基于DSP的动态匀场放大器设计

摘要

Shim amplifier is a component in magnetic resonance devices.It is actually a high precision current amplifier used to compensate the local magnetic field With the development of high-field magnetic resonance equipment, static shim amplifiers has been limited because of its slow response speed.In order to improve its performance in high-field application, this design uses TI's DSP provided with high-resolution PWM module to design a digital dynamic Shim amplifiers,and using fuzzy self-tuning PI as the control algorithm.Simulation and experimental results show that the dynamic shim amplifier, with high response speed and high accurate steady state, can meet the high field applications.%匀场放大器是一种应用于磁共振设备上,对局部高阶磁场进行补偿的高精度电流放大器.随着磁共振设备往高场方向发展,局部高阶磁场的畸变使磁共振成像的伪影变得越来越严重,市场上已有的匀场放大器由于其响应速度过慢,不能对这种伪影进行有效的抑制,而受到了局限.为了改善其在高场应用中的性能,该设计以TI公司的具有高分辨率PWM模块的TMS320F2808 DSP作为主控芯片,设计了一个数字动态匀场放大器,并采用模糊自整定PI作为控制器算法.实验结果表明该动态匀场放大器,具有响应速度快和稳态精度高的特点,能满足高场应用的要求.