Improvements relating to the stabilisation of electrical power supply units

摘要

1,142,514. Automatic control of current and voltage. INDUSTRIAL INSTRUMENTS Ltd. Oct. 24, 1967 [Oct. 28, 1966], No. 48519/66. Heading G3R. In a power supply unit, thyristors in the primary circuit of a transformer forming part of an inverter and thyristors in a phase-controlled rectifier which is connected to the secondary circuit of the transformer and from which is derived a D.C. output receive their firing pulses from a common oscillator, and a control circuit responsive to output variations provides an adjustable delay in the firing of the rectifier thyristors relative to the firing of the primary circuit thyristors so that the output is stabilized at a desired level. As shown, an A.C. input is rectified and chopped by one pair of the thyristors X1, Y1 or X2, Y2 &c. connected in the primary circuit of a transformer T1 having its secondary circuit connected over thyristors A, B to provide a D. C. output. The relative phase of firing of A, B and X, Y is determined by a control circuit which receives inputs representative of output voltage and output current and which is arranged to operate so that "constant voltage" control is superseded by "constant current" control when the output current reaches a pre-set maximum. A suitable control circuit arrangement is described with reference to Fig. 2 (not shown). A logic circuit M, Figs.3 & 4 (not shown), provides outputs to select an appropriate pair of primary thyristors X, Y in dependence upon fluctuations in the input voltage.