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1、PWM逆变器的控制及并联运行控制的研究 南京航空航天大学博士学位论文PWM逆变器的控制及并联运行控制研究姓名:何中一申请学位级别:博士专业:电力电子与电力传动指导教师:邢岩20081201南京航空航天大学博士学位论文 摘 要 数字控制技术是实现高性能逆变器的关键技术之一,并联运行控制技术是实现模块化、高可靠性冗余逆变电源系统的基础。随着数字信号处理器技术的迅速发展和逆变电源系统的应用日益广泛,数年来上述问题一直是电力电子领域的研究热点和难点。 本文对 PWM Pulse Width Modulation逆变器的数字控制方法和技术进行了较为系统的研究,建立了逆变器系统的等效数学模型,研究了调节器
2、的设计和实现方法。提出了利用数字调制信号中心值对数字电压基准信号进行实时调节的方法,有效地消除了数字运算截断误差累积等因素造成的输出变压器直流偏磁问题;提出了一种采用电压电流双闭环控制与重复控制相结合的复合控制策略,有效地改善了逆变器带非线性负载的输出特性。 提出了一种基于电力线通信(PLC)的逆变器并联系统结构和控制方法,将并联控制解耦成为基准同步控制和输出均流控制,简化了并联控制尤其是模块热插拔控制的实现,实现了很好的均流特性。各并联模块之间首先交换电压基准信号的相位信息,直接据此分别调节各自电压基准信号的频率、达到相互同频同相,并且在并联运行时也始终进行电压基准信号的同步控制,在此基础上
3、,模块间交换输出电流或功率信息,结合电压调节器统一实现逆变桥 PWM 脉宽调节。 研究了基于同步母线的电压基准同步控制,采用线与逻辑方法在逆变器并联系统中实现基准同步控制;提出了基于电力线通信(PLC)的基准同步控制方法,各模块均根据相同的相位参考信号计算各自方波同步信号的相位,在各逆变器之间传递各方波同步信号的频率和相位差信息,据此调节各基准信号的相位,实现各逆变器基准相位信号始终保持同频同相。 提出了一种基于功率差调节的逆变器输出均流控制方法,各模块分别计算本机输出的有功功率和无功功率,经 PLC 交换相互之间的输出有功功率差和无功功率差,利用功率差异信息调节各自电压基准信号的相位和幅度。
4、提出了功率调节累加算法,实现了负载功率的均分。 逆变器中通常采用输出有效值调节以获得好的负载调整率。本文研究了带输出有效值调节逆变器分布式并联系统的环流特性,揭示了均流控制与有效值调节之间的互相妨碍,提出了一种克服逆变器中输出有效值调节器影响均流效果的控制方法,在各模块中将其输出电流有效值或其输出环流信号引入输出电压有效值调节算法,能够兼顾实现并联系统很好的负载调整率和均流精度。 将上述研究的正弦波 PWM 逆变器并联运行控制的原理和实现方法推广应用到 U/f 控制三相通用变频器并联系统中,在规定的输出频率变化范围内实现两模块的电压基准信号同频同相;采用主从式均流控制方法,在从机中检测各相输出
5、环流,分别对从机各相电压基准信号进行调I PWM 逆变器的控制及并联运行控制研究 节,实现了并联系统带三相异步电机负载的均流控制。 研制了单相全桥逆变器、单相二极管箝位型三电平半桥逆变器和三相通用变频器等实验系统样机,实验证实了研究结果的正确性和可行性。研究成果已经成功应用于民用和军用逆变器产品样机中。关键词:功率变换器,逆变器,不间断电源,控制,同步,均流,并联,电力线通信II 南京航空航天大学博士学位论文 Abstract Digital control and parallel operation control are among the key techniques for high
6、 performance inverters with the features of excellent regulation, modular, high reliability, and redundancy etc, and the corresponding research activities have been implementing since the development of digital signal processing and wide application of inverter power supply systemsMethods and techni
7、ques for digital control PWM Pulse Width Modulation inverters are researched systematically. Equivalent mathematical model of inverter is built, and digital regulators are designed and implemented. The control strategy for real-time regulation of digital voltage reference signal with mean value of d
8、igital modulating signal is proposed to eliminate the flux imbalance in output transformer or output filter inductor effectively. A compound digital control strategy combining output voltage and inductor current dual-loop control with repetitive control is proposed for inverter to improve its voltag
9、e regulation and nonlinear load performanceA novel system configuration and parallel control method for inverter parallel system based on power line communication PLC are porposed, in which the parallel operation control is decoupled to voltage reference synchronization control and output current di
10、stribution control to simplify the parallel realization, especially the module hot-swap operation realization. The frequency and phase information of voltage reference signal in each module is delivered to all the other modules in the parallel system, and the frequency of each voltage reference sign
11、al is adjusted accordingly to realize synchronization control. Based on pre-synchronized voltage reference signals, output current or output power information is shared among the parallel system, and current distribution control is implemented by modified SPWM Sinusoidal PWM output regulationThe vol
12、tage reference synchronization control based on synchronization bus is researched and realized by means of interconnecting line and wired-and logic in uninterruptible power supply UPS parallel system. The voltage reference synchronization control based on PLC is proposed, in which the phase angle of
13、 each voltage reference signal is calculated with the same phase reference, and phase difference information is exchanged by PLC among the parallel modules. With the same synchronization regulation algorithm as that of the former method, all the voltage reference signals share the identical frequenc
14、y and phaseA load distribution control based on output power difference is proposed, in which the active power and reactive power are calculated in each module to obtain the active power difference and III PWM 逆变器的控制及并联运行控制研究 reactive power difference among the modules by PLC, and the phase and ampl
15、itude of each voltage reference signal are regulated in accordance with output power difference. The power regulation accumulative algorithm is proposed to realize load power distributionIn inverter system, output voltage root-mean-square RMS regulation is a common solution to improving good load re
16、gulation. The circulating current characteristics of the distributed inverter parallel system with analog control are researched to reveal the interference between current distribution and load regulation. A novel control method for compensating the impact on load distribution by output voltage RMS regula
