The common DC bus five-level inverter has many advantages over the three-level inverter and has been widely used in high-power applications. However, the stray characteristics of the switching devices and the internal factors of the topology can lead to the imbalance of the DC-side capacitor voltage, and the traditional five-level neutral-point capacitor voltage balance modulation strategy is more complicated. Therefore, this paper proposes a hybrid modulation strategy for neutral-point capacitor voltage balancing based on dual modulation waves. By equivalenting the five-level system to a dual three-level system, the three-level modulation strategy with simpler algorithm is analyzed. In low modulation ratio region (m<0.5), the bipolar carrier pulse width modulation strategy with zero-sequence voltage compensation is adopted. In high modulation ratio region (m≥0.5), the improved dual modulation wave strategy is adopted to balance the DC-side capacitor voltage. Finally, the five-level capacitor voltage balancing model is simulated in MATLAB/Simulink to verify the feasibility of the proposed hybrid strategy.

This article takes the fast locking mechanism as the application background and uses a daul-winding permanent magnet synchronous motor instead of the permanent magnet synchronous motor as the actuator of the motor drive system to ensure high reliability of the system. The motor is characterized by having two sets of stator windings with a phase shift angle of 0 and sharing a set of rotors, forming a double redundant structure. The controller, driver and other parts also use dual-channel, hot backup working mode to control the drive unit motors respectively to further ensure the reliability of the system. Based on the mature vector control strategy and planned fault working mode, the entire rapid locking mechanism is cross-coupled and modeled in the multi-domain simulation platform Dymola/ Modelica, and corresponding mechanical, electrical, control and other modules are built. Finally, based on the actual working conditions of the fast locking mechanism, the corresponding speed curve is planned, and the entire system is simulated in fault-free, single-channel, hot backup mode to verify the correctness and fault tolerance of the redundant design.

To achieve impact load resistance for the marine container, the paper designs a novel vibration isolation system. The dynamic characteristics of the system are experimentally investigated to verify the mathematical model. Based on the model, the vibration isolation rate is predicted under different conditions and its sensitivity to different influencing factors is investigated. The system is optimally designed for multiple parameters using adaptive particle swarm optimization (APSO). The results show that the vibration isolation system temporarily enters the pressure building displacement stage which does not affect the properties of the system. The model calculations coincide with the test results by more than 97%, except for the pressure building displacement stage. The predictions of vibration isolation rate are more than 80% and the sensitivity to excitation direction, load mass, system frequency and damping ratio is significant. The optimal system can meet the design requirements of engineering applications.

The demand for transferring the heavy load on marine mobile platform is steadily increasing, surpassing the capabilities of the current system. This paper introduces a chain heavy load transfer system and develops its dynamic model. This paper studies the sensitivity laws of the system's energy demand to unknown parameters and proposes an adaptive mutation particle swarm optimization (AMPSO), whose identification accuracy is verified through comparative analysis. Experimental verification confirms the reliability of the system model while studying the influence of environmental loads on the system's energy demand. The results demonstrate that the chain transfer system meets the requirements of marine mobile platforms, and the system model incorporates the primary influencing factors. Unknown parameters significantly influence the system's energy demand, and the displacement error after parameter identification using AMPSO is 0.00056 rad, substantially enhancing the accuracy of model calculations. The model calculations of the system closely align with experimental measurements, with a maximum displacement error not exceeding 0.004 rad. Sway exerts a greater influence on the system's energy demand compared to tilt. When tilt and sway are superimposed, the friction torque between the load and the track results in increased input torque and power for the vertical arrangement of the system, with a maximum torque of 328.6kNm and maximum power of 400 kW.

针对多模块旋转货架装置的作业效率和安全性能要求,构建了多目标优化的储位分配模型,并提出了一种基于自适应策略(AS,adaptive strategy)的非支配排序遗传算法(NSGA-Ⅱ,non-dominated sorting genetic algorithms);依据仓储系统的调度管控原则,以货品转运能耗、货架存储重心、货品入库时间为目标建立多旋转货架储位优化模型;为了提升算法对解空间的搜索效率,引人基于轮盘赌法的并列选择操作,根据进化次数、目标函数适应度、非支配分层等级动态调整种群个体的交叉、变异操作参数,改进了 NSGA-Ⅱ遗传算子的自适应能力;仿真测试表明,文章提出的算法在求解多目标储位分配优化时,具有更优的执行效率,相比于典型NSGA-Ⅱ算法、多种群遗传算法具备更好的收敛性与多样性,研究结果可为多目标优化问题提供较好参考.

针对多模块网格存储系统中的多分拣点货物排列问题,提出一种解耦的分散式控制方法,将问题解耦为各存储模块的独立调度和模块之间的协调调度.模块内采用循环移动方式进行独立调度,模块间通过交换需求和模块状态控制协调过程.在不同参数条件下进行仿真实验,并与集中式控制方法进行对比仿真,结果表明分散式控制方法能够在各种工况下稳定有效地求解,且相比于集中式控制方法的结果更优,求解时间更短,验证了所提方法的有效性和通用性.

