IMPROVE THE KINETIC PERFORMANCE OF THE PUMP CONTROLLED CLAMPING UNIT IN PLASTIC INJECTION MOLDING MACHINE WITH ADAPTIVE CONTROL STRATEGY

The kinetic characteristics of the clamping unit of plastic injection molding machine that is controlled by close loop with newly developed double speed variable pump unit are investigated. Considering the wide variation of the cylinder equivalent mass caused by the transmission ratio of clamping unit and the severe instantaneous impact force acted on the cylinder during the mold closing and opening process, an adaptive control principle of parameter and structure is proposed to improve its kinetic performance. The adaptive correlation between the acceleration feedback gain and the variable mass is derived. The pressure differential feedback is introduced to improve the dynamic performance in the case of small inertia and heavy impact load. The adaptation of sum pressure to load is used to reduce the energy loss of the system. The research results are verified by the simulation and experiment, The investigation method and the conclusions are also suitable for the differential cylinder system controlled by the traditional servo pump unit.

MODELING, VALIDATION AND OPTIMAL DESIGN OF THE CLAMPING FORCE CONTROL VALVE USED IN CONTINUOUSLY VARIABLE TRANSMISSION

Associated dynamic performance of the clamping force control valve used in continuously variable transmission （CVT） is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and five structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm （GA） with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indexes of the optimized valve are much better than those of the prototype workpiece.

基于矢量分类的NPC型三电平双三相PMSM的改进模型预测电压控制

多电平多相电机驱动系统存在电压矢量数目多、冗余复杂及多目标非线性约束等问题。以二极管钳位型三电平六相逆变器驱动双三相永磁同步电机为研究对象,以电机谐波电流抑制和逆变器直流侧中点电位平衡控制为目标,提出一种基于电压矢量三角区域分类的改进模型预测电压控制策略。首先,以基波子平面大投影幅值为原则,对729个电压矢量进行初筛;接着,基于三角区域分类方法对筛选后的电压矢量进行分类,并对期望电压进行所属三角区域定位、确定候选矢量。设计满足电机定子电流谐波抑制及逆变器中点电位平衡控制的目标函数;根据电机数学模型和逆变器特征研究多目标控制权重因子的理论设计方法。不同工况下的有效性及对比实验表明,所研究的控制策略不仅能改善多电平多相电机驱动系统的多目标控制性能,还能有效降低控制器计算负担。

Design of a novel high holding voltage LVTSCR with embedded clamping diode

In order to reduce the latch-up risk of the traditional low-voltage-triggered silicon controlled rectifier(LVTSCR), a novel LVTSCR with embedded clamping diode(DC-LVTSCR) is proposed and verified in a 0.18-μm CMOS process. By embedding a p+implant region into the drain of NMOS in the traditional LVTSCR, a reversed Zener diode is formed by the p+implant region and the n+bridge, which helps to improve the holding voltage and decrease the snapback region.The physical mechanisms of the LVTSCR and DC-LVTSCR are investigated in detail by transmission line pulse(TLP)tests and TCAD simulations. The TLP test results show that, compared with the traditional LVTSCR, the DC-LVTSCR exhibits a higher holding voltage of 6.2 V due to the embedded clamping diode. By further optimizing a key parameter of the DC-LVTSCR, the holding voltage can be effectively increased to 8.7 V. Therefore, the DC-LVTSCR is a promising ESD protection device for circuits with the operation voltage of 5.5–7 V.

