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Evans Electric Unveils A Direct-Drive Car (July 2013)

Evans Electric, based in Australia, unveiled an electric vehicle which has a pancake-shaped electric motor embedded in, not at each of the wheels of the vehicle.

Evans Electric In-WHeel Motor. Image obtained with thanks from: Evans Electric.
Evans Electric In-Wheel Motor.
Image obtained with thanks from: Evans Electric.

This design provides the benefit of mechanical efficiency (less friction due to a lack of gears) and simplicity, due to a lack of a transmission. Direct drive means that the motor directly turns the wheel. This enables it to recover up to 85% of its kinetic energy via regenerative braking, if the press release is correct.

Any direct drive device is turned directly by a motor’s own shaft without being coupled to any gears or belts.

Each of the motors produces 75 kW (100 HP), and 625 Newton-metres (460 foot-pounds) of torque. The peak power output is 600 kW (800 HP). This vehicle also uses its motors to brake using electromagnetism instead of friction brakes, which are inherently inefficient.

*While the torque figure could at first glance appear fantastic, standard automotive industry practice only quotes torque at the flywheel not at the wheels. As an example the Tesla Model S Performance has a quoted peak motor torque of 600 Nm. With a single speed reduction gear ratio of 9.73:1 that equates to a total of 5,838 Nm (minus gearing losses) at the wheels. The Evans Electric motors are direct drive, so the rotor turns at the same speed as the wheel. Instead of mechanical reduction gearing, they are electrically geared using an 8 pole stator winding configuration.

Source: Autoblog Green (Click “Show Press Release” at the bottom)

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