GB782930A - Improvements in or relating to apparatus for converting a sinusoidal alternating voltage into a dependent direct voltage - Google Patents

Abstract

782,930. Converting. SIEMENS-SCHUCKERTWERKE AKT.-GES. Feb. 17, 1956 [Feb. 25, 1955], No. 5059/56. Class 38 (2). An alternating voltage of maximum valve or #Û is converted into smooth direct voltage of corresponding value by deriving a second alternating voltage 90 degrees displaced in phase from the first, deriving from these two voltages, voltages having the values Û sin <SP>2</SP>wt and Û cos<SP>2</SP>wt and adding them. Where the value of the direct voltage is to have a value dependent on the difference of the speed of a motor 1 from a set speed, the motor drives a dynamo 2 having two windings 3, 4, 90 degrees electrical apart. Each winding is connected to a bridge comprising a resistor 6, capacitor 8, inductor 9 and the two halves 7a, 7b of the primary winding of transformer 7. As the resistance of 6 is equal to that of the other branch 8, 9 which is tuned to the set frequency, the currents in winding halves 7a, 7b are equal and opposite at the set frequency, and current flows in the secondary winding to a value proportional to the amount the frequency departs from that set. The voltages of values Û sin<SP>2</SP>wt and Û cos<SP>2</SP>wt are derived in Hall generators whose input terminals a, b and control field windings are fed respectively from the output of a bridge and opposite winding of the generator. The direct voltage is obtained by connecting the output probes c, d, e, f of the Hall generators in series.