Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the ac...Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.展开更多
This paper deals with two basic issues of fuel cell research： modelling and experimental validation. In particular, the EIS （electrochemical impedance spectroscopy） technique is applied to a PEMFC （proton exchange...This paper deals with two basic issues of fuel cell research： modelling and experimental validation. In particular, the EIS （electrochemical impedance spectroscopy） technique is applied to a PEMFC （proton exchange membrane fuel cell）. Experiments have been performed using a low-cost test bench and instrumentation developed around a 1,200 W Ballard Nexa fuel cell system. An electrical and dynamic model in VHDL-AMS language for PEM fuel cell stack is described. The privileged approach in this paper is an electrical method. Few papers deal with the modelling of a fuel cell in VHDL-AMS language with an electric approach. The fuel cell is characterised cell wise in VHDL-AMS; AC and DC measurements show the good agreement between the simulation results of the model and those measured in experiments. The model is capable to predict accurate stack profiles. The model is validated using temporal and impedance spectroscopy method; the impedance spectroscopy is performed at low and high frequencies. The experimental and simulated Nyquist plots show that the frequency response of the fuel cell stack can be predicted by the proposed fuel cell stack model. At high frequencies, comparisons between experimental and model impedance results are performed and show some similarities between the two Nyquist. Error between the two approaches is below 1.5%.展开更多
脉宽调制技术的应用会产生高频开关纹波,一般采用LCL滤波器对其加以滤除,以保证有源电力滤波器的补偿性能。首先根据系统对纹波电流的抑制要求和最大电流跟踪能力要求,对LCL中的滤波电感取值进行优化设计。然后针对传统电感设计过程复...脉宽调制技术的应用会产生高频开关纹波,一般采用LCL滤波器对其加以滤除,以保证有源电力滤波器的补偿性能。首先根据系统对纹波电流的抑制要求和最大电流跟踪能力要求,对LCL中的滤波电感取值进行优化设计。然后针对传统电感设计过程复杂繁琐、带有重复性且很难求得可靠解析解的缺点,提出一种四维可视化算法,先推导建立各设计目标和已知自变量之间的三元函数表达式,然后通过四维数据场可视化编程直接给出满足多目标设计要求的最优解集,直观、清晰且简单、实用。最后,根据所提算法结果绕制相应电感,并应用于一台50 k V·A三相四线制有源电力滤波器样机,实验结果验证了该策略的可行性和有效性。展开更多
基金National Natural Science Foundation of China(Nos.51204147,51274175,51574206,51574207)Program for International S&T Cooperation Projects of China(No.2014DFA50320)+1 种基金Program for International S&T Cooperation Projects of Shanxi Province(No.201381017)Technological Projects of Shanxi Province(No.20150313002-3)
文摘Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.
文摘This paper deals with two basic issues of fuel cell research： modelling and experimental validation. In particular, the EIS （electrochemical impedance spectroscopy） technique is applied to a PEMFC （proton exchange membrane fuel cell）. Experiments have been performed using a low-cost test bench and instrumentation developed around a 1,200 W Ballard Nexa fuel cell system. An electrical and dynamic model in VHDL-AMS language for PEM fuel cell stack is described. The privileged approach in this paper is an electrical method. Few papers deal with the modelling of a fuel cell in VHDL-AMS language with an electric approach. The fuel cell is characterised cell wise in VHDL-AMS; AC and DC measurements show the good agreement between the simulation results of the model and those measured in experiments. The model is capable to predict accurate stack profiles. The model is validated using temporal and impedance spectroscopy method; the impedance spectroscopy is performed at low and high frequencies. The experimental and simulated Nyquist plots show that the frequency response of the fuel cell stack can be predicted by the proposed fuel cell stack model. At high frequencies, comparisons between experimental and model impedance results are performed and show some similarities between the two Nyquist. Error between the two approaches is below 1.5%.
文摘脉宽调制技术的应用会产生高频开关纹波,一般采用LCL滤波器对其加以滤除,以保证有源电力滤波器的补偿性能。首先根据系统对纹波电流的抑制要求和最大电流跟踪能力要求,对LCL中的滤波电感取值进行优化设计。然后针对传统电感设计过程复杂繁琐、带有重复性且很难求得可靠解析解的缺点,提出一种四维可视化算法,先推导建立各设计目标和已知自变量之间的三元函数表达式,然后通过四维数据场可视化编程直接给出满足多目标设计要求的最优解集,直观、清晰且简单、实用。最后,根据所提算法结果绕制相应电感,并应用于一台50 k V·A三相四线制有源电力滤波器样机,实验结果验证了该策略的可行性和有效性。
