Motor drive device for electric bicycle

The utility model discloses a motor drive device for an electric bicycle. The motor drive device comprises a machine shell (3), motor stator assemblies (7), motor rotor assemblies (11), a central spindle (9), a clutch device and a flange plate (20); the motor stator assemblies are fixed in the machine shell (3); the motor rotor assemblies (11) are rotatably fixed on the central spindle (9) through rotor supports (6) and bearings; a front end cover (1) and a rear end cover (8) are connected with the machine shell (3); the motor drive device is characterized by also comprising a primary planetary gear train and a secondary planetary gear train; the primary planetary gear train comprises a primary central external gear (10), a primary planet gear (12) and a primary internal gear (4); and the secondary planetary gear train comprises a secondary central external gear (13), a secondary planet gear (15) and a secondary internal gear (2). The electric bicycle and two-stage planetary gear train transmission are adopte