Improved Clamped Diode Based Z-Source Network for Three Phase Induction Motor

The 3Φinduction motor is a broadly used electric machine in industrial applications,which plays a vital role in industries because of having plenty of beneficial impacts like low cost and easiness but the problems like decrease in motor speed due to load,high consumption of current and high ripple occurrence of ripples have reduced its preferences.The ultimate objective of this study is to control change in motor speed due to load variations.An improved Trans Z Source Inverter(ΓZSI)with a clamping diode is employed to maintain constant input voltage,reduce ripples and voltage overshoot.To operate induction motor at rated speed,different controllers are used.The conventional Proportional-Inte-gral(PI)controller suffers from high settling time and maximum peak overshoot.To overcome these limitations,Fractional Order Proportional Integral Derivative(FOPID)controller optimized by Gray Wolf Optimization(GWO)technique is employed to provide better performance by eliminating maximum peak overshoot pro-blems.The proposed speed controller provides good dynamic response and controls the induction motor more effectively.The complete setup is implemented in MATLAB Simulation to verify the simulation results.The proposed approach provides optimal performance with high torque and speed along with less steady state error.

Model predictive control of three-level active front-end converter with low switching frequency

In medium voltage-high power(MV-HP)applications,the high switching frequency of power converter will result in unnecessary energy losses,which directly affect efficiency.To resolve this issue,a novel finite control set-model predictive control(FCS-MPC)with low switching frequency for three-level neutral point clamped-active front-end converters(NPC-AFEs)is proposed.With this approach,the prediction model of three-level NPC-AFEs is established inα-βreference frame,and the control objective of low average switching frequency is introduced into a cost function.The proposed method not only achieves the desired control performance under low switching frequency,but also performs the efficient operation for the three-level NPC-AFEs.The simulation results are provided to verify the effectiveness of proposed control scheme.

A Novel Multilevel Inverter Circuit for the Performance Enhancement of Direct Torque Controlled Induction Motor

Induction motor is the most sought after motor in the industry for excellent performance characteristics and robustness. Developments in the Power Electronic circuitry have revolutionised the induction motor industry leading to the developments in various control strategies and circuits for motor control. Direct Torque Control (DTC) is one of the excellent control strategies preferred by industries for controlling the torque and flux in an induction machine. The main drawback of DTC is the presence of torque ripple which is slightly more than the acceptable limit. There are various parameters that introduce ripples in the electromagnetic torque, one of them being the type of inverter circuit. There are various types of inverter circuits available and the effect of each of them in the production of torque ripple is different. This work is an attempt to identify the influence of various multilevel inverter circuits on the torque ripple level and to propose the best inverter circuit. The influence of multilevel diode clamped inverter and cascaded H bridge inverter circuits on torque ripple minimization, is analysed using simulation studies for identifying the most suitable multilevel inverter circuit which gives minimum torque ripple. The results obtained from the simulation studies are validated by hardware implementation on 0.75 kW induction motor.

Hybrid Control Strategy for Matrix Converter Fed Wind Energy Conversion System

In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.

急倾斜特厚煤层冲击地压防治探索与总结

急倾斜特厚煤层开采顶板破断运动复杂,应力和能量演化规律特殊,在深部“三高一扰动”影响下,冲击地压防治不容乐观。基于某矿2016年冲击地压事故后急倾斜特厚煤层水平分段开采冲击地压防治经验,从急倾斜特厚煤层水平分段开采冲击地压发生机理、瓦斯突出与冲击地压综合防治和冲击地压管理详细介绍了该矿7年来急倾斜特厚煤层冲击地压防治经验。冲击地压发生机理方面,建立了顶板岩层倾斜悬臂梁模型,揭示了顶、底板覆岩结构破断失稳演化过程,划分了夹持煤体受力状态分区,提出了急倾斜特厚煤层冲击“夹持理论”。瓦斯突出与冲击地压综合防治方面,基于冲击地压灾害控制解危技术的强度弱化减冲理论,结合原有防突措施体系,提出了既能防冲且对防突有利的解危措施,形成了某矿瓦斯/CO_(2)突出-冲击地压“双防”技术体系,建立了适用于某矿急倾斜特厚煤层水平分段开采的冲击地压防治体系,以钻屑量和瓦斯吸解值验证了瓦斯突出防治的强度保障,同时以加强实施卸压措施工作面的微震事件分布及各能级总频次和能量对比,论证说明了卸压方案防治效果的有效性。冲击地压管理方面,形成了预测评价、监测预警、治理预防、效果检验、安全防护和教育培训“六位一体”综合防治架构,基于《煤矿安全规程》和《防治煤矿冲击地压细则》等各项规定,制定了Q/YJMD-—FC 0104-2022《窑街煤电集团有限公司煤矿冲击地压防治第四部分:冲击地压防治技术规范》。

