四桥臂有源电力滤波器脉宽调制机理及电流预测控制研究

The harmonic and imbalance problems in the three-phase four-wire systems have become prominent increasingly. Four-leg active power filters (APF) have become one of the effective measures to solve the problems above. According to the four-leg converter topology, this project starts with the physical means of the given signal, studies the modulation mechanism of the four-leg converter, and then the essential relation between the carrier-based PWM (CBPWM) and the space vector PWM (SVPWM) is discussed. In order to reduce complexity of the algorithm and take advantage of the fourth leg, a simplified modulation algorithm which is easy to achieve and has a clear physical meaning is proposed. The dead-time of APF has great influence on its compensation characteristics. In order to improve the performance of converter, dead-time effect has been analyzed and dead-time compensation methods applied in four-leg converter are studied. The application of the predictive current control in the three-phase four-wire APF systems and the control feature of the “current predictive control combining PWM” and finite control set-model predictive control (FCS-MPC) under the condition of the unbalance voltage is analyzed. The relationship between the stability of the system and the time-delay of the system, the pulsation of DC voltage, and the parameter variation of the main circuit is studied. Base on the relations, a more precise model of the predictive current control is built. Furthermore, the current predictive control scheme applied in four-leg converter is proposed, through inter-infiltration and optimization of the two control schemes.

三相四线制系统中谐波和不平衡问题日益突出，并联型四桥臂有源电力滤波器是解决上述问题的有效措施之一。本项目根据四桥臂变流器拓扑结构，从给定信号的物理意义入手，研究四桥臂变流器调制机理，讨论载波脉宽调制(CBPWM)与空间矢量脉宽调制（SVPWM）的本质联系，为降低算法复杂程度、灵活利用第四桥臂，提出一种物理意义清晰、易于实现的调制算法。死区时间对有源滤波器的补偿特性有较大影响，分析死区效应，研究适应于四桥臂变流器的死区补偿方法，以提高变流器输出性能。分析电流预测控制在三相四线制有源滤波系统中的应用，探讨电网电压不平衡条件下“电流预测+PWM”与有限控制集模型预测控制（FCS-MPC）两种控制方案的控制性能，研究系统延时、直流侧电压波动以及主电路参数变化与系统稳定性的关系，在此基础上，建立更为精确的电流预测模型，通过相互渗透及优化提出适用于三相四线制系统的有源电力滤波装置的电流预测控制方案。

本项目以四桥臂有源电力滤波器为研究对象，研究其脉宽调制机理及电流预测控制。主要研究成果包括：提出了两种新型的3D-SVPWM算法，大大减小了计算量，易于实现，并将其推广应用到三电平四桥臂变流器中；对比CBPWM和3D-SVPWM两种算法调制波的数学关系，分析两种算法归一化条件；针对四桥臂变流器死区补偿实现困难的问题，提出一种基于脉冲调整的死区补偿策略，该方法仅需判断电流极性即可确定待调整的驱动信号及其触发调整方式，在同一电流极性下脉冲调整具有一致性，易于实现；借鉴基于虚拟矢量的三桥臂APF模型预测控制方法，在四桥臂变流器控制集空间合理位置上构造虚拟矢量，将基于虚拟矢量FS-MPC应用于四桥臂APF；分析直流侧电容电压对APF跟踪性能的影响，对APF功率损耗及补偿性能进行了分析，采用基于模型预测的优化控制方法控制直流侧电压。期间，申请获批“江苏省煤矿电气与自动化工程实验室”，协助培养博士研究生1人，培养硕士研究生6人，在培养硕士研究生8人，在培养博士研究生1人，在国际学术期刊、国内会议及核心期刊上发表论文13篇，SCI收录1篇，EI收录1篇，EI期刊待发表2篇，申请国家发明专利4项，授权3项。