With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this pape...With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage （MFL） in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.展开更多
A novel high-frequency and high power density planar insulated core transformer(PICT) applied to high voltage DC generator is introduced. PICT's operating principle and fundamental configuration are described,and ...A novel high-frequency and high power density planar insulated core transformer(PICT) applied to high voltage DC generator is introduced. PICT's operating principle and fundamental configuration are described,and preliminary experimental results in self-designed PICT apparatus are presented. Emphatically, magnetic leakage flux(MFL) giving rise to the output voltage drop is analyzed in detail both theoretically and by finite element method(FEM). Showing good consistency with experimental result, FEM simulation is considered to be practicable in physical design of PICT. To cancel out leakage inductance and improve the voltage uniformity,compensation capacitor is adopted and experimental verification is also presented. All shows satisfactory results.展开更多
针对传统电机输出端口单一的问题,提出一种新型多端口盘式永磁电机(multi-port disk permanent magnet motor,MDPMM)。首先,介绍该电机的结构及工作原理;其次,针对该电机环形弧线定子周向端部使其漏磁和磁场分布较为复杂的问题,引入磁...针对传统电机输出端口单一的问题,提出一种新型多端口盘式永磁电机(multi-port disk permanent magnet motor,MDPMM)。首先,介绍该电机的结构及工作原理;其次,针对该电机环形弧线定子周向端部使其漏磁和磁场分布较为复杂的问题,引入磁通分布系数,对受环形弧线定子端部影响的区域建立等效磁网络模型,计算各等效磁阻,解析该区域漏磁系数表达式;最后,考虑永磁体电流密度等效,建立环形弧线定子及对应盘式转子区域的分区域解析模型,运用等效磁化强度法推导该区域气隙磁场解析式,并采用许−克变换分析定子齿槽结构对气隙磁场的影响。研究结果表明:该电机可以同时实现双盘式转子和行星轮转子多自由度动力输出;受环形弧线定子端部截面影响和未受影响的2种磁路的气隙漏磁系数计算值分别为1.263、1.167,有限元仿真值分别为1.375、1.222,计算值和仿真值的相对误差分别为8.15%、4.50%;2种磁路的平均气隙磁密计算值分别为0.481、0.492,有限元仿真值分别为0.497、0.503,计算值和仿真值的相对误差分别为3.22%、2.19%,满足工程计算精度要求。展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61273164 and 61034005)the National High Technology Research and Development Program of China (Grant No. 2012AA040104)the Fundamental Research Funds for the Central Universities, China (Grant No. N100104102)
文摘With the increase of pipelines, corrosion leakage accidents happen frequently. Therefore, nondestructive testing technology is important for ensuring the safe operation of the pipelines and energy mining. In this paper, the structure and principle of magnetic flux leakage （MFL） in-line inspection system is introduced first. Besides, a mathematic model of the system according to the ampere circuit rule, flux continuity theorem, and column coordinate transform is built, and the magnetic flux density in every point of space is calculated based on the theory of finite element analysis. Then we analyze and design the disposition of measurement section probes and sensors combining both three-axis MFL in-line inspection and multi-sensor fusion technology. Its advantage is that the three-axis changes of magnetic flux leakage field are measured by the multi-probes at the same time, so we can determine various defects accurately. Finally, the theory of finite element analysis is used to build a finite element simulation model, and the relationship between defects and MFL inspection signals is studied. Simulation and experiment results verify that the method not only enhances the detection ability to different types of defects but also improves the precision and reliability of the inspection system.
基金Supported by the Science and Technology Commission of Shanghai Municipality under Grant No.12ZR1436500the Knowledge Innovation Programm of the Chinese Academy of Sciences
文摘A novel high-frequency and high power density planar insulated core transformer(PICT) applied to high voltage DC generator is introduced. PICT's operating principle and fundamental configuration are described,and preliminary experimental results in self-designed PICT apparatus are presented. Emphatically, magnetic leakage flux(MFL) giving rise to the output voltage drop is analyzed in detail both theoretically and by finite element method(FEM). Showing good consistency with experimental result, FEM simulation is considered to be practicable in physical design of PICT. To cancel out leakage inductance and improve the voltage uniformity,compensation capacitor is adopted and experimental verification is also presented. All shows satisfactory results.
文摘针对传统电机输出端口单一的问题,提出一种新型多端口盘式永磁电机(multi-port disk permanent magnet motor,MDPMM)。首先,介绍该电机的结构及工作原理;其次,针对该电机环形弧线定子周向端部使其漏磁和磁场分布较为复杂的问题,引入磁通分布系数,对受环形弧线定子端部影响的区域建立等效磁网络模型,计算各等效磁阻,解析该区域漏磁系数表达式;最后,考虑永磁体电流密度等效,建立环形弧线定子及对应盘式转子区域的分区域解析模型,运用等效磁化强度法推导该区域气隙磁场解析式,并采用许−克变换分析定子齿槽结构对气隙磁场的影响。研究结果表明:该电机可以同时实现双盘式转子和行星轮转子多自由度动力输出;受环形弧线定子端部截面影响和未受影响的2种磁路的气隙漏磁系数计算值分别为1.263、1.167,有限元仿真值分别为1.375、1.222,计算值和仿真值的相对误差分别为8.15%、4.50%;2种磁路的平均气隙磁密计算值分别为0.481、0.492,有限元仿真值分别为0.497、0.503,计算值和仿真值的相对误差分别为3.22%、2.19%,满足工程计算精度要求。
