收效率和延长超级电容器的使用寿命。通过试验得出结论,利用超级电容快速存储电能的特性实现电梯的安全运行与节能降耗。同时利用超级电容取代传统应急平层装置的蓄电池,开发了一种全新的应急平层装置,进一步提高了电梯节能的效果。     

Adaptive B‐spline neural network‐based vector control for a grid side converter in wind turbine‐DFIG systems

This paper presents a novel control system design for the grid‐side converter of doubly fed induction generator wind power generation systems. The control method proposed in this work is a vector control based on adaptive B‐spline neural network by using a simple fixed‐gain stabilizing control topology. The adaptive control is designed both for inner current loops and an outer DC‐link voltage loop of the grid side converter control system. To guarantee the control stability, the weights updating rule for the B‐spline neural network is synthesized by utilizing Lyapunov's direct method. To verify the effectiveness of the proposed control system, extensive simulations are performed using MATLAB/Simulink. Based on the simulation results, it is concluded that the proposed controller has improved performance compared to an optimum proportional integral control system. It is also relatively robust against external disturbances and variations of the control parameters. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.