A variable-speed direct current motor comprising a stator (22), a rotor (23) arranged within the stator, and a motor drive device (40) arranged partly at the stator and partly at the rotor, wherein the stator comprises a yoke (25) defining a cylindrical cavity (31), and a plurality of permanent magnets (24) arranged at the yoke, wherein the rotor comprises a cylindrical core (26) and a conductor structure (47) arranged at the core, wherein the motor drive device comprises an alternating current transformer (41) having a primary winding (42) arranged at the stator and a secondary winding (43) arranged at the rotor, a rectifier device (44) arranged at the rotor and connected with the secondary winding, a direct current supply device (45) arranged at the rotor (23) and connected with the rectifier device (44), and with the conductor structure (47), and an operation control device (48) comprising a first unit (49) arranged at the rotor (23) and a second unit (50) arranged externally of the rotor and wirelessly communicating with the first unit.

A variable-speed direct current motor comprising a stator (22), a rotor (23) arranged within the stator, and a motor drive device (40) arranged partly at the stator and partly at the rotor, wherein the stator comprises a yoke (25) defining a cylindrical cavity (31), and a plurality of permanent magnets (24) arranged at the yoke, wherein the rotor comprises a cylindrical core (26) and a conductor structure (47) arranged at the core, wherein the motor drive device comprises an alternating current transformer (41) having a primary winding (42) arranged at the stator and a secondary winding (43) arranged at the rotor, a rectifier device (44) arranged at the rotor and connected with the secondary winding, a direct current supply device (45) arranged at the rotor (23) and connected with the rectifier device (44), and with the conductor structure (47), and an operation control device (48) comprising a first unit (49) arranged at the rotor (23) and a second unit (50) arranged externally of the rotor and wirelessly communicating with the first unit.

A variable-speed direct current motor comprising a stator (22), a rotor (23) arranged within the stator, and a motor drive device (40) arranged partly at the stator and partly at the rotor, wherein the stator comprises a yoke (25) defining a cylindrical cavity (31), and a plurality of permanent magnets (24) arranged at the yoke, wherein the rotor comprises a cylindrical core (26) and a conductor structure (47) arranged at the core, wherein the motor drive device comprises an alternating current transformer (41) having a primary winding (42) arranged at the stator and a secondary winding (43) arranged at the rotor, a rectifier device (44) arranged at the rotor and connected with the secondary winding, a direct current supply device (45) arranged at the rotor (23) and connected with the rectifier device (44), and with the conductor structure (47), and an operation control device (48) comprising a first unit (49) arranged at the rotor (23) and a second unit (50) arranged externally of the rotor and wirelessly communicating with the first unit.