Permanent magnet motor, compressor and refrigeration system

Disclosed are a permanent magnet motor, a compressor and a refrigeration system. In the permanent magnet motor, the diameter D of a contour circle of the smallest inner periphery of a stator, the diameter d of a contour circle of the largest outer periphery of a rotor, the fundamental wave amplitude Bm1 of an air-gap flux density at an average gap between the stator and the rotor, the axial length L of the rotor, the total number of serially connected turns Ns of each phase winding, and a bus DC voltage Udc of a frequency converter supplying power to the permanent magnet motor before inversion are set as: 0.003 Udc≤(D+d)×L×Bm1×Ns≤0.008 Udc.