GB657042A - Improved circuit for the production of direct voltages - Google Patents

Abstract

657,042. Rectifying; automatic control systems. PHILIPS LAMPS, Ltd. Nov. 20, 1946, No. 34407. Convention date, Nov. 20, 1945. Addition to 640,640. [Class 38 (ii)] In a D.C. voltage generator of the type described in the parent Specification in which a current flows through an inductor and is periodically interrupted to produce a voltage pulse, the current being interrupted for a greater time than it flows, the amplitude or frequency of interruption is made dependent on the output voltage or current in the circuit for rectifying the generated pulse. It is shown mathematically that the internal resistance of a generator as described in the parent Specification may be reduced by arranging that the rate of change of the square of the peak valve current with respect to the square of the D.C. output voltage is negative and by increasing the frequency of the interruptions. Valve B, Fig. 5, fed from a sawtooth generator G is cut off once per cycle to generate a high-voltage pulse across inductor L, the pulse being rectified by diode D1 to charge capacitor Ch. A small coupling coil W also feeds a diode D2 to develop across storage capacitor Cr a control potential proportional to the peak voltage across inductor L. This control potential supplies the grid bias for valve B, thus varying the peak anode current. By using a cascade rectifier arrangement, Fig. 7 (not shown), the first negative peak of the oscillation is also utilized. Since the forward resistance of diode D1 may not be negligible, the amplitude of the second positive peak may be employed for the derivation of the control potential. The cathode of diode D2 (Fig. 9, not shown) is returned to the join of a capacitor and resistor connected across the output load, the diode being biassed off while rectifier D1 is conducting. In a modification, Fig. 11, two auxiliary windings W feed a double-diode, the rectified potential being integrated over R1, C1 to give a control potential proportional to the area of the damped oscillations. In a modification, Fig. 12, the sawtooth generator comprises a capacitor C, resistor R and thyratron T, the control potential varying the thyratron bias to change the sawtooth amplitude. Alternatively, the load current is used to charge the capacitor, the grid of thyratron T being held at a constant potential so that variations in the load current cause the sawtooth frequency to vary. If large variations of frequency are necessary, a resonant circuit may be included in the output so that the output voltage or current is more dependent on frequency.