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关键词： 电动拖拉机   无刷直流电机   矢量控制   电驱系统  

摘要： 双碳背景下,针对温室大棚作业需求,设计了一种电动拖拉机用低成本、高效率、大转矩电驱控制系统。为此,提出将永磁无刷直流电机用作电动拖拉机驱动电机,并将电压空间矢量控制方法应用于该电驱系统。首先,针对电动拖拉机行驶和耕作的典型工况进行动力性能需求分析,建立永磁无刷直流电机数学模型;然后,进行矢量控制系统建模与仿真分析;最后,搭建试验平台,实现电动拖拉机用无刷直流电机高效稳定控制。试验结果证明:电驱控制系统在重载时最大效率可达85%以上,将其应用在四轮驱动电动拖拉机上,不仅荷载能力强,且具有优异的经济性和稳定性,适用于温室大棚作业场所。

关键词： 码垛机器人   滑模控制   超螺旋算子   参数整定   萤火虫算法   最优控制  

摘要： 针对桶装水码垛机器人关节空间最优运动控制问题,提出一种基于改进萤火虫算法的超螺旋滑模控制策略。首先,利用DH参数法建立码垛机器人运动学模型,并通过Lagrange方程推导出其动力学模型;接着,采用三次多项式将码垛机器人在笛卡尔空间中的位姿转换成光滑连续的关节空间运动轨迹;进而,设计超螺旋滑模控制器实现各关节对参考轨迹的快速精准跟踪;同时,以综合时间与绝对误差为目标评价函数,引入改进萤火虫算法来整定所设计控制器中的参数,实现关节空间最优运动控制;最后,通过典型仿真算例验证了所设计控制方法的有效性和优越性。仿真结果表明,所设计控制器的响应速度、跟踪精度及调整时间要优于积分滑模控制器,并能有效抑制系统抖振。

关键词： 三相永磁同步电机   电驱动系统   旋转变压器   电机冷却   纯电动轿车   驱动电机   水冷结构   矢量控制  

摘要： 八、奇瑞小蚂蚁。电驱动系统结构图如图205所示。(一)功能介绍及参数。1.驱动电机功能介绍。驱动电机为三相永磁同步电机,用作纯电动轿车的驱动,安装于后舱位置,如图206所示。此类电机具有结构简单、体积小、重量轻、效率高等特点。在控制器的控制下,电机能在宽广的速度范围内工作,以满足纯电动轿车的运行工况。电机内置旋转变压器一个,用于检测转子的转速和位置,以实现对电机的矢量控制;电机冷却方式为水冷结构。

关键词： Lock-in thermography   Mobile ions   Intrusion   Contamination   Power electronics   Nondestructive   Transfer characteristic   HTGB  

摘要： Small mobile ions, especially sodium and potassium are known to have the ability to infiltrate and move within gate oxide layers of silicon MOS devices. The ion transport in silicon oxide is either a temperature-driven, isotropic diffusion process, or an electrical ion current in presence of an electric field. Therefore, the high temperature gate bias test with negative polarity provides ideal conditions to identify the presence of mobile ions in the gate oxide of IGBT and MOSFET. Mobile ions in sufficient concentration can severely affect the electric characteristics, such as the turn-on and turn-off behavior of the MOS channel, by creating a shift in the gate threshold voltage or excessive sub-threshold currents. This paper shows several examples of how mobile ions can get into the gate oxide, e.g., via cracks in top side metallization, or by corrosive attack of cap layers. All these different failure modes develop the same electrical failure signature after temperature and/or gate bias stress. During the investigations on mobile ions, a special lock-in thermography method was developed that allows to localize the defect sites in the semiconductor by taking advantage of exclusive excitation of MOS cells affected by mobile ion contamination. Finally, after defect localization, further analytical methods can be applied to identify the exact nature of the access path to the gate oxide. Based on the test and analytical routine described above, a special test method was developed that allows to evaluate the permeability of the semiconductor chip top side structures towards mobile ions and to check for weak spots and potential leakage paths.

