大功率逆变型特高压直流电源输出电压纹波特性研究

Accelerator grid power supply which is one of the key components in neutral beam injection system based on negative ion source usually adopt inverter-type high-voltage power supply scheme which is characterized by high power, high voltage and low inverter frequency, and its performance determines the heating capacity of NBI system. The output voltage ripple which directly affects the safety and efficiency of NBI system is an important parameter of the inverter-type high-voltage power supply, and must be strictly restricted. At present, the control strategy of the inverter-type high-power ultrahigh-voltage power supply which based on the engineering experience in small power application field is lack of scientific theoretical basis. And the output voltage ripple cannot meet the system requirements in some case under the current control strategy. This project takes the megavoltage inverter-type power supply of ITER NBI accelerator grid as the research object. The output characteristics, especially the ripple characteristics of this kind of high-power ultrahigh-voltage inverter-type power supply are studied through circuit analysis and mathematical modeling. A scientific method for analyzing the output voltage ripple of high-power ultrahigh-voltage inverter-type power supply is summarized. What’s more, a low ripple control strategy is proposed and implemented by developing a controller based on PXI technology. After adopting the new control strategy proposed in this project, the output voltage ripple can be strictly meet the requirements of less than ±5% in any case. The research results of this project can provide an important reference for the control and operation of the high-power ultrahigh-voltage inverter-type power supply of the auxiliary heating system on the future fusion device.

加速极高压电源作为负离子源中性束注入（NBI）系统的核心部件，多采用逆变型直流高压电源方案，其性能参数决定着NBI系统的加热能力。输出电压纹波作为关键参数之一，直接影响着NBI系统的效率和安全，必须严格加以限制。当前，此类大功率逆变电源的控制完全基于中小功率应用领域的工程经验，缺乏科学的理论依据，存在某些工况下输出电压纹波不能满足系统要求的问题。本项目以ITER装置NBI加速极兆伏级逆变电源为研究对象，针对其电压高、功率大、逆变频率低等特点，通过电路分析和数学建模，对此类大功率逆变电源的输出特性，特别是纹波特性进行了研究，总结出一套逆变型直流高压电源输出电压纹波的科学分析方法。提出一种大功率逆变电源的低纹波控制策略，并研发基于PXI技术的控制器加以实现，使输出电压纹波在任何情况下都严格满足小于±5%的要求。本项目的研究成果可为未来聚变装置辅助加热系统的高压电源控制和运行提供重要参考。

中性束（NBI）加热是未来大型聚变堆实现点火条件和稳态运行的必要手段，其核心部件——大功率逆变型直流高压电源存在输出电压较低时电压纹波过大的问题，危害负载安全、影响加热效率。本项目首先通过对大功率逆变型高压电源的输出特性和纹波特性的研究，提出了一种能在各种工况下既能保证电压精度又能严格限制输出电压纹波的控制策略；其次，结合逆变型高压电源特点，研制了基于PXI技术的控制系统对低纹波控制策略加以实现；最后，搭建10kV/6A的电源样机进行了实验验证。实验结果表明，本文提出的低纹波控制策略和基于PXI技术的控制系统方案，可很好地解决此类电源高精度、低纹波的供电需求，也可以为其他聚变装置加热系统大功率逆变型高压电源的运行和控制提供重要参考。