Open-loop excitation and electrical parameter estimation of LHD superconducting coils

The LHD contains six sets of large-scale superconducting coils and six dc power supplies to charge them. In its usual operation, the current regulator installed in the power supplies controls the coil currents. This paper focuses on an open-loop control of the current controller, which has no current feedback. The electrical parameters that are estimated and the open-loop controller was designed and tested. The results show that the open-loop control can be adapted to the LHD power supplies for short-term plasma experiments and can provide a new tool for plasma experiment, in which the coil current controller exerts no effect on plasma.