Design and experimental testing of robust MIMO controllers on TCV

This paper describes the design and the experimental validation of a multivariable digital controller for a tokamak, the TCV. The design of the controller is based on a linearized, validated model of the plasma confined in the tokamak. The plant is 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 H^∞ technique, guarantees the control of the plasma current and of the plasma shape. After massive simulations, this controller was successfully tested on the plant. The experimental results show a significant improvement of the performance with respect to those obtained with a PID MIMO controller, that was used before on the plant