Electric motor

An electric motor, comprising:

• a rotor comprising a rotor core;
• a stator comprising a stator core, the stator core comprising a core ring and a plurality of stator teeth extending radially toward an inner side of the core ring;
• and
• a coil winding configured to be wound around the plurality of stator teeth;
• wherein a continuous wall surface exists on an inner side wall of the stator core, and a natural frequency of the stator core on the inner side wall on which the continuous wall surface exists increases by at least 10% compared with a natural frequency of the stator core on the inner side wall on which no continuous wall surface exists.

An electric motor, comprising:

• a rotor comprising a rotor core;
• a stator comprising a stator core, the stator core comprising a core ring and a plurality of stator teeth extending radially toward an inner side of the core ring;
• a coil winding configured to be wound around the plurality of stator teeth;
• a first insulating end cover disposed on a first end of the stator core;
• a second insulating end cover disposed on a second end of the stator core;
• and
• a plurality of fillers, each of which is disposed at least between adjacent ones of the plurality of stator teeth;
• wherein a material of the plurality of fillers is different from a material of the first and second insulating end covers.