Design, development, testing and operation of Regulated High Voltage power Supplies (RHVPS) utilized by NBI and RF heating systems for SST1

Regulated High Voltage Power Supplies (RHVPS) are major components of any high power heating and current drive system for a Tokomak. A typical RHVPS need to have fast dynamics, good ripple and regulation performance and most importantly μS order fault clearing time. The development of a series of RHVPS ranging from 14 kV to 100 kV and several MW power to be used for the RF and NB heating systems of the SST-1 Tokomak and results thereof are presented here. Extensive tests on an 80kV, 75A power supply were done and the RHVPS is regularly used on a Neutral Beam Injector. The system uses the pulse step modulation technique for control of the series switches of each switched power module fed from multi-secondary transformer. A special switching transition matrix controls the series switches with which the rise/fall slope control could be programmed from few μS to hundreds of m Sec range. The fast protection clears any over current fault in less than 2 μS; fault energy has been measured to be less than 5 Joules. Apart from the major features of the system, the presentation describes some studies from fault conditions of the system and mitigations thereof.