LEDA LLRF control system performance: model and operational experience

In modern industrial control, a relay experiment can be used for auto-tuning a PI controller. It gives the ultimate frequency and ultimate gain of the open loop system. Based on the ultimate gain and the ultimate frequency, the PI control parameters, the proportional gain, and the integration time, are determined. A relay experiment can be used to determine the sensitivity of a closed loop system against external disturbances. This paper addresses a method to estimate the sensitivity represented by the gain margin of a closed loop low-level RF (LLRF) control system based on the Matlab/Simulink model of the Low Energy Demonstration Accelerator (LEDA) RFQ. This paper discusses some of the modeling performed and our operational experience to date.