【作者】 黄继强；

【导师】 殷树言； 陈树君；

【作者基本信息】 北京工业大学 ， 材料加工工程， 2003， 博士

【摘要】 常规弧焊逆变电源的前级多为采用二极管整流的不控桥式整流器，后接较大的电容滤波，这种电路结构将导致弧焊逆变电源在电网端的输入电流产生畸变的尖角波，而并非正弦波。同时，弧焊逆变电源经常出现负载变动过程，变动负载也会造成输入电流的畸变。弧焊逆变电源输入电流的畸变不仅对电网造成污染，而且降低设备本身的功率因数，增加了设备对电网配备容量的要求，造成电网容量的浪费。随着人们对电网污染认识的不断加深以及相关谐波限制标准的出台和实施，解决弧焊逆变电源产生的输入电流的谐波污染势在必行。常规弧焊逆变电源所采用的不控电压型整流器是一种通用整流器的电路结构形式，稳态负载情况下，具有这种电路结构的整流器会产生相应的电流畸变，电流波形呈非连续的尖角波形，输入电流的谐波分布为：单相为2n+1次，三相为6n±1次。当弧焊逆变电源的负载为理想的稳态负载时，输入电流的谐波具有这一特点。实际焊接负载是变动的，尤其是脉冲焊接时，人为地产生出了脉动的负载，脉动负载会对输入电流产生调制作用，这时的输入电流畸变不仅包含电路结构造成的电流畸变，还包含有负载调制作用产生的电流畸变。负载调制作用使输入电流的谐波分布发生明显变化，出现了偶次谐波和直流分量，因为很多供电系统中设置的滤波设备主要是针对3次、5次、7次和11次等特定次谐波。谐波限制标准中一般不允许有直流分量的出现，且对偶次谐波的限制严格，所以从这个角度来说，偶次谐波和直流分量对电网的污染程度大，也就是弧焊逆变电源对电网的造成污染更为严重。弧焊逆变电源输入电流的谐波分析有利于了解其谐波的分布情况，通过分析可以得到其稳态负载工作时的近似电流解析表达式，对其进行傅立叶级数展开就可以得到各次谐波含量。但是当弧焊逆变电源处于脉动负载工作状况下，其输入电流的表达式比较复杂，为此利用双边带调幅原理(DSBM)，在一定的工作条件下，得到了弧焊逆变电源输入电流谐波的近似解析表达式，经过傅立叶级数展开可得各次谐波含量，对变动负载状况下输入电流谐波的分析作了有益的探索，丰富了输入电流谐波的分析手段。弧焊逆变电源功率因数校正的电路结构采用了三相PWM整流器。通过理北京工业大学工学博士学位论文论推导，在各坐标系下得出了PWM整流器的开关状态模型和平均状态模型。并在此基础上，得到了三相PWM整流器小信号模型，为PWM整流器的分析提供了理论基础，同时分析了PWM整流器的系统特性。结合瞬时功率理论和功率平衡的关系，分析了整流器的功率控制的实质，为三相PWM整流器的控制提供了理论依据。 弧焊逆变电源功率因数校正的控制最终都体现在PWM整流器的开关的动作上，对于PWM整流器的开关调制方式的研究是很有必要的。通过滞环调制方式、SPWM调制方式和空间矢量调制方式等开关方式的对比分析，利用开关周期内纹波电流轨迹的概念，描述了各种开关调制方式谐波电流情况，得出开关调制方式中以空间矢量调制方式的纹波电流最小。通过对比分析，得出空间矢量隐含的调制波为注入零序分量的调制波，并分析了零矢量分配方案。借助调制比的概念解释了空间矢量调制线性调制范围大的特点。 PWM整流器的控制策略的选取也直接关系到弧焊逆变电源功率因数校正的实施效果，所以对整流器的三种控制方式进行了分析和比较，尤其对电压控制方式和直接电流控制方式进行了详细的分析，得出了各自的控制模型，并由此分析了它们各自的控制特点:电压控制方式为单电压闭环控制，电流为开环控制，动态响应慢，且振荡剧烈;电流控制方式为双闭环控制，引入了电流内环控制作为电压外环的一个随动系统，整个控制可以达到较好的控制品质。 将整流器的控制方式和调制方式结合起来组成弧焊逆变电源功率因数校正系统的整体控制方案，通过仿真分析，结合弧焊逆变电源的特点，采用了矢量调制电流控制方案，电流控制方式使PFC系统既有较好的动态响应品质，适应弧焊逆变电源负载变动的要求，矢量调制方式又具有较低的电流纹波，利于降低输入电流谐波。 在前面研究分析的基础上，研制了一台带有功率因数校正功能的三相弧焊逆变电源样机。样机的研制工作主要是弧焊逆变电源功率因数校正系统的设计，包括对主电路的构成、以DSP为控制核心的控制电路以及控制软件的编制工作作了详细的介绍，展示了弧焊逆变电源功率因数校正过程实际实施过程和工作要点。最后对研制的样机进行了实验和测试，并对测试结果进行了分析。实验证明研究的实验样机有较好的功率因数校正效果，功率因数可以达到98%以上，同时对输入电流的谐波抑制效果明显，THDi可以控制在16%以下。摘要 采用功率因数校正的弧焊逆变电源在进行脉冲焊时，在一定程度仍然存在脉冲负载的调制效应，不利于降低输入电流的总谐波畸变率和提高弧焊逆变电源的功率因数。在满足其它设计要求下，适当调整PFC系统的响应速度，可以降低调制作用对输入电流产生的影响，改善输入电流的波形，将输入电流畸变率控制在合适的范围内，更多还原

