【作者】 王鹏；

【导师】 王远波；

【作者基本信息】 西南交通大学 ， 电力电子与电力传动， 2011， 硕士

【摘要】 脉冲整流器是一种以脉宽调制(PWM)方式工作的整流器,又称为四象限变流器。脉冲整流器与传统的相控变流器具有功率因数高、谐波含量低、体积小、重量轻及动态响应快等优点。经过几十年的发展传统的两电平脉冲整流器已经相当成熟,但是在大功率的应用中有很多的问题难以解决,如需要昂贵且笨重的变压器、较高的开关损耗及功率开关难以达到规定的耐压要求等。从而出现了三电平脉冲整流器,三电平脉冲整流器每个桥臂上使用的IGBT的个数是两电平的两倍,因此它的每个回路中每个开关所承受的电压只有两电平的一半,从而增加了功率开关的使用寿命。而且三电平脉冲整流器能产生五种电平的线电压,在相同开关频率及控制方式下,其输出电压和电流中的谐波含量远小于传统的两电平脉冲整流器。最后,功率器件的造价是随着电压等级的提高而增加的,所以对于一些大功率电路来说三电平的性价比是优于两电平的。正是由于三电平脉冲整流器的优越性能,目前我国生产的CRH2型动车组正是采用的三电平脉冲整流器。三电平脉冲整流器的主要控制方法包括间接电流控制直接电流控制两大类,直接电流控制又主要包括滞环电流控制、固定开关频率的瞬态电流控制及预测电流控制三种。本文详细分析了三电平脉冲整流器上述的几种控制方式及中点电位不平衡的原因和危害及中点电位滞环控制法和判断H桥功率法两种控制中点电位平衡的主要策略,给出了三电式脉冲整流器主要参数的计算方法,分析验证了在一定程度上增加支撑电容从而去除二次滤波回路的可能性。最后以CRH2型车上使用的二极管钳位型三电平脉冲整流器的主要参数在Matlab/Simulink环境下分别搭建了以间接电流控制,瞬时直接电流控制及预测电流控制方式的仿真模型,并分别针对其在不同负载之间切换时电路各主要性能指数进行了详细系统的仿真分析。结果表明：在三种控制方式下的三电平脉冲整流器的功率因数都始终接近于1,针对中点电位控制方案快速有效。间接电流控制下输出电压纹波较大,且直流侧支撑电容电压均衡度较差,负载由再生满载向牵引满载切换时输出电压存在震荡。瞬时直接电流控制与预测控制输出电压纹波小,负载切换时直流输出电压跌落小、调整较快,但瞬时直接电流控制下负载由再生满载向牵引满载切换时直流输出电压跌落较大,而预测电流控制下直流侧支撑电容电压均衡度在再生情况下较差。总体来看,瞬时直接电流控制与预测控制策略能满足脉冲整流器对各种工况下的动静态性能要求。更多还原

【Abstract】 Pulse rectifier is a kind of rectifier under the pulse-width modulation. Pulse rectifier had the advantages of low harmonic, small size, light weight and fast dynamic response compared to the conventional phased converter.Two-level pulsed rectifier is already quite mature after decades of development, but has a lot of difficult problems in the high-power applications. Such as need expensive and bulky transformers, high switching loss and the power switch is difficult to achieve the required. So three-level rectifier comes into being. For the IGBT in the three-level rectifier is double to the two-level, so voltage that each switch is exposed only half to the two-level, thus increasing the life of the power switch. After all the three-level can produce five kinds of line voltage level, Harmonic content of output voltage and current is far less than two-level rectifier under the same control. Finally, the cost of power devices is to engage with the high voltage levels increased, so the three-level is better than two-level in the high- power circuit. For these, the three-level PWM rectifier was used in the CRH2.Indirect current control and direct current control were the two major control methods for the three-level rectifier. Direct current control including hysteresis current control, transient control and predict current control. The paper analyzed the every control mode. Aiming at neutral point shift problem of three-level Neutral Point Clamping rectifier, two effective control schemes were presented. Calculations of main parameters were given in the paper. A supposes was confirmed that the LC circuit can remove through increase the support capacity in some certain circumstances. At last three simulation models are designed in Matlab/Simulink environment, carried out a systematic simulation and analyze when the loads were changed.The simulation results show that the whole system can achieve the unity power factor, the neutral point voltage control is fast and effective. The output voltage ripple is larger under the indirect current control, In contrast the other two control methods are better, output voltage drop is small and adjustment time is short when the load changed. However, the instantaneous current control and predict current control have some problems in some certain circumstances. In a word, the instantaneous current control and predict current control can meet the static and dynamic performance requirements for various conditions.更多还原