三电平辅助变流器寿命优化控制

辅助变流系统是动车组车辆上关键的电气组成部分,主要为空调机组、风机、照明等交流负载提供稳定的三相电源。结温是影响动车组三电平辅助变流器IGBT(Insulated-gate Bipolar Transistor)模块寿命的主要因素。为了提高动车组三电平中点钳位(Neutral-Point Clamped,NPC)型辅助变流器寿命,提出一种降低结温的模型预测电流控制(Model Predictive Current Control,MPCC)策略。首先,考虑传统MPCC在每个采样周期需要代入27个电压矢量循环计算,计算量较大,因此将三电平基本电压矢量划分在间隔60°的6个扇区中,通过计算电压矢量在两相静止坐标下的相角,进而判断参考电压矢量所处扇区,将备选矢量数目从27缩减至10,减少了计算量;其次,传统MPCC直接应用于动车组辅助变流器会使IGBT模块的结温较高,老化速度加快,对变流器安全稳定运行产生不可预测的损害,本文对IGBT模块的开关损耗和导通损耗进行近似等效,得到了和集射极电压、集电极电流相关的功率损耗因子。通过预测每相电流的方向,进而预测IGBT模块的开关和导通情况,动态加入功率损耗因子,并在代价函数中约束每相IGBT及其续流二极管(Free Wheeling Diode,FWD)的功率损耗,使得最优电压矢量在降低功率损耗的同时保证一定的控制性能。通过仿真与实验验证,本文所提方法相比传统MPCC策略降低了功率器件的结温,提高了变流器寿命。

不同测试方法在精密手术器械功能质量检查中的比较效果研究

目的:分析对比不同测试方法在精密手术器械功能质量检查中的测试效果,保障手术器械额安全使用。方法:通过查询相关文献及专业书籍,选定精密手术剪和持针器,选用不同的测试材料及方法。精密手术剪依次采用纱布、棉毛布及Interlock手术器械测试套装内的硅胶薄膜方法测试器械切割性能;精密持针器依次采用光照、夹针和Interlock手术器械测试套装内的夹线方法测试器械夹持性能。选取医院清洗消毒合格的100件精密手术剪和100件持针器进行测试效果研究,自制满意度问卷调查手术医生对器械使用的满意度。结果:100件精密手术剪经纱布、棉毛布和硅胶薄膜3种方法测试后,切割性能合格数量分别为94件、76件和58件,其差异有统计学意义(χ^(2)=36.526,P<0.05);手术医生对采用硅胶薄膜测试合格的精密手术剪使用满意率最高,为100%,棉毛布和纱布法分别为82.0%和67.0%,其差异有统计学意义(χ^(2)=48.439,P<0.05)。100件精密持针器经光照、夹针和夹线3种方法测试后,夹持性能合格数量分别为96件、78件和62件,其差异有统计学意义(χ^(2)=38.160,P<0.05);手术医生对采用夹线测试合格的精密持针器使用满意率最高,为100.0%、夹针和光照分别为79.0%和62.0%,医生使用满意率比较,差异有统计学意义(χ^(2)=57.705,P<0.05)。结论:采用Interlock手术器械测试套装内的测试物检查精密手术剪及持针器功能质量,能客观精准地反映器械功能状态,为器械定期维护与保养提供参考,确保器械安全使用。

