带Boost变换器的并联型12脉波整流器研究

发布时间：2018-07-28 11:31

【摘要】：大功率整流器在国民经济的各个领域有着广泛的应用。但是,整流器件的强非线性和时变性使大功率整流器成为交流电网的主要谐波源。多脉波整流技术是解决大功率整流器谐波污染问题的有效途径。该技术可以有效抑制输入电流中的低次谐波,但对高次谐波无能为力。为进一步增强多脉波整流器的谐波抑制能力,本文将多脉波整流技术与直流侧谐波抑制技术结合,在常规自耦型12脉波整流电路的基础上,研究了一种带Boost变换器的并联型12脉波整流器。为了在仿真软件中模拟星形自耦变压器,建立了星形自耦变压器的全解耦模型。首先,通过分析星形自耦变压器输入、输出电压相量的关系,确定了星形自耦变压器的绕组结构及变比;应用相分量法,分析了星形自耦变压器耦合电路中支路电压、支路电流、节点电压、节点电流之间的关系,得到了节点导纳矩阵,该矩阵包含星形自耦变压器的绕组连接特性、阻抗参数等相关信息,进一步确定了星形自耦变压器的全解耦模型。仿真与实验结果表明,应用该模型,可对使用星形自耦变压器的12脉波整流器进行有效模拟。为在直流侧抑制并联型12脉波整流器的输入电流谐波,研究了理想状态下12脉波整流器的直流侧谐波抑制机理,并分析了输入电压不对称谐波抑制性能的影响。利用开关函数,计算了整流器网侧输入电流、电感电流的数量关系,分析了输入电流为正弦波时所需电感电流波形,并给出了可实现的电感电流波形。引入输入电压不对称因数,分析了不对称因数对三相输入电压、自耦变压器输出电压的影响,确定了输入电压不对称因数与整流器输入电流的关系。理论分析表明,当电感电流满足一定要求时,使用Boost变换器可有效抑制输入电流谐波;输入电压的轻微不对称对整流器的谐波抑制能力影响较小。为使整流器具有较好的稳态特性和动态特性,建立了带Boost变换器的并联型12脉波整流器在峰值电流控制模式下的精确模型,并应用该模型给出了电压补偿网络的设计方案。考虑元件部分寄生参数的影响,建立了非理想Boost变换器的小信号模型;研究了整流器在峰值电流控制模式下稳定运行条件,给出了电压补偿网络的设计方法。对带Boost变换器的并联型12脉波整流器进行了设计,并研制了一台功率为2.25k W的实验样机。仿真和实验结果表明,该系统具有优良的谐波抑制性能和较快的动态响应速度,且实现成本较低。
[Abstract]:High-power rectifiers are widely used in various fields of national economy. However, the high power rectifier becomes the main harmonic source of AC power grid because of its strong nonlinearity and time variation. Multi-pulse rectifier is an effective way to solve the problem of harmonic pollution in high power rectifier. This technique can effectively suppress the low order harmonics in the input current, but it is powerless for the high order harmonics. In order to further enhance the harmonic suppression ability of the multi-pulse rectifier, this paper combines the multi-pulse rectifier technology with the DC side harmonic suppression technology, based on the conventional self-coupled 12-pulse rectifier circuit. A parallel 12 pulse rectifier with Boost converter is studied. In order to simulate star-shaped autotransformer in simulation software, a fully decoupling model of star-shaped autotransformer is established. Firstly, by analyzing the relationship between input and output voltage phasor of star-shaped autotransformer, the winding structure and variable ratio of star-shaped autotransformer are determined, and the branch voltage in the coupling circuit of star-shaped autotransformer is analyzed by using phase-component method. The relationship among branch current, node voltage and node current is obtained. The node admittance matrix includes the winding connection characteristics of star autotransformer, impedance parameters and other related information. Furthermore, the fully decoupling model of star autotransformer is determined. The simulation and experimental results show that the 12 pulse rectifier using star autotransformer can be effectively simulated by using this model. In order to suppress the input current harmonics of the parallel 12-pulse rectifier at the DC side, the harmonic suppression mechanism of the 12-pulse rectifier in ideal condition is studied, and the effect of the asymmetric input voltage on the harmonic suppression performance is analyzed. By using switching function, the relationship between input current and inductor current in rectifier is calculated. The waveform of inductance current when input current is sinusoidal wave is analyzed, and the realizable inductance current waveform is given. The influence of asymmetry factor on three-phase input voltage and output voltage of autotransformer is analyzed, and the relation between the asymmetry factor of input voltage and input current of rectifier is determined. Theoretical analysis shows that when the inductance current meets certain requirements, the input current harmonics can be effectively suppressed by using Boost converter, and the slight asymmetry of input voltage has little effect on the harmonic suppression ability of rectifier. In order to make the rectifier have better steady-state and dynamic characteristics, an accurate model of parallel 12-pulse rectifier with Boost converter in peak-current control mode is established, and the design scheme of voltage compensation network is given. Considering the influence of some parasitic parameters of components, the small signal model of non-ideal Boost converter is established, and the stable operation condition of rectifier in peak current control mode is studied, and the design method of voltage compensation network is given. A parallel 12-pulse rectifier with Boost converter is designed, and an experimental prototype with power of 2.25kW is developed. The simulation and experimental results show that the system has excellent harmonic suppression performance, fast dynamic response speed and low cost.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM46
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本文编号：2149994