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为了实现磁共振成像系统中梯度放大器前级电源对负载电流阶跃的高速响应,提出了一种单电压环非线性PID控制器,该控制器的控制参数是基于误差变化的指数函数。为了进一步提高性能,在此非线性PID控制器的基础上,增加了一个电流内环比例控制器。在一台120V/30A的前级电源样机上进行了实验验证,将这2种控制策略对负载电流阶跃时输出电压动态响应结果与系统的动态物理极限进行了对比。实验结果表明:所设计的电压电流双闭环非线性控制器比单电压环非线性PID控制器有更好的动态响应性能,更接近系统的动态物理极限。
In order to realize high-speed response to the load current step of gradient power amplifier in the magnetic resonance imaging system, a single voltage loop nonlinear PID controller is proposed. The control parameters of the controller are based on the exponential function of error variation. In order to further improve the performance, based on this nonlinear PID controller, an internal current loop proportional controller is added. Experimental results on a 120V / 30A front-end power supply prototype are compared. The dynamic response of the two control strategies to the output voltage during the load current step is compared with the dynamic physical limit of the system. The experimental results show that the designed double-loop nonlinear voltage-current controller has better dynamic response than the single-loop nonlinear PID controller, which is closer to the dynamic physical limit of the system.