Comparative Study of Real-Time Control Systems of Vertical Plasma Position in Tokamak with Different Power Supplies for Horizontal Control Field Coil

The paper is devoted to a comparative analysis of voltage inverters in the relay mode and in the multilevel pulse-width modulation (PWM) mode as actuators in closed-loop control systems of the vertical plasma position in the T-15MD tokamak. The systems are compared on a first-order plasma model obtained by approximation of the plasma model with distributed parameters by a second-order model of the plasma with a control coil. Both systems have been put in equal conditions in terms of the same response to external signals. The method of Linear Matrix Inequalities (LMI) is used to identify an AutoRegressive with eXternal input (ARX) model of the serial connection of the both actuators with the horizontal field coil (HFC) and to synthesize a robust controller of the vertical plasma position in the tokamak. The main criteria for comparison are the control power and the HFC signal spectrum. A digital controller in the multilevel PWM mode has been developed. Simulations are performed using a real-time digital test bed. According to the criteria chosen, the new results of comparison demonstrate a significant superiority of the voltage inverter in the 9-level PWM mode over the voltage inverter in the relay mode.