【作者】 王铁军；

【导师】 辜承林；

【作者基本信息】 华中科技大学 ， 电机与电器， 2009， 博士

【摘要】 本论文研究多相逆变器-感应电动机驱动系统中的谐波抑制问题。围绕这个问题,本文在相关理论基础、谐波抑制技术、仿真和实验分析等方面开展了比较系统的研究工作。首先,从多相电机相数定义出发,探讨了多相绕组的构成规律,并以此为基础,分析了主要类型的多相绕组磁动势谐波的成分及其性质。由于应用了空间矢量概念,绕组的空间相位和时间相位关系得以统一,分析过程较其他方法明显简化。此外,基于伏-秒平衡原则,还对由多套三相绕组构成的多相电机推导了合成电压空间矢量,借助合成电压空间矢量分析磁场谐波,分析过程更为简捷。根据多相感应电动机模型建立和谐波分析以及谐波抑制的需要,对各种基于解耦目的的多相参照系变换原理,从数学上进行了详细推导,从物理上给出了明确说明,阐述了变换之间的联系,并分析了它们的特点与适用范围,从而形成了趋于完整的多相变换理论体系,充实了多相电机谐波研究的理论基础。基于多相变换理论,建立了主要几类多相感应电动机的仿真模型,所建模型能广泛适合于谐波及动、静态问题的分析。多相感应电机谐波主要是指显著定子谐波电流和低频脉动电磁转矩。显著定子谐波电流是多相感应电机的特有现象,必须予以考虑;而脉动电磁转矩是逆变器供电时交流电机的普遍问题,在多相电机中虽然有所改善,但仍有进一步改善的必要。文中分析了这两类谐波的产生机理和对电机运行性能的影响,系统介绍了抑制谐波的主要方法及其相关理论,归纳总结了它们各自的特点与适用范围。本文在传统滤波电抗器基础上,提出了新型滤波电抗器方案。该电抗滤波器采用和交流电机定子类似的电磁结构,通过调整电抗器绕组的空间分布,使多相感应电动机定子绕组中的显著谐波电流在滤波电抗器中产生旋转磁场,形成高值耦合电抗,从而对谐波电流予以有效抑制。而对于基波电流,滤波电抗器却只呈现很小的阻抗。实施结果表明,新型滤波电抗器滤波效果显著,体积小,重量轻,呈现出传统滤波电抗器所无法比拟的优势。本文还基于特定谐波消除(SHE)PWM技术,研究了多相感应电动机低频脉动转矩的抑制问题。分析了应用SHEPWM技术调节逆变器输出电压时开关角的变化规律,探讨了应用查表和线性插值混合方法生成SHEPWM开关角的技术。在实际应用方面,提出了在幅压供电条件下,用多相电机替代直流电机并采用SHEPWM技术实现稳压控制的技术方案。就常规方法计算SHEPWM开关角的求解困难问题,探讨了一种新的PWM信号生成方法,即通过对双Y移30°绕组和4Y移15°绕组的电压空间矢量谐波进行比较,再把谐波差变换为控制双Y移30°感应电动机的PWM信号。该方法尤其适合逆变器直流侧电压可调节的逆变控制类型。论文对所提出的定子谐波电流和脉动转矩抑制方法进行了充分仿真研究。最后,在仿真研究基础上,建立了双Y移30°感应电动机实验系统。结合新型电抗滤波器的研制与试验,进一步验证了理论分析方法的合理性和有效性。更多还原

【Abstract】 The theme of this dissertation focuses on eliminating the harmonics in multi-phase induction motor fed by voltage source inverter (VSI). On the theme, the research is carried out systematically by combining theoretical analysis, numerical simulation as well as laboratory experiments. The contents are summarized as follows.First of all, principles of winding’s configurations of multi-phase induction motors are investigated according to the precise definition of the multi-phase order. And the harmonics of magneto-motive-force (MMF) produced by typical multi-phase windings are analyzed. The process of estimating harmonics is simplified based on the principle of space vector. For those machines that are constructed by multiple three-phase windings, the space vector voltages are selected for analyzing magnetic harmonics. By composing the space vector voltages according to the rule of volt-second, the process of harmonic analysis is further simplified.Several types of multi-phase reference transformation are discussed. Their principles of decomposition are investigated mathematically and physically. And their charateristics and application scopes are analyzed. Thus the theory of multi-phase reference transformation for harmonics research is formed. Based on the theory, models of multi-phase induction motors are set up. The models can be extensively used for analyzing harmonic, steady and dynamitic problems.Harmonic problems of multi-phase motor can be classified as substantial harmonic currents in stator and the pulsing electromagnetic torque. Substantial harmonic currents, which have drawn much attention, are phenomenon specially occurring in multiphase induction motor. The pulsing torque, which has been reduced obviously by multi-phase scheme, should be further reduced to meet more strict requirements. In this dissertation, the causes of these harmonics are explained and their influences on motors are discussed. The main methods for harmonics elimination presented previously are summarized according to their relations and features. This summarization is helpful to propose more perfect schemes.To eliminate the substantial harmonic currents in stators, a novel reactance filter based on the previous ideas is proposed in this dissertation. The construction of the filter is resembled to the stator of multi-phase motor in the system. When the distribution of multi-winding being properly adjusted, the filter is able to eliminate the substantial harmonic currents selectively but free to the fundamental currents. The research results show that the scheme of the novel filter has obvious advantages of minimizing the weight and the space.To eliminate the pulsing torques of a multi-phase motor, selected harmonic elimination (SHE) PWM is introduced. The rules of switch angles for regulating the output voltage of inverter are investigated. The strategy to realize SHEPWM by combining lookup table and interpolation is discussed. An improved method is proposed to avoid the complicated calculation of switch angles in traditional way. According to the method, when controlling a motor of dual three-phase spatially shifted by 30°, the switch angles of SHEPWM can be acquired from the harmonics existing in the difference between the practical system and a supposed system of fourfold three-phase spatially shifted by 15°.Finally, based on extensive numerical simulation, laboratory prototype of dual three-phase induction motor and the proposed filter were set up. The experimental results show the validity of the schemes for harmonic elimination proposed by the dissertation.更多还原