embodiments describe a motor . the motor includes a stator , and a rotor , which is arranged within the stator . an end part of at least one air - gap slot of the rotor has an offset with a predetermined distance and / or a predetermined angle relative to a main body part adjacent immediately to the end part . with the offset of a predetermined distance and / or a predetermined angle configured at the end part of at least one air - gap slot of the rotor , ripple torque of the motor is effectively lower down while complexity of the motor , stator or rotor will not be increased .