An empirical I‐V model of tunneling real‐space transfer transistors for monostable–bistable transition logic element application

We proposed an empirical I‐V model to represent the negative differential resistance (NDR) regime of fabricated tunneling real‐space transfer transistors (TRSTTs). For TRSTTs to have great potential in monostable–bistable transition logic element (MOBILE) design, our model is able to accurately reproduce the NDR regime including gate‐source‐bias‐controlled NDR values and modulated peak to valley drain current ratios. The modeled I‐V curves, tranconductances, and NDRs with multiple gate biases are in good agreement with measured data. The key parameters in the model have clear physical meanings, and the value of these parameters is easy to be extracted directly from the test I‐V curves. The model is used to simulate a practical MOBILE, and excellent agreement between the simulated and measured data was found. Copyright © 2015 John Wiley & Sons, Ltd.     

基于GaN HEMT的半桥LLC优化设计和损耗分析

较之于传统硅器件,新出现的增强型氮化镓晶体管GaN HEMTs(gallium nitride high electron mobility transistors)具有很高的开关速度和高功率密度的特性,可以为直流变换器提供有效的改进。为了解决GaN HEMT在硬开关应用场合下的波形振荡并提高功率密度和效率,采用半桥LLC谐振变换器为本次应用的拓扑结构。以减小损耗为目的,优化了LLC的谐振参数和死区时间。在400 V输入电压、开关频率300 kHz和输出电压18 V电流12 A的测试条件下,效率达到95.59%。最后对变换器的损耗来源进行分析,损耗的理论计算值接近实际测量值,证明了方法具有一定的实用性。     

Smith圆图辅助设计低噪声宽频带放大器

接收微弱射频信号需要研究低噪声放大器的设计,文中在分析传统低噪声放大器设计的基础上引入对放大器匹配电路品质因数,扩宽放大器的频带;通过加入电流负反馈及在负载端并联电阻,提高放大器的稳定性、降低放大器驻波比,得到宽频带低噪声放大器的设计方法.仿真结果表明设计的放大器工作绝对稳定.     

电涌保护器脱离器的设计与研究

阐述了SPD脱离器的重要性,从不同功能脱离器的设计要求入手,重点对SPD脱离器的热保护功能和过电流保护功能进行了研究。通过对其中涉及的关键技术进行研究并提出解决方案,总结出不同功能脱离器的设计要点。     

Optimization Design and Direct Torque Control of a Flux Concentrating Axial Flux Permanent Magnet Motor for Direct Driving System

Optimization design and direct torque control (DTC) of a flux concentrating axial flux permanent magnet motor (AFPMM) are presented in this paper, which leads the AFPMM to exhibit high torque capability at low-speed and wide speed operation range for direct driving system. Firstly design parameters and manufacturing materials which affect the output performances of the motor are discussed, and then based on finite element analysis (FEA) and response surface methodology (RSM), slot and pole number combinations, and structure dimensions are optimized. Furthermore, a novel DTC based on stator flux linkage tracking is introduced, which combines maximum torque per ampere (MTPA) control and field weakening (FW) control. Independent H-bridge inverter is used to enhance the voltage limit and enlarge the speed operation range. A prototype AFPMM is fabricated on the basis of the optimum model, and experimental measurements are conducted to verify the usefulness of the proposed optimization design and control methods.