快循环同步加速器射频加速电压幅度的数字化控制

 中国散裂中子源(CSNS)快循环同步加速器（RCS）中的射频低电平控制系统是基于FPGA的全数字控制系统，旨在完成对射频频率、加速电压和同步加速相位的控制。介绍了CSNS/RCS射频系统的低电平数字化控制设计方案，并着重对射频加速电压幅度控制回路进行了分析与讨论。电压幅度控制环路通过射频电压幅度信号与电压幅度设定值的比较，得到误差信号。误差信号经过控制器来控制输入到射频腔的功率，以达到稳定和改变腔压的目的。通过对控制对象的分析和建模，得到了满足系统要求的控制器。详细介绍了数字系统的实现，尤其是信号的解调和控制算法的实现。用ALTERA公司的DSP builder进行数字控制系统开发，系统仿真结果表明，环路误差信号大约于10 μs（400个系统时钟）后归于0，整个电压幅度控制环路能稳定运行。

Voltage control loop for rapid cycling synchrotron digital low-level RF control

Beam loss control is a key point in the design of high power facilities like the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS). The patterns of the RF acceleration voltage, frequency and phase are the main factors to determine the longitudinal motion of beam and the beam loss level. Therefore, the low-level RF system (LLRF) control system of CSNS/RCS must be stable and precise. In this paper, the design of the LLRF control system of CSNS/RCS was presented, especially the voltage control loop. In the loop, the difference between the deteeted voltage and a pattern is fed to a PI compensation function, and the PI output controls the amplitude of the RF signal. Through the modeling and analysis of each part of the control loop, a proper PI controller design was