A Design study of stable coil current control method for back-to-back thyristor converter in JT-60SA

Shimada, Katsuhiro; Terakado, Tsunehisa; Matsukawa, Makoto; Cara, P.*; Baulaigue, O.*; Gaio, E.*; Coletti, R.*; Candela, G.*; Coletti, A.*

This paper describes the stable coil current control method of back-to-back thyristor converters as a design study. The back-to-back thyristor converter is applied to "Base PS" which is low-voltage power supply for PF coil in JT-60SA. This converter has six arms of anti-parallel connected thyristor devices to enable to operate with 4 quadrant operation. The dead beat control method is applied on the current feedback control algorithm. In addition, the non-interacting control method is adopted between coil current and circulating current among converters, which is necessary for smooth reversing of the coil current polarity. The rate limiter for control angles of thyristor converter is introduced to suppress the excessive current unbalance between converters. To estimate the proposed coil current control method, the real "Base PS" models are simulated by "PSCAD/EMTDC" code. From the simulation results, the stable control capability was obtained.