电磁场数值计算基本原理概要.pptx
2023年3月19日1电磁场电动力学电磁理论电磁学第1页/共50页2023年3月19日2Charles-Augustin de Coulomb(1736-1806)库仑第2页/共50页2023年3月19日3Charles-Augustin de Coulomb(1736-1806),a military civil engineer,retired from the French army because of ill health after years in the West Indies.Forced from Paris by the disturbances of the revolution,he began working at his family estate and discovered that the torsion characteristics of long fibers made them ideal for the sensitive measurement of magnetic and electric forces.He was familiar with Newtons inverse-square law and in the period 1785-1791 he succeeded in showing that electrostatic forces obey the same rule.第3页/共50页2023年3月19日4Andr-Marie Ampre(1775-1836)安培第4页/共50页2023年3月19日5Andr-Marie Ampre(1775-1836)was a child prodigy whose early life was marred by tragedy:Ampres father was beheaded in his presence during the Revolution and,later,his wife died four years after their marriage.As a scientist,Ampre had flashes of inspiration which he would pursue to their conclusion.When he learned of rsteds discovery in 1820 that a magnetic needle is deflected by a varying nearby current,he prepared within a week the first of several papers on the theory of this phenomenon,formulating the law of electromagnetism(Ampres law)that describes mathematically the magnetic force between two circuits.第5页/共50页2023年3月19日6Michael Faraday(1791-1867)法拉第第6页/共50页2023年3月19日7Michael Faraday(1791-1867)was born in a village near London.His father was a migrant blacksmith often ill and incapable of providing for his four children.Faradays great opportunity came when he was offered a ticket to attend chemical lectures by Sir Humphrey Davy in London.Faraday went and sent a bound copy of his notes to Davy asking for employment.Faraday began as Davys laboratory assistant.It has been said that Faraday was Davys greatest discovery.Faraday became the greatest experimentalist in electricity and magnetism of the 19th century.He produced an apparatus that was the first electric motor and in 1831 he succeeded in showing that a magnet could induce electricity.Queen Victoria rewarded his lifetime of achievement by granting him the use of a house at Hampton Court and a knighthood.Faraday accepted the cottage but rejected the knighthood.第7页/共50页2023年3月19日8James Clerk Maxwell(1831-1879)麦克斯韦第8页/共50页2023年3月19日9James Clerk Maxwell(1831-1879)came from a middle class Edinburgh family.He is ranked with Newton and Einstein for the fundamental nature of his many contributions to physics.Most importantly,he originated the concept of electromagnetic radiation and his field equations(1873)led to Einsteins special theory of relativity,It is ironic that when in 1860 the University of Aberdeen was formed by a merger between Kings College and Marischal College where he held a post,Maxwell was redundant.He applied at the University of Edinburgh,but was turned down in favor of another.He found it necessary to move to Londons Kings College.In 1871,Maxwell was appointed the first Cavendish professor of experimental physics at Cambridge.Maxwell died at forty-nine after a short illness.He was buried in Scotland in the family plot;there were no public honors at his passing.第9页/共50页2023年3月19日10Heinrich Rudolf Hertz(1847-1894)赫兹第10页/共50页2023年3月19日11Heinrich Rudolf Hertz(1847-1894)was the first to broadcast and receive radio waves.Maxwells theory had been based on unusual mechanical ideas about the ether and had not been universally accepted.In 1884,Hertz rederived Maxwells equations by a new method,casting them in modern form.Then,between 1885 and 1889,as a professor of physics at Karlsruhe Polytechnic,he produced electromagnetic waves in the laboratory and measured their wavelength and velocity.He showed that the nature of their reflection and refraction was the same as those of light,confirming that light waves are electromagnetic radiation obeying the Maxwell equations.