Circuit arrangement for generating a digital signal which characterizes predetermined amplitude values, particularly the zero passages (polarity reversals) of an alternating voltage

Abstract

Abstract At the times of the zero transitions (polarity reversals) of an alternating voltage (for example a sinusoidal alternating voltage), switching process (for example the switching of a polarity reverser) are to be carried out. For this purpose, the alternating voltage is subjected to a two-way rectification in a rectifier circuit which contains at least one proportional amplifier (V1) and one current-direction-dependent threshold element (rectifier diode G) which is connected to the output of the latter. At least one comparator (K1) having a first input is connected to the junction between the output of the proportional amplifier and the threshold element (G). A reference voltage, the magnitude of which at least approximately corresponds to half the value of the threshold voltage (us) of the threshold element (G) is applied to the second input of the comparator (K1). With every zero transition of the alternating voltage (uE), the output signal of the proportional amplifier (V1) passes through a voltage range, given by the threshold voltage (us) of the threshold element (G), in which the feedback branch of the proportional amplifier (V1) is not effective due to the high differential resistance of the threshold element (G) so that the rate of change of the output voltage (uA) in this voltage range corresponds to the rate of change of the input voltage (uE) multiplied by the no-load gain of the proportional amplifier (V1) and is correspondingly very high. As a result, the comparator (K1) is switched very accurately at the time of the zero transitions and supplies the required digital switching signal at its output (P1). <IMAGE>

Inventors

• 👤 Robert Nicolaus

Bibliographic Details