Advantages of a variable DC-link voltage by using a DC-DC converter in hybrid-electric vehicles

In electric and hybrid-electric vehicle applications, power electronic converters are used to couple the traction machine with the battery stack. The simplest topology consists of an inverter between the battery stack and the machine. In an often discussed alternative, a DC-DC converter is used to feed the traction machine with a higher and stable voltage level. This paper deals with the differences which arise in terms of the applied control strategy and identifies operating regions of improved efficiency.