Abstract：Thermal design of the converter can be optimized if the power losses are precisely known. The device’s conduction and switching characteristics are very sensitive to the temperatures, so the influence of junction temperatures must be taken into consideration when calculating the power losses. In this paper, a practical loss calculation method is derived based on the analysis of the conduction and switching principles of the neutral point clamping three-level converters. Using thermal resistance equivalent circuit, the devices junction temperatures are acquired. An 1MVA NPC converter is tested in inverter and rectifier operating modes, and the infrared thermal imager is used to measure the devices temperatures. The error rates between measured and calculated temperatures are within 5% range and thus the validity of the loss calculation method is verified.
[1] 何湘宁, 陈阿莲. 多电平变换器的理论和应用技 术[M]. 北京: 机械工业出版社, 2006. [2] Rajapakse A D, Gole A M, Wilson P L. Electro- magnetic transients simulation models for accurate representation of switching losses and thermal performance in power electronic systems[J]. IEEE Transactions on Power Delivery, 2005, 20(1): 319- 327. [3] 毛鹏, 谢少军, 许泽刚. IGBT模块的开关暂态模型及损耗分析[J]. 中国电机工程学报, 2010, 30(15): 40-47. [4] Bierhoff M H, Fuchs F W. Semiconductor losses in voltage source and current source IGBT converters based on analytical derivation[C]. IEEE 35th Annual Power Electronics Specialists Conference, Aachen, Germany, 2004, 4: 2836-2842. [5] 胡建辉, 李锦庚, 邹继斌, 等. 变频器中IGBT模块损耗计算及散热系统设计[J]. 电工技术学报, 2009, 24(3): 159-163. [6] Kim T J, Kang D W, Lee Y H, et al. The analysis of conduction and switching losses in multi-level inverter system[C]. IEEE 32nd Annual Power Electronics Specialists Conference, 2001, 3: 1363- 1368. [7] Dieckerhoff S, Bernet S, Krug D. Power loss-oriented evaluation of high voltage IGBTs and multilevel converters in transformerless traction applications[J]. IEEE Transactions on Power Electronics, 2005, 20(6): 1328-1336. [8] 王群京, 陈权, 姜卫东, 等. 中点钳位型三电平逆变器通态损耗分析[J]. 电工技术学报, 2007, 22(3): 66-71. [9] 陈权, 王群京, 姜卫东, 等. 二极管钳位型三电平变换器开关损耗分析[J]. 电工技术学报, 2008, 23(2): 68-75. [10] 吴洪洋, 何湘宁. 多电平载波PWM法与SVPWM法之间的本质联系及其应用[J]. 中国电机工程学报, 2002, 22(5): 10-15. [11] 周卫平, 吴正国, 唐劲松, 等. SVPWM的等效算法及SVPWM与SPWM的本质联系[J]. 中国电机工程学报, 2006, 26(2): 133-137. [12] 朱英文, 陆晓东. 大功率半导体器件用散热器风冷热阻计算[J]. 电力电子, 2009(6): 47-51.
2011, Vol. 26 
