Final Design and Analysis of Control Strategies on ITER PF Converter

The ITER poloidal field (PF) coil power supply system consists of 14 basic converter units that feed six superconducting coils. The converter unit is the complicated, challenging, and unique system to realize four-quadrant operation compatible with the superconductive load and the demand for plasma control. This paper describes the final design of the control strategies, which are implemented in the local controller of the PF converter system. They are zero crossing current control strategy in circulating operation mode, current balance control strategy in parallel operation mode, and hysteresis band control strategy in mode transition. In addition, the performance of the control system is demonstrated by the analysis, and the control strategies are validated by the simulations and corresponding tests.