新型功率可调MIT激励源设计及其磁场分析

Design for New Type Excitation Source with Adjustable Output and Analysis of Magnetic Excitation Field on MIT System

目的:设计输出功率可调的MIT激励源和3种类型的激励线圈,以提高MIT相位检测的精度。方法:通过选取PA19放大器芯片,设计200 kHz工作频率下可调输出的功率放大电路;通过计算,设计制作了螺线管线圈和2种聚焦线圈;最终测试比较各激励线圈的磁场分布,并在不同激励线圈的磁场下对圆柱形铁块进行相位测试。结果:激励源输出峰值电流大于1 A,圆形螺旋聚焦线圈的磁场由线圈轴线向两边衰减斜率最大,约为0.06 T/cm,且在该激励线圈磁场中,对铁块的相位检测结果最大。结论:该激励源输出功率可调范围大,采用圆形螺旋聚焦线圈磁场聚焦效果最佳、相位检测效果最好。

Objective To improve the precision of phase detection of MIT by designing an excitation source with adjustable output and three kinds of excitation coils, Methods At 200 kHz, a power amplifier circuit with the adjustable output was designed by choosing high performance amplifier PA19. The solenoid coil and two kinds of focused coils were designed and implemented. Finally, the distributions of magnetic excitation field of three kinds of coil were detected and compared, and then the experiment of detecting the phase of iron cylinder was done with the different excitation coils. Results The peak value of output current of excitation source was over 1A. The attenuation rate of magnetic field of discal focused coil was fastest among other coils, the approximate rate was 0.06 T/cm, and the value of phase detection of iron in the magnetic field of discal focused coil was biggest. Conclusion The excitation source can produce wider adjustable output power. The focused effect of discal focused coil is optimal and the discal focused coil is the most effective to phase detection.