【Abstract】 Uncontrolled diode-rectifiers are usually adopted as the primary stage of general arc welding inverter supply, and followed by a big smoothing capacitor. These circuits are lead to distorted waveforms of input current in AC side. At the same time, there are usually variable loads when the supply is working. Variable loads will also cause currents distortion. These distorted input currents including a lot of different order harmonic currents will contaminate the supply system when they inject into the supply net. At the mean while, they will reduce the power factor of welding supply themselves, increase the demand of supply power capacity and finally result in wasting electricity power. With acknowledging the pollution of supply system and related standards being released and put into use, it is indispensable to deal with these contamination produced by these general arc welding inverter supply.These uncontrolled diode-rectifiers belong to an universal type of rectifiers-voltage rectifiers, whose common features of input harmonics currents include as following: single-phase input current contains 2n + 1 orders harmonics currents and three-phase input currents contain 6n ?1 orders harmonics currents. So when with an ideal stable load, the input harmonics currents of arc welding inverter supplies share the common features. However, the loads of arc welding inverter supplies are always dynamic, they are to have their individual features, especially with pulse welding. Additional currents distortion caused by dynamic loads will be occurred. Pulse loads are purposely introduced into welding progress. These pulse loads will engender an accessory modulation effect on input currents, and change the distribution of input harmonics currents. It occurs preferable even order harmonics currents and DC components. The filters in supply system are usually equipped to deal with certain odd order harmonics such as 3 order, 5 order, 7 order and 11 order, and standard values of harmonics current are more strict with even order harmonics currents and DC component current is not allowed. To these extends, it is worse than other diode-rectifiers that the arc welding inverter supply contaminate the supplysystem.Analyzing input harmonics currents of arc welding inverter supply is benefit to understand the distribution of the harmonics currents. When with stable loads, the approximate analytical expression of input current is obtained through analyzing input current in one supply period. One also can get every order harmonics currents through Fourier series transformation. When with pulse loads, it is difficult to get the approximate analytical expression of input current. Under a certain condition, double side band modulation (DSBM) is adopted to deduce the approximate expression of input current of arc welding inverter supply when with pulse loads. Then, every order harmonics current value can be obtained by Fourier series transformation. It is a useful try to analyze the input harmonics currents of arc welding inverter supply when with pulse load and offer a new method to analyze harmonic current.Three-phase PWM rectifier is adopted to implement power factor correction function in arc welding inverter supply. Different models of PWM rectifier are deduced when under static coordinate or rotating coordinate. An average status modeling is also obtained and based on it, a small signal modeling is deduced to offer a principle to analyze PWM rectifier. The stability and static features of PWM rectifier are also analyzed. According to instantaneous power theory and power balance relationship, one gets the essence of power factor correction control that is to make reactive current to zero.It is necessary to study switching modulation patterns of PWM rectifier because it is the most direct measurement to realize power factor correction function of arc welding inverter supply. Compared with several switching modulation patterns such as hysteresis modulation pattern and SPWM pattern, space vector modulation mode has the smallest harm更多还原