Design and preliminary experimental results of 5 MW-NBI arc power supply for HL-2M tokamak

Highlights: • Completed design of a 5 MW NBI APS for HL-2M tokamak based on super capacitor energy storage and switching power technology. • A structure of multiple composite choppers is used on the DC/DC converter of the APS power circuit, which is composed of ten interleaving buck converters. • The APS has the characteristics of excellent constant current, high rate of current rise, small overshoot and short adjusting time. • The APS fits well in all kinds of arc discharge experimentations including constant voltage control mode, small arc current discharge cleaning, rating current beam extraction etc. Due to the nonlinear characteristic of the gas-discharge plasma and influenced of the gas pressure, outside magnetic field and state of cathode, the arc discharge process in ion sources for neutral beam injection(NBI) is difficult to be closed-loop controlled stably with the arc power supply (APS). A 5 MW-NBI APS for HL-2M tokamak based on super capacitor energy storage and switching power technology is designed, results are presented in this paper. A structure of multiple composite chopping is used on the DC/DC converter of the APS power circuit, which is composed of ten interleaving buck converters. With the increasing of the operating frequency, the volume and weight of the filter inductor have been greatly reduced. The APS obtains a higher di/dt and a rapid dynamic response, and the stability of the closed-loop control has been significantly increased. The electrical parameters of factory test of the APS: the maximum output specification is 220 kW/1500 A, output ripple current less than 1%, current rise-times in the order of 100 μS, maximum overshoot less than 3%. The preliminary experimental results of arc discharge showed that: the APS has the characteristics of excellent constant current, and fits well in all kinds of arc discharge experimentations including constant voltage control mode, small arc current discharge cleaning, rating current beam extraction etc.