Low-speed large-torque permanent magnet synchronous motor for plunger pump

The invention discloses a low-speed large-torque permanent magnet synchronous motor for a plunger pump. The low-speed large-torque permanent magnet synchronous motor comprises a shell assembly composed of an annular shell, a front flange and a rear flange, a stator assembly, a rotor assembly and a chain coupling. Bottom feet connected with the installation base are arranged at the bottom of the front flange in an extending mode. The chain coupling comprises a first sleeve arranged on the inner side of the motor shaft through key connection; the first sleeve extends to the outer side of the front flange and is provided with a first outer flange, a second sleeve used for being connected with a plunger pump shaft in a sleeved mode is embedded in the first sleeve, the second sleeve is providedwith a second outer flange opposite to the first outer flange, and the first outer flange and the second outer flange are fixed through a chain and used for transmitting torque. The low-speed large-torque permanent magnet sy