A hybrid electric vehicle
(HEV) equipped with an electric drive works with two different drive systems: an electric motor and an internal combustion engine. There are different concepts of how and when which drive system is used or whether both are combined. One concept works in parallel operation. In this case, both drives, the electric motor and the combustion engine, are optimally combined and both motors act directly on the drive axle.
, is referred to as a plug-in hybrid electric vehicle
(PHEV). The electrical system for both concepts is generally a 48 V electrical system.