EVs’ in-wheel motors: A fast-paced evolution

August 14, 2019 //By Julien Happich
in-wheel motors
Electric motor drive is key to all electric vehicles (EV) and it is taking new forms, observes IDTechEx in its report "Electric Motors for Electric Vehicles: Land, Water, Air 2019-2029".

In-wheel motors are successful in two-wheel EVs but they have rarely been seen in larger vehicles due to safety and cost concerns and a fear that unsprung weight gives a rougher ride. Near-wheel motors are a compromise, note the market research firm. However, eliminating transmission and freeing up space is attractive and, to good effect, BYD electric buses have two front motors in hubs with wheels fitted on top. Developed in-house, they are used in volume.

There is now a continuum of design options with in-wheel motor design leading to extra benefits as one progresses to self-sufficient wheels. These may incorporate their own motors, controllers, clutches and back-up brakes. In effect, the motor may act as several for redundancy with no single point of failure. Promised benefits include vectored steering and scalability, there being six in-wheel motors on the planned Nikola fuel cell truck and four on the Lightyear solar family car both with deliveries in 2020.

Protean’s latest module combines powertrain, 360 degree steering and suspension technologies in a single component. Called Protean360+, it is the first of its kind for use in commercial vehicles, giving them unrestricted steering capability because each wheel can be steered 360 degrees around its own axis like castors on a trolley. A rotating interface is located above the main arm of the module.

This manoeuvrability is combined with innovative suspension and pneumatic height adjustment of the vehicle. The EV can be positioned sideways, frontally or with the rear directly on the kerb: Passengers can step to the sidewalk without gaps. Any EV can park in very confined spaces benefitting cities.

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