电磁超声相控阵激励源高频隔离驱动电路

High-frequency Isolation Drive Circuit of Exciting Source for Electromagnetic Ultrasonic Phased Array

为了进一步提高电磁超声相控阵激励源的工作效率,基于半桥拓扑放大结构提出了一种电磁超声相控阵激励源高频隔离驱动电路的设计方法.根据金属氧化物半导体场效应晶体管(metal oxide semiconductor field effect transistor,MOSFET)的简化模型,分析了MOSFET在开通和关断过程中的开关损耗,从而给出了高频隔离驱动电路所必须满足的条件.通过采用光纤器件隔离脉冲信号和DC-DC隔离电源对参考电位进行转换,有效解决了驱动电路的高频"浮栅"问题,并利用RC微分电路和施密特反相器设计了驱动信号死区时间可调电路.实验结果表明:设计的驱动电路能够输出频率为1.1 MHz、死区时间为0.32μs、驱动电压为18.8 V、占空比为26%的互补驱动信号,并且在驱动MOSFET栅极的实际应用中,有效降低了功率开关管的功率损耗.

In order to further improve the work efficiency of exciting source for electromagnetic ultrasonic phased array, a method of gate drive circuit design of high frequency isolation for exciting source of electromagnetic ultrasonic phased array was presented in this paper based on half bridge topology structure. Through analyzing the process of turn-on and turn-off loss of MOSFET based on the simplified model structure of MOSFET, satisfied conditions of drive circuit with high frequency isolation were put forward and the reference potential was converted by using fiber optic components isolated pulse signal and DC-DC power supply. The high frequency “floating gate” problem of drive circuit was solved effectively, and the dead-time adjustable circuit was designed by combining the RC differential circuit with Schmitt inverter. The experimental results show that the design of drive circuit can output drive signal in which the frequency is 1.1MHz, the dead-time is 0.32μs, the voltage amplitude is 18.8V, and the duty ratio is 26%. The drive circuit reduces power loss of power switch tube effectively in the practical application of driving MOSFET.