Method of manufacturing rotor core

A method of manufacturing a rotor core comprising:

• acquiring individual weights of first to Lth permanent magnets, wherein L is a natural number equal to or greater than 5;
• preparing a core body configured to rotate around a predetermined rotational axis, the core body comprising first to Lth attaching locations arranged in a circumferential direction of the rotational axis;
• and
• when acquired weights m1, m2, . . . mL−1, mL of the first to Lth permanent magnets satisfy the expression
• m1≥m2≥ . . . mL−1≥mL
• the first to Lth permanent magnets are attached one by one to the first to Lth attaching locations such that a dth permanent magnet of the first to Lth permanent magnets is not adjacent to a (d−1)th permanent magnet of the first to Lth permanent magnets in the circumferential direction of the rotational axis, and the dth permanent magnet is also not adjacent to a (d+1)th permanent magnet of the first to Lth permanent magnets in the circumferential direction of the rotational axis, wherein d is a natural number from 2 to L−1.

A method of manufacturing a rotor core comprising:

• acquiring individual weights of first to Kth permanent magnets, wherein K is an even number equal to or greater than 4;
• preparing a core body configured to rotate around a predetermined rotational axis, the core body comprising first to Kth attaching locations arranged in a circumferential direction of the rotational axis;
• and
• when acquired weights m1, m2, . . . mK−1, mK of the first to Kth permanent magnets satisfy the expression
• m1≥m2≥ . . . mK−1≥mK
• the first to Kth permanent magnets are attached one by one to the first to Kth attaching locations such that an eth) permanent magnet of the first to Kth permanent magnets and a fth permanent magnet of the first to Kth permanent magnets face each other with the rotational axis interposed therebetween, wherein e is an odd number from 1 to K, and wherein f is an even number from 1 to K that satisfies the expression f=e+1.

A method of manufacturing a rotor core comprising:

• acquiring individual weights of first to Jth permanent magnets, wherein J is an even number equal to or greater than 6;
• preparing a core body configured to rotate around a predetermined rotational axis, the core body comprising first to Jth attaching locations arranged in a circumferential direction of the rotational axis;
• and
• attaching the first to Jh permanent magnets to the first to Jth attaching locations when the acquired weights m1, m2, . . . mJ−1, mJ of the first to Jth permanent magnets satisfy the expression
• m1≥m2≥ . . . mJ−1≥mJ,
• wherein attaching the first to Jth permanent magnets to the first to Jth attaching locations includes:
• categorizing permanent magnets as comprising lighter permanent magnets and heavier permanent magnets,
• forming J/2 magnet pairs each by selecting different combinations of two permanent magnets from among the lighter permanent magnets and the heavier permanent magnets, and
• attaching the first to Jth permanent magnets to the first to Jth attaching locations one by one such that the heavier permanent magnets of the magnet pairs are not adjacent to each other in the circumferential direction of the rotational axis, the lighter permanent magnets of the pairs are not adjacent to each other in the circumferential direction of the rotational axis, and the permanent magnets in each magnet pair face each other with the rotational axis interposed therebetween.