关键词： Insulated gate bipolar transistors (IGBT)  

摘要： The purpose of this work is to study the influence of different parameters on short-circuit type III (SC-III) robustness limit of the IGBT and freewheeling diodes (FWD) beyond the specified datasheet values. SC-III measurements without gate-emitter voltage (VGE) clamping show a reduced SC-III safe operating area (SOA) at higher DC-link voltages because of high collector current peaks (IC,peak) induced by transient gate-emitter overvoltage and subsequent high negative diC/dt values. By applying a VGE clamping circuit, SC-III last-pass collector-current (IC,sat,Lastpass) can be fully recovered to the level of SC-I, even though the IGBT and diode encounter harder conditions in the SC-III event. Parameters such as parasitic inductance (Lpar), load current (Iload) and temperature (Tstart) have an influence on the SC-III robustness limit of the IGBTs and FWDs. Also, the second reverse-recovery peak of the FWD during an SC-III event is strongly influenced by whether the gate -emitter voltage is applied across the sense or load-emitter terminal.

关键词： Suspension chopper   soft-switch   phase-shifted full-bridge   voltage spike   IGBT  

摘要： Suspension chopper is a high-power electrical equipment which controls the suspension state of maglev train. Its performance directly determines the stability and safety of maglev train. However, the traditional suspension chopper has the problem of high voltage spikes of IGBT and load, which poses a threat to the safe operation of high-speed maglev train. In order to solve this problem, this paper designs a phase-shifted full-bridge suspension chopper, which only adds an auxiliary circuit and four parallel capacitors. The soft-switch is realized by using the phase-shifted control signals, so as to reduce the voltage spikes. Compared with other voltage spike suppression methods, the method has the advantages of good suppression of voltage spikes, simple circuit structure, less use of components, and insensitive to component parameters. The performance of the designed circuit is simulated by ANSYS Simplorer, and verified by experimental test platform. The simulation and experimental results show that the phase-shifted full-bridge suspension chopper can greatly reduce voltage spikes of the load and IGBT.

关键词： IGBTs   thermal management   reliability   junction temperature  

摘要： One of the most important causes of the failure of power electronic modules is thermal stress. Proper thermal management plays an important role in more reliable and cost-effective energy conversion. In this paper, we present an advanced active thermal control (ATC) strategy to reduce a power device's thermal stress amplitude during operation, with the aim of improving the reliability and lifetime of the conversion system. A state-space model based on a Foster-type thermal model is developed to achieve junction temperature estimation in real time. A feedback controller based on finite-time boundedness (FTB) is proposed to precisely regulate the temperature in order to reduce the thermal stress according to the temperature profile. The designed controller permits the precise control of the temperature and strongly reduces the thermal stress during fast transients in the power demand. Simulation and experimental results are provided to validate the effectiveness of the proposed method.

关键词： Strain   Fatigue   Standards   Plastics   Load modeling   Switching loss   Temperature measurement   High cycle fatigue (HCF)   insulated gate bipolar transistor (IGBT)   lifetime estimation   power cycling   reliability  

摘要： To speed up the testing time in a power cycling test, normally high-acceleration factors induced by high temperature swings are applied. With a classical Coffin-Manson lifetime approach, the induced fatigue can be modeled. This work uses test conditions at the transition between the elastic and plastic deformation zones. Testing the high cycle fatigue zone requires evolved equipment, so active power cycling with switching losses is implemented. It was found that for high junction temperatures (T-vj,T-max = 150 degrees C), a transition between the plastic and the elastic zones could not be detected down to Delta T = 18 K. However, for reduced junction temperatures (T-vj,T-max = 115 degrees C), the start of the elastic zone was found at around Delta T < 29 K. The main failure mechanism was found to be chip solder fatigue in the center of the solder layer. The experimental data are transferred into a 3-D simulation environment to further investigate the failure mode. With the findings, a lifetime model is described and applied, which predicts, depending on conditions, lifetime benefits up to 268% compared with a standard lifetime approach.

关键词： 功率变流器   热网络模型   IGBT结温提取   观测器  

摘要： IGBT模块的结温提取是其健康监测和寿命评估的一项重要环节。常用的开环观测器缺乏抗干扰能力，闭环方案则由于传热系统的状态不完全能观而不可行。因此，提出了一种适用于IGBT结温在线提取的复合观测器，其闭环部分通过能观状态构建，其余不能观状态则构成开环部分。文中针对以FF225R12ME4型号IGBT为器件的H桥逆变器，给出了IGBT结温复合观测器的详细设计过程。最后，在硬件在环（HiL）系统dSPACE DS1202上对该复合观测器进行了实时仿真验证。HiL仿真结果验证了所提出的复合观测器在抑制损耗计算误差对估计精度的影响方面优于传统的开环观测器。