Three-phase four-wire shunt active power filter based on the SOGI filter and Lyapunov function for DC bus control

The three-phase four-wire shunt active power filter (SAPF) was developed to suppress the harmonic currents generated by nonlinear loads, and for the compensation of unbalanced nonlinear load currents, reactive power, and the harmonic neutral current. In this work, we consider instantaneous reactive power theory (PQ theory) for reference current identification based on the following two algorithms: the classic low-pass filter (LPF) and the second-order generalized integrator (SOGI) filter. Furthermore, since an important process in SAPF control is the regulation of the DC bus voltage at the capacitor, a new controller based on the Lyapunov function is also proposed. A complete simulation of the resultant active filtering system confirms its validity, which uses the SOGI filter to extract the reference currents from the distorted line currents, compared with the traditional PQ theory based on LPF. In addition, the simulation performed also demonstrates the superiority of the proposed approach, for DC bus voltage control based on the Lyapunov function, compared with the traditional proportional-integral (PI) controller. Both novel approaches contribute towards an improvement in the overall performance of the system, which consists of a small rise and settling time, a very low or nonexistent overshoot, and the minimization of the total harmonic distortion (THD).     

单相并联型有源电力滤波器主电路参数耦合关系研究

单相并联型有源电力滤波器(SAPF)主电路参数之间存在一定的耦合关系,这对各参数值的合理选择有较大的影响。通过分析现有单/三相SAPF主电路交流侧电感以及直流侧电压、电容值等参数的计算方法,得到了具体的单相SAPF电路参数解析表达式。针对所得表达式各变量之间的耦合关系,在MATLAB中进行建模优化分析,得出一套完整的参数设计方案。保证在特定负载下补偿后谐波含量低于2%的综合优化目标。仿真和实验过程验证了所选参数的正确性。     

基于康复训练中力信号的人体参与度建模

设计一种基于人机接触力的人体主动参与程度评估模型,用于康复机器人应用中的主动康复训练。通过人体的肌电信号得到肌肉活跃度,确定肌电信号与人体参与度的关系。分析这一过程中人机接触力的变化,将腿部力信号平均值以及腰部力信号方差作为模型输入,对基于肌电信号的参与度模型进行拟合,得到基于力信号的参与度模型,使用肌电信号参与度模型对力信号参与度模型进行验证,证明了该模型的有效性。该方法避免了肌电信号采集时干扰较大且准备工作繁琐等缺点,具有良好的实用性。     

葵花籽粕综合利用研究进展

葵花籽粕是葵花籽提油后的副产品。葵花籽粕蛋白品质优,各氨基酸组成平衡,此外葵花籽粕中还含有绿原酸、黄酮等多种活性物质,营养价值高,具有广阔的应用前景。从葵花籽粕作为原料提取有效成分及作为饲料用原料两方面对葵花籽粕资源的综合利用情况进行了阐述,以期为葵花籽粕的进一步开发利用提供参考。     

Anodic process on Cu−Al alloy in KF−AlF3−Al2O3 melts and suspensions

Anodic processes on Cu−10Al electrode in molten KF−AlF₃−Al₂O₃ (saturated) and suspensions were characterized using chronopotentiometric and cyclic voltammetric techniques. Effects of cryolite ratio (CR= x(KF)/x(AlF₃)), temperature and particle volume fraction (ϕ) on the electrochemical behaviour of the anode were demonstrated. Initially, the anode was polarised in the galvanostatic mode in melt and suspensions (ϕ=0.12, 0.15) at 750 °C with 0.4 A/cm² current density. The anode potential in melt varied between 2.5 and 3.2 V and in suspensions (ϕ= 0.12) between 3.3 and 3.4 V. XRD analysis was conducted to study the oxide phases on the anode surface. Anode limiting current densities and mass transfer coefficients drastically decreased with the increase of ϕ in the suspension. The results suggest that the Cu−10Al electrode works better in suspensions with CR of 1.4 and particle volume fraction of 0.09 at 800 °C.     

低浓度挥发性有机物吸附浓缩材料的研究进展

由于挥发性有机物（VOCs）会对环境造成严重的危害，因此VOCs的处理一直备受人们的关注，但发展高效的VOCs处理技术仍然存在严峻的挑战。本文针对大风量、低浓度VOCs的处理展开了综述，重点围绕吸附、催化燃烧处理展开讨论。对于大风量的低浓度VOCs，虽然浓度较低但VOCs排放量非常巨大。通过VOCs浓缩技术，提高浓度减少风量成为降低VOCs处理成本的有效途径。其中，发展高性能VOCs吸附材料是VOCs浓缩技术的关键。阐明了活性炭、分子筛等重要吸附材料的性质及其吸附VOCs的原理，并对吸附材料性质和VOCs种类对吸附效果的影响进行了探讨。展望了活性炭浓缩-催化燃烧技术和分子筛转轮浓缩-催化燃烧技术在大风量的低浓度VOCs处理中的应用前景。     

并联有源滤波器的改进重复控制策略研究

针对三相整流负载产生的6k±1次谐波,提出静止坐标系下的改进型6k±1重复控制策略。同时将比例控制与改进型重复控制相结合,设计改进重复控制并联比例的复合控制结构。为减小改进重复控制中延时环节不为整数的影响,采用基于Lagrange插值近似的FIR滤波器逼近分数延时特性。最后对系统进行稳定性分析和详细设计方法进行推导。通过Matlab仿真验证改进重复控制策略能有效跟踪6k±1次谐波且具有良好的补偿效果,动态响应较快。     

高温悬浮态下石灰石与菱镁矿热分解 特性比较及动力学研究

利用悬浮态高温炉,对比研究了菱镁矿及石灰石的热分解特性,探讨了其热解模型及动力学参数。结果表明:低温段(650~750℃)时,菱镁矿比石灰石易分解,达到一定高温后其分解速率相差不大;菱镁矿、石灰石在悬浮态下的热解机理均符合收缩核模型,其活化能分别为50 kJ/mol、79 kJ/mol;随着菱镁矿粒度的增大,其分解速率趋缓,分解表观活化能增大。     

Decreasing Filter Cake Resistance by Using Packing Structures

Packed beds used in absorption columns are evaluated to determine whether they can also be beneficial for cake‐forming filtrations. To assess this, model systems are characterized and separated by using a dead‐end filter cell. Filtrations are conducted with different packings; the filtrate amount over time and resulting turbidity are evaluated. Packings increase the filter cake resistance and the separation time of the cakes formed with approximately incompressible solids. However, they exhibit a positive effect on the filtration of a more complex, compressible substance; the process is not only accelerated, but also the quality of the obtained filtrate is not compromised. These results demonstrate potential in the use of packed beds for the filtration of complex biogenic suspensions.     

基于多参数特征保留的载荷谱加速耐久性编辑

为了得到时间更短加载效果相同的加速耐久性试验载荷谱,提出了基于多参数特征保留的载荷谱编辑方法。该方法同时考虑载荷谱的损伤、功率谱密度以及统计参数等信息,对零部件载荷谱的时间进行压缩。以汽车悬架螺旋弹簧的载荷谱为例,采用该方法进行缩减,同时从多个参数特征方面与传统的基于损伤保留的编辑方法所得到的载荷谱进行对比。为了进一步验证编辑效果,采用编辑谱和原始谱对弹簧进行疲劳仿真。结果表明,该方法能够有效缩短汽车零部件的载荷谱,可得到与原始载荷谱具有相同加载效果的编辑载荷谱。