Electric circuit for converting an AC voltage into a DC voltage or a voltage variable at a lower frequency
AssigneeThomson-Brandt
InventorsJoseph Colineau, Jean Y. Maheo
Life of this patent
Estimating the term…
Abstract
The circuit comprise a switch controlled so that at each period of the AC voltage it is conducting for a period of time which depends on the desired output voltage, and a control of the output voltage slaved to an instruction or reference signal. The measuring signal of the control is the mean value of the voltage at the terminals of said switch during a period of the AC voltage. For establishing the mean value there is provided, an integrator whose input receives the voltage signal at the terminals of the controlled switch.
Claims19
An electrical circuit for converting an ac voltage applied to an input (S1) to a dc voltage (Vs) variable at a lower frequency at an output (1), comprising
- (a) a filter (LS,CF) connected between said input and output;
- (b) switch means (I) having an output (6) connected in series with said input, said filter, and said circuit output and on that side of the filter which is connected to said input, for conducting during each cycle of the ac voltage for a period of time in accordance with the desired dc output voltage;
- (c) means for receiving a reference signal (112,VREF) proportional to the desired dc output voltage;
- and
- (d) control means (11,12) connected to said switch means (I) for operating said switch means and thus controlling the output dc voltage (VS), having an input (at 112) for receiving said reference signal (VREF), and an input (121) connected to said switch means (I);
- said control means including means for establishing (12) a mean value of a voltage at said switch means output (6) during a cycle of input ac voltage, and including an output (to 14) connected to said switch means for operating said switch means, said control means operating said switch means in accordance with and slaved to instructions from said reference signal and proportional to a mean value of said voltage at said switch means output (6).
The circuit as claimed in any one of the preceding claims, wherein said control switch comprises a thyristor in parallel with, but in opposite direction to, a diode.
Dependencies are inferred from the claim text.