Generic power supply feedback controller for control of plasma parameters in SST-1

Highlights: • SST-1 radial control coil (RCC) physics requirements -random and step perturbation. • RCC power supply description and issues associated with old customized controller. • VME hardware and software architecture, application and its algorithm development. • Hysteresis band controller techniques. • Results of step and random perturbation on dummy load coil with Generic controller. - Abstract: Steady State Superconducting Tokamak (SST-1) uses Radial Control Coil (RCC) for radial control of the plasma in initial experiments. RCC is a resistive single turn coil. There are two radial coils placed symmetrically up and down. These coils are connected either in saddle or parallel configurations. The requirement of rate of rise of current in RCC is 1 MA/s with peak current as ±10 kA. The power supply consists of IGBT based 72 H bridge inverter modules connected in parallel, L-C filter, 12 pulse SCR rectifier circuit, water cooling system and transformer. A versa module euro card (VME) bus based Generic Controller (GC) has been developed to control current in RCC in feedback loop. GC controls gate pulse firing of 72 IGBT based H bridge inverter module using hysteresis band control. GC provides 2.5 kHz to 10 kHz switching with fiber optic gate pulse interface to RCC power supply. This paper describes existing controller along with associated issues, development of VME bus based GC, its hardware and software with flow chart, RTOS VxWorks programming, integration of GC with H bridge inverter, MATLAB simulation, testing results of random and step perturbation with power supply operations.