| 摘要 |
1,121,518. Control of A.C. motors. BROWN BOVERI & CO. Ltd. 29 Dec., 1966 [31 Dec., 1965], No. 58137/66. Heading H2J. [Also in Division G1] In an arrangement for deriving the slip frequency of an asynchronous machine 1, and which may alternatively be used to obtain a control frequency for speed control of the machine, the rotor shaft n of the asynchronous machine is coupled to that of an auxiliary measuring machine 4, which has symmetrical multiphase windings mounted on its rotor connected via slip rings to a multiphase source PQR. The auxiliary machine has no stator winding, but has Hall plates 8 symmetrically arranged in the air gap between stator and rotor which produce an output directly related to the induction in the gap at either the slip or control frequency, depending on the arrangement of the supply at PQR. To derive slip frequency, PQR is fed with the same frequency as that used to supply the asynchronous machine at RST, and arranged to rotate in the same way as the shaft n. The Hall plate output is then at a frequency fx-fn, the slip frequency. To provide a speed control frequency, PQR is fed with a desired slip frequency arranged to rotate in the opposite direction to the shaft n. The Hall plate output is then at a frequency fx+fn, the frequency which should be supplied to the machine 1 to produce the desired slip. |
