Powertrain modularity

This paper outlines the main innovations of the EM-TECH and HighScape projects, targeting a wide range of vehicle applications, including passenger cars and commercial vehicles. Specifically, EM-TECH deals with: i) modular designs of on-board axial flux machines (AFMs) for reducing the implementation costs of scalable centralised powertrains for electric axle (e-Axle) solutions; ii) in-wheel motors (IWMs) integrated with electric gearing, for expanding the high efficiency region of electric corner (e-Corner) powertrains; and iii) the use of permanent magnets deriving from recycling processes to improve sustainability. In parallel, HighScape targets the physical and functional integration of the PE of WBG based traction inverters, onboard chargers, DC/DC converters, and electric drives for auxiliaries and actuators.

Permanent magnet synchronous machines (PMSMs) are still the first choice for use in electric vehicles, due to their unparalleledefficiency and power density. However, they suffer from an inherently limited speed range. As field weakening or the addition of amechanical gearbox deteriorates the efficiency of the drive, it is suggested in this paper to equip the drive with reconfigurationswitches, giving rise to a so-called e-gear. The switches—which are implemented by means of mechanical relays—allow to change the winding connection of the electric machine from a series to a parallel connection and hence to double its efficient speed range.Simulations and experimental results on a 4-kW axial-flux PMSM confirm the feasibility of the concept and prove that the reconfiguration can be conducted in less than 35 ms.