【作者】 殷幼军；

【导师】 陆继明； 毛承雄；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2007， 硕士

【摘要】 中高压变频器(VFDs)通过改变大中型异步电动机输出电压的频率,可以实现电机转速的无极调节,并能有效地节约能源,在国内外受到广泛的关注。本论文研究的6kV中性点箝位(NPC)三电平变频器针对我国电压等级而设计制造,目前装置已经研制成功并通过6kV/2500kW的重载试验,即将进入现场运行。本文基于6kV/2500kW的中性点箝位三电平变频器,在分析国内外中高压变频器研究现状的同时,对其主电路结构做了全面分析与介绍,包括24脉波整流器、直流环节、IGCT串联的三电平逆变器及输出LC滤波器,通过仿真和试验证明了这种主电路结构方案的可行性。针对这台变频器装置,对其相关问题进行了具体研究:基于三电平变频器的DC-Link环节,研究了其对变频器安全运行的影响。通过分析三电平变频器的开关暂态过程,建立了变频器暂态开关数学模型,并对该环节的限流电抗器进行了设计。在综合考虑三电平的开关过程、限流电抗器的大小及IGCT的过压能力的基础上,研究了箝位电容对变频器逆变侧持续性直流电压的影响,并进行了箝位电容和限流电阻的设计推导。基于国家自然科学基金(批准号:60274037),将罗式线圈的传感理论应用于变频器中IGCT的电流检测。分析了罗式线圈的传感理论,并制作了用于IGCT电流检测的罗式线圈,仿真和试验结果均表明罗式线圈可以应用于IGCT电流的一般检测,而且有望用于IGCT开通和关断特性的研究。针对主要功率器件IGCT进行了变频器强迫风冷散热系统的分析与设计,包括IGCT的功率损耗计算、散热器的设计与选型、风机的选型与风道的设计,并对于在大功率变频器中散热优势更为明显的水冷散热进行了基本介绍及探讨,为今后应用于6kV三电平变频器做下铺垫。本文研究相关问题的结果均应用于6kV/2500kW实际变频器装置,并通过了6kV重载试验的检验,证明了设计的合理性与有效性。更多还原

【Abstract】 Media and High Voltage Variable Frequency Drives (VFDs) can output a variable AC voltage/frequency to provide continuous over the full speed range and save energy efficiently, which catch the worldwide attention. The 6kV Neutral Point Clamped (NPC) Three-level VFD studied in this paper is aimed at our nation’s voltage level , which has been passed the 6kV/2500kW tests and is about to run on the spot.With the analysis of currently worldwide Media and High VFDs, this paper gives a general introduction and analysis of topology of the lab’s series IGCTs three level VFD, including 24-pulse Rectifier, DC-Link, series IGCTs three-level Inverter and output LC filter, and the feasibility of which is proved by the simulation and experiment. Contrapose the VFD device, the paper makes specific research about several issues. The paper discusses the contribution of the DC-Link to the VFD safe operation. Through the analysis on the turn-on and turn-off transience of NPC three-level VFD, the corresponding mathematical models are developed, based on which the DC-Link choke value is deduced. Synthetically thinking about the switching transient state, the DC-Link chock and the VFD over-voltage capability, the influence of clamped capacitor to inverter’s permanent DC voltage is studied, and the design of DC-Link capacitor and resistance is deduced. Based on the National Nature Science Funds of China (No.60274037), the Rogowski coil sensor theory is applied in IGCT’s current measure and for which the coil is made. Both simulation and experiment results show that the Rogowski coil can be used for generic IGCT’s current measure, and very probably for the research of IGCT’s turn-on and turn-off. For the power IGCTs, the VFD forced air cooling heat-sink system is analyzed and designed, which includes the power losses calculation of IGCTs, design and type-choose of radiator and fan, and the scheme design of air conduit. And due to the much better heat-sink efficiency of the water cooling choice, which a basic introduction and discussion is made for, and is expected to apply in 6kV three-level VFD in future.All above researches are applied for the 6kV/2500kW NPC Three-level VFD device, which has passed the 6kV tests.更多还原