| 摘要 |
An electrical machine comprising a member (3) of magnetic material, and a stator (1) supporting windings which when energised generate magnetic fields in a gap defined between the member (3) and the stator (1). The stator (1) supports at least two windings each of which is energisable to generate a different number of magnetic pole pairs from the other winding or windings. At least one winding comprises a plurality of subwindings arranged to be energised by respective phases of a polyphase current so as to generate a moving magnetic field in the gap. A resultant magnetic field appears in the gap which is a moving magnetic field that is the sum of the magnetic fields resulting from energisation of each of the windings. The resultant distribution of attractive force between the two members (1, 3) may have a long wavelength compared to the winding pole pitches, which is of value in harmonic drive type devices, or may rotate at twice the angular frequency of a supply current, which enables high speed operation. |
