With major OEMs committing to increasing numbers of EVs and greater electrification, the total electric car stock could reach between 9 million and 20 million by 2020. To make this possible, the UK’s Advanced Propulsion Centre (APC) have outlined target costs, power densities and efficiencies for passenger vehicle traction e-machines.
They also note that one key technological enabler is the closer integration of e-machines into transmissions and internal combustion engines (ICEs), and eventually fully integrated powertrains. This means that there will be a shared cooling and lubrication strategy within the transmission and e-machine, tending towards oil cooled e-machines.
A passive (splash) lubrication regime is likely to maximise the efficiency of the integrated powertrain whilst minimising cost and weight but may not deliver sufficient cooling for high power density e-machines. Down-sized, low power electric pumps will be required to balance efficiency, mass and cooling.