电容电压平衡的四电平有源中性点钳位逆变器的改进模型预测电流控制

多电平有源中点钳位(ANPC)逆变器具有功率器件电压应力小、电流谐波低和器件损耗可调控等优点,被广泛应用于工业驱动中。针对四电平ANPC(4L-ANPC)逆变器的控制与调制研究相对较少,现有的调制方案实现复杂,中点电压(NPV)控制难度较大。因此,该文针对三相4L-ANPC逆变器,提出一种改进的有限集模型预测电流控制(FS-MPCC)算法,避免了复杂的调制过程。首先,使用仅包含电流误差的代价函数对位于六边形顶点的6个大电压矢量进行寻优;其次,对参与第一步寻优的大矢量划分扇区,使用包含电流误差和电容电压误差的代价函数对最优大矢量所在扇区的所有电压矢量滚动寻优,得到目标电压矢量并作用于逆变器;最后,仿真和实验结果表明,与传统的FS-MPCC相比,所提方法在降低系统计算负担的同时,还具有较好的控制性能和电容电压平衡能力。

基于SHEPWM的三电平三相逆变器中点电位主动平衡控制策略

在大功率系统中,常采用特定次谐波消除脉宽调制(SHEPWM)以降低系统的开关损耗。针对三电平中点钳位(NPC)型三相逆变器在SHEPWM下的中点电位偏移问题,分析SHEPWM下逆变器输出相电压基波与3次谐波在不同电压相位范围内对中点电位的影响,设计两种在基波周期内对中点电位总充放电效果相反的开关角组合方案,并提出一种通过测量中点电位偏移值及中点电位滞环控制,选择不同的开关角组合方案进行调制的中点电位主动平衡控制策略。实验结果验证了所提出方法的实用性及有效性。

高速磁浮背靠背三电平ANPC变流器中点电压偏移机理与协同控制策略

高速磁浮交通牵引变流器采用24 MVA背靠背三电平有源中点钳位拓扑,其中两台整流器和两台逆变器共用直流母线。该文分析整流侧和逆变侧在不同功率因数下中点电压(neutral point voltage,NPV)偏移机理及不同电压矢量对NPV的具体影响。据此,针对高速磁浮逆变器并联和串联两种模式,建立NPV偏移模型,得到在调制比和功率因数同时变化时NPV的可控区域。为在全速范围保证NPV平衡,提出一种基于平移调制波的协同控制策略。为减轻整流器功率因数和调制比对NPV的影响,采用一种具有相电压半波对称性的载波脉宽调制,并证明其具备NPV自平衡能力。仿真和硬件在环实验表明,所提策略具有NPV恢复到平衡状态所需时间短、可控范围大等优点,可在高速磁浮全速工况下保证NPV平衡。

多自由度球形裹夹型行波超声波电机阻尼增强型精准定位控制方法

多自由度球形裹夹型行波超声波电机具有可多自由度旋转、结构体积小、不受电磁干扰等特点,可被应用于航天、机器人等特殊场景。但球形裹夹式设计以及超声波电机的特性,导致此电机结构需同时应对模型非线性、转动阻尼低、轴间耦合严重以及运转范围受限等问题。电机转子定位控制过程中振荡和偏差问题突出。因此,为实现精准的定位控制,并避免电机的超速运转可能造成的过热和卡死问题,文中提出一种适用于多自由度球形裹夹型行波超声波电机的阻尼增强型精准定位控制方法。该方法可实现电机精准定位控制,并同时对转子进行定量增阻与转速约束,有效避免运转中的振动和过速。此外,针对裹夹型行波超声波电机的多轴耦合性和模型非线性等问题,采用状态扩张观测器对模型非线性状态进行估计,实现模型的线性化和轴间的解耦处理,便于控制的设计与实现。最后,通过精准定位和抗扰实验验证该方法的有效性。

