Potentials and Limits of Reducing Switching Losses in Motor Drive Power Converters by using fast switching SiC Bipolar Junction Transistors

本项目的目的是研究在不损坏逆变器或所连接的电机的情况下，采用快速开关碳化硅双极型晶体管的电机驱动功率变流器的开关损耗。首先，需要找到尽可能低的转换器损耗的驱动器配置。除了传统的基于电压源的驱动器外，还应该使用新的电流源。在任何情况下，都必须通过适当的驱动器和整流电路设计来防止可能导致转换器损坏的无源开关动作。其次，为了在不危及绕组绝缘的情况下通过电机电缆将电机直接连接到逆变器，需要找到晶体管上可容忍的最大电压上升。本项目的重点是在降压转换器设置中通过双脉冲测试来精确测量快速开关半导体器件的开关损耗，以及使用功率分析仪和量热仪来测量转换器的整体损耗。为了确定逆变器和变流器的整体损耗，连接到逆变器的感应电机由另一台扭矩控制的机器加载。此外，开启状态的损耗也应该被测量。尤其是每种测量技术的测量不确定度都需要确定，以便对测量结果进行评定。在这些调查的基础上，选择具有最精确测量结果的测量装置。因此，可以确定在有和没有输出滤波器的情况下最低的转换器损耗。如果采用正弦波滤波，则需要研究脉冲频率和滤波间隔之间的相关性。在没有任何输出滤波器的情况下，应检查电压上升时间低于50 ns对临界电缆长度的影响。此外，基于双脉冲测量计算的开关损耗应该与所测量的转换器的开关损耗相关地设置。

The purpose of this project is to investigate what extent the switching losses in a power converter for motor drive by using fast switching silicon carbide bipolar junction transistors without damaging the inverter or the connected electrical machine. At first a driver configuration for the lowest possible converter losses needs to be found. Besides the conventional voltage source based driver a new current source is supposed to be used. In any case, passive switching actions that could lead to converter destruction have to be prevented by appropriate driver and commutation circuit design. Secondly, the sharpest tolerable voltage rise across the transistors is to be found, in order to connect an electrical motor via motor cable directly to the inverter without endangering the winding insulation. A major focus of this project is the precise measurement of switching losses of fast switching semiconductor devices by double pulse test in buck converter setting as well as the measurement of the overall converter losses by using power analyzer and calorimeter. For the determination of the inverter and overall converter losses the induction motor connected to the inverter is loaded by another machine that is torque controlled. Additionally the on-state losses are supposed to be measured, too. Especially the uncertainty of measurement of each measuring technique needs to be determined to evaluate the measuring results. Based on these investigations the measuring set-ups with the most precise measurement results are to be selected. Thus, the lowest converter losses with and without an output filter can be determined. If a sine-wave filter is applied, the correlation between pulse frequency and filter-space needs to be explored. In case there is not any output filter, the effect of voltage rise times under 50 ns on critical cable length should be examined. Furthermore switching losses, that have been calculated based on double pulse measurements are supposed to be set in correlation with measured switching losses of the converter.