轨道交通无变压器牵引传动系统控制策略研究

In order to overcome the drawbacks of the traditional railway traction drive systems, such as huge volume and weight and realize the development target of China’s high-speed railway which are lightweight, miniaturization, energy saving and environmental protection, a transformerless topology structure of traction drive system is studied in this project. This topology possesses the advantages of simple structure, modularization and easy to control, so is a very practical topology. This project is presented in the special application background of traction drive system in our country. The modulation method and capacitor voltage balancing method of the cascaded H-bridge multilevel converter and vector control strategy and modulation strategy of six-phase induction motor in the condition of low switching frequency will be studied in this project. Based on maintaining the input and output power balanced at all levels of suspended capacitors, the voltage balancing of DC-link capacitors can be achieved. Meanwhile, as the vector control technology and modulation technology of three-phase induction motor are mature, we can apply them to six-phase induction motors and achieve similar results. The ultimate goal is to provide a complete solution of a variable frequency adjustable-speed system based on the transformerless H-bridge cascaded multilevel converter and six-phase induction motors with high performance, high efficiency, low cost, high reliability and perfect control function and lay a solid foundation for the future application in railway traction drive systems.

为降低传统铁路大功率牵引传动系统庞大的体积和重量，实现我国高速铁路轻量化、小型化、节能环保的发展目标，本课题研究了一种无变压器牵引传动系统，具有结构简化、模块化程度高、易于控制等特点，同时融合了多相电机固有的优点，是一种非常实用化的拓扑结构。针对我国轨道交通牵引传动系统的特殊应用背景，本课题对H桥级联型有源前端的调制策略、电容电压平衡控制算法以及低开关频率条件下六相异步电机的矢量控制策略和调制策略等关键问题展开研究，拟采用基于维持各级悬浮电容输入输出功率平衡的方法，实现悬浮电容电压平衡控制；同时利用三相异步电机成熟的矢量控制技术和调制技术，实现六相异步电机的高性能矢量控制和调制控制。最终目标是实现一整套基于无变压器H桥级联型多电平变换器和六相异步电机的性能好、效率高、成本低、可靠性高且控制功能完善的高压大容量变频调速系统，为其以后在我国铁路牵引传动系统的推广应用奠定技术基础。

随着经济社会的发展，轨道交通在我国运输体系中扮演着越来越重要的作用。目前，轨道交通大功率牵引传动系统中普遍使用工频牵引变压器，其庞大的体积和重量无法适应我国铁路轻量化、小型化、节能环保的发展目标。本项目研究的无变压器牵引传动系统融合了级联H桥变换器和多相电机在大功率场合的应用优势，具有结构简单、模块化程度高、易于控制等特点，是一种有应用前景的拓扑结构。课题针对传动系统中级联型H桥有源前端的电流控制策略、电容电压平衡算法、稳定工作域以及双定子感应电机低开关频率条件下控制和调制、多电机协同控制方面的关键问题展开研究。在级联H桥整流器方面，课题详细分析了虚拟矢量电流控制策略的稳定性问题，提出了一种调节能力更强的直流侧电容电压平衡算法。此外，课题还给出了一种多级级联H桥整流器稳定运行区域的通用分析方法。在双定子感应电机控制方面，课题结合轨道交通等大功率牵引传动系统高电压大电流、低开关频率的特点，提出了双定子感应电机在全速度范围内的矢量控制策略及多模式SVPWM调制策略，可以实现牵引电机在整个调速范围内的可靠运行。课题最终实现了一整套基于无变压器H桥级联型整流器和双定子感应电机的系统样机，并进行了实验验证。本课题的研究成果可以为其以后在我国铁路牵引传动系统的推广应用奠定技术基础。