磁共振成像系统中梯度放大器的控制算法

Control algorithm for gradient amplifiers in magnetic resonance imaging systems

针对磁共振成像对梯度放大器的性能要求,提出一种状态反馈和比例积分相结合的控制算法。介绍了放大器的主电路结构,对输出滤波器进行了优化设计。基于滤波器和负载模型,采用状态量反馈法,设计了二次型最优调节器以使系统具有良好的动态性能。为减小模数转换的有限有效位数对控制算法稳态性能的影响,进一步使用了差值放大结合比例积分的调节器。仿真和实验结果证明,系统具有良好的动态和稳态性能。

State feedback and proportional-integral（PI） control were combined to develop a control algorithm to meet the requirements of the gradient power amplifier performance in magnetic resonance imaging（MRI）.The main circuit topology was introduced,with the output filter optimally designed.Based on the system model,a state feedback controller designed using the quadratic optimal rule was applied to improve the dynamic characteristics,with a PI controller with an error amplifier further used to reduce the effects of the insufficient A/D sampling precision on the steady performance of the algorithm.Simulations and experimental results indicate that the system has good dynamic and steady performances.