高频交流强磁场激励源的研制

Development of High Frequency Strong AC Magnetic Field Power Source

励磁线圈中的磁场强度与流过线圈的电流大小成正比,要想获得较强磁场,就需要在线圈中激励产生大电流。励磁线圈呈感性,其感抗与频率成正比,使得在高频情况下激励获得大电流非常困难。本文在研究励磁线圈高频电路模型的基础上,研制出能够获得激励励磁线圈高频交流强磁场的电源系统。该电源系统的激励源由直流电源、高频逆变电路、阻抗匹配电路等几部分组成。直流电源为系统工作提供能量;高频逆变电路基于全桥逆变结构,将直流电源的输出逆变为高频交流电源;阻抗匹配电路利用谐振的原理降低线圈在高频情况下的阻抗,并利用高频变压器实现阻抗变换,以达到高频情况下驱动线圈的目的。试验结果表明,该激励源可在频率500kHz情况下,获得峰峰值最高达0.018T的较强的交流磁场。

Magnetic field strength in the excitation coil is proportional to the current flowing through the coil. In order to get strong magnetic field, it is necessary to motivate large current in the coil. The coil appears inductive, and its inductance is proportional to frequency, which makes it difficult to drive large current at high frequencies. This paper designs and develops a power source system specifically for driving excitation coil to get strong AC magnetic field based on working over the high frequency circuit model of the excitation coil. The power source system is made of sev- eral parts such as DC power supply, high-frequency inverter circuit and impedance matching circuit. DC power supply provides energy for the system. High-frequency inverter circuit inverts the output of DC power to AC. Impedance matching circuit reduces the impedance of the coil in high-frequency case utilizing resonance principle and achieves impedance transformation using transfer so as to drive coil in high-frequency case. The results show that the system can drive coil get AC magnetic field as strong as 0. 018T at 500 kHz.