Power losses evaluation of power semiconductors via transient calorimetric method

The demand for highly efficient power electronics has led to the development of wide-bandgap (WBG) power semiconductors such as gallium nitride (GaN) and silicon carbide (SiC). These WBG devices offer superior switching characteristics compared to traditional silicon-based semiconductors, resulting in higher efficiency, higher power density, and reduced size of power electronic systems. However, the fast switching of WBG devices presents significant challenges in accurately measuring power losses during a switching transition. The widely accepted double-pulse-test (DPT) has limitations due to electrical measurement difficulties, and thus, new experimental methods are required for determining power losses in modern power semiconductors. The approach employed in this thesis to measure power losses in power semiconductors is the transient calorimetric method. This method measures the temperature rise of an aluminum heat sink attached to a power transistor during continuous operation. Unlike traditional calorimetric methods, the transient calorimetric method requires only a single measurement and can be performed in minutes, making it a convenient and time-efficient tool for measuring power losses. Furthermore, the proposed method allows for a quick and accurate evaluation of power losses in power transistors. The method measures the total power losses of the metal-oxide-semiconductor field-effect transistor (MOSFET), including both conduction and switching losses. The experimental results show that the selected power transistors exhibit power dissipation in the 6 W to 30 W range at 300 V DC-link voltage and switched currents in the range of 10 A to 25 A. The proposed method has a calibration-based uncertainty of less than 10%, making it a reliable tool for evaluating power semiconductor performance. The results obtained have been used to build a 3D look-up table (LUT) representing power losses with respect to several operating points defined by different voltage and current levels. The LUT can be used to design power electronic systems with improved efficiency and reduced power losses. In conclusion, the transient calorimetric method is a promising approach for measuring power losses in modern power semiconductors, especially WBG devices. The method offers the advantages of simplicity, speed, accuracy, and reliability, making it a helpful tool for power semiconductor design, optimization, and evaluation. The results presented in this thesis demonstrate the feasibility and effectiveness of the method and suggest that it has great potential in power applications.