【作者】 李光叶；

【导师】 万健如；

【作者基本信息】 天津大学 ， 电力电子与电力传动， 2011， 博士

【摘要】 基于双PWM变换器的调速系统因其网侧电流近似正弦。功率因数可控和能实现能量的双向流动等特性而受到广泛关注。本文以双PWM变换器为研究对象,针对该技术目前存在的问题,从理论分析。计算机仿真和实验样机验证三个方面进行了深入的研究。本文的主要内容和创新点:针对网侧PWM整流器的功能和特点,根据瞬时功率理论,建立了网侧PWM整流器的功率数学模型,对PWM整流器的瞬时功率流向进行了分析。分析了传统PWM整流器直接功率控制(Direct Power Control,DPC)系统中开关矢量的作用原理,指出传统PWM整流器DPC系统在靠近基本电压矢量的地方容易出现无功功率失控现象,导致网侧电流和直流电压出现较大波动。基于PWM整流器功率数学模型,设计了一种18扇区空间矢量划分方法,并得出了相应的开关矢量选择表,克服了传统PWM整流器DPC系统对无功功率控制的缺陷,获得了良好的稳态和动态效果。对基于负载功率前馈的双PWM变换器协调控制进行了研究,分析了功率前馈补偿原理和两种典型的功率前馈控制方式的动态响应,指出采用负载功率预测实现功率前馈时,通过合理选择控制器参数,可使直流母线电压不受负载功率指令的影响;分析了功率估算误差对直流母线电压波动的影响,指出当功率估算误差较小时,基于预测功率前馈的双PWM变换器具有较好抑制直流母线电压波动的能力。此外,对永磁同步电机矢量控制方式进行了分析,给出了预测功率的计算方法。为了提高直流母线电压动态响应速度,抑制直流母线电压的波动,选择直接电容功率控制方法作为研究对象,并分析了传统前馈控制方法的不足。在对双PWM变换器进行小信号模型分析的基础上,设计了一种基于直接电容功率控制的双PWM变换器协调控制方法,该方法用电容功率控制环代替网侧PWM整流器有功功率控制环,通过直接控制电容瞬时功率为零实现双PWM变换器的解耦控制。在传统负载功率的估算中,估算精度受电机参数影响较大,为此,本文设计了一种负载功率观测器,该方法只需测量整流器输出电流和直流母线电压,即可实现对逆变器输入功率的估算。更多还原

【Abstract】 Speed control system based on dual PWM converter have been paid close attention to for its sinusoidal current of grid side, controlled power factor and bidirectional energy flow. In view of the existing problems of the dual PWM converter, deep researches have been done in the aspects of the theoretical analysis, computer simulation and experimental prototype in the paper.The main research contents and innovation are shown as following. The mathematical model of PWM power converter is constructed based on the function and characters of PWM converter and instantaneous power theory. The instantaneous power flow of PWM converter is analyzed. The principle of switching vector in traditional DPC control system is analyzed. The reactive power is out of control near the fundamental voltage vector in traditional DPC system, which leads to the current distortion at AC side and the voltage fluctuation at DC side. The 18 sector division method is proposed and the corresponding switching table is obtained based on power mathematical model of PWM converter. The defects on reactive power control in traditional DPC are overcome, and the steady and dynamic effects are improved.The integrated control of dual PWM converter based on load power feed-forward method is researched. The compensation principle and dynamic response of two typical power feed-forward control models are analyzed. The prediction of load power to be fed forward is developed, from which the DC bus voltage is immune from load power command through the rational controller parameters. The influence of power estimation error on DC bus voltage is analyzed. It is pointed out that the performance of dual PWM converter is excellent when the power estimation error is small. Furthermore, the vector control of permanent magnet synchronous motor is studied, and the estimation power calculation method is obtained.In order to improve the DC bus voltage dynamic response speed, and restrain DC bus voltage fluctuations, the direct capacitance power control method is proposed. The deficiency of traditional feed-forward control method is analyzed. The small signal model of dual PWM converter is analyzed. Dual PWM converter integrated control based on the direct capacitance power control is put forward. Instead of reactive power control loop, a capacitance power control loop is used. The decoupling control of the dual PWM converter is realized by setting capacitance instantaneous power zero. In traditional load power estimation, the accuracy depends on motor parameters. A load power observer is introduced in this paper, the inputs of which are merely through measuring rectifier output current and DC bus voltage, and it can estimate the inverter input power.更多还原