基于电流源型变频器长距离传输系统研究

发布时间：2018-07-04 19:08

本文选题：集中变频 + 电流源型变频器　；参考：《中国矿业大学》2015年硕士论文

【摘要】：目前,市场上存在大量变频传动产品,它们采用不同功率开关器件拓扑结构和控制策略各具特色,其中,电流源型变频器基于其结构以及控制的优越性,在高压大功率场合传动领域获得广泛应用。针对煤矿井下恶劣环境以及防爆变频器设计的复杂性,往往选用长距离变频传输系统,但同时由长距离带来的电机端过电压和传导干扰等负面影响也随功率和开关频率的提高变得越来越严重。本文基于煤矿井下工作面地面集中变频系统研发项目,结合电流源型变频器控制优越性,针对电流源型变频器的长距离传输系统带来的负面影响,主要展开了以下工作。首先,分析了系统结构特点,以电流源型逆变器为研究对象,对电流源型逆变器调制策略进行深入研究,重点研究了两种调制策略:梯形波脉宽调制(TPWM)、电流空间矢量脉宽调制(SVPWM),在MATLAB软件中分别建立仿真模型,通过改变调制波频率和直流电流大小实现了逆变器输出电流频率和幅值的控制,并对两种调制算法的特点进行了对比分析。其次,基于传输线理论分析了电压、电流反射现象及电动机端过高电压的产生机理,分析结果表明,负载与电缆阻抗不匹配是电机端过电压形成的主要原因;针对电流源型逆变器共模电压进行定义,公式推导分析PWM变频器中共模电压的产生机理和表达式,建立共模等效电路,分析了逆变器九种开关状态分别对应的共模电压,建立仿真模型仿真分析了逆变器输出的共模电压;为进一步分析,建立适用于长距离电缆系统分析的高频电缆模型和高频电机模型,通过实验计算得到模型各参数,验证了模型的有效性。再次,结合MATLAB与PSPice仿真软件建立系统仿真模型,对比电压脉冲仿真分析了电流脉冲反射规律,结合两种调制策略仿真分析了电流PWM波对电机端电压的影响,结果表明:电流源型逆变器输出不受电缆长度限制,建立电流源型变频器实验平台,采用SVPWM调制策略进行了实验验证。最后,针对共模电压产生规律对共模电压的抑制策略进行研究,从硬件和软件两个方面进行分析,硬件方面主要通过一体化电抗器结构和输入输出电容连接结构减少共模电压对系统的影响,软件方面,基于SVPWM调制策略重点研究了三种非零矢量抑制策略和一种三相四桥臂抑制策略,在MATLAB中分别建立仿真模型验证了几种抑制策略的有效性并进行了对比分析。
[Abstract]:At present, there are a large number of variable-frequency drive products in the market, which adopt different topology and control strategy of different power switch devices. Among them, the current-source inverter is based on its structure and advantages of control. It is widely used in the field of high-voltage and high-power transmission. In view of the complexity of the design of the bad environment and explosion-proof frequency converter in coal mine, the long distance frequency conversion transmission system is often used. But at the same time, the negative effects such as overvoltage and conduction interference brought by long distance also become more and more serious with the increase of power and switching frequency. Based on the research and development project of ground centralized frequency conversion system in underground working face of coal mine, combined with the control superiority of current source converter, the paper mainly carried out the following work in view of the negative influence brought by the long distance transmission system of current source converter. Firstly, the characteristics of the system structure are analyzed, and the modulation strategy of the current-source inverter is deeply studied, taking the current-source inverter as the research object. Two modulation strategies: trapezoidal pulse width modulation (TPWM) and current space vector pulse width modulation (SVPWM) are studied. The output current frequency and amplitude of the inverter are controlled by changing the modulation frequency and DC current, and the characteristics of the two modulation algorithms are compared and analyzed. Secondly, based on the transmission line theory, the mechanism of voltage, current reflection and over-high voltage at motor terminal is analyzed. The results show that the mismatch between load and cable impedance is the main reason for the formation of over-voltage at motor end. According to the definition of common-mode voltage of current-source inverter, this paper deduces and analyzes the mechanism and expression of common-mode voltage of PWM inverter, establishes the common-mode equivalent circuit, and analyzes the common-mode voltage corresponding to nine switching states of inverter. The common mode voltage of inverter output is simulated and analyzed by the simulation model. For further analysis, the high frequency cable model and the high frequency motor model suitable for the analysis of long distance cable system are established, and the parameters of the model are obtained by experimental calculation. The validity of the model is verified. Thirdly, with MATLAB and PSPice simulation software to establish the system simulation model, compared with the voltage pulse simulation analysis of the current pulse reflection law, combined with two modulation strategies to simulate the impact of current PWM wave on the motor terminal voltage. The results show that the output of current-source inverter is not limited by cable length. The experimental platform of current-source inverter is established and the SVPWM modulation strategy is used to verify the experiment. Finally, aiming at the common mode voltage generation rule, the common mode voltage suppression strategy is studied, and the hardware and software are analyzed. In the hardware aspect, the common mode voltage is reduced by the integrated reactor structure and the input and output capacitance connection structure. Based on SVPWM modulation strategy, three non-zero vector suppression strategies and one three-phase four-arm suppression strategy are studied. Simulation models are established in MATLAB to verify the effectiveness of several suppression strategies.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM921.51

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