主动磁轴承(active magnetic bearing,AMB)是飞轮储能系统中实现飞轮转子非接触支撑的核心部件,其对飞轮转子施加的作用力与多种非线性因素相关。采取"两步线性化"方法的传统线性模型抹除了非线性特性,难以准确描述其宽频谱...主动磁轴承(active magnetic bearing,AMB)是飞轮储能系统中实现飞轮转子非接触支撑的核心部件,其对飞轮转子施加的作用力与多种非线性因素相关。采取"两步线性化"方法的传统线性模型抹除了非线性特性,难以准确描述其宽频谱的工作状态,也影响了控制系统的设计精度。针对该问题,文中基于替代映射的观点建立非线性的AMB模型。通过AMB的三维有限元计算模型的参数化计算和BP神经网络训练来获得对应的转移和偏执矩阵,然后建立描述转子位移和绕组电流与作用力之间映射关系的零维非线性动力学模型,并在Matlab/Simulink软件平台仿真实现。计算结果表明,AMB内存在四次高次项、交叉项等复杂非线性特性。与线性模型的对比表明,建立的非线性模型可以更准确描述AMB的非线性特性。该模型对飞轮储能系统仿真和控制系统开发具有一定意义。展开更多
The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.A three-dimensional thermal-...The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.A three-dimensional thermal-fluid numerical model including electrochemical reactions and water-gas-shift(WGS)reaction for a single channel solid oxide fuel cell was developed to study the steady-state characteristics,which include distributions of the temperature(T),temperature gradient((35)T/(35)x),and fuel utilization.It was shown that the maximum temperature(Tmax)changed with operating voltage and the maximum temperature gradient(((35)T/(35)x)max)occurred at the inlet of the channel of a solid oxide fuel cell by simulation.Moreover,the natural convection condition had a great influence on T and(35)T/(35)x.The thermal stress generated by temperature differences was the key parameter and increasing the convection heat-transfer coefficient can greatly reduce the thermal stress.In addition,the results also showed that there were lower temperature gradients and lower current density at high working voltage;therefore,choosing the proper operating voltage can obtain better cell performance.展开更多
文摘主动磁轴承(active magnetic bearing,AMB)是飞轮储能系统中实现飞轮转子非接触支撑的核心部件,其对飞轮转子施加的作用力与多种非线性因素相关。采取"两步线性化"方法的传统线性模型抹除了非线性特性,难以准确描述其宽频谱的工作状态,也影响了控制系统的设计精度。针对该问题,文中基于替代映射的观点建立非线性的AMB模型。通过AMB的三维有限元计算模型的参数化计算和BP神经网络训练来获得对应的转移和偏执矩阵,然后建立描述转子位移和绕组电流与作用力之间映射关系的零维非线性动力学模型,并在Matlab/Simulink软件平台仿真实现。计算结果表明,AMB内存在四次高次项、交叉项等复杂非线性特性。与线性模型的对比表明,建立的非线性模型可以更准确描述AMB的非线性特性。该模型对飞轮储能系统仿真和控制系统开发具有一定意义。
基金National Natural Science Foundation of China(No.51376018)。
文摘The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.A three-dimensional thermal-fluid numerical model including electrochemical reactions and water-gas-shift(WGS)reaction for a single channel solid oxide fuel cell was developed to study the steady-state characteristics,which include distributions of the temperature(T),temperature gradient((35)T/(35)x),and fuel utilization.It was shown that the maximum temperature(Tmax)changed with operating voltage and the maximum temperature gradient(((35)T/(35)x)max)occurred at the inlet of the channel of a solid oxide fuel cell by simulation.Moreover,the natural convection condition had a great influence on T and(35)T/(35)x.The thermal stress generated by temperature differences was the key parameter and increasing the convection heat-transfer coefficient can greatly reduce the thermal stress.In addition,the results also showed that there were lower temperature gradients and lower current density at high working voltage;therefore,choosing the proper operating voltage can obtain better cell performance.
