对极型高温超导直流感应加热装置电磁优化

Electromagnetic optimization of dipole-type high temperature superconducting DC induction heater

基于高温超导(High Temperature Superconductivity,HTS)直流感应加热技术加热质量好、加热效率高等优点,提出一种基于圆筒形多极直流电机结构的对极铁芯高温超导直流感应加热装置.首先,针对加热装置气隙磁场与铝棒温升特性,采用麦克斯韦方程组与法拉第电磁感应定律,并结合固体热传导方程,建立铝棒加热过程数值模型;其次,兼顾加热装置环形铁芯与直流电机多极结构模式,构建4极与2极电磁模型与热模型;再次,针对铝棒电导率、转速以及长度对铝棒加热过程的影响,利用对极加热装置电磁热模型,研究铝棒内涡流与加热功率的变化过程;最后,针对加热区域磁场强度不足的问题,基于直流电机极靴长度对气隙磁场大小的影响,提出极靴结构改善气隙磁场模型.研究结果表明:2极铁芯结构下铝棒最大磁通密度高于4极结构0.16 T,铝棒最大温度高于4极结构54 K;铝棒内涡流密度和加热功率与铝棒电导率、长度以及转速呈正相关性;极靴结构提高了铝棒磁通密度0.11 T,铝棒温度提升了4.2℃.

In light of the advantages of High Temperature Superconductivity(HTS)DC induction heating technology,such as good heating quality and high heating efficiency,this paper proposes a dipoletype HTS DC induction heating device based on a cylindrical multi-pole DC motor structure.Firstly,a numerical model of the aluminum billet heating process is established,taking into account the air gap magnetic field of the heating device and the temperature rise characteristics of the aluminum billet,using Maxwell’s equations and Faraday’s law of electromagnetic induction,and the solid heat conduction equation.Secondly,considering the toroidal core of the heating device and the multi-pole structure of the DC motor,this paper constructs electromagnetic and thermal models for both 4-pole and 2-pole configurations.Furthermore,the influence of aluminum billet conductivity,rotational speed,and length on the heating process is investigated by using an electromagnetic-thermal model of the dipole-type heating device,studying the variation process of eddy currents and heating power within aluminum billets.Finally,to address the problem of insufficient magnetic field intensity in the heating region,a polar boot structure is proposed to improve the air gap magnetic field model,based on the influence of the length of the DC motor’s polar boot on the magnitude of the air gap magnetic field.The research results show that under the 2-pole core structure,the maximum magnetic flux density and temperature of the aluminum billet are higher than those under the 4-pole structure by 0.16T and 54K,respectively.There is a positive correlation between the eddy current density and the heating power inside the aluminum billet and its conductivity,length,and ro‐tational speed.The use of a pole boot structure increases the magnetic flux density of aluminum billets by 0.11T and raises the temperature of aluminum billet by 4.2℃.