| 摘要 |
<p>An electric machine (10; 100) comprises a rotor (14) having permanent magnets (24) and a stator (12) having coils (22) wound on stator bars (16) for interaction with the magnets across an air gap (26a, b) defined between them. The rotor has two stages (14a, b) arranged one at either end of the bars. The bars have a shoe (18a, 8) at each end of each bar that links magnetic flux through the bars with said magnets on each stage. Adjacent shoes facing the same stage of the rotor have a high-reluctance shoe gap (27) between them; adjacent magnets on each stage of the rotor have a high-reluctance magnet gap (25) between them; and the shoe and magnet gaps (25, 27) are angled with respect to each other such that they engage progressively as the rotor rotates. Alternatively, the shoes facing each stage are in a ring of connected shoes such that the magnets experience a continuous reluctance that is at least 90% constant as a function of rotor position. The bars (16) and shoes (18) are formed separately from one another and at least a part of each is formed by moulding soft-iron particles so that the particles have a short dimension that is arranged transverse a reluctance-plane. The bars and shoes are assembled so that the reluctance-plane of the bar is parallel a longitudinal axis (16a) of the bar and said reluctance-plane of the shoe is transverse said longitudinal axis.</p> |
