课程文献中心 更多>>

关键词： 双有源桥变换器   三重移相控制   电流应力   软开关   虚拟直接功率控制  

摘要： 针对双有源桥变换器存在电流应力大、全部开关管软开关实现困难以及动态响应慢的问题,提出1种基于三重移相控制的多目标统一优化控制策略。分析三重移相控制正向功率流的全局模式,选出其中3种高效率模式并建立电流应力和软开关解析模型。结合模型,采用成本函数优化方程推导不同模式下的最优移相比组合和最小电流应力,使开关管运行在零电压开关功率约束范围内。同时在效率优化过程中引入虚拟功率分量,构建小信号模型并阐明不同状态变量的小扰动对输出电压的影响较小。实验结果表明,所提控制策略可以在全功率范围内降低双有源桥变换器的电流应力且使所有开关管实现零电压开通,同时还能够提高输出电压的动态性能。

关键词： Energy analysis   Nonlinear energy conversion and transmission model   DC off-grid hydrogen system   Energy hubs   Energy hubs   IGBT   SIMULATION   FLOW   GAS   HUB  

摘要： The dynamic response characteristics between the multiple energy flows of electricity-hydrogen-heat in the renewable energy DC off-grid hydrogen production system are highly coupled and nonlinear, which leads to the complexity of its energy conversion and transmission law. This study proposes a model to describe the dynamic nonlinear energy conversion and transmission laws specific to such systems. The model develops a nonlinear admittance framework and a conversion characteristic matrix for multi-heterogeneous energy flow subsystems, based on the operational characteristics of each subsystem within the DC off-grid hydrogen production system. Building upon this foundation, an energy hub model for the hydrogen production system is established, yielding the electrical, thermal, and hydrogen energy outputs along with their respective conversion efficiencies for each subsystem. By discretizing time, the energy flow at each time node within the hydrogen production system is computed, revealing the system's dynamic energy transfer patterns. Experiments were conducted using measured wind speed and irradiance data from a specific location in eastern China. Results from selected typical days were analyzed and discussed, revealing that subsystem characteristics exhibit nonlinear variation patterns. This highlights the limitations of traditional models in accurately capturing these dynamics. Finally, a simulation platform incorporating practical control methods was constructed to validate the model's accuracy. Validation results demonstrate that the model possesses high accuracy, providing a solid theoretical foundation for further in-depth analysis of DC off-grid hydrogen production systems.

关键词： RC-IGBT   Impact ionization   Snapback effect   Silicon germanium   Tunneling   REVERSE-CONDUCTING IGBT   SIMULATION   GE  

摘要： In this study, two new structures are proposed for reverse-conducting insulated gate bipolar transistors (RC-IGBT) that effectively prevent snapback by relocating the N-collectors and utilizing silicon-germanium in the collector region of each device. The forward mode of the proposed structures shows IC- VC characteristics without snapback, since the position of the N-collector is changed to prevent electron extraction. In the reverse mode, the silicon-germanium induces currents through tunneling and impacts the ionization mechanisms. Importantly, the proposed structures generate a stable current value even if there are errors in the length of the N-collector during ion implantation, which enhances the reliability of the device. In addition, the proposed structures exhibit similar values for the breakdown voltage at around 700 V and the turn-on and turn-off losses when compared to the conventional RC-IGBT. Thus, this paper improves the reliability of RC-IGBTs by mitigating the snapback effect while maintaining their unique electrical properties.

关键词： AC-DC power converters   Power electronics   Pulse-width modulation converters   Submarine battery   SINGLE-SWITCH   VOLTAGE   CAPACITY  

摘要： This innovative charger-discharger utilizing the technology of IGBT, designed for lead-acid submarine batteries, is discussed in the present manuscript. Within the system, a bidirectional DC-DC converter links the Battery-Ultra Capacitor system, ensuring Depth of Charge and State of Charge are controlled very precisely to avoid sulfation. Over 12 months of field tests, IGBT chargers succeeded in obtaining 93 % charge efficiency; at its turn, the one with linear charging, provided by traditional rectifiers, for instance, was already 85 %, meaning it literally snatched huge energy savings and was cost-wise beneficial. The system showed a better thermal stability at just 2.3 degrees C standard deviation fluctuation. As per the regression, if the efficiency is improved by 1 %, the life of the battery is extended to nearly 0.53 months. The result was further confirmed by ANOVA, and the fall of batteries was predicted with 92 % accuracy with the help of a Random Forest model. As such, on balance of performance, cost, and reliability, the most appropriate technology for the submarine application is that of the IGBT rather than the SiC MOSFETs or GaN transistors. It conserves power and gas generation for improved operational efficiency and higher battery life, and improves overall sustainability.

