【作者】 方宇；

【导师】 胡育文； 邢岩；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2008， 博士

【摘要】 消除电网谐波污染、提高功率因数是电力电子领域研究的重大课题。本文研究高功率因数可逆PWM(Pulse Width Modulation)变换器及其控制策略,以三相两电平电压型可逆PWM变换器及二极管箝位型三电平(Three-level,TL)可逆PWM变换器作为研究对象。对三相两电平电压型PWM变换器和三电平电压型PWM变换器均采用电压空间矢量PWM(Space Vector PWM, SVPWM)调制方法,以获得网侧低电流谐波,提高直流侧电压利用率。分析和研究了两电平三相电压型PWM变换器的工作原理及其控制策略。研究了空间矢量算法,提出了一种预分解矩阵的快速算法,避免了非线性算法,节省了DSP(Digital Signal Processor)的资源;在两相静止坐标系下,研究了两电平三相PWM变换器的预测电流控制,将预测电流控制算法和预分解SVPWM算法相结合,实现了DSP全数字控制的高频调制和快速控制,这对提高功率密度和减小整机体积重量有重要意义;在两相静止坐标下控制量是正弦的,系统是有静差的,直流侧电压也是有纹波的,故文中进而在同步旋转坐标系下研究了无电网电压控制策略,并提出了基于无电网电压传感器的一种新的控制算法。研究了三电平三相电压型PWM变换器工作原理和数学模型,研究了三电平空间矢量的调制方法,将两电平预分解矩阵快速算法推广到三电平SVPWM,实现了三电平SVPWM的线性运算,提高了程序运行效率和工作矢量作用时间的精度;研究了三电平三相PWM变换器中点(Neutral Point, NP)电位平衡控制方法,提出了无电流传感器滞环控制策略,实现了中点电位平衡;提出了基于模糊控制的控制因子法,将之与SVPWM相融合,实现了冗余小矢量作用时间的智能选择,尽一步改善了中点电位在静态和动态状态下的平衡特性。借鉴交流电机矢量控制策略,实现电流解耦。在同步旋转坐标系下设计三电平三相电压型PWM变换器和两电平三相PWM变换器的双闭环控制控制器。双环调节器都采用经典的PI调节器,解耦后的三电平PWM变换器和直流电机调速系统相似,因此文中借用直流电机调速系统的控制器设计思想,将变换器的模型作了合理的简化处理,研究了三电平三相PWM变换器的工程化设计方法,以缩短三电平变换器的设计及调试周期,避免了控制参数整定的盲目性。基于整流和逆变运行状态的分析研究,研究了上述PWM变换器的可逆运行及转换状态原理和特性。基于电网电压定向矢量控制策略,两种整流器系统的可逆运行基理是一样的,电压调节器的输出正、负状态决定了变换器整流和逆变运行状态。对上述研究内容进行了仿真和实验。研制了两电平三相PWM变换器和三电平三相PWM变换器实验样机。基于TI公司定点DSP芯片TMS320F2808,实现了PWM变换器的全数字控制。仿真和实验验证了所提出控制方法及控制算法的正确性。更多还原

【Abstract】 Eliminating harmonic pollution and improving power factor are the quite important task in the field of power electronics. In this thesis power factor correction and reversible property are studied and the existing two kinds of reversible PWM rectification topologies and control strategy are analyzed. These two kinds of reversible PWM rectifier mainly include two-level three-phase PWM rectifier and three-level(TL) three-phase diode-clamped PWM rectifier. The space vector PWM(SVPWM) is employed to achieve low harmonic distortion and raise the utilizable ratio at DC side.Firstly, the operation basis and its control strategy for three-phase two-level PWM rectifier are dicussed and analyzed in detail. Here, the fast algorithm called pre-discomposition matrix is presented for SVPWM. This method can avoid the nonlinear algorithm and save the resource of DSP. Also the predictive current controller is proposed in three-phase two-level PWM rectifier in the two-phase fixed reference frame. The combination of the predictive current control and pre-discomposition SVPWM can realize high-frequency digital control, raise power density and minish the size. Due to that the control quantities are still sine wave in two-phase fixed reference frame, the system exists static error and the voltage ripple at DC side. Therefor no AC-line voltage sensors with SVPWM is studied and the new algorithm for no AC-line voltage sensors is proposed.Based on the studies of operation principle and mathematical models for three-phase three-level PWM converter, the TL SVPWM is analyzed and the pre-discomposition matrix method in two-level SVPWM is extended to TL SVPWM. So the linear algorithm for TL SVPWM is gotten and the run efficiency of DSP routine and the computing precision are improved greatly. The neutral point(NP) balancing problem is impersonal for TL PWM converter, the NP balance guarantees the high power factor and the safety of switches and DC capacitors. Hence, the current-sensorless hysteresis control strategy is proposed for NP balance. This control technique can keep the balance between the two DC capacitors in steady state but not perfectly in dynamic condition. So the control index method based on fuzzy controller is proposed. Fuzzy controller can automatically and intelligently adapt the value of the control index and change the operation time duration of the small vectors, to implement the NP balancing wonderfully whether in steady state or dynamic state.The current-decoupled controller is introduced into the control strategy for TL PWM converter just as two-level one. The decoupled TL PWM converter resembles the speed regulation for DC motor. From this, the design method for engineering is proposed in the thesis. This design method can shorten the design period and avoid the blindness for looking for control parameters.Besides, the reversible operation for two-level and TL PWM rectifiers is discussed in the thesis. The basis of the reversible operation in these two kinds of topology is same based on VOC. i.e. it is the output of the voltage regulator that deside the operating state of the PWM converters.Two kinds of PWM rectifier profiles are designed based on DSP TMS320F2808. The experimental and simulation waveforms verify these proposed control strategies and algorithms in this thesis.更多还原