Patent GB-758765-A (GB)
Title: Electric remote-control positioning system
Inventor: FOUASSIN MARCEL
IPC: H03M1/00
Filed: 1954-04-30
Abstract: 758,765. Electric selective signalling. ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE CHARLEROI. April 30, 1954 [May 1, 1953], No. 12558/54. Class 40(1) [Also in Groups XXXV and XXXVII] In a selsyn system the usual transmitter is replaced by a transformer 18, Fig 2, comprising a polyphase winding 19 for connection to the polyphase winding of the selsyn receiver 12, and a multiphase winding 21, any one phase of which may be rendered operative by a selector 24. A winding 21 having ten phases, derived by conversion from three phases, Figs. 3, 4 (not shown), is illustrated, selection of any one phase 0 ... 9, by the selector 24 driving the receiver rotor to a corresponding angular position, either directly, or through the usual discriminator 15, amplifier 14, and servomotor 16. The single phase supply 23 may be connected to the receiver rotor and the discriminator input across the selected phase winding 21, or vice versa. Fine control for setting the receiver to positions between the phase "points" 0 ... 9, may be effected in various ways. For example, the receiver rotor 31, Fig. 6, may have, in addition to the usual coil 29 energized from the source 23, a quadrature coil 44 adapted to be energized through a vernier transformer 35, the magnitude and phase-sense of the energizing current in coil 44 being determined by selective operation of one of ten keys 41. This gives ten settings between adjacent settings determined by the multiphase windings a, b, ... j, which, in this case, are selected by keys 27. Alternatively a three phase wound rotor may be used at the receiver, Fig. 30 (not shown), two of the rotor windings in series functioning as the normal single phase winding and the third winding functioning as the quadrature vernier winding of Fig. 6. In a modification the voltage derived from the vernier transformer 35 is injected in series with the selected phase of winding 21, Fig. 8 (not shown), the receiver coil 44 being dispensed with. In another embodiment, Fig. 7 (not shown), the vernier voltage from transformer 35 is injected into a winding in quadrature with the selected phase winding a, ... j. A three phase vernier transformer may alternatively be interposed in the lines 13, Fig. 2, and function in manner similar to a differential selsyn. For still finer control multi-channel systems are used as described below. Multi-channel control, Fig. 14 shows a three channel system in which receivers 12a, 12b, 12c are set according to a decimal number set up on keyboards 27A (hundreds), 27B (tens), and 27C (units). The receivers are geared at 97, 98 in the ratio 10: 1-and driven by a common motor 16 through an amplifier 14 controlled by the discriminators 15A, 15B, 15C associated with the respective channels I, II, III. Each channel functions as described in Fig. 6, except that the vernier connections for the respective coarser channels I, II are made by the keys controlling the multiphase control transformer of the next finer channel II, III, and no vernier signal is used in the finest channel III. The power amplifiers associated with the respective discriminators are cascaded with common bias resistors, Fig. 19 (not shown), so that while the coarse amplifier associated with channel I is operative the amplifiers of the finer channels II, III are cut-off; being brought into operation successively as the receiver setting approaches that of the key boards. The motor speed will drop in steps as control is switched to finer stages if flat response amplifiers Fig. 15 (not shown), are used; a gradual speed transition may be effected, however; by using amplifiers having a rising response curve, Fig. 16 (not shown). Anti-hunt control Figs. 14, 22. As applied to the system of Fig. 6, an anticipatory signal is induced in a coil 123 connected in series with the vernier control coil 44. The coil 123 is carried on a shaft 122 biased by a spring 121 to a neutral position in which zero voltage is induced in the coil 123 by its primary coil 124. The shaft 122 is deflected in one sense or the other according to the speed and direction of rotation of the servomotor 16, e.g. through a voltmeter movement 119 energized in parallel with the servomotor, so that the induced anticipatory signal is of a magnitude proportional to motor speed and always opposes the error signal. In the case of a multi-channel system, Fig. 14, hunting due to residual magnetism of the selsyn rotors is prevented by energizing the coil 44 of the finest stage III wjith A.C. modulated at a low frequency and supplied by a selsyn 120 whose rotor 165 is energized from source 23 and driven slowly. Back-lash compensation. This is effected by injecting a constant alternating voltage in series with the vernier voltage and having a phase sense which is reversed as the motor 16 reverses. Modifications. The amplifiers used may be electronic and operate the servomotor 16 through an amplidyne and Ward- Leonard system, Figs. 15, 16, 19 (not shown), or magnetic amplifiers may be used, Fig. 31 (not shown), and operate the Ward-Leonard system directly. The Ward- Leonard system may be replaced by contactor-control of the motor by means of relays in the electronic amplifier output circuits Figs. 23, 24 (not shown). The application of the three channel system of Fig. 14 to end limit switching of heavy machinery is described, Fig. 25 (not shown).