有轨电车电子机械制动系统夹紧力控制优化方法

针对有轨电车电子机械制动(EMB)系统,提出一种夹紧力控制优化方法。首先建立EMB系统的数学模型,依据其物理结构及刚度非线性特性,将控制器设计为夹紧力控制层与转速控制两级控制结构。针对夹紧力控制层,仅考虑间隙消除与夹紧力的跟踪控制,采用速度曲线规划与夹紧力非线性PI控制相结合,以在期望时间内实现制动间隙快速消除;针对控制层,将系统中存在不确定扰动等效于综合干扰项,提出一种自适应增益超螺旋算法(AGSTA),提高了电机控制层对未知干扰的鲁棒性及速度跟踪的快速性,减小转速超调,使EMB系统的夹紧力保持一致。仿真及实验结果表明,所提出的夹紧力控制优化方法能够有效地改善系统的控制性能。

商用车电控机械制动器结构设计与制动性能验证

提出了商用车电控机械制动器(electro-mechanicalbrake,EMB)结构方案,对其进行了结构设计与参数匹配,并建立了EMB三维模型。为验证EMB制动性能,建立了机电耦合动力学模型,制定了制动夹紧力控制策略,并在输入为阶跃信号、斜坡信号和正弦信号时对EMB的动态响应特性进行了仿真分析。结果表明:在典型工况下,EMB响应过程中各项参数变化趋势与预期相符。

数控铣床工装夹具的设计研究

夹具装置在数控铣床制造加工中具有十分重要的作用,可以提高加工精度与劳动生产率,满足工作需求。数控铣床工装夹具的设计应根据要求合理选择对刀点,筛选刀具和切削用量,重视原始工艺文件,注重防碰撞校核。在数控铣床制造加工过程中,应优化工装夹具的设计,改进夹紧动力装置,改进多工件一次加装,改进多件装工装夹具,并结合工件特性改进。

温州瓯江北口大桥施工期索夹抗滑移控制

温州瓯江北口大桥为主跨2×800 m的三塔四跨双层钢桁梁悬索桥,主跨钢桁梁采用1000 t缆载吊机大节段吊装,施工期索夹受力大、索夹螺杆紧固力损失大,索夹滑移风险高。为给施工期索夹滑移风险评估和抗滑移控制措施提供依据,在《公路悬索桥设计规范》(JTG/T D65-05—2015)索夹抗滑移系数计算公式的基础上,考虑索夹上临时荷载、主缆轴力增加引起的主缆直径变小和主缆丝股重新排列、螺杆时变效应造成的索夹螺杆紧固力损失,提出适用于大跨悬索桥施工期的索夹抗滑移系数计算方法,分析主要参数对施工期索夹抗滑移系数的影响,并评估该桥施工期索夹抗滑移风险,提出索夹抗滑移控制措施。结果表明:钢桁梁吊装过程中,索夹倾角变化大,应采用当前施工阶段索夹倾角计算施工期索夹抗滑移系数,主缆轴力增加引起主缆直径变小是造成索夹滑移的主要原因之一;该桥除主跨跨中钢桁梁节段对应索夹抗滑移系数满足规范要求外,其余索夹抗滑移系数均不满足规范要求。根据索夹滑移风险评估结果,采取紧固索夹螺杆的抗滑移控制措施,并明确了该桥索夹螺杆紧固次数和时机。该桥采取索夹抗滑移控制措施后,施工过程中索夹均未出现滑移现象。

一种电杆智能攀爬机器人的设计与开发

针对电杆施工检修工作效率低、安全隐患大的问题,结合四足攀爬动物的仿生学原理,设计了一种电杆智能攀爬机器人,提出了结构设计方案并对其进行基于三维模型的构建与控制系统分析.首先,结合实际的应用场景,确定攀爬机器人夹持结构、移动机构的设计方案.其次,根据分析结果进行三维模型建立,并进行主机结构的装配;移动机构由电机驱动,实现攀升、下降等运动;基于轮式夹持方式的可靠性和普适性,夹持结构采用轮式夹持方式;最后,采用模块化思想进行智能控制部分的设计.试制物理样机,验证攀爬机器人的可靠性,经测试,达到预期功能.