Gearbox increases output torque or changes motor speed. Engine operates over limited speed range producing low torque. Gearbox maintains engine speed while sacrificing road speed
Gearbox transfers power from engine to wheels through gear shifting. Manual transmissions use clutch and lever, automatic use hydraulic or electronic control. Transmission provides high torque for starting, hill climbing, and acceleration
PMSM is a brushless motor using permanent magnet for excitation. Provides sine-shaped flux distribution in air gap between stator and rotor. Requires only one AC supply instead of two DC and AC. Lacks slip rings and field windings unlike conventional synchronous motors