单相级联多电平H桥整流器有限集模型预测电流控制

摘要

This paper focuses on a single phase cascaded multilevel H bridge rectifier adopted as the front-end converter in power electronic transformer (PET) in high-speed train application.A two-vector-based model predictive current control (MPCC) scheme is proposed to improve controller's dynamic responsibility and reduce current harmonic distortion.Firstly,the single phase cascaded multilevel H bridge rectifier is modeled in α-β3 stationary coordinate frame.Secondly,the basic vectors and the corresponding sector definition are designed for single phase cascaded multilevel rectifiers based on the space vector modulation.On the basis of this principle,the optimal dwell time of two vectors is derived from minimizing the cost function which evaluates the current error.Then,the appropriate redundancy vector is selected according to the DC-link capacitor voltage balance rule in each module.Compared with the traditional instantaneous current control (ICC) based on proportional-integral (PI) controller,the proposed MPCC scheme can achieve fast dynamic response,keep DC-link capacitor voltage balance,and be free of PI current controller as the inner loop.Finally,the proposed MPCC and the traditional PI-ICC scheme are compared and verified by hardware-in-loop (HIL) experiment platform.HIL experimental results verify the feasibility and validity of the proposed MPCC scheme.%本文以基于电力电子变压器的高速列车牵引传动系统中的单相级联多电平H桥整流器为控制对象,以提升系统动态响应速度、减小网侧电流谐波含量为控制目标,提出了一种基于两矢量的有限集模型预测电流控制算法.首先,推导单相级联多电平H桥整流器的α-β静止坐标系下数学模型;然后,基于空间矢量调制思想,对单相级联多电平整流器进行基本电压矢量定义与空间扇区划分;在此基础上,建立包含最小电流误差的目标函数,通过对其求导实时计算出两个矢量的最优占空比,同时为了保证各模块直流侧电容电压的平衡关系,设计了选取冗余矢量的原则.与基于PI的瞬态电流控制算法相比,所提出的模型预测控制算法无需内环PI控制器,显著提高了电流内环的动态响应速度;最后,对所提算法与传统的瞬态电流控制算法进行硬件在环半实物实验对比研究,结果表明了所提算法的可行性与有效性.