Abstract: Provided are a magnetism modulating ring structure, a magnetic gear assembly, and a compound motor. The magnetism modulating ring structure includes a plurality of modulating units and a plurality of connection parts. Each two adjacent modulating units are connected by one of the plurality of connection parts to form the magnetism modulating ring structure, and the magnetism modulating ring structure is arranged within an annular gap enclosed by a first rotor structure and a second rotor structure. A groove structure is formed on one side of the modulating unit facing the first rotor structure, and two sides of the groove structure respectively form a curved boot-like part, and an edge of the curved boot-like part facing the second rotor structure has a curved contour line parallel to flux lines passing through an inside of the curved boot-like part.

Abstract: A single-phase permanent magnet synchronous motor and dust collector. The single-phase permanent magnet synchronous motor includes a plurality of stator teeth, the plurality of stator teeth include at least: a first-type and second-type stator tooth; the first-type and second-type stator teeth enclose an annular working cavity for accommodating a rotor part, where the size of a central angle corresponding to a first contour line of an end face of the first-type stator tooth facing the rotor part is different from the size of a central angle corresponding to a second contour line of an end face of the second-type stator tooth facing the rotor part The motor has a significantly reduced cogging torque, a greatly reduced torque ripple, and an obviously increased motor output torque. The single-phase permanent magnet synchronous motor is small in size, light in weight, simple in structure, convenient for large-scale manufacture and low in manufacturing cost.