Comparison of multiphase versus multilevel DC/DC-converters for automotive power

Further automotive efficiency improvements require higher voltage levels than 14 V for electric energy generation and distribution. As long as not all electric consumers can be adapted to the higher voltage level, DC/DC-converters link automotive power nets with different voltages. For low voltage converters without galvanic isolation mostly multiphase DC/DC-converters with coupled or uncoupled inductors are proposed due to their high power density. Multilevel architectures like the Flying Capacitor Multilevel DC/DC-Converter offer similar benefits and it will be shown that they need a smaller inductor size and provide better fault behaviour for short-on-failure switches. Efficiency is similar despite serial connected switches. This paper compares the two architectures regarding component count, control, size, fault tolerance and efficiency.