Comparison of converter topologies for battery-powered high-speed drives considering different cooling conditions and semiconductor materials for ultra light-weight hybrid systems

This paper presents a comparison of two-level and three-level converters for high frequency drives. The maximum output power per chip area is calculated and compared by the Total Harmonic Distortion (THD). A variable DC-link voltage is assumed and it is derived, that the three-level topologies suffer more from an increasing DC-link voltage than the two-level inverter. The influence of the cooling system on the choice of topology is discussed. It is shown that three-level converters do not profit as much as two-level inverter of the benefit from liquid cooling system in comparison to forced-air cooling. Regarding fast switching silicon carbide devices, a calculation shows, that the converter weight can be reduced significantly.