【作者】 杨青；

【导师】 沈锦飞；

【作者基本信息】 江南大学 ， 电力电子与电力传动， 2011， 硕士

【摘要】 串联谐振感应焊接电源在国内已经有了很大的发展,但与国外相比还有较大的差距,尤其在大功率及高频率领域与西欧和日本的差距明显。目前国内的焊接电源研究的方向及面临问题主要包括提高功率变换器的工作频率问题、高频化带来的开关器件以及无源器件的损耗提高问题、感应焊接电源对电网产生的谐波污染及损耗问题、数字化控制的应用等。感应焊接电源AC/DC环节一般采用晶闸管相控整流或者二极管不控整流,造成输入电流失真,波形畸变,不仅严重干扰电网线电压,而且导致电源的利用效率低下,加大了能源的损耗。本课题采用功率因数校正技术,通过在整流与逆变环节之间加入一种改进的软开关boost电路—串联电感及无损SNUBBER电路取代传统的LC滤波电路来实现功率因数校正,从而减少了boost电路在高频开关状态下的损耗,提高了校正电路应用范围,采用TMS320LF2407A实现了功率因数校正电路的平均电流模式控制。比较了感应焊接电源的几种功率调节方式,采用逆变侧移相脉宽功率调节方法实现功率调节。针对当前IGBT工作频率较低的情况,逆变桥侧通过IGBT的分时控制来实现倍频工作。最后,控制电路采用由集成锁相电路、DSP和CPLD组合的数字化控制系统。DSP实时计算负载功率与额定功率的差值,从而得到移相角。CPLD接受移相角信号和锁相信号,进行移相PWM控制。控制系统外围电路包括过压、过流等保护电路以及由IXDN404组成的IGBT驱动电路。在分析了软开关boost电路和倍频逆变电路的工作原理的基础之上,对主电路做了MATLAB仿真,为后面的实验奠定了基础。实验结果和仿真结果是一致的,验证了功率因数校正技术应用到感应电源中的合理性与可行性。更多还原

【Abstract】 Series resonant induction welding power has made great progress in our country, but there is still large disparity comparing with foreign countries. Especially in high power and high frequency fields, we have significant diaparity with Western Europe and Japan. At present, the direction of welding power and the problems faced by research include improving the operating frequency of power converter, problems caused by high frequency switching devices and loss improve problem of passive devices, Harmonic pollution and loss issues on the power grids caused by induction welding power, the application of digital control.The input current and waveform distortion is due to the rectifying part, because it usually adopts the thyristor phase-controlled rectifying or diode rectifying in the AC/DC link.It will not only seriously interfere with the power line voltage, but also reduce the energy efficiency, which means the energy wastage is increased.Power Factor Correction technology has been applied to this paper. For the negative impact on the grid, we try to add an improved soft boost circuit-lossless snubber circuit between the rectifier and the inverter, which is used to replace the traditional LC filter to achieve power factor correction.Thereby it reduced the boost circuit switching loss at high frequency and improved the correction circuit application. TMS320LF2407A was used to achieve power factor correction with the average current mode control. We compared several power regulation method, and finally chose the phase shifted pulse width modulation as power regulating methods on the AC side.For the current situation of IGBT’s low frequency, we chose a new inverter—through IGBT parallel to achieve multiplier work.In the end of the study, we researched the digital control system of induction welding power, which is mainly constituted by the integrated PLL chip 74HC4046, DSP (digital signal processor) and CPLD (compelx programmable logic device) component.The DSP calculated the difference between actual power and rated power of the load, then got phase shift angle.CPLD received signal of phase shift angle and phase-lock, which is used to accomplish the phase-shifted PWM control. In addition, we also designed the external circuit of the control system, such as over-voltage, over current protection circuit and IGBT driving circuit based on chip IXDN404. After analysis of soft boost circuir and multi-frequency inverter, we made MATLAB simulation on the main circuit, as the basis for subsequent experiments. Experimental results and simulation results are consistent, it confirmed that power factor corrections applied to the induction welding power in the technical is reasonable and feasible.更多还原