【作者】 张军伟；

【导师】 王兵树；

【作者基本信息】 华北电力大学 ， 热能工程， 2011， 博士

【摘要】 作为一种新型的节能调速技术,斩波串级调速技术因其节能效率高、控制功率小、结构简单、安全可靠等优点,逐渐受到人们的重视,尤其是在高压大容量异步电动机调速方面,展现出良好的节能前景,越来越多地被应用到了多种工业现场。目前,对斩波串级调速系统在结构和控制设计方面多从经验出发,缺乏深入、详尽的理论分析依据。针对以上不足,本文从稳态、动态回路特性,机械特性,控制方法,系统功率因数计算、无功补偿、谐波分析以及新型电力电子装置对其逆变部分的改造等多方面对斩波串级调速系统做以深入、系统的分析和总结,如下所述:深入分析了斩波串级调速系统的主回路各主要电量之间的输入输出稳态关系,借助各主要电量在一个斩波周期平均以及纹波特性,给出系统主电路参数选择的原则和工程计算方法;参照传统串级调速方法给出了两种计算、绘制系统机械特性的工程实用方法,说明了斩波串级调速系统优于传统串级调速系统机械特性的原因。建立了斩波串级调速系统在一个斩波周期平均条件下的数学模型,分析了平波电感、电容、转差率等回路结构参量对母线直流脉动和电容电压波动的影响;给出了斩波串级调速系统双闭环控制设计方法,并通过仿真实验加以验证。利用Graham-Schonholzer和Dobinson方法对斩波串级调速系统定、转子电流,逆变侧电流的谐波特性加以分析计算,总结了定、转子电流、逆变侧电流的谐波特点、变化趋势,给出了各次谐波的估算公式;解释了入网电流振荡的原因。阐释了斩波串级调速系统功率因数低的原因,画出了两类负载情况下的系统矢量变化示意图;借助大容量、高压异步电动机一般使用Γ型电路等效的特点,给出了另一计算系统功率因数的思路,最后参照计算结果完成了系统无功补偿的工程设计算例,并通过仿真试验加以验证,也说明该方法具有一定的工程实用价值。说明了电压型SPWM三相VSR变流设备的工作原理,分析了其在三相静态坐标和两相动态d-q坐标时的数学模型。以此为基础,总结了SPWM电压型三相VSR变流器的电压、电流双闭环控制方法;给出了三相VSR在四象限工况下的重要参数的设计方法,并通过仿真加以验证。将三相VSR变流器技术应用在了斩波串级调速系统的逆变部分,使其工作在容性逆变工况,产生容性无功功率补偿系统无功,从而提升系统的功率因数,同时利用三相VSR输出电流近似正弦波的特点改善系统谐波,达到了提升系统特性的目的,并给出了仿真验证,该方法的验证成功对斩波串级调速系统技术未来的发展有着重要意义。更多还原

【Abstract】 As a kind of new energy saving technology, the chopped wave cascade speed control driver system is given more and more attentions to, and used in various industrial sites gradually, because of higher energy converstion efficient, lower controlling power, simple structure and safty, reliablility and so on merits, which unfolds the good application prospect, particularly in the high-voltage and large content asynchronous motor velocity regulation aspect.At present, the design about structure and control parameters of the chopped wave cascade speed control system resorts experience, lacking a deep thorough theoretics analysis basis. In view of existing situation, the deep systemical analysis and summary about the chopped wave cascade speed control system is finished in this paper such as the main circuit steady and dynamic properties, mechanical characters, control parameter design, system power factor calculation, reactive power compensation, harmonic current analysis and new type electronics and electric devices application to the inverter, and so on.The relationship between the input and output of the main electrical quantities in steady state is analysed thoroughly. By means of the the mean value in one cut period and ripple wave features of the main electrical quantities, the engineering calculation methods and selection principles are given. The two practical ways to compute and draw the mechanical characteristic curve are put forward according to the theory of the traditional cascade speed control system adopting shift-phase triggle mode. The reasons of the chopped wave mode mechanical characters superior to the shift-phase mode mechanical characters is illustrated.The methmatical model under the mean in one cut period of the chopped wave cascade speed control system is built up. The impact on the pulsation of the bus direct current and the capacitor voltage from the inductance and the capacitor and the slip ratio is analysed. The double closed-loops controlling design method is given about the chopped wave cascade speed control system, meanwhile, which is verified by the simulation model.Using the Graham-Schonholzer and Dobinson methods to calculate and study the harmonic features of the stator, the rator and the inverter sides. The relevant features and changing trend about the above harmonic currents is summarized. The various order harmonic current estimate formula is given and the reasons about the current vibration entering into the electric net is explained.The reasons about the lower power factor of the chopped wave cascade speed control system are explained. The system vector graph under two types of load is drawn. In view ofΓequivalent circuit, another method about computering the power factor is put up forward, and according to which, the engineering design to compensate system reactive power by capacitor is finished. At last, the compensatation design is verified by simulation model, and which proves its practicability.The principle of three-phases VSR is illustrated. The mathmetics models in three dimension static coordinate and d-q rotation coordinate of VSR are discussed. On base of that, the voltage and current double closed-loops designing way is deduced and summarized. The key parameters design way of VSR is offered under four quadrantal work conditions, and which is proved by simulation.Three phases VSR is applied in the chopped wave cascade speed control system to make capacitive reactive power to compensate the system reactive power in order to promote the power factor. Meanwhile, because the output current from the VSR is similar to the sine wave, the harmonic is repressed effectively, and the gain of improving the system features is attained, which is significant to the future development of the chopped wave cascade speed control system.更多还原