Modeling of vacuum vessel pressure and model-based controller design for pressure profile control in Damavand Tokamak

Abstract

One of the essential systems for the upgrade of Damavand Tokamak is the automatic control of the vacuum vessel pressure profile. This research performs the identification, modeling, and control of the vacuum chamber pressure in Damavand Tokamak. As a first step, the experimental structure is designed and implemented for the application of an identification signal and for the collection of data from the vacuum vessel pressure. Following the creation of the base vacuum, the input voltage to the piezoelectric is changed and applied. At the same time, both the vacuum vessel pressure and applied voltage are measured. Using experimental data, several linear models are identified for control. Then, considering the practical limitations of the control signal (25<Vp<65), Ziegler-Nichols-based PID and predictive controllers are designed and simulated. Also, their performance results were compared and evaluated based on compensating for the system’s inherent delay, disturbance rejection, and reference model following. The simulation results show the performance of controllers.

Keywords

• tokamak
• plasma
• vacuum vessel
• rotary pump
• turbo molecular pump
• piezoelectric
• model identification
• predictive controller