Current control of 12-pulse regenerative converter for 20 kA magnetic power supply

High current magnetic power supply for superconductivity coil of a tokamak requires fast dynamic performance of di/dt and smooth change over of current direction. To meet the specification high performance DSP-based controller is designed for 12-pulse thyristor dual converter with interphase transformer (IPT). Not only the total current of Y and /spl Delta/ converter units but also the difference for those should be regulated fast and accurately. Proportional and integral controller is designed for difference current control and the controller output is compensated to /spl Delta/ converter. A new algorithm for the calculation of the initial firing angle is proposed for the minimization of nonideal effect during the change over of dual converter currents.