Patent ID: 11879915
Assignee: SIEMENS AKTIENGESELLSCHAFT
Field: Measurement (Instruments)
Classification: CPC G | IPC G  H

Claim 8:
9. A system for evaluating an input voltage of a switched-mode power supply, the input voltage having a predetermined polarity, the system comprising:
an analog-to-digital converter for digitizing the input voltage, the input voltage being sampled at a predetermined sampling rate;
at least one filter for filtering the digitized input voltage as the input signal, the at least one filter being formed such that an output signal from the at least one filter lags the digitized input signal of the at least one filter;
a comparator for comparing the input signal of the at least one filter with the output signal from the at least one filter;
a counter for measuring a respective evaluation period, the counter being reset at a start of the respective evaluation period;
a sequence control system which is configured to:
start a respective evaluation period by resetting at least the counter;
evaluate comparison results delivered by the comparator until, subsequent to a first change in state of a comparison result, a further change in state of a comparison result being identified;
terminate a respective evaluation period after the further change in the starting state of the comparator; and
retrieve at least a present count value of the counter to determine the duration of at least one of a period and a frequency of an AC voltage component of the input voltage; and

a timer which utilizes a clock signal to set a time control and the sampling rate of the analog-to-digital converter.