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

本项目的目的是调查在何种程度上的开关损耗在功率转换器的电机驱动器，通过使用快速开关碳化硅双极结型晶体管，而不损坏逆变器或连接的电机。首先，需要找到一种尽可能降低变换器损耗的驱动器配置，除了传统的基于电压源的驱动器之外，还应该使用一种新的电流源。在任何情况下，都必须通过适当的驱动器和换向电路设计来防止可能导致转换器损坏的被动开关动作。其次，要找到晶体管两端的最大容许电压升高，以便通过电机电缆将电机直接连接到逆变器，而不会危及绕组绝缘。该项目的一个主要重点是在降压转换器设置中通过双脉冲测试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热量计测量整体转换器损耗。为了确定逆变器和总的转换器损耗，连接到逆变器的感应电动机由另一个转矩控制的机器加载。此外，还应该测量通态损耗。特别是需要确定每种测量技术的测量不确定度，以评估测量结果。根据这些调查，选择具有最精确测量结果的测量设置。因此，可以确定带和不带输出滤波器的最低转换器损耗。如果应用正弦波滤波器，则需要探索脉冲频率和滤波器空间之间的相关性。如果没有任何输出滤波器，则应检查50 ns以下的电压上升时间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转换器的测量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.