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研制了基于双H桥并联拓扑结构的高性能梯度放大器。提出使用动态死区方法来减小金属氧化物半导体场效应管(metallic oxide semiconductor field effect transistor,MOSFET)的反向恢复电流,设计并优化了输出滤波器,使其具备良好的共模及差模滤波效果,在达到较好阻尼性能的同时,具有较小的损耗。进一步在梯度放大器模型共模与差模解耦的基础上,设计了结合状态反馈、前馈以及非线性比例积分的高性能电流跟踪控制器,并在稳态使用比例积分控制以减小算法对采样系统的精度要求。针对控制算法的要求设计了基于双DSP处理器的数字控制系统,完成了一台200A/150V梯度放大器的研制工作。实验结果表明,跟踪200μs上升时间、幅值200A梯形波参考电流时,超调仅为1%;输出直流时,低频电流波动为mA量级。
A high performance gradient amplifier based on double H-bridge parallel topology is developed. A dynamic dead zone method is proposed to reduce the reverse recovery current of a metal oxide semiconductor field effect transistor (MOSFET). The output filter is designed and optimized to have good common mode and differential mode The filtering effect, while achieving better damping performance, has less loss. Based on the decoupling of common mode and differential mode in gradient amplifier model, a high performance current tracking controller combining state feedback, feedforward and non-linear proportional integral is designed and used in steady state to reduce the error of algorithm Sampling system accuracy requirements. According to the requirements of the control algorithm, a digital control system based on dual DSP processors is designed and a 200A / 150V gradient amplifier is developed. The experimental results show that the overshoot is only 1% when the 200μs rise time and the amplitude of 200A trapezoidal wave reference current are tracked. When the output DC current is low, the low frequency current fluctuates to mA level.