Patent ID: 6990415

Claim:
A method for operating a current sensor according to the compensation principle for measuring direct and alternating currents, comprising the steps of: passing a current to be measured through a primary winding of a magnet core, thereby generating a primary magnetic field, passing a compensation current through a secondary winding of the magnet core, thereby generating a compensation magnetic field, controlling the compensation current so as to cause a total magnetic flux produced by the primary magnetic field and the compensation magnetic field to be zero, detecting deviations of the total magnetic flux from zero with a magnetic field probe and converting the detected deviations into a pulsed drive signal and amplifying the pulsed drive signal to obtain the compensation current, wherein the pulsed drive signal is derived from the probe current by the following steps: exciting the magnetic field probe with a probe current at a predetermined frequency, thereby obtaining at least one potential that depends on the probe current, converting the at least one potential into at least one digital signal having discrete values by comparing the at least one potential with at least one threshold value, measuring characteristic time values of the at least one digital signal in the form of discrete values and discrete times, digitally controlling by (Proportional-Integral) PI control the magnetic flux to a zero value by using the at least one measured time value, and deriving binary switching signals by using at least one of pulse-width modulation (PWM) and sigma-delta modulation of a first or higher order.