Rotating electrical machine

A rotating electrical machine comprising:

• a magnetic field-producing unit including a magnet unit which is equipped with a plurality of magnetic poles whose polarities alternate in a circumferential direction of the magnet unit;
• an armature which is arranged to face the magnet unit and equipped with a multi-phase armature winding;
• and
• a rotor which is implemented by one of the magnetic field-producing unit and the armature, wherein
• the magnet unit includes a plurality of magnets and magnet covers, the magnets being arranged adjacent each other in the circumferential direction of the magnet unit, the magnet covers being made from magnetic material and arranged to cover armature-facing peripheral surfaces of the magnets, respectively,
• the armature-facing peripheral surface of each of the magnets has formed therein magnet recesses located to face a q-axis defined on a boundary between the magnetic poles, the magnet recesses being concaved in a radial direction of the magnet unit,
• the magnet covers being recessed in the radial direction in accordance with a shape of the magnet recesses, and
• if the armature-facing peripheral surface of each of the magnets between a circumferentially adjacent two of the magnet recesses is defined as a main magnetic pole surface, and an angle representing a circumferential range occupied by the main magnetic pole surface is defined as a main magnetic pole angle θa, the main magnetic pole angle θa is selected to meet a relation of 2π/5<θa<2π/3.