Patent GB-1390849-A (GB)
Title: Control circuit for a stepping motor power supply
IPC: G05B19/02
Filed: 1972-08-30
Abstract: 1390849 Control of stepping motors ROYAL INDUSTRIES Inc 30 Aug 1972 [13 Sept 1971] 40127/72 Heading H2J In the control system of a six winding, four pole reluctance motor including gate drives ACC controlling thyristor, triggerable D.C. sources 11 as disclosed in Specification 1,294,949, the winding energization sequence is controlled by programmer 13 whose register 2 comprises six binary circuits, Fig. 2 (not shown), connected in a ring, Fig. 3 (not shown), and connected via amplifiers 18 to give twelve distinct energization states for the windings, Figs. 4A, 4B (not shown), corresponding to, alternately three and two windings energized, for either direction of motion, the output shaft of the motor, via a worm-gear, driving a control rod of a nuclear reactor. Sequencing reqister 2.-Each binary circuit (100, Fig. 2) comprises NAND gates (50A- 50D) with a partial enable characteristic should the input conditions not be fully satisfied, connected to AND-flip-flop array (10A, 10B, 10C) receiving at input (100-10) clock pulses from clock 1, at one of two rates, and providing complementary outputs (100-9, 100-11) controlling winding energization. Six such binary circuits corresponding to the motor windings are cross-coupled in the manner designated in Fig. 3 (not shown) to provide trigger signals (A, B, C, AA, BB, CC). If, after supplying interruption the register assumes a state not corresponding to any allowed motor energization, such a state is detected by NAND gates (101, 102, Fig. 3) causing each binary circuit to be set at input (8) corresponding to a state with windings A, B energized. The presence of one or other of signals (IN, OUT) ensures the appropriate sense of rotation. Multi-rate clock 1, Fig. 7 (not shown), the direct output of pulse source (90) is divided by four to provide also a reduced pulse rate. AND gates (93, 95) receive one or other of such rates respectively and a signal representing the presence of a motion command in either sense, which is also fed to flip-flop 94 whose complementary outputs provide the third inputs to the AND gates, whose outputs are coupled via OR 97, providing as output, upon the reception of either an IN or OUT signal, four low frequency pulses, followed by the high frequency ones as long as a motion command is present. Drive direction detector 3, Fig. 5 (not shown).- A unit (40) for each of three pairs of windings, e.g. B, AA comprises a pair of differentiators 30, respectively differentiating the signal for winding B, and its inverse, NAND gates (42, 43) indicating whether or not B is transferred to the energized state while AA is energized, hence defining the direction, a signal being provided via transistor inverters (46), or (47), NAND (45) giving a pulse for each change of motor state, corresponding to a given motion of the reactor rod. Counter and display 4, Fig. 6 (not shown).- The up-down counter counts the nett number of motor movements, and its count hence represents the rod position. It comprises five cross coupled logic circuits (60-1-60-5) each including a single pole double throw magnetic relay for state retention in spite of power source removal. The count may be displayed on a panel, for example by lamps. The pulses counted are received from NAND (45, Fig. 5), the counter also receiving the IN, or OUT signals from units (46) or (47).