A new steering wheel electric motor designed to make it easier and faster for manufacturers to develop EVs is due to the production later this year.
The weight-saving technology, called Protean Drive, has been under development by Farnham-based Protean Electric for the past eight years.
“There are a number of different applications for it,” explained Protean Gabriel Donaldson. “It can be used for two-wheel EVs, to hybridise an existing vehicle or to convert a two-wheel-drive vehicle to four-wheel drive.”
The Protean Drive is completely self-contained actuator intelligent ” which includes a permanent magnet and synchronous electric motor, as well as the necessary electronics to make it work. Each engine produces 81kW (109bhp) and 922lb ft, so a two-wheel-drive electric vehicle that could produce the maximum power and torque of 160kW (214bhp) and 1844lb ft.
Independent use of wheel motors, such as Protean Drive to eliminate the transmissions and transmission shafts and free up space in the center of the car, between the drive wheels. The wiring is reduced to a minimum – two cables from the power supply and another smaller than the one used by the main vehicle computer to control the engine.
Donaldson, who, at 72 kg; a pair of engines weighs 30 kg less than the power electronics of the BMW i3 (102kg). However, the wheel motors still weigh more than a conventional wheel.
With this in mind, the Protean Drives were fitted to a Volkswagen Golf, the suspension of which has been granted by an agency independent of the vehicle dynamics expert. According to Donaldson, the extra unsprung weight has been managed successfully and the test of the car was made to handle as well as a standard VW Golf GTE.
The elimination of the transmission reduces the load losses of 6% to 8% compared to a conventional two-wheel electric drive system. The most effective is an asset to both acceleration and deceleration, thus the higher the energy recovered during regenerative braking.
The Protean Drive can be produced to fit wheel sizes from 14in to over 20in. He is currently in pre-production and will be built in China, first at the rate of five to ten units per week.
Although there are significant packaging and efficiency benefits, the technology is more expensive than the conventional electric powertrain and the work continues to make it more price-competitive. “Although there are business benefits to using it,” said Donaldson, “nobody is going to pay for it.” A Chinese automaker will be the first to adopt the technology this year.
What is a motor in the wheel and how it works?
Like a lot of the EV motor, the Protean Drive is a permanent magnet-synchronous unit is running on alternating current (AC), such as a household appliance.
Sitting between an ac motor and the direct current (DC) of the battery is an inverter which converts the direct current to alternating current to power the motor. During regenerative braking, the converter converts the AC generated by the motor to recharge the battery.
The engines are usually separated and the vehicle manufacturer has to source an inverter adapted. The Protean Drive incorporates an inverter can therefore be used by an EV manufacturer on a “plug – and-play”.
Protean Electric describes the new wheel design as a “inside” of the engine.
Traditionally, permanent magnets are mounted in rotation on a central axis called rotor. It is surrounded by a stationary electric coils, called the stator.
In the Protean Drive, the rotor is outside and the stator inside. The engine of the wheel directly and does not require major modifications to the vehicle. Protean, which he describes as the “closest to the automotive industry could ever get to a bolt on the electric drive system”.
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