5MW中性束弧电源DC/DC变换器的设计与实现

中性束离子源弧放电具有气体放电等离子体的非线性特性,工作时还会受到气体压强、外磁场、阴极状态等因素的影响,采用晶闸管相控调压技术的弧电源很难实现对这种大功率电弧的稳定的闭环控制。为此,提出了一种多相多重的大电流DC/DC变换器,具有响应速度快、电流上升时间短、电流纹波小等特点,大幅提高了离子源弧放电闭环控制的稳定性。设计了滤波电感能量回馈电路,弧电源可以根据中性束系统的需要使弧电流快速减小0%~100%(可调),然后根据控制信号迅速恢复正常弧电流输出,形成一个弧电流凹坑。电源还采用超级电容储能技术,使电源体积减小了2/3,电网容量小于10kV·A。离子源放电时不会受到电网波动的影响,弧放电更加稳定。实验数据显示:该电源最大输出为220kW/1500A,电流纹波在1%以内,电流上升时间约100μs,最大超调量小于3%,可以满足5 MW中性束离子源及系统的要求。

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.