为了抑制复杂工况下变压器的直流偏磁,提出了考虑抑制措施的变压器绕组直流电流分布计算模型以及变压器直流偏磁风险的磁动势评估模型。通过实例对各种抑制措施的效果进行了交叉对比。结果表明:绕组的等效直流磁动势是变压器直流偏磁风...为了抑制复杂工况下变压器的直流偏磁,提出了考虑抑制措施的变压器绕组直流电流分布计算模型以及变压器直流偏磁风险的磁动势评估模型。通过实例对各种抑制措施的效果进行了交叉对比。结果表明:绕组的等效直流磁动势是变压器直流偏磁风险的决定性因素。在复杂运行工况下,不合理地使用抑制措施会令变压器直流偏磁危害加剧。电流注入法可以令自耦变串联绕组和公共绕组通过反向的直流电流,实现了等效磁动势的相互抵消,可以有效抑制复杂运行方式下500 k V变压器的直流偏磁危害。展开更多
We propose a novel axis-symmetric modified hybrid permanent magnet(PM)/electromagnet(EM) magnetomotive force actuator for a variable valve timing camless engine. The design provides a large magnetic force with low ene...We propose a novel axis-symmetric modified hybrid permanent magnet(PM)/electromagnet(EM) magnetomotive force actuator for a variable valve timing camless engine. The design provides a large magnetic force with low energy consumption, low coil inductance, PM demagnetization isolation, and improved transient response. Simulation and experimental results confirm forces of about 200 N(in the presence of coil current) at the equilibrium position and 500 N(in the absence of coil current) at the armature seat. We compared our proposed design with a double solenoid valve actuator(DSVA). The finite element method(FEM) designs of the DSVA and our proposed valve actuator were validated by experiments performed on manufactured prototypes.展开更多
为了研究不同形式绕组产生的谐波磁动势对电机推力的影响,设计了3种绕组(双层整距绕组、双层短距绕组、单层整距绕组)形式的短初级双边直线感应电机(Double Sided Linear Induction Motor,DLIM),在考虑谐波磁动势的前提下,对比不同绕组...为了研究不同形式绕组产生的谐波磁动势对电机推力的影响,设计了3种绕组(双层整距绕组、双层短距绕组、单层整距绕组)形式的短初级双边直线感应电机(Double Sided Linear Induction Motor,DLIM),在考虑谐波磁动势的前提下,对比不同绕组的谐波磁动势分布及其对推力特性的影响.首先分别计算在三相对称电流源激励时3种绕组产生的磁动势并利用傅里叶分解得到各次谐波;其次,建立短初级DLIM的一维场数学模型,在考虑各次磁动势谐波的情况下,采用解析法推导出短初级DLIM电磁推力的数学表达式,并分析了各次谐波磁动势对推力的影响.最后,搭建有限元仿真模型,计算推力特性并与解析结果进行比较,二者具有较好的一致性,验证了解析计算的正确性.展开更多
文摘为了抑制复杂工况下变压器的直流偏磁,提出了考虑抑制措施的变压器绕组直流电流分布计算模型以及变压器直流偏磁风险的磁动势评估模型。通过实例对各种抑制措施的效果进行了交叉对比。结果表明:绕组的等效直流磁动势是变压器直流偏磁风险的决定性因素。在复杂运行工况下,不合理地使用抑制措施会令变压器直流偏磁危害加剧。电流注入法可以令自耦变串联绕组和公共绕组通过反向的直流电流,实现了等效磁动势的相互抵消,可以有效抑制复杂运行方式下500 k V变压器的直流偏磁危害。
基金supported by National Natural Science Foundation of China(No.50807027)Ph.D.Candidate Scientific Research Innovation Foundation of Tsinghua University(No.2010025)
基金supported by the State Key Laboratory of Automotive Safety and Energy,Tsinghua University(No.KF14112)the State Key Laboratory of Engines,Tianjin University(No.K2014-6)
文摘We propose a novel axis-symmetric modified hybrid permanent magnet(PM)/electromagnet(EM) magnetomotive force actuator for a variable valve timing camless engine. The design provides a large magnetic force with low energy consumption, low coil inductance, PM demagnetization isolation, and improved transient response. Simulation and experimental results confirm forces of about 200 N(in the presence of coil current) at the equilibrium position and 500 N(in the absence of coil current) at the armature seat. We compared our proposed design with a double solenoid valve actuator(DSVA). The finite element method(FEM) designs of the DSVA and our proposed valve actuator were validated by experiments performed on manufactured prototypes.
文摘为了研究不同形式绕组产生的谐波磁动势对电机推力的影响,设计了3种绕组(双层整距绕组、双层短距绕组、单层整距绕组)形式的短初级双边直线感应电机(Double Sided Linear Induction Motor,DLIM),在考虑谐波磁动势的前提下,对比不同绕组的谐波磁动势分布及其对推力特性的影响.首先分别计算在三相对称电流源激励时3种绕组产生的磁动势并利用傅里叶分解得到各次谐波;其次,建立短初级DLIM的一维场数学模型,在考虑各次磁动势谐波的情况下,采用解析法推导出短初级DLIM电磁推力的数学表达式,并分析了各次谐波磁动势对推力的影响.最后,搭建有限元仿真模型,计算推力特性并与解析结果进行比较,二者具有较好的一致性,验证了解析计算的正确性.
