GB1124019A - Pulse generator - Google Patents

Abstract

1,124,019. Converting SOC. DE CONSTRUCTIONS ELECTROMECANIQUES JEUMONTSCHNEIDER 23 Aug., 1965 [21 Aug., 1964], No. 36144/65. Heading H2F. To provide pulses at a variable firing angle α for a phase controlled rectifier a sinusoidal reference waveform (which is displaced by 90 degrees from the supply) is compared with a variable direct voltage to initiate square pulses which commence at angle a and terminate at the angle #, these pulses being used to derive further short positive pulses at α and short negative pulses at #, the positive pulse being utilized as firing pulses. As shown the A.C. supply signal (36, Fig. 2, not shown) at 4 is supplied to a transformer TR1 whose output is phased-displaced by 90 degrees by components 1, 2, to give the reference signal (37, Fig. 2). This is fed with a variable D.C. voltage from 8, 9 to the base of transistor T2, whose output (in the absence of a parallel transistor T3) is a square pulse of duration from α to 2#- α (Fig. 3d). A further output is derived from the transformer TR1, which during positive half cycles causes a transistor T1 to conduct, thereby controlling the transistor T3 which-in the absence of T2-would give an output pulse from 0 to #, (Fig. 3e). The output of the combination of T2 and T3 is a pulse lasting from a to # (Fig. 3f) which is applied to the base of an amplifier transistor T4 whose output is applied to a shaping circuit comprising a mono-stable multivibrator T5, T6. Bias voltage for this circuit is derived from transformer TR2 at diode 25. The output of this circuit is applied to a saturable transformer TR3, giving short positive pulses at a and short negative pulses at #, and the latter are suppressed by a diode 33. The purpose of the circuit T1, T3, is to ensure that for firing angles very near to 0, proper pulses are produced. A circuit for giving firing pulses in both half cycles of the supply and comprising essentially of a duplication of the above is disclosed (Fig. 4, not shown).