| 摘要 |
<p>A synchronisation arrangement for delaying excitation of the field winding 5 of a brushless synchronous motor, until the rotor has run up approximately to synchronous speed and is correctly positioned relative to the stator field, comprises a control unit 1 responsive to two signals derived from across diodes 13, 17 respectively to fire a thyristor 3 to connect winding 5 to the DC output of AC exciter 4 either when the slip frequency of the winding current is below a predetermined value or the rotor has synchronised on reluctance. The former condition is derived from the diode 13 signal which, providing thyristor 15 is not conducting, causes unit 1 to produce a firing pulse each time diode 13 starts to conduct. The latter condition is derived from the diode 17 signal which, provided thyristor 15 has been non-conductive for a predetermined time, causes unit 1 to produce a train of firing pulses. Operation of the unit 1, Fig. 2 (not shown) is described for the two conditions and also for other conditions such as reluctance synchronisation on the wrong pole, pull-out of the motor or variation of the winding voltage due to motor shaft swinging and rectification of harmonic voltages during reluctance synchronisation. <IMAGE></p> |
