According to Franco Gonzalez, Technology Analyst, IDTechEx, there are about 200 companies making traction motors for electric vehicles, just as there are about 200 making the lithium-ion batteries that increasingly power them.
However, whereas three types of lithium-ion battery chemistry and construction are taking almost all of the business, with traction motors the situation is much more complex because the diversity of needs calls for many very different types of motor from brushless outrunner motors for quadcopters to claw pole torque assist reversing alternators (TARA) for the new 48V mild hybrids that will be in volume production from 2017. Those mild hybrids will now qualify as electric vehicles because they will have pure electric silent take-off like regular "strong" hybrids.
While it is true that an increasing number of traction motors for regular electric vehicles also work in reverse to generate electricity from braking and even when coasting, they are very different from TARAs which typically appear as belt-drive starter generators (BSG) and integrated starter generators (ISG) in 48V mild hybrids appearing in volume from 2017.
Mainstream electric vehicle reversing traction motors generate very infrequently whereas the opposite is true for a TARA. Regular hybrids and pure electric vehicles used hundreds of volts in most cases though there are a few that work at 48V including industrial and leisure runabouts and one supercar announced in 2016. The new IDTechEx Research report, Mild Hybrid 48V Vehicles 2016-2031, looks at the synergies, opportunities and market potential in 48V systems for mild hybrids and, much less important, pure electric vehicles.