US Patent 9130424 Rotor of interior permanent magnet motor

A rotor of an interior permanent magnet motor includes a rotor core configured to form a body of the rotor. An upper permanent magnet group is configured to be inserted into the rotor core to form a magnetic pole. A lower permanent magnet group is configured to be inserted into the rotor core below the upper permanent magnet group to form a two-layered structure with the upper permanent magnet group. Each of the upper and lower permanent magnet groups may include two V-shaped permanent magnets. A polar arc angle formed by the two permanent magnets of the upper permanent magnet group may be different from a polar arc angle formed by the permanent magnets of the lower permanent magnet group.