NNBI加速极电源控制系统分析与设计

Design of Control System for NNBI Accelerator Power Supply

聚变堆主机关键系统综合研究设施(Comprehensive Research Facility for Fusion Technology,CRAFT)负离子源中性束注入(Negative Neutral Beam Injection,NNBI)电源首次采用逆变型整流方案,但离子源的时变、非线性及高可控等负荷特征给电源电压和纹波控制带来了挑战。采用傅里叶变换分析逆变型直流高压电源拓扑,针对低频开关信号,提出一种新的逆变型直流高压电源传递函数分析方法以快速建立系统近似模型。通过PWM方式控制逆变器开关管占空比,相控整流控制直流母线电压,实现系统输出电压闭环控制以及提升纹波抑制能力,并设计1200 V/5 A实验测试平台验证控制方法的有效性。

The power supply for Negative Neutral Beam Injection(NNBI)at the Comprehensive Research Facility for Fusion Technology(CRAFT),a key system in the main reactor,has adopted a novel inverter-type rectification scheme.This consequently makes voltage and ripple control of power supply confront challenges owing to the time-varying,nonlinear and highly controllable load characteristics of ion source.In this paper,a new transfer function analysis method is proposed for the low frequency switching signal based on the Fourier transform analysis of DC high voltage power supply.In the control system,the duty cycle of inverter switches and the DC bus voltage are handled by PWM mode and phase controlled rectifier,respectively,to achieve closed loop control of the system output voltage and enhanced suppression of ripples.The proposed control system has been verified effective through a specifically designed 1200 V/5 A experimental test platform.