Electric vehicle makers and legacy automakers have launched in earnest the race to make such EVs so as to win over the public with increased range and powerful batteries.
In all EVs, an electric motor uses power from batteries to drive either two or all four wheels. Now auto equipment manufacturers have started to develop and test in-wheel electric motors—a technology that puts the motor in the hub of the wheel and drives it directly. Some of those in-wheel technology developers claim that they have overcome or are close to overcoming the challenges of using in-wheel motors—costs, additional mass, and road shocks.
The idea of direct in-wheel drive in cars is more than a hundred years old, but at the turn of the 20th century, it lost the race to its rival—the internal combustion engine mounted under the hood of the gasoline and diesel-powered cars.
Ferdinand Porsche (yes, that Porsche) is credited with inventing the electric wheel-hub motor, as in-wheel motors are also known. The Lohner-Porsche car with the electric hub wheel drive was one of the sensations at the Paris World’s Fair in 1900. Ferdinand Porsche also built the world’s first hybrid car—powered by gasoline and electricity.
Yet, for more than one hundred years the internal combustion engine (ICE) has been dominating car designs and manufacturing.
Now with the EV craze and the race to challenge and beat Tesla, car makers and propulsion makers are testing again the in-wheel technology, helped by the technological advances of the 21st century.
In-wheel motors have a few challenges to overcome. One is that they add more weight to the unsprung mass of the vehicle. Unsprung weight is the wheels, tires, brakes, and anything directly connected to the wheels. The sprung weight includes the chassis, motor, transmission, body, and interior, as well as the passengers and cargo. Another challenge is the higher exposure to road shocks and heat from braking due to the proximity of the in-wheel motor to the wheels.
But companies are trying. Protean Electric, for example, says that it has been testing how in-wheel motors affect unsprung mass and that with its technology, “unsprung mass really isn’t a showstopper after all.”
Protean is building manufacturing facilities in China, and its first factory—in Tianjin—already makes in-wheel motors in low volumes. The company is working with Chinese carmakers to incorporate its in-wheel technology into their electric and plug-in hybrid vehicles.
In April, Protean and U.S. open-source vehicle designers LM Industries partnered to provide the in-wheel technology for Olli—the world’s first co-created, self-driving, electric and cognitive shuttle.
Slovenian company Elaphe is also making in-wheel technology for application in electric vehicles. Elaphe has tested its fully electric in-wheel drive on a frozen river in China at temperatures of below -30 Celsius (-22 F) to prove that traction control on ice is better than in ICE cars.
The Fisker Orbit autonomous electric shuttle will be using in-wheel motor technology for improved interior space, and it will be the first vehicle to test Fisker solid state batteries, company founder Henrik Fisker said earlier this month. The in-wheel technology is that of Protean Electric.
German company Ziehl-Abegg has developed a motor for in-wheel hub drive that could be used in serial hybrid, battery, and fuel cell commercial vehicles.
Of the big carmakers, Nissan, has developed in-wheel motors for the Nissan BladeGlider—a working prototype of its futuristic concept car.
More than 100 years after the world’s first in-wheel motor prototype, manufacturers are testing again the idea of powering a car’s wheels directly, hoping to make breakthroughs in EV technology, design, performance, and driving power. Time will tell if this time around, in-wheel motors can challenge a centrally mounted engine.