主动反馈控制下无绝缘层缠绕线圈的匝间损耗和力学行为

Turn-to-turn loss and mechanical behaviors of no-insulation layer-wound coil with active feedback control

高温超导无绝缘层缠绕线圈具有较长的充放电延迟.比例积分(PI)主动反馈控制方法可以有效降低无绝缘线圈的充电延迟,但该方法需要给线圈提供更高的电源电流,这可能会带来额外的损耗能量和力学损伤,因此需要研究层缠绕线圈在PI控制下的电磁和力学性能.本文结合电路模型和有限元方法,采用混合数值模型计算了PI控制下线圈的匝间损耗和力学响应.数值计算结果表明,对于无绝缘层缠绕线圈,使用PI控制进行充电需要更大的电源电流,同时充电过程中会产生更高的匝间损耗能量和环向应力.PI控制下线圈内会产生更大的应力,但相比于匝间损耗的显著增加,线圈内应力增大并不显著.在10 T背景场下,两种线圈环向应力差别为20 MPa.另外,随着线圈匝数或层数的增加,PI控制下线圈内的损耗及应力会进一步增大.考虑到匝间损耗的上升趋势,应优先选择轴向匝数较少的线圈.此外,增加充电时间也可以减少充电过程中的匝间损耗和峰值应力.

The no-insulation high-temperature superconducting layer-wound coil has a long charging delay,which can be mitigated through proportional and integral(PI)active feedback controls.However,PI control requires a larger power supply current,potentially causing additional energy loss and mechanical damage.Thus,analyzing the electromagnetic and mechanical behaviors of the layer-wound coil with PI control is necessary.In this article,a hybrid numerical,combining the equivalent circuit network model with the finite element model,is used to calculate the turn-to-turn loss and mechanical response of the coil with PI control.The numerical calculation demonstrates that the layer-wound coil with PI control requires a larger power supply and generates higher turn-to-turn loss energy and hoop stress compared with a coil without PI control.Higher stress is generated in the coil with PI control,while the difference in the hoop stress is relatively smaller than that in the turn-to-turn loss.In a background field of 10 T,the difference in the hoop stress is 20 MPa.The loss of energy increases rapidly with increasing number of turns in the axial direction.Thus,a coil with fewer axial turns is preferred to reduce the turn-to-turn loss and hoop stress.In addition,increasing the charging time can decrease the loss of energy and peak stress.