混合型多电平变流器桥臂电容电压平衡的原理与控制

混合式多电平变流器(HMC)能够实现有功无功独立控制,在直流侧发生故障时,交流侧电流仍然可控,这对于构成直流电网有重要意义。文中研究了HMC的电压合成方法以及在静止同步补偿器(STATCOM)模式下和高压直流(HVDC)模式下的能量平衡原理。基于能量平衡的原理,提出了STATCOM模式下和HVDC模式下桥臂电容稳压控制方法,并提出了HVDC模式下桥臂电容稳压的具体实现方法。为了验证所提出的能量平衡原理及控制策略,根据仿真算例所提供的参数,搭建了端对端直流输电的PSCAD仿真模型,对HMC的启动充电、解锁、有功渐变和直流故障过程进行了仿真。仿真结果显示,HMC能够实现有功无功独立控制,能够隔离直流侧故障,所提出的能量平衡原理与控制方法能够实现桥臂电容的稳压控制。     

车用磁阻传感器式电子罗盘系统的开发

基于磁阻传感器HMC1055的带姿态补偿功能,开发了包含信号放大和置位/复位模块的三维罗盘系统的硬件电路,并提出了干扰校正的软件算法以适应车内复杂的动态工作环境。     

浅谈HMC160卧式加工中心结构特点

详细介绍了HMC160卧式加工中心的结构特点,并从机床使用者的角度提出了一些注意事项,同时对一些关键部位的详细结构及技术参数做了明确的描述。     

磁阻传感器在车辆航位推算系统中的应用研究

与陀螺仪相比,在车辆航位推算系统中采用磁阻传感器具有较高的性价比。本文阐述了航位推算以及磁阻传感器的工作原理,详细分析了磁阻传感器的误差,提出了相应的误差修正方法,给出了一个用于航向角推算的实用电路。     

Cyclone V FPGA在高带宽存储接口中的应用

文中详细地分析了Altera公司Cyclone V FPGA器件的硬核存储控制器底层架构和外部接口,并在此基础上对Controller和PHY进行了功能仿真。仿真结果表明硬核存储控制器和PHY配合工作时的功能与设计预期相符,性能优良,适合于在当前FPGA的外部存储带宽需求日益增长的场合下应用。     

磁阻传感器在车辆航位推算系统中的应用研究

本文阐述了航位推算以及磁阻传感器的工作原理,详细分析了磁阻传感器的误差并提出了误差解决办法,最后给出了用于航位推算的实用电路。     

Evaluation of hydro-mechano-chemical behaviour of bentonite-sand mixtures

Bentonite-sand mixtures are widely used in engineering barrier of deep geological disposal of high-level radioactive nuclear waste and anti-seepage barrier of civil geotechnical engineering. Under the action of groundwater solution infiltration and external stress, the hydro-mechanical (HM) behaviour of bentonite-sand mixtures, i.e. the swelling characteristics and permeability, will change. Once the anti-seepage and filtration effect is weakened or lost, the pollutants will spread to the biosphere. Therefore, it is necessary to study the swelling characteristics and permeability of bentonite-sand mixtures under coupled mechano-chemical (MC) effect and to establish corresponding prediction model. For this reason, swelling tests under salt solution with different concentrations are conducted on pure bentonite and its mixtures with 30%, 70% and 90% sand contents, the compression tests are carried out on saturated samples, and the saturated permeability coefficient k of the sample under each load is calculated by Terzaghi's one-dimensional consolidation theory. The concepts of true effective stress p_e, montmorillonite void ratio e_m and critical sand content α_s are introduced to determine the e_m-p_e relationship and finally the k-e_m relationship of bentonite-sand mixtures. It is found that when the sand content α ≤ α_s, the e_m-p_e relationship of the mixture is linear and independent of the salt solution concentration, and when α > α_s, the e_m-p_e relationship of bentonite-sand mixture is bi-linear with the true effective deviatoric stress p_esα as the intersection. In addition, the e_m-k relationship also shows the linear trend when α ≤ α_s, and the slope of the line increases with the increase of the salt solution concentration. When α > α_s, the k-e_m relationship will deviate from the linear relationship. Moreover, the larger the sand content is, the farther the deviation is. On the basis of summing the regularity, a model for predicting the HM behaviour of bentonite-sand mixture under the coupled MC effect is proposed. By comparing the swelling and permeability test results with model prediction results of different types of bentonite and its sand mixtures, the predictive model is verified. The study on the HM behaviour of bentonite-sand mixtures under salt solution infiltration and the model establishment can provide experimental and theoretical basis for the design and construction of anti-seepage engineering by bentonite-sand mixtures.     

基于HMC470LP3的程控衰减器设计

基于程控衰减器[1]广泛用于信号接收机和信号发生器,利用HMC470LP3[2]数字衰减器设计了一款程控衰减器。并列举了该设计过程中碰到的信号损耗过大、低频信号衰减精度差、阻抗不匹配、信号泄露大等问题,以及解决办法。最后通过测试结果验证了基于HMC470LP3的程控衰减器有较好通道损耗、通道频响、信号泄露指标,达到了预期的目标。     

基于磁阻传感器的地磁数据采集装置

传统的姿态测量方法一般应用陀螺、加速度计或者与GPS组合对载体参数进行数据采集,但是由于成本高、器件精度与结构水平的限制,现在已经无法满足现在复杂的作战环境.提出应用三维磁阻传感器采集地球磁场三维磁场强度,然后经过放大、处理,最终得到理想的地磁数据.经过实验测试,采集装置能够获得理想的地磁信号.