基于离散趋近律与无差拍双闭环结构的单相LCL型PWM整流器控制策略  

A Double Closed-Loop Control Method for Single-Phase PWM Rectifiers with LCL Filter Based on Discrete Reaching Law and Deadbeat Algorithm

作　　者：李景灏 吴爱国 Li Jinghao;Wu Aiguo(School of Electrical and Information Engineering Tianjin University,Tianjin 300072 China)

机构地区：[1]天津大学电气自动化与信息工程学院,天津300072

出　　处：《电工技术学报》2021年第6期1290-1303,共14页Transactions of China Electrotechnical Society

摘　　要：对于单相LCL型PWM整流器,传统双闭环控制以PI控制为电压外环,电流内环常采用以变换器侧电流为受控量的无差拍控制。该方案存在两个问题:(1)电压外环的积分器会限制系统动态性能;(2)无法精确实现网侧单位功率因数。为此,该文提出一种以离散趋近律控制为电压外环、以改进无差拍控制为电流内环的双闭环控制策略。对于电压外环,该文推导网侧半波电流峰值与该半波周期内直流侧电压增量之间的数学关系,在此基础上提出一种离散趋近律控制策略。对于电流内环,提出一种以网侧电流和变换器侧电流的加权和为受控量的改进无差拍算法,并给出实现精确单位功率因数所需的电流参考值。该文还讨论网侧电流欠阻尼振荡引起的电流过冲问题,并提出解决方法。仿真和实验结果表明,所提双闭环控制显著改善了系统动态性能,且实现了精确网侧单位功率因数。For the single-phase PWM rectifier with LCL filter,the traditional double closed-loop control method usually uses PI compensator as the voltage outer loop controller,and deadbeat control,with the converter side current as the controlled variable,as the current inner loop controller.There are two problems in this scheme:one is that the integrator in the voltage outer loop will limit the dynamic performance of the system;the other is that the unit power factor on the grid side cannot be realized accurately.Thus,this paper presents a double closed-loop control method for the single-phase PWM rectifier,which takes the discrete reaching law control as the voltage outer loop controller and the improved deadbeat control as the current inner loop controller.For the voltage outer loop,the mathematical relationship between the peak value of half wave current on the grid side and the voltage increment on the DC side is derived,and a control strategy based on discrete reaching law is proposed.For the current inner loop,this paper presents an improved deadbeat algorithm with the weighted sum of the grid side current and converter side current as the controlled variable,and derives the current reference for achieving the accurate unit power factor.This paper also discusses the current overshoot caused by the under-damped oscillation,and puts forward the solution.Simulation and experimental results show that the proposed control strategy improves the dynamic performance of the system andachieves accurate unit power factor on the grid side.

关 键 词：单相PWM整流器 LCL型滤波器 离散趋近律 无差拍控制 欠阻尼振荡 

分 类 号：TM46[电气工程—电器]