Permanent-magnet rotating machine

A permanent-magnet rotating machine comprising:

• a rotor having a rotor core carrying, on a curved outer surface, multiple permanent magnets which are arranged in four rows along an axial direction so that the permanent magnets in one of two upper rows are skewed from the permanent magnets in the other of the two upper rows, in a circumferential direction, by a row-to-row skew angle θe1, expressed in terms of electrical angle, the permanent magnets in one of two lower rows of the permanent magnets are skewed from the permanent magnets in the other of the two lower rows by the row-to-row skew angle θe1, expressed in terms of electrical angle, and the permanent magnets in the lower two rows are skewed from the permanent magnets in the upper two rows, in the circumferential direction, by a row-to-row skew angle θe2, expressed in terms of electrical angle;
• and
• a stator having a tubular stator core in which the rotor is disposed, the stator core including stator coils for producing a rotating magnetic field which causes the rotor to rotate, wherein the ratio of number of rotor poles to number of stator poles is 2:3, a lower limit of the row-to-row skew angle θe1 is larger than a theoretical angle θs of 30 degrees, and an upper limit of the row-to-row skew angle θe1 is approximately 52 degrees.

A permanent-magnet rotating machine comprising:

• a rotor having a rotor core carrying, on a curved outer surface, multiple permanent magnets which are arranged in four rows along an axial direction so that the permanent magnets in one of two upper rows are skewed from the permanent magnets in the other of the two upper rows, in a circumferential direction, by a row-to-row skew angle θe2, expressed in terms of electrical angle, the permanent magnets in one of two lower rows are skewed from the permanent magnets in the other of the two lower rows by the row-to-row skew angle θe2, expressed in terms of electrical angle, and the permanent magnets in the lower two rows are skewed from the permanent magnets in the upper two rows, in the circumferential direction, by a row-to-row skew angle θe1, expressed in terms of electrical angle;
• and
• a stator having a tubular stator core in which the rotor is disposed, the stator core including stator coils for producing a rotating magnetic field which causes the rotor to rotate, wherein the ratio of number of rotor poles to number of stator poles is 2:3, a lower limit of the row-to-row skew angle θe1 is larger than a theoretical angle θs of 30 degrees, and an upper limit of the row-to-row skew angle θe1 is approximately 35 degrees.