Tandem coaxial diesel-electric combined propulsion system

The invention discloses a tandem coaxial diesel-electric combined propulsion system. Each mechanical propulsion part comprises a main diesel engine, a propulsion clutch, a tandem coaxial permanent magnet motor and a fixed-pitch propeller, wherein a shaft system of the fixed-pitch propeller directly penetrates through a winding of the tandem coaxial permanent magnet motor and is connected with a propulsion shaft of the main diesel engine. An electric propulsion part comprises an auxiliary diesel generating set, the tandem coaxial permanent magnet motors, grid-connected inverters and a ship power station. The ship power station comprises an alternating-current busbar, a direct-current busbar, a storage battery set, a grid-side converter and a DC/DC rectifier. The auxiliary diesel generating set is connected with the alternating-current busbar. The storage battery set is connected with the direct-current busbar through the DC/DC rectifier. The grid-side converter is connected between the alternating-current busbar and the direct-current busbar. The tandem coaxial permanent magnet motors are connected with the direct-current busbar through the grid-connected inverter. According to the tandem coaxial diesel-electric combined propulsion system, a pure-diesel propulsion mode, a pure-electric propulsion mode and a diesel-electric combined propulsion mode are flexibly configured according to different working conditions, and high operation efficiency of a ship is guaranteed under all the working conditions.