The Trend in Power Electronics
Power electronics enables applications such as electromobility or renewable energy conversion. In particular, high electrical efficiency (low losses) in combination with high power density (compact size) and low cost are crucial. A further requirement for power electronic systems is a high degree of robustness with respect to EMC and reliability. For these reasons, the trend is towards higher switching frequencies, more compact systems and efficiency optimization. This is made possible by the use of novel semiconductor materials having a large band gap, for example silicon carbide (SiC) and gallium nitride (GaN). In order to promote this trend, the research at the ILH focuses on areas as outlined in the following.
Characterization and Modeling
Characterization is the first step to properly design power electronic circuits. A good knowledge of the semiconductor devices enables the optimal utilization of the devices capabilities in the application. The work at ILH in the field of characterization is focused on semiconductor devices based on novel wide-bandgap materials such as GaN and SiC.
Modeling is an important aspect to predict the behavior of electronic systems in simulations. This enables the optimization of the circuit during its design phase prior to the first prototype building.
An accurate simulation requires a detailed model which describes the transistor behavior in all operation regions. Moreover, transistor models must also ease the circuit simulators' convergence and be computational efficient. The ILH concentrates research on development of equivalent circuit based transistor models for SiC and GaN power devices.
Integration, Packaging and Assembly Technology
High power density and high switching frequencies impose stringent requirements on packaging technologies. By appropriate approaches such as 3D packaging, parasitic effects that are caused by packages, substrates and layouts, can be systematically influenced and reduced. Due to compact hot spots, heat spreading and heat dissipation are more important than ever.
Efficiency, Power Density and Robustness
Increasing the electrical efficiency of power electronic systems enables e.g. increased ranges in electromobility or higher profits in renewable energy conversion. One approach to reduce losses is the usage of novel semiconductor materials (e.g. GaN, SiC). These materials have superior physical properties compared to silicon-based power semiconductors. Another approach is to increase the slew-rates in power converters to reduce switching losses.
Increasing the power density results in smaller passive components, smaller system components and thereby in potential weight, size and cost advantages. Approaches to increase the power density are the hybrid and monolithic integration of gate-driver and power converter circuits, as well as active and passive components.
To ensure robustness of the systems, the thermal behavior and EMC of power modules is studied and optimized.