GB1187312A - Improvements relating to the Stabilisation of Electrical Power-Supply Systems - Google Patents

Abstract

1,187,312. Automatic control of current and voltage. HARMER & SIMMONS Ltd. Sept. 5, 1968 [Jan.12, 1968], No.1822/68. Heading G3R. A D. C. load 1 is supplied from an A. C. source 2 by way of two circuits in parallel, the first circuit being capable of supplying the major proportion, e.g. 95% of the maximum load current and comprising a thyristor or transductor arrangement 6, a transformer 7 and a rectifier 8 and the second circuit being capable of supplying a small predetermined proportion, e. g. 5% of the load current and comprising a conventional series transistor regulating circuit 3, 4, 5, 9, 10, 11; a tapping on a resistor 12 in the emitter circuit of transistor 5 is connected to the control terminal of the arrangement 6, which is thus controlled to conduct when, assuming the above numerical example, the output of the transistor 5 is equal to 5% of the maximum load current. When the load current increases the arrangement 6 is then controlled to pass more current whereby the current through transistor 5 is maintained at the said value of 5% of maximum full load current. Thus variation in the output voltage caused by transients of the order of Œ5% of maximum full load current can be compensated-for by the high-speed response of the relatively lightly loaded transistor regulator only, with consequent increase in the efficiency of the system as a whole. The second circuit, including the series regulator, may be replaced by a shunt transistor regulator circuit connected across the load Figs.3 and 4 (not shown), in which case the arrangement 6 must be capable of supplying, say, 105% of the maximum load current. The system may be modified to provide constant current rather than constant voltage control.