In order to improve the efficiency of rotating shelf scheduling, the optimal picking path optimization problem with time interval constraint (MCS-OOIP) is considered, the mathematical model of MCS-OOIP is established, and an improved hybrid particle swarm optimization algorithm is proposed., By introducing the crossover strategy and mutation strategy of genetic algorithm and the acceptance criterion of simulated annealing algorithm, a hybrid particle swarm optimization algorithm for solving MCS-OOIP problem is constructed by combining it with particle swarm optimization algorithm. The simulation results are compared with the simple genetic algorithm, which shows that the algorithm can more effectively solve the MCS-OOIP problem under the single rotating shelf. The research results can be used as a reference for the transportation path optimization of rotary storage system.

由于受到动态纵向边端效应和铁心饱和的影响,直线感应电机传统等效电路模型电磁参数时变.针对此,本文提出了多因素耦合影响下高速短初级直线感应电机等效电路模型及其时变参数辨识方法.首先,分析不同工况下电机推力变化规律;其次,分析电机电磁参数与运行工况之间的规律,提出激磁电感和次级电阻修正系数,构建直线感应电机改进等效电路模型,并通过响应面分析法计算两个修正系数;最后,开展样机静态堵驻实验和动态实验.计算和实测结果表明:推力计算值与实测值误差不超过4.1％,端口基波正序阻抗的实部、虚部计算值与实测值误差不超过4.7％,验证了时变参数辨识的准确性.

端部漏感是多相直线电机初级漏感的重要组成部分,对电机设计、性能分析及高性能控制有着重要作用.该文提出一种双边十二相直线感应电机端部漏感参数的计算方法.通过引入气隙电流和镜像电流,以Biot-Savart定律为基础,把线圈端部各大段分成若干小段,用数值方法计算2线圈间端部电感,根据直线电机端部绕组排列方式,构造线圈位置矩阵;再根据各相端部绕组的空间位置,构造各相绕组的关联矩阵,最后在此基础上推导出电机初级绕组端部漏感矩阵.该方法具有应用灵活、计算速度高的优点.以研制的样机为例,给出该方法计算端部漏感的具体过程和结果,并通过样机试验验证该计算方法的准确性.

Because of its simple structure, linear induction motor(LIM) is widely used in rail transit, precise positioning, and electromagnetic emission. Due to the dynamic longitudinal end effect, the distribution of the magnetic field is distorted. As a result, the axial thrust of the motor fluctuates twice the power supply frequency. In this paper, taking pulse-driven high-speed linear induction motor as an example, the thrust performance under the influence of end effect is analyzed, whether under the excitation of a voltage source or current source. Combined with the characteristics of motor aperiodic transient motion, the influence of variable parameters on thrust ripple coefficient is analyzed. It is revealed that the thrust ripple of aperiodic transient LIM presents unsteady characteristics, which is different from that of traditional LIM.

Additive manufacturing is becoming increasingly popular because of its unique advantages, especially fused deposition modelling (FDM) which has been widely used due to its simplicity and comparatively low price. However, in current FDM processes, it is difficult to fabricate parts with highly accurate dimensions. One of the reasons is due to the slicing process of 3D models. Current slicing software divides the parts into layers and then lines (paths) based on a fixed value. However, in a real printing process, the printed line width will change when the process parameters are set in different values. The various printed widths may result in inaccuracy of printed dimensions of parts if using a fixed value for slicing. In this paper, a mathematical model is proposed to predict the printed line width in different layer heights. Based on this model, a method is proposed for calculating the optimal width value for slicing 3D parts. In the future, the proposed mathematical model can be integrated into slicing software to slice 3D models for precision additive manufacturing.

The primary current of the multiphase linear induction motor(LIM) reaches tens of thousands of amperes in short-time pulse operation. The motor end windings are subject to a large amount of alternating electromagnetic force. Accurate calculation of the alternating electromagnetic force is the theoretical basis for the fixed design of the end windings. Taking the end structure of twelve-phase LIM as the research object, based on Biot-Savart law, this paper calculates the magnetic density and electromagnetic force density in different directions of each end winding segments in a pole distance and analyzes the fluctuation law of end electromagnetic force, to provide a reference for the end windings structure of the motor. This method has the advantages of high computing speed and flexible application.

采用两条独立能量链供电,工作于非周期瞬态工况的双三相直线感应电机系统,在功率等级、功率密度、控制自由度、系统冗余度等方面具有诸多优势.该文基于考虑动态边端效应的双三相直线感应电机模型,给出了矢量控制策略.结合非周期瞬态系统的运行特性,提出一种故障模式下通过开环计算给定推力作为矢量控制输入的能量链切换控制策略.该控制策略避免了故障暂态过程中给定电流变化与输出电流尖峰的耦合,通过在考虑动态边端效应时电机在最大推力的约束下根据控制目标调整给定推力,实现了系统故障后单能量链的安全运行.仿真和实验验证了所提控制策略的正确性与可行性.

