Control algorithm tests using a virtual CW SRF cavity

TL;DR

This paper develops a simulation environment using Matlab/Simulink to compare various control algorithms for superconducting RF cavities, focusing on detuning reduction due to microphonics and mechanical perturbations.

Contribution

It introduces a comprehensive simulation framework for testing and comparing control strategies for CW SRF cavities, including PID, adaptive feedforward, and ADRC methods.

Findings

PID feedback loops effectively reduce perturbations.

Adaptive feedforward algorithms improve detuning control.

Active disturbance rejection techniques show promising results.

Abstract

Superconducting cavities (SRF) are widely used in new generation particle accelerators, increasing the requirements and specifications for new designs. The LLRF control system, including the detuning control due to mechanical perturbations, must fulfill more exigent specifications, and its design have gained increasing relevance. The Helmhoz Zentrum Berlin, among others, have been working in the development of simulation and Hardware-in-the-loop tools to facilitate the test of control algorithms. The main goal of this work is to use an existing cavity model in CW mode, a Tesla cavity including a Saclay style piezo-tuner, and simulation tools to compare and test different control strategies focused in the detuning reduction, specially microphonics. The design process consist of the use of pure simulation environment based on Matlab/Simulink, where the mathematical model includes a cavity model, a LLRF control system and detuning control strategies, considering the mentioned actuator. Different control strategies are considered for the RF and mechanical parts: perturbation reduction by PID based feedback loops, adaptive feedforward algorithms, and active disturbance rejection techniques (ADRC). The aim is the performance comparison of the different algorithms with different perturbations, by using realistic cavity models which include Lorenz force detuning, microphonics derived from the cryogenic module and so forth. The simulation environment allows the inclusion of other effects as the non-collocated control problem.