In 2018, 93% of all passenger BEVs, PHEVs and HEVs sold globally used permanent magnet (PM) traction motors, an increase of 1% over 2017 penetration rates, according to a model-by-model build-up using Adamas Intelligence’s “EV Motor Power and Motor Metals Tracker”.

A PM traction motor has NdFeB permanent magnets mounted on or embedded in its rotor, which cause the rotor to spin when exposed to a rotating magnetic field produced by windings in the stator.

Permanent magnets traction motors are up to 15% more efficient than induction motors and are the most power-dense type of traction motor available (in terms of kW/kg and kW/cm³).

Despite generally having a higher bill-of-materials than incumbent traction motor types, such as induction, use of a PM traction motor is substantially more economically attractive from an automaker’s perspective because its high efficiency enables thrifting of costly battery capacity without compromising vehicle range (distance driven per charge), Adamas observes.

For example, the cost of increasing the capacity of a 60-kWh battery pack by just 5% to compensate for use of an induction traction motor can increase powertrain costs by upwards of $300 (optimistically assuming an added cost of just $100 per kWh).