Electrical protection device with a sigma-delta analog-to-digital converter

摘要

The device uses analogue-digital conversion to provide accurate measurement of current to provide protection. The electrical protection device comprises a number of sensors, a multiplexer and a sigma-delta type analogue-digital converter. The converter comprises a sigma-delta modulator in series with a decimation digital filter. The decimation filter comprises weighting coefficients (k-i) of order 1 to n, such that the product of the dynamic value of the signals measured by the sensors, and a ratio ( (1-m) ki /( (1-n) ki) derived from the sums of the k values, is less than the precision required for the signals. The coefficients of order 1 to m are the coefficients used during the stabilization time (TS) of the modulator. The coefficients of the filter of order 1-m are null, whilst the non-null coefficients are symmetric.