Design and experimental testing of a robust multivariable controller on a Tokamak

This paper describes the design and the experimental validation of a multivariable digital controller for a Tokamak, the Tokamak A configuration variable (TCV). The design of the controller is based on a linearized model of the plasma confined in the Tokamak. The plant is multiple-input-multiple-output (MIMO) and the various outputs are strongly coupled. Moreover the plant is open-loop unstable. The scope of the controller is to stabilize the plasma and to guarantee some closed-loop performance in terms of decoupling among the plant outputs. The proposed controller is composed of two nested loops: one is devoted to the vertical stabilization, the other, designed using the W. techniques guarantees the control of the plasma current and of the plasma shape. After massive simulations, this controller has been successfully tested on the plant. The experimental results show a significant improvement of the performance with respect to those obtained with a proportional integral derivative (PID) MIMO controller, that was used before on the plant.