为研究与电机智能制造生产线相匹配的高存储密度仓储系统,提出一种由多个回型存储模块连接而成的多模块网格仓储系统,并提出一种最优循环动作方法,使系统内的负载快速地循环移动出库.将系统抽象为节点和边组成的图模型,提出环和循环移动的概念,证明得到一次循环移动所需的最少动作步数.结果 表明:在规定的负载配置下,最少可通过2步动作完成一次全库负载的循环移动.最后以一个系统实例为对象,利用所提方法构建最优循环移动,实现系统全负载的快速循环移动与拣选.研究结果可为多模块网格仓储系统的性能分析和设计优化提供理论依据.

The modular puzzle-based storage system consists of multiple storage modules. The system has multiple input/output (IO) points which can simultaneously deal with multiple orders in one batch. When a batch of orders comes in advance, it is necessary to rearrange the items near each IO point to reduce the picking time of customers. To complete the rearrangement quickly, this paper proposes a two-stage path planning method considering the simultaneous movement of multiple items. This method includes two stages: planning single moves and merging single moves. In the first stage, the sequence of single moves of each module needs to be obtained so as to convert the system from an initial state to a target state. In the second stage, the single moves in the sequence are merged into block moves and parallel moves to reduce the steps of movement. The simulation results show that the single move planning method can be used to solve the rearrangement problem stably and effectively and that the single move merging method can greatly optimize the experimental results with the optimization rate more than 50% in different configurations.

Due to the change of parameters caused by the dynamic longitudinal end effect, the operation characteristics of linear induction motors (LIMs) applied in an electromagnetic launch field are different from that of ordinary LIM. Due to the continuous increase of the LIM port voltage under high acceleration, the phase voltage is close to the inverter output limit. The conventional indirect field-oriented control (IFOC) strategies of LIM based on the flux attenuation compensation or maximum thrust control cannot solve the problem well. Based on the LIM mathematical model, this study analyses the output thrust characteristics of the LIM and discusses different control methods. This study presents an improved vector control strategy. By dynamically adjusting the value of ‘k’ based on the moving speed of the LIM, the maximum thrust output is maintained at medium and low speeds, and the voltage rise of a motor port is restrained at high speed. The effectiveness of the proposed control method is verified by simulation and experiment. The method proposed in this study is helpful to broaden the application of the LIM in the higher speed field.

Linear induction motors (LIMs), applied in the field of electromagnetic emission, due to end effect, show the characteristics of thrust rapid decline, and current asymmetry increasing in the process of high-speed movement. This article studies the effect of stator winding connections on thrust and current asymmetry of six-phase shifted 30° LIM considering the static and the longitudinal end effect. The study compares three connections by finite-element analysis, namely, open-end, star, and triangular connections. The theory of symmetric component method is introduced to analyze the asymmetric characteristics caused by the end effect. The output thrust and current asymmetries of the motor under three connection modes are compared in detail. The simulation results show that there is no difference among the three connection modes when only considering static end effect, but once considering dynamic end effect, the output current symmetry of star connection is better than that of the open and triangular connection. Also, Adopting variable slip frequency control method can not only improve output thrust of motor, but also improve current symmetry, especially at high speed obviously, when compared with constant slip frequency control method. The research will be helpful to motor thrust optimization control and winding design in the future.

针对电磁发射用直线感应电机的位置检测系统无处理器、信号的采集分析装置需额外配置的缺点,提出了一种集成位置信号采集、运算处理、数据上传、数据存储与分析等功能的智能位置检测系统,采用FGPA+ARM架构的处理芯片,设计了位置检测系统的运算处理、采样、网络上传和上位机软件等功能模块,并在实际电磁发射平台上进行了实验测试.实验结果表明:该智能位置检测系统具备良好的工作性能,而且克服了原有位置检测系统的缺点.

This paper introduces a linear induction motor with segmented power supply, which transforms the electric energy into the kinetic energy of the load movement in electromagnetic launch system. Based on the characteristics of electromagnetic emission mode, a special electromagnetic force analysis method of the motor is proposed. Firstly, considering secondary edge leakage, based on the principle of port equivalence, the equivalent circuit model is modified, and the calculation method of normal electromagnetic force of linear induction motor which is suitable for aperiodic transient operation in electromagnetic emission situation is analyzed. The accuracy of the method is verified by the finite element software. Secondly, combined with the kinematic model of Newton's second law, the relationship between the magnitude of electromagnetic force and the time of the stator in each section of the motor in the launching process is analyzed in detail, which lays the foundation for the dynamic response analysis and structural optimization design of the subsequent launching device.

为研究复杂软件系统中的内存泄露问题,首先从嵌入式协议栈LwIP使用过程中的一种网络传输性能下降现象出发,基于协议栈控制块内存管理参数,确定了协议栈内存泄露是导致设备长期运行出现该现象的直接原因;然后,结合协议栈源码详细分析了内存泄露的原因和机理,提供了一种解决此类问题的方法,并从编程接口的角度给出了避免出现内存泄露问题的使用原则,对LwIP协议栈的正确使用具有一定的指导意义.