LCL型PWM整流器电流内环无阻尼控制技术研究

发布时间：2018-03-01 17:10

本文关键词： PWM整流器 LCL滤波器谐振频率无阻尼谐波抑制　出处：《华中科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：LCL滤波器由于具有良好的高频谐波抑制特性在新型PWM整流器中得到广泛的应用。但是LCL滤波器存在谐振尖峰，容易造成系统不稳定，增加了控制系统设计难度。本文针对采用桥侧电流反馈方案的三相LCL型PWM整流器，研究了其电流内环系统无阻尼控制技术。论文分析了LCL型PWM整流器电流内环数学模型，指出数字控制系统固有延时对系统稳定性有着关键作用。研究了LCL谐振频率和数字控制延时对系统稳定性的影响，，推导出了理想LCL模型下系统无阻尼稳定的边界条件。针对实际LCL滤波器电感存在铁耗的问题，建立实际电感数学模型，研究了电感铁耗、LCL滤波器谐振频率和数字控制固有延时三者共同作用对系统稳定性的影响，指出实际LCL模型下，系统的稳定条件更宽。为抑制电网电压背景谐波对电流内环控制系统的影响，减少电流纹波，增强系统无阻尼稳定性，论文首先分析了电网电压全前馈控制策略的优缺点，指出了全前馈控制策略存在可能会引入干扰的固有局限性，然后提出了一种基于网侧电流估算的PR调节器谐波抑制控制策略。搭建理想仿真模型，验证了理想LCL模型下稳定性理论分析正确性，基于一台22kW三相LCL型PWM整流器样机，通过实验验证了实际模型下稳定性理论分析正确性和谐波抑制策略可行性。
[Abstract]:LCL filter has been widely used in new PWM rectifier because of its good high frequency harmonic suppression characteristics. However, the LCL filter has resonance spike, which can easily lead to system instability. The design difficulty of the control system is increased. In this paper, the undamped control technology of the current inner loop system is studied for the three-phase LCL type PWM rectifier with bridge side current feedback scheme. This paper analyzes the current inner loop mathematical model of LCL type PWM rectifier, points out that the inherent delay of digital control system plays a key role in the stability of the system, and studies the influence of LCL resonant frequency and digital control delay on the stability of the system. The boundary condition of undamped stability of the system under ideal LCL model is derived. Aiming at the problem of iron loss in actual LCL filter inductors, a mathematical model of actual inductors is established. The influence of resonance frequency and inherent delay of digital control on the stability of the system is studied. It is pointed out that under the actual LCL model, the influence of the resonant frequency of the LCL filter and the inherent delay of digital control on the system stability is studied. The stability condition of the system is wider. In order to restrain the influence of the voltage background harmonics on the current inner loop control system, reduce the current ripple and enhance the undamped stability of the system, this paper first analyzes the advantages and disadvantages of the full feedforward control strategy of the power network voltage. The inherent limitation of full feedforward control strategy which may introduce interference is pointed out, and then a harmonic suppression control strategy for PR regulator based on network side current estimation is proposed. An ideal simulation model is built to verify the correctness of the stability theory analysis under the ideal LCL model. Based on a 22kW three-phase LCL rectifier prototype, The theoretical analysis of stability and the feasibility of harmonic suppression strategy are verified by experiments.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM461

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