Enhanced 1.32 µm fluorescence and broadband amplifying for O-band optical amplifier in Nd3+-doped tellurite glass

WO3 oxides with relatively high phonon energy and different concentrations were introduced into the Nd3+-doped tellurite-based glasses of TeO2-ZnO-Na2O to improve the 1.32 µm band fluorescence emission. The absorption spectra, Raman spectra, 1.32 µm band fluorescence spectra and differential scanning calorimeter (DSC) curves were measured, together with the Judd-Ofelt intensity parameters, stimulated emission and gain parameters were calculated to evaluate the effects of WO3 amount on the glass structure and spectroscopic properties of 1.32 µm band fluorescence. It is shown that the introduction of an appropriate amount of WO3 oxide can effectively improve the 1.32 µm band fluorescence intensity through the enhanced multi-phonon relaxation (MPR) processes between the excited levels of Nd3+. The results indicate that the prepared Nd3+-doped tellurite glass with an appropriate amount of WO3 oxide is a potential gain medium applied for the O-band broad and high-gain fiber amplifier.     

自动均流控制在有轨电车充电装置中的应用

针对新型有轨电车充电装置DC/DC变换器采用并联结构拓扑时两回路输出电流相差较大的问题,提出将自动均流控制技术应用到该装置中。给出了装置拓扑结构,详细分析了其工作原理;推导了系统状态方程,根据实际需求设计了仿真及实验参数。仿真及实验结果表明,采用自主均流控制技术的充电装置,能够很好地均衡两回路的输出电流。     

大功率交错并联在有轨电车充电装置中的应用

针对新型有轨电车充电装置DC/DC变换器采用单相控制技术时输出电流纹波较大的问题,提出将交错并联技术应用到该装置中。给出了装置拓扑结构,采用四相两回路交错并联,同一回路的两相开关管导通时刻相差1/2周期,满足单/双回路运行;推导了输出滤波电抗器的设计方案,列出了变换器PWM控制策略。仿真及实验结果表明,采用交错并联技术的充电装置,既减小了输出电流纹波,又提高了启动电流的响应速度。     

储能式有轨电车停车场充电装置研究

针对传统两电平变流器电能质量差的问题,介绍了一种三电平的变流器拓扑,该拓扑可以在不提高开关频率的情况下有效提高并网电能质量,给出了经典三电平SVPWM算法。针对电能多级变换效率低的问题,提出DC/DC采用移相全桥电路。将三电平变流器拓扑和移相全桥电路应用于储能式有轨电车充电装置,结合PIR的控制策略,改善了电网电能质量,提高了整机效率。仿真及实验结果验证了该拓扑的有效性和可行性。     

Pr3+/Nd3+ codoped tellurite glass for O+E+S-band broad emission

In this work, Pr3+ was introduced into Nd3+-doped tellurite glass with composition TeO2-ZnO-Na2O-Nb2O5 to achieve broadband near-infrared emission. A broadband fluorescence emission ranging from 1 250 nm to 1 530 nm was obtained under the excitation of 808 nm LD, which is contributed by the Pr3+:1D2 →1G4 and Nd3+:4F3/2→4I13/2 transitions emitting the fluorescence located at around 1.47 µm and 1.35 µm bands, respectively. The 1.47 µm band fluorescence of Pr3+ is attributed to the energy transfer from Nd3+ to Pr3+ ions and the energy transfer mechanism was further investigated by calculating relevant micro-parameter and phonon contribution ratio. Meanwhile, the studied tellurite glass possesses good thermal stability. The present work indicates that Pr3+/Nd3+ codoped tellurite glass is an excellent gain medium for potential O+E+S-band broad optical amplifiers.     

基于超级电容有轨电车的充电装置控制研究

超级电容快速储能技术在短时大功率应用中有较好的技术经济性,非常适用于新型有轨电车储能。针对有轨电车充电装置整流器采用传统多脉波整流技术导致的整流器输入侧交流电压畸变、交流电流谐波含量高,直流母线电压纹波大,功率因数不可控等问题,提出采用脉宽调制(PWM)整流方式。该整流方式具有功率因数高,谐波含量低等优点,采用电压-电流双闭环与电压前馈相结合的控制策略,来抑制直流母线电压在超级电容接入瞬间引起的波动。通过设计LCL滤波来吸收整流器交流侧的电流谐波,并推导了LCL滤波器的计算公式。系统仿真和实验证实了该控制的有效性。