Increasing the Power Density of In-Wheel Motor Using Direct-Drive Technology

This paper proposes a direct-drive in-wheel motor. The proposed technology enables the installation of a high-power motor into the wheel and more expansive interior and battery installation spaces, thus moving the world one step closer to a zero-emissions society. The new in-wheel motor transmits the high drive force directly to the wheels by using a Halbach magnet array. Moreover, the direct-drive system rotates at a much lower speed than the gear drive, which allows for heating parts to be immersed cooling oil within the motor without a significant increase in fluid friction loss. A prototype demonstrated a maximum output torque of 960 Nm at 600 min<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>.