Rotor of a rotary electrical machine, and rotary electrical machine comprising a rotor of this type

Rotor (1) of a rotary electrical machine comprising a plurality of alternating north (N) poles and south poles (S) formed from a plurality of permanent magnets (3) arranged in first recesses (4) which extend axially, and are distributed regularly between a circumferential part (5) and a central part (6) of the magnetic mass (2) of said rotor (1), such as to define a plurality of circumferential polar sections (11), said permanent magnets (3) each comprising a first part close (7) to said circumferential part (5) adjacent to a second part (8) close to said central part (6), said first part (7) having a first rectangular radial section with a first predetermined width (L1) in a circumferential direction, and said second part (8) having a second rectangular radial section with a second predetermined width (L2) in a circumferential direction, said second width (L2) being smaller than said first width (L1), wherein it additionally comprises a plurality of second recesses (9) which extend axially, and are each arranged between two consecutive examples of said magnets (3) at said second part (8).