交流接触器分闸相位控制器

提出了一种交流接触器分闸相位控制器。设计了信号调理、嵌入式控制、开关控制等模块,并论述了部分主要硬件电路及软件实现方法。控制器实现了主回路电流相位检测及选相分闸的功能,为交流接触器在不同相位分闸时电弧特性的研究提供了条件,对提高接触器电气寿命有重大意义。     

新能源汽车预充控制原理及故障案例分析

近年来,新能源汽车发展势头迅猛,已然成为未来汽车的必然趋势。2021年,我国新能源汽车销量预计将达到340万辆,较上一年翻了约1.5倍。新能源汽车动力系统采用高压电,对不同使用环境下的安全性、稳定性、可靠性等方面都有着极高的要求。比如新能源汽车高压上电时,都设计有预充控制环节来保护高压回路及高压部件免受大电流损坏。本文主要针对新能源汽车预充控制过程及原理进行分析讨论,并结合实际故障案例诊断排除过程,讲述预充故障的检测方法。     

Transport Phenomena in Zonal Centrifuge Rotors. III. Particle Sedimentation in Gradient Solutions

Abstract

An analysis is presented for the prediction of (a) a particle position as a function of rotation time, (b) an instantaneous particle sedimentation velocity, and (c) an instantaneous observed particle sedimentation coefficient in a gradient solution characterized by viscosity and density profiles which are expressed in polynomials as functions of radial distance of the zonal rotor. Effect on variation of those predicted quantities with (a) particle size and rotor speed, (b) the density ratio between a particle and the light end of the gradient solution, and (c) the profiles of a gradient solution are also discussed from the computed numerical results.     

Mathematical model of five-level ac/dc converter in abc reference frame

This paper proposes a mathematical model for three-phase multilevel diode clamped ac/dc converter (DCC) in abc-reference frame, in order to study dynamic responses and stability of the system, where multilevel converters are employed. An attempt is made to model the converter adopting 5-level DCC and can be easily extended to DCC with any number of levels. The converter output and dc capacitor voltages are expressed in terms of input source currents and switching functions; which are basic inputs provided to a converter. Connection and capacitor currents of the converter have been analyzed. The effectiveness of the proposed mathematical model is verified by the computer simulations and experimental results. The obtained mathematical model has been validated with the physical converter model in MATLAB/Simulink environment and the prototype model using dSPACE DS under closed loop control system. The developed mathematical model equations are able to represent the physical converter with similar characteristics.     

Single‐Stage ZVS‐PWM AC‐AC Power Converter Using All SiC Power Module for High‐Frequency Induction Heating Applications

This paper presents a novel prototype of a single‐stage zero voltage soft‐switching pulse‐width modulation ‐controlled ac‐ac converter with a silicon carbide (SiC)‐MOSFET/SiC‐SBD power module for high‐frequency (HF) induction heating (IH) applications. The newly developed ac‐ac converter can achieve higher efficiency than a Si‐IGBT/Si‐PN diode power module‐based prototype due to a low ON‐resistance of SiC‐MOSFET and a low forward voltage of SiC‐SBD under the condition of HF switching. The performances of the new prototype converter are evaluated by experiment with a single‐phase IH utensil of ferromagnetic stainless metal, after which the high‐efficiency and low switching noise characteristics due to the all SiC power module are actually demonstrated.     

不同喷丸材料对交流接触器铁心极面喷丸处理性能影响的研究

通过分析交流接触器铁心制造工艺中两种不同喷丸材料对产品性能的影响,从而提高表面的抗锈能力和铁心机械寿命,为低压交流接触器铁心制造和质量控制提供了一定的技术参考。     

直流接触器断电不释放问题分析与研究

针对某型直流幅压接触器断电不释放问题,主要从接触器在长时间通电后,铁心剩磁因积累效应而增大产生的剩磁力,以及上下铁心吸合时极面上的防锈油漆在高温下出现较大黏结力两个方面进行了分析与研究。详细叙述了剩磁力和油漆黏结力对接触器的影响,通过计算和试验验证,明确了油漆黏结力高温下较大导致某型直流接触器断电不释放,并提出了相应的改进措施。     

智能交流接触器动态电感测量及合闸位移预测

动态电感和合闸位移是衡量智能交流接触器动态特性的两项重要参数,为对动态电感和位移进行预测,引入空气间隙与等效磁阻之间的数学关系,建立了一种智能交流接触器等效磁路模型。通过在线检测线圈输入电压和电流,实现对动态电感和合闸位移在线实时监测的目的,可有效掌握和评估智能交流接触器的实时动态特性。采用激光位移传感器对接触器动态特性进行同步对比实验,实验结果显示预测位移与位移传感器实际测量位移较为吻合,表明在无需位移传感器的条件下,可有效预测接触器的动态特性。