Design and implementation of 5 MW neutral beam injection arc power supply DC/DC converter

The arc discharge of ion source in neutral beam injection has the nonlinear characteristic of gas discharge plasma, and this high-power electric arc is influenced by the gas pressure, outside magnetic field and state of cathode in the process of discharging. It is difficult to be closed-loop controlled stably with a power supply of phase control thyristor voltage scaling technology. Therefore, this paper puts forward a multiphase and multiple high-current DC/DC converter with fast response speed, high rate of current rise, lower output ripple current, et al. The converter greatly improved the closed-loop control stability of the arc discharge of ion source. An inductance energy recovery circuit was designed, thus the arc power supply is able to rapidly reduce the output current by 0%-100% (adjustable) according to the system requirements, then return to normal output in accordance with the control signal, forming a notch in the arc current waveform. Using the super capacitor energy storage technology, the volume of the power supply is decreased to one third, with the power output not affected by the power network fluctuation. The experimental waveforms prove that: the maximum output specification of the arc power supply is 220 kW/1500 A, output ripple current is less than 1%, current rise-time is in the order of 100 s, the maximum overshoot is less than 3%, and the power supply meets the requirements of the 5 MW neutral beam injection system and the ion source device.