【作者】 伍健；

【导师】 何礼高；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2010， 硕士

【摘要】 电源是等离子切割的动力来源,电源变换技术是现代等离子切割设备中的核心技术之一,研究高效高可靠性的等离子切割电源对于提高切割效率和质量具有重要意义。本文设计了一种以两相并联带无源低损缓冲电路的Buck变换器为主电路的等离子切割电源,尤其对无源低损缓冲电路的参数设计作了细致、深入的研究。在分析无源低损缓冲电路的基础上,还对一种适用于大功率场合的耦合电感式无源无损缓冲电路进行了研究。详细分析了该缓冲电路的各个工作模态,并对谐振元件参数作了优化设计。通过一台原理样机验证了理论分析和设计方法的正确性。等离子切割电源工作中的引弧是产生等离子弧的重要环节,本文详细分析了引弧电路的工作原理和数学模型,讨论了产生高频振荡的条件,对引弧用高频振荡器进行了仿真建模,并给出了引弧电路关键参数的设计原则。针对等离子切割电源陡降外特性的特点,通过建立等离子切割电源主电路的小信号模型,设计了满足其外特性要求的电流闭环控制系统,给出了控制参数的设计原则,并完成了单片机控制系统、PWM控制电路及驱动电路的设计。结合主电路和电流闭环控制系统的设计参数,对其进行了仿真研究。在理论分析和仿真研究的基础上,完成了一台30kW的等离子切割电源工程样机的研制,并进行了静态满负载烤机实验和现场切割实验,测试了相关性能指标参数。实验结果表明,所研制的等离子切割电源效率高、可靠性好,符合陡降外特性的要求。更多还原

【Abstract】 Power supply is the power source of plasma cutting, power conversion technology is one of the core technologies of modern plasma cutting equipments, reseaching the plasma cutting power supply has important significance for improving the cutting efficiency and quality.A plasma cutting power supply based on two parallel Buck converter with passive low lossy snubber is designed in this paper, especially the parameter design of the passive low lossy snubber is researched in detail and deeply. Based on the analysis of the passive low lossy snubber, this paper also researchs a passive lossless snubber with coupled-inductor applicable to high-power situation. The operation process of the snubber and the optimization of the resonance parameters are analyzed in detail. A prototype is built to verify the correctness of the theory analysis and design methodology.Arc ignition is an important step to form the plasma arc when the plasma cutting power supply is working, this paper analyzes the working principle and mathematic modle of the arc ignition circuit, discusses the realize conditions of the high frequency oscillator. Also the simulation modle of the high frequency oscillator for arc ignition is built, and the design principle of key parameters is analyzed.For the dramatic decreasing external characteristics of the plasma cutting power supply, the current closed-loop control system is designed through small signal model of the plasma cutting power supply, which is in accordance with the external characteristics. The design of control parameters, microprocessor control system, PWM control circuit, and drive circuit are respectively analyzed.Combined with designed parameters, the simulation model of the plasma cutting power supply system is built. Based on the theory analysis and simulation, a 30kW plasma cutting power supply prototype is built. The static full-load and cutting experiments are finished, and the relevant performance parameters are tested. The experimental results show that the built prototype possesses high efficiency, high reliability and meets the requirements of dramatic decreasing external characteristics.更多还原