GB1421871A - Electrical power supply unit for synchronous motors - Google Patents

Abstract

1421871 Control of A.C. and D.C. motors LINSER-TEXTILMASCHINEN G.m.b.H. 22 Oct 1973 [21 Oct 1972] 49020/73 Heading H2J In a stretch twisting machine of conventional construction, the synchronous motors 22, 24 driving the thread feed roller 20 and the flanged rollers 23 are controlled by a supply unit 10 comprising an alternator 16 feeding the motors and being driven by a variable speed D.C. motor 15 which is coupled to an asynchronous motor 11 through a step-down gear train 12 and an overrunning clutch 13, the arrangement being such that the motor 11 is energised to drive the alternator 16 up to a predetermined idling speed via members 12, 13, 15, switch 30 is then closed to simultaneously energise the motors 22, 24, the resultant increase in load on the alternator 16 being absorbed without hunting by virtue of the chosen size of the motor 11, and finally the motors 22, 24 are run up to operating speed by control of the D.C. motor 15, which takes over the drive of the alternator 16 from the motor 11 allowing the latter to be switched off. The motor 15 may be manually or automatically controlled through a thyristor controller 19 responsive to a tachogenerator 17 coupled to the alternator 16 and may be switched on when it is desired to run motors 22, 24 up to operating speed or when the motor 11 is switched on, in which case controller 19 is preset to produce a speed lower than that of the motor 11. The latter may be of the polechanging type to produce a number of different idling speeds. The unit 10 ensures that the motors 22, 24 are run up to speed and subsequently operated in phase, which condition is also obtained during stopping by opening a switch 31 to de-energise the motor 15 and closing a switch 40<SP>1</SP> to dissipate the energy of the motor through resistances 41, the motors 22, 24 thereby driving motor 15 as a generator through the alternator 16 acting as a motor. The synchronous motors 33 driving the bobbins 32 of the stretch twisting machine are supplied from an alternator 37 driven only by a D.C. motor 36 having a controller 40, the operating conditions of the motors 33 being less critical than for the motors 22, 24. If desired, the D.C. motor 15 may be switched on to assist the motor 11 whilst it is driving the alternator.