Multi-channel charge readout ASIC for X-ray detection

To solve the problem of large area and high power consumption of the traditional multi-channel charge readout circuit for X-ray detection,a new multi-channel charge readout circuit structure is presented.The circuit integrates 32 charge acquisition channels,including an integrator,a differential output buffer,a digital control logic circuit and other functional modules.The proposed structure reduces the power consumption and area by integrating the sample and hold circuit and the correlated double sampling circuit into the output buffer.In order to reduce the offset and low-frequency noise,the correlated double sampling technology has been adopted.In addition,the way of overlapping the outputs between the even and odd channels is adopted to realize continuous transmission of the multi-channel signals.The chip has been fabricated using the CMOS 0.25 μm process with the chip size of 2.87 mm×2.68 mm.Measurement results show that the power consumption of each channel is 1.5 mW under the 5.0 V voltage supply and 2.5 V reference voltage.When the integrated capacitor is 7.8 pF,the integration non-linearity is less than 0.1% and the dynamic range reaches 13 100.     

A practical Equivalent Electrical Circuit model for Proton Exchange Membrane Fuel Cell (PEMFC) systems

An alternative Equivalent Electrical Circuit for Proton Exchange Membrane Fuel Cells is modelled in this study. Both I–V characteristics and H₂ consumptions corresponding to generated power under load and no-load conditions are investigated. For this purpose, H₂ consumptions and I–V characteristics of three different sized PEMFCs are tested. There is a very good harmony between the model results and measured values (relative error %0.7, %6.4 and %2.5 for FC-A, FC-B and FC-C respectively). In the proposed model current passes only on parallel resistance and not on serial resistance at no-load condition. Thus, a FC with higher parallel resistance should be preferred. Another key output of this study is that based on the proposed model, performance comparison of FCs can be performed with the parameters defined in this work. Proposals made in this study can easily be used for performance analysis of FCs under for both steady state and transient analysis.     

An active balancer with rapid bidirectional charge shuttling and adaptive equalization current control for lithium-ion battery strings

This article proposes an active balancer, which features bidirectional charge shuttling and adaptive equalization current control, to fast counterbalance the state of charge (SOC) of cells in a lithium-ion battery (LIB) string. The power circuit consists of certain bidirectional buck-boost converters to transfer energy among the different cells back and forth. Owing to the characterization of the open-circuit voltage (OCV) vs SOC in LIB being relatively smooth near the SOC middle range, the SOC-inspected balance strategy can achieve more precise and efficient equilibrium than the voltage-based control. Accordingly, a compensated OCV-based SOC estimation is put forward to take into account the discrepancy of SOC estimation. Besides, the varied-duty-cycle (VDC) and curve-fitting modulation (CFM) methods are devised herein to tackle the problems of slow equalization rate and low balance efficacy, which arise from the diminution in balancing current as the SOC difference between the cells decreases in the later duration of equalization especially. The proposed strategies have taken the battery nonlinear characteristic and circuit parameter nonideality into account and can adaptively modulate the duty cycle with the SOC difference to keep balancing current constant throughout the balancing cycle. Simulated and experimental results are given to demonstrate the feasibility and effectiveness of the same prototype constructed. Compared with the fixed duty cycle and the VDC methods, the proposed CFM has the best balancing efficiency of 81.4%, and the balance time is shortened by 27.1% and 18.6%, respectively.     

减少矩阵变换器输出电压谐波的控制策略

在传统的双电压合成原理的基础上，提出了一种减少输出电压谐波的矩阵变换器控制策略.新调制策略在一个采样周期内，通过在高输出电压时，使最大输出线电压由三输入线电压脉冲波形成，其他两相输出电压由非最大的两输入线电压脉冲波和零电压形成，同样条件下窄脉冲数量较传统的双电压合成调制策略减少；在低电压输出时，三输出线电压均由非最大的两输入线电压脉冲和零电压形成，较传统的双电压合成调制策略窄脉冲数量有大量的减少，输出电压谐波得到较大的抑制；在输入电压的最高及最低相电压间无换流，降低了开关损失；低电压输出时的零矢量为输入相电压的中间值相，负载中性点的共模电压得到了抑制.在Matlab软件仿真研究的基础上，通过dSPACE硬件实时仿真平台对该控制策略进行了实验，仿真及实验结果验证了该控制策略的正确性.     

基于金属Gd的室温旋转式磁致冷演示样机的设计

磁致冷是利用磁介质在其居里温度Tc附近具有较大磁热效应的特性实现的一种物理现象.以稀土金属Gd为磁致冷材料,对室温旋转式磁致冷演示样机进行了结构设计,演示样机可达4.4K的制冷温跨,用于设计性实验教学,具有良好的示范作用.     

铜冶炼急冷转炉渣与缓冷电炉渣混合浮选生产实践

本文针对云南楚雄滇中有色金属有限责任公司生产过程中产生的急冷转炉渣、缓冷电炉渣混合浮选进行生产实践,采用二段一闭路破碎,两段连续磨矿,两粗选,两扫选和三次精选工艺。通过采取控制入选品位,改造渣浮选碎矿系统,改变药剂添加位置及添加比例,优化浮选流程等措施,急冷转炉渣与缓冷电炉渣混合浮选后获得铜精矿品位为20.6%,尾矿品位0.43%,铜回收率达87%以上,取得了较好的浮选工艺指标。     

磨矿回路加入重选回收柿竹园钨矿的选矿新工艺研究

柿竹园多金属矿黑、白钨矿的比例约为３：７，根据黑钨矿的矿石性质，在磨矿回路中加和重选早收已角度的单体钨矿物，有利于减轻黑钨矿过粉碎和减少黑钨细泥。小型试验、扩大试验和工业试验，在磨矿回路中获得１１．８２％￣１６．９７％的黑钨回收率，使全流程合格钨精矿的总回收率达８１．８９％￣８６．２３％。     

一种功能齐全的高可靠性雷管引爆执行电路设计

本章提出了一种针对工程爆破的功能齐全的高可靠性执行电路设计,该电路可执行"安全/充电"、"起爆"及"自毁"三种工作指令。系统采用电压逆变电路设计,提高了引爆负载的能力,保证了大电流的输出和点火需要;系统设置了"自毁"功能,可靠销毁未起爆的雷管,保障后继清理工作的绝对安全。设计合理,性能稳定,精确度高,实现了在有外界干扰的情况下能够无串控、无误动作。     

防爆变频器功率元件的散热设计

防爆变频器的散热问题十分重要,通过对变频器功率元件的功率损耗进行分析,提出了采用热管技术对变频器的电力电子元件进行散热。