【作者】 刘明先；

【导师】 康勇； 裴雪军；

【作者基本信息】 华中科技大学 ， 电力电子与电力传动， 2007， 硕士

【摘要】 以由三个单相全桥逆变器所组成的组合式三相电压源型逆变器为研究对象,对三相逆变器的数学模型、控制技术及其并联系统作了分析与研究,详细分析研究了逆变器并联控制系统、数字锁相技术以及并联控制策略。建立了三相逆变器在ABC、αβ、dq坐标系中的数学模型,分析了基于同步坐标系下三相逆变器数学模型中的耦合现象,并分析了基于同步坐标系下瞬时值PID闭环控制与重复控制相结合的波形控制技术;同时分析了基于硬件封锁与软件相结合的限流技术,提高了逆变器的可靠性。对以三相逆变器组成的并联系统,可看作为三个单相逆变器组成的并联系统,故本文以单相逆变器为单元对逆变器的并联控制系统进行了分析。详细分析了两台以及多台逆变器并联时系统环流的特性,以及逆变器并联时输出有功无功的特性,从而根据实际逆变器的输出阻抗特性而获得相应的并联控制策略;分析了逆变器电压闭环控制时,逆变器输出阻抗对输出电压抑制负载扰动以及对并联系统环流的影响。分析了无功闭环调压有功滞后相位并联控制策略的控制思想、原理及其实现,分别建立了无功闭环调压、有功滞后相位的控制系统模型,同时建立了并联控制系统的小信号模型,并分析了控制器参数对控制系统的影响以及相位突变引起的相位环流变化及其收敛包络线。基于该并联方法,建立了两台三相逆变器的并联仿真模型,并对电压突变以及相位突变引起的环流作了仿真分析。建立了逆变器中数字锁相环的离散以及连续域的数学模型,该模型真实的反映了实际工程中逆变器的同步锁相原理,详细分析了数字锁相环控制系统;并建立了数字锁相环的仿真模型,分别对给定相位突变、输出相位突变时,对锁相环的锁相过程作了仿真分析。本文提出了一种同步脉宽跟踪的并联控制策略,分析了其并联控制的原理以及功率脉宽调制的原理,分析建立了无功闭环调压、有功闭环调相的控制系统模型,并对调压调相控制系统以及控制器参数对调压调相环节的影响作了详细分析。针对逆变器并联系统由于输出阻抗的特性,而导致输出有功无功与输出电压幅值、相位之间的耦合关系,提出了改进型的同步脉宽跟踪并联控制策略。最后建立了两台三相逆变器的并联仿真模型,对电压、相位差异引起的环流作了仿真分析,并联控制策略有效地抑制了系统的环流。本文最后由两台10kVA组合式三相逆变器组成的并联控制系统,对两种并联控制策略作了并联实验,实验结果验证两种并联控制策略有效地抑制了环流。更多还原

【Abstract】 Taking combined three-phase voltage sourced inverter which is composed by three single full-phase inverters as object of study, the paper analyzes and studies its mathematical model, control technology, parallel control system, and thus studies specially in detail the parallel control system, the digital phase-locked loop(DPLL) as well as the parallel control strategy.The paper establishes mathematical models of three-phase inverter in ABC,αβand dq reference frame, and analyzes control technology which based on combination of immediate PID closed-loop control and repetitive control in Synchronized reference frame. It also analyzes current limiting control technology based on the combination of hardware lcokout and software, which increases the reliability of inverter.Since we may regard the parallel system composed by the three-phase inverters as three single inverters’parallel system, the paper carries on the analysis to inverters’parallel system by taking a single-phase inverter as one unite. It analyzes not only circulating current’s characteristic of parallel system which consisted of two or more inverters but also inverter’s output reactive and active power’s characteristics in parallel system, and thus relative parallel control strategy can be obtained according to the characteristics of the actual inverter’s output impedance. The paper includes how the output impedance of inverter makes an affect on restraining load’s disturbance as well as circulating current in parallel system when inverter is controlled with closed-loop control of voltage.The paper includes thought, principle and realization of the parallel control method of closed-loop control of reactive power for voltage adjusting and active power for phase lagging. It presents model of parallel control system and small signal model for the strategy, analyzes influences of controllers’parameters upon the control system and circulating current’s change and its convergent envelope curve caused by phase’s break. It makes two three-phase inverters’parallel simulation model on the basis of the parallel strategy, and simulates their circulating currents caused by breaks of voltage and phase.It constructes discrete and continuous mathematical models about DPLL in the inverter. The models reflect vividly the principle of synchronous phase-locked technique in the inverter. DPLL control system is studied in detail. The paper establishes a simulation model of DPLL, which simulates its phase-locked process while given or output phase varies abruptly.The paper proposes a parallel control strategy based on synchronous pulse-width tracking. It analyzes the strategy’s parallel control principle and its power pulse-width modulation’s principle, establishes the models for closed-loop control of reactive power to adjust voltage and closed-loop control of active power to regulate phase respectively also, and thus analyzes parallel control system and adjusting voltage and regulating phase’s influences with controllers’parameters in detail. In view of characteristics of inverter’s output impedance in parallel system causes coupling between inverter’s output power and amplitude and phase of voltage, an improved synchronous pulse-width tracking strategy for parallel control is proposed. It establishes two three-phase inverters’parallel simulation model, simulates circulating currents’convergence in parallel system by differences of voltage’s amplitude and phase. The parallel strategy restrains the circulating current effectively.The paper finally establishes a parallel system with two 10kVA prototypes of combined three-phase inverters, experimentes with the parallel strategies advanced forward. We can learn by the experiments that the parallel strategies restrain system’s circulating current effectively.更多还原