Characterization of power semiconductors

Semiconductors are indispensable in power electronic circuits. When designing a circuit, it is essential to know the switching and conducting properties of the power semiconductor used as exactly as possible for the thermal and electrical design.

State of the art

For each specific application, however, the characteristic values such as switching behavior, conduction loss and switching loss of the semiconductor are individual. Here, insufficient or difficult-to-adapt specifications from manufacturers make additional measurements of the semiconductors imperative. Measurements at manual test stations, which vary in design and setting, are usually very time-consuming, especially if a large number of operating points are to be measured.

Technology

At the Institute of Electrical Engineering (ETI), an automated test bench has been developed for the characterization of semiconductor power devices, which evaluates switching on and off processes of the devices fully automatically and analyzes its loss processes. The measuring principle of double pulse test is used to determine the switching behavior and the switching energies. Parameters such as load current, intermediate DC link voltage and junction temperature can be set. This allows the conduction and switching behavior of the power semiconductors to be measured in different voltage, current and temperature combinations. For the operating points, the test bench provides multi-dimensional characteristic diagrams and graphically processed measurement results for complete characterization. The test bench was specially designed for silicon carbide (SiC)- and silicon (Si)-based semiconductor devices with a maximum reverse voltage of 1.7 kV.

Advantages

By means of the test bench presented here, large series of measurements can be recorded and evaluated fully automatically and in a reproducible manner. The data obtained help to analyze the switching behavior and thus to design new power converters and power modules more precisely in terms of thermal and electrical properties. In addition, the overvoltages and overcurrents that occur can be analyzed and the findings can thus contribute to optimizing the design.

Options for companies

The semiconductor test bench at KIT is available for industrial partners for the measurement and qualification of power semiconductors as well as complete power converters. All hardware components required for automated measurement, the software implementation and the design of the electrical components were completely realized at the institute.