三相PWM整流器无差拍控制死区补偿方法研究
发布时间：2018-07-27 17:08
【摘要】：PWM整流器具有可在单位功率因数下运行、网侧电流高度正弦化、能量可双向传输等优势,被普遍应用在有源电力滤波、高压直流输电、可再生能源并网发电等诸多方向。而应用无差拍控制技术可以完成在单个开关周期内被控信号对参考信号的准确跟踪,并能提供快速的动态响应,减小网侧电流的波形畸变程度。但是为了防止上下功率桥臂同时导通损坏整流桥,必须加入死区时间进行保护,而死区时间的加入会造成低次谐波增加、电流发生畸变等不良影响,不利于无差拍技术对三相PWM整流器的电流精准跟踪。所以对死区时间补偿十分有必要。本篇在编写过程中,首先以PWM整流器发展为背景,简单对其分种类介绍,并着重对电压型PWM整流器的控制方法进行论述。通过数学建模的方式展示整流器在静止坐标系中由三相到两相变换,以及两相静止到同步旋转坐的标系变换过程。并将空间矢量PWM技术应用到整流桥驱动控制。系统的控制方法为经典的外环电压、内环电流控制。并且在内环应用无差拍技术,并说明其快速性在电流环控制中应用的优势。其次,本文着重论述了死区时间对PWM整流器的不良影响的原因以及造成后果:为了避免整流桥上下桥臂发生直通人为添加的保护时间,导致较低次谐波增加,网侧电流波形发生畸变。同时对现行的几种死区时间补偿方法进行原理分析和仿真实验对比,得出死区时间补偿的关键在于对网侧电流极性的精准判断,由于电流存在过零箝位现象干扰极性判断,于是引入根据网侧电流纹波估计值进行电流极性的准确判断。通过MATLAB/Simulink搭建系统的仿真模型,并证明补偿方法的可行性。最后,本文参照三相电压型PWM整流器的运行相关参数和实验室已有器件,综合考虑后对软件程序和硬件设备进行设计。软件方面,是以STM32F407ZG为控制核心设计软件程序;硬件方面,主要对控制电路和主电路进行设计,包括采样电路、外部基准电源电路、保护电路等电路计算和设计。并通过实验平台的实验调试最终验证了三相PWM整流器无差拍控制的优越性和基于纹波电流判断电流极性的死区时间补偿的可行性和有效性。
[Abstract]:PWM rectifier is widely used in many fields, such as active power filter, HVDC transmission, renewable energy grid-connected generation and so on, because of its advantages such as unit power factor, high sinusoidal current, two-way energy transmission and so on. The deadbeat control technique can accurately track the reference signal in a single switching cycle and provide a fast dynamic response to reduce the waveform distortion degree of the network side current. However, in order to prevent the upper and lower power arms from simultaneously conducting and damaging the rectifier bridge, the dead-time must be added to protect the rectifier bridge, and the addition of the dead-time will result in the increase of low order harmonics, the distortion of current and other adverse effects. It is unfavorable to accurate current tracking of three-phase PWM rectifier by non-beat technique. So it is necessary to compensate for dead time. In the process of compiling this paper, the development of PWM rectifier is taken as the background, and the control method of voltage source PWM rectifier is discussed in detail. The mathematical modeling is used to show the transformation process of rectifier from three-phase to two-phase in stationary coordinate system and from two-phase static to synchronous rotation. And the space vector PWM technology is applied to the rectifier bridge drive control. The control methods of the system are classical outer loop voltage and inner loop current control. The beat-free technique is applied in the inner loop, and the advantages of its rapidity in current loop control are explained. Secondly, this paper focuses on the causes and consequences of the bad effect of dead-time on PWM rectifier: in order to avoid the artificially added protection time of the upper and lower leg of the rectifier bridge, the lower harmonics are increased. The current waveform of the network side is distorted. At the same time, the principle of several dead-time compensation methods are analyzed and compared with simulation experiments. The key to dead-time compensation lies in the accurate judgment of the current polarity on the network side, and the interference polarity judgment due to the zero-crossing clamping phenomenon of the current exists. Therefore, the current polarity can be accurately judged according to the current ripple estimation of the network side. The simulation model of the system is built by MATLAB/Simulink, and the feasibility of the compensation method is proved. Finally, according to the operating parameters of three-phase voltage-source PWM rectifier and the existing devices in the laboratory, the software program and hardware equipment are designed. In the software aspect, the software program is designed with STM32F407ZG as the control core, and the control circuit and the main circuit are mainly designed in the hardware aspect, including sampling circuit, external reference power circuit, protection circuit and so on circuit calculation and design. The advantages of non-beat control of three-phase PWM rectifier and the feasibility and effectiveness of dead-time compensation based on ripple current to judge the polarity of current are finally verified by the experimental debugging of the experimental platform.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM461
[Abstract]:PWM rectifier is widely used in many fields, such as active power filter, HVDC transmission, renewable energy grid-connected generation and so on, because of its advantages such as unit power factor, high sinusoidal current, two-way energy transmission and so on. The deadbeat control technique can accurately track the reference signal in a single switching cycle and provide a fast dynamic response to reduce the waveform distortion degree of the network side current. However, in order to prevent the upper and lower power arms from simultaneously conducting and damaging the rectifier bridge, the dead-time must be added to protect the rectifier bridge, and the addition of the dead-time will result in the increase of low order harmonics, the distortion of current and other adverse effects. It is unfavorable to accurate current tracking of three-phase PWM rectifier by non-beat technique. So it is necessary to compensate for dead time. In the process of compiling this paper, the development of PWM rectifier is taken as the background, and the control method of voltage source PWM rectifier is discussed in detail. The mathematical modeling is used to show the transformation process of rectifier from three-phase to two-phase in stationary coordinate system and from two-phase static to synchronous rotation. And the space vector PWM technology is applied to the rectifier bridge drive control. The control methods of the system are classical outer loop voltage and inner loop current control. The beat-free technique is applied in the inner loop, and the advantages of its rapidity in current loop control are explained. Secondly, this paper focuses on the causes and consequences of the bad effect of dead-time on PWM rectifier: in order to avoid the artificially added protection time of the upper and lower leg of the rectifier bridge, the lower harmonics are increased. The current waveform of the network side is distorted. At the same time, the principle of several dead-time compensation methods are analyzed and compared with simulation experiments. The key to dead-time compensation lies in the accurate judgment of the current polarity on the network side, and the interference polarity judgment due to the zero-crossing clamping phenomenon of the current exists. Therefore, the current polarity can be accurately judged according to the current ripple estimation of the network side. The simulation model of the system is built by MATLAB/Simulink, and the feasibility of the compensation method is proved. Finally, according to the operating parameters of three-phase voltage-source PWM rectifier and the existing devices in the laboratory, the software program and hardware equipment are designed. In the software aspect, the software program is designed with STM32F407ZG as the control core, and the control circuit and the main circuit are mainly designed in the hardware aspect, including sampling circuit, external reference power circuit, protection circuit and so on circuit calculation and design. The advantages of non-beat control of three-phase PWM rectifier and the feasibility and effectiveness of dead-time compensation based on ripple current to judge the polarity of current are finally verified by the experimental debugging of the experimental platform.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM461
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