第11页/共50页2023年3月19日12Albert Einstein(1879-1955)爱因斯坦第12页/共50页2023年3月19日13Albert Einstein(1879-1955),one of the great geniuses of physics,grew up in Munich where his father and his uncle had a small electrical plant and engineering works.Einsteins special theory of relativity,first printed in 1905 with the title On the Electrodynamics of Moving Bodies had its beginnings in an essay Einstein wrote at age sixteen.The special theory is often regarded as the capstone of classical electrodynamic theory.第13页/共50页2023年3月19日14Gustav Robert Kirchhoff(1824-1887)基尔霍夫第14页/共50页2023年3月19日15Gustav Robert Kirchhoff(1824-1887),German physicist,announced the laws which allow calculation of the currents,voltages,and resistances of electrical networks in 1845 when he was only twenty-one.In further studies he demonstrated that current flows through a conductor at the speed of light.His other work established the technique of spectrum analysis which he applied to determine the composition of the Sun.第15页/共50页2023年3月19日16电磁场的工程应用领域1、机电能量转换 发电机、电动机、变压器2、电力系统 传输线参数、线路结构、杆塔、绝缘子等3、通信 电磁波辐射、波导、微波，散射4、生物电磁学 辐射对人体影响、生物影响、治疗5、电磁兼容6、信息 计算机存储、磁带记录第16页/共50页2023年3月19日17地磁场、太阳耀斑、磁暴第17页/共50页2023年3月19日18雷电第18页/共50页2023年3月19日19汽轮发电机第19页/共50页2023年3月19日20水轮发电机第20页/共50页2023年3月19日21变压器第21页/共50页2023年3月19日22变电站第22页/共50页2023年3月19日23雷达第23页/共50页2023年3月19日24电磁波暗室（无反射）第24页/共50页2023年3月19日25电场脉冲模拟器第25页/共50页2023年3月19日26开阔地试验第26页/共50页2023年3月19日27电场脉冲模拟器第27页/共50页2023年3月19日28磁悬浮分析For 1 cm levitation:For 1 cm levitation:Drive:Drive:Current 1320 ACurrent 1320 AFreq 400 kHzFreq 400 kHzCoil:Coil:Radius 1.0 cmRadius 1.0 cmWire 0.89 mmWire 0.89 mmCopper Ball:Copper Ball:Diameter 1 cmDiameter 1 cmMass 4.66 gMass 4.66 gRef:W.Brisley&B.S.Thornton:Brit.J.Appl.Phys.,v.14,p.682,1962 第28页/共50页2023年3月19日29Magnetic ForceReaction FieldLevitation Force(mN):Theory 45.72Lorentz 42.04 Maxwell Str 44.60 Virt Work 44.73提升力 第29页/共50页2-D Magnetostatics (2-D静磁场)第30页/共50页2023年3月19日31波导电磁场场分布第31页/共50页2023年3月19日32HF Application example:同轴波导上波的传播第32页/共50页2023年3月19日33ANSYS/Emag:微波 Coax-to-Waveguide同轴电缆波导输入口输出口第33页/共50页2023年3月19日34电磁场数值计算电磁场数值计算一、电磁场理论基础二、电磁场的边值问题三、电磁场数值计算数学基础 1、泛函分析 2、变分法 3、变分原理 4、加权余量法 5、伽辽金法伽辽金法 6、里兹法里兹法第34页/共50页2023年3月19日35三、有限元法1、有限元的网格剖分有限元的网格剖分2、有限元的单元插值有限元的单元插值3、有限元的离散化有限元的离散化4、有限元方程组的求解有限元方程组的求解5、矢量有限元矢量有限元四、边界元法边界元法五、有限差分法差分法六、模拟电荷法 七、ANSYS软件简介软件简介八、工程电磁场分析工程电磁场分析举例第35页/共50页2023年3月19日36电磁场模型：1、源模型2、媒质模型3、场域模型电磁场问题：1、正问题（内问题、外问题）2、逆问题第36页/共50页2023年3月19日37一、电磁场理论基础1、静电场的基本原理库仑定律电场强度点电荷线电荷面电荷体电荷库仑扭秤实验试验电荷第37页/共50页2023年3月19日38静电场的环路定理高斯通量定理辅助方程线性材料？各向同性材料？均匀材料？第38页/共50页2023年3月19日392、恒定电流场的基本原理电流连续性定理恒定电场的环路定理辅助方程电动势包括库仑电场强度和据外电场强度第39页/共50页2023年3月19日403、恒定磁场的基本原理安培定律电流元对电流元线圈对电流元线圈对线圈（可测量）第40页/共50页2023年3月19日41磁感应强度点电流线电流面电流体电流第41页/共50页2023年3月19日42磁通连续性定理安培环路定理辅助方程磁化强度磁场强度第42页/共50页2023年3月19日434、时变电磁场的基本原理法拉第电磁感应定律磁链磁通代替磁链微分形式第43页/共50页2023年3月19日44麦克斯韦位移电流全电流定律运流电流位移电流传导电流第44页/共50页2023年3月19日45麦克斯韦方程组电磁场理论基础第45页/共50页2023年3月19日46电磁场理论总结电磁场理论总结库仑定律安培定律法拉第定律位移电流假设电磁学三大实验定律麦克斯韦电磁场方程组第46页/共50页2023年3月19日47问题：1：静电场的基本物理量？2：静电场的基本方程？3：恒定电流场的基本物理量？4：恒定电流场的基本方程？5：恒定磁场的基本物理量？6：恒定磁场的基本方程？7：时变电磁场的基本方程？8：基本物理量的分界面条件？9：电磁场的源及其分布形式？第47页/共50页2023年3月19日48电磁场理论基础部分结束电磁场问题：正问题：已知源、材料、边界条件。逆问题：已知部分场，部分源、部分材料、部分边界条件。第48页/共50页2023年3月19日49电磁场理论基础部分结束主要数值计算方法：1、有限元法（微分方程变分法）2、时域有限差分法（微分方程差分法）3、矩量法（积分方程法）第49页/共50页2023年3月19日华北电力大学（北京）电力工程系高电压与电磁兼容研究所50感谢您的观看！第50页/共50页