关键词： 船舶避碰   多项式混沌展开   碰撞危险度   最优控制   遗传算法  

摘要： 现有的船舶避碰轨迹规划大部分是以精确的运动模型和环境信息为前提，难以应对实际环境中存在的多种不确定海况因素并导致规划出的轨迹安全可靠性降低。针对以上问题，提出一种基于多项式混沌展开法的船舶鲁棒轨迹规划方法，将船舶水动力学模型中的水动力系数视为不确定性参数，以碰撞危险度及舵角控制量为目标函数，建立船舶轨迹规划的最优控制模型，并使用遗传算法求得控制量与优化后的轨迹。试验结果表明，优化后的轨迹最小距离以及最大会遇距离均提升10%-20%，平均碰撞危险度降低10%，试验结果证明考虑不确定性后的船舶轨迹更加安全可靠。

关键词： 碳中和   经济增长   碳中和能力   生态碳汇   最优控制  

摘要： 碳中和对人类社会可持续发展具有重要意义， 而碳中和技术与生态碳汇是影响碳中和能力的重要因素. 本文首先将这两种因素以及碳中和目标中明确的时间节点纳入考虑， 构建了碳中和目标影响下的有限时域经济增长模型， 然后运用最优控制理论获得了该问题最优解的显式表达式， 并在此基础上分析了最优消费、投资、资本存量、碳中和能力的性质， 最后基于理论分析与数值仿真结果， 提出了相关政策建议. 研究表明， 各国需根据自身禀赋以及目标资本存量等因素， 制定与之相匹配的碳中和目标; 不同国家或者同一国家的不同地区， 应当根据碳中和过程所处的不同阶段选择不同技术水平的碳中和投资; 与通常预期不同的是， 碳中和能力路径可能随碳中和技术投资产出弹性的上升而下降; 在接近碳中和时间节点时碳中和投资可能出现“反常”现象.

关键词： 离散事件系统   定向监控器   强化学习   最优控制   数值优化   交通系统  

摘要： 对于多个可控事件（控制指令）允许同时执行的情形，离散事件系统的监控器进行随机选择.然而，在实际应用中，如交通调度、机器人路径规划，可控事件的定向选择和数值优化是必须要考虑和解决的两个问题.对此，引入一种优化机制量化控制成本，将监督控制理论与强化学习结合，提出一种基于强化学习的离散事件系统最优定向监控器求解方法，使被控系统实现以下三个目标：（1）遵循安全性和活性控制规范；（2）每个状态下至多允许一个可控事件执行；（3）从初始状态到标记状态事件执行累计成本最小.首先，建立系统和控制规范的自动机模型，做同步积运算后可得到目标模型，通过定义的成本函数为目标模型中每个事件的执行赋予成本.其次，利用监督控制理论求解无阻塞且行为最大许可的监控器.最后，将监控器转化为马尔可夫决策过程，并利用Q学习算法求解出最优定向监控器.使用单向列车导轨控制案例和多轨道列车控制案例验证所提方法的有效性和正确性.仿真结果表明，所提出方法能够实现系统的无阻塞定向控制，并且使得定向监控器的数值成本最小.

关键词： 矿用变频器   高频电路模型   损耗模型   电热耦合  

摘要： 矿用变频器一般工作在密闭空间下，电热耦合效应显著，易导致热退化和热失效。另外，矿用变频器和电机通常采用长电缆连接，需要考虑电缆带来的高频负面效应。本研究以630kW/1140V四象限矿用变频器为对象，建立其一体化电热耦合模型并对其相关特性进行研究分析。首先，建立了矿用变频器的高频电路模型。其次，研究各功率器件损耗受温度影响的机理，分析了部分损耗随温度的非线性关系，推导了各损耗随温度变化的解析模型。最后，分析了高频电路模型、损耗模型以及温度场模型之间的耦合关系，建立了矿用变频器的一体化电热耦合模型。耦合仿真结果表明了电热耦合建模的必要性，实验和仿真结果最大误差仅为0.9℃，验证了所建模型的准确性。

关键词： 状态监测   IGBT   非接触式   嵌入式装置  

摘要： 绝缘栅双极型晶体管(Insulated gate bipolar transistor, IGBT)是中大功率电力电子变流器的核心器件。为提高IGBT状态监测的安全性与经济性，研究了一种基于高频开关振荡的三相两电平变流器非接触式状态监测技术。采用专用传感器首先通过非接触方式在线测量变流器PWM开关电压自激产生的高频振荡电流，然后利用三相高频振荡与基波电流的极性关系在无门极信号的条件下实现了变流器中所有IGBT开关事件定位，最后根据振荡信号中开关暂态拐点特征检测出IGBT关断时间。基于以上技术原理，采用嵌入式平台研发了一套变流器IGBT非接触式状态监测装置并在380 V/3 kW变频电机对拖平台上开展了技术验证工作。试验结果表明，该装置能对变频器逆变器中6个IGBT的开关特性及其健康状态实施在线监测，具有安全、准确以及经济等优点。