Method for measuring a current, and current-measuring device

Abstract

In a method for measuring a current, a plurality of flux-gate field sensors is arranged with radial symmetry on a first circumferential path, and a plurality of Hall sensors is arranged with radial symmetry on a second circumferential path such that a one of the flux-gate field sensors is placed adjacent a one of the Hall sensors, with the flux-gate field sensors having a sensitivity which is higher by a factor 5 to 20 than a sensitivity of the Hall sensors. At least one of the plurality of flux-gate field sensors is evaluated so as to determine a current intensity, when two of the flux-gate field sensors generate measurement values within a measurement range, or at least one of the plurality of Hall sensors is evaluated so as to determine a current intensity, when the measurement values of the two flux-gate field sensors are outside of the measurement range.

Claims

1. A method for measuring a current, said method comprising: arranging a plurality of flux-gate field sensors with radial symmetry on a first circumferential path; arranging a plurality of Hall sensors with radial symmetry on a second circumferential path such that a one of the flux-gate field sensors is placed adjacent a one of the Hall sensors, with the flux-gate field sensors having a sensitivity which is higher by a factor 5 to 20 than a sensitivity of the Hall sensors; and evaluating at least one of the plurality of flux-gate field sensors so as to determine a current intensity, when two of the flux-gate field sensors generate measurement values within a measurement range, or evaluating at least one of the plurality of Hall sensors so as to determine a current intensity, when the measurement values of the two flux-gate field sensors are outside of the measurement range.

2. The method of claim 1, wherein the at least one of the plurality of flux-gate field sensors is evaluated, when the measurement values of all flux-gate field of the plurality of flux-gate field sensors lie within the measurement range, and when not affirmative, evaluating all Hall sensors of the plurality of Hall sensors to determine the current intensity.

3. The method of claim 1, further comprising ascertaining during determination of the current intensity by the at least one of the plurality of flux-gate field sensors a correction value for an offset of the Hall sensor as a function of the current intensity determined by the flux-gate field sensors.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention is described and explained in more detail below on the basis of the exemplary embodiments shown in the figures, in which:

(2) FIG. 1 shows a first exemplary embodiment of a current-measuring device,

(3) FIG. 2 shows a second exemplary embodiment of a current-measuring device, and

(4) FIG. 3 shows a possible implementation of a method for offset correction.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) FIG. 1 shows a first exemplary embodiment of a current-measuring device 1 around an electrical conductor 2. Here, the current-measuring device 1 has a multiplicity of sensors 11 of a first type and, adjacent to this in each case, a plurality of sensors 12 of a second type. In this exemplary embodiment, adjacent means that the spacing between two sensors is smaller than the smallest extent of the sensors. The types differ, for example, in their measuring principles in this context. The sensors of different types are arranged on a common circular path K. In this context, the arrangement takes place such that the field orientation 20 which can be measured by the respective sensor is oriented tangentially to the circular path. In order to be able to evaluate the measurement signals of the individual sensors, the current-measuring device 1 has an evaluation electronics unit 13. In order to arrange the measuring device 1 around the electrical conductor in a simple manner, it has proved advantageous in the circular construction of the current-measuring device 1 to provide an angular opening 21. The more flexible the current-measuring device 1, the smaller it is possible to embody the angular opening 21.

(6) FIG. 2 shows a further exemplary embodiment of the current-measuring device 1. For the avoidance of repetition, reference is made to the description relating to FIG. 1 and to the reference characters introduced there. In this exemplary embodiment, the sensors of the different types are in each case arranged adjacently on different, concentric circular paths K.sub.1, K.sub.2. In this exemplary embodiment, adjacent means that the spacing between two sensors is smaller than the smallest extent of the sensors. In this arrangement too, it is possible for a comparably good measurement result to be achieved, as in the construction of the exemplary embodiment explained above.

(7) FIG. 3 shows a flow diagram for an advantageous measurement method for an offset correction. In a first step 101, the measuring of a current takes place by way of the sensors of the first and the second type. In a decision 102, it is checked whether all measurement values of the sensors of the first type are situated in the permitted measurement range. If this is not the case, then the method returns to the first step 101 in the path N (for “no”) and new measurement values are recorded. In the other case Y (for “yes”), in which the measurement values of the sensors of the first type then lie in the permitted range, the offset K.sub.offB is determined from the values of the sensors 12 of the second type in step 103. Only when a minimum quantity of values for K.sub.offB is reached, is an offset value for the sensors of the second type stipulated in step 105. Otherwise, the decision 104 ensures that the method continues with the determination of new measurement values in step 101 once more.

(8) In summary, the invention relates to a current-measuring device. In order to improve the measurement accuracy, it is proposed that the current-measuring device has at least two sensors of a first type and at least two sensors of a second type, wherein the sensors of the first type have a higher sensitivity than the sensors of the second type, wherein the first sensors are arranged with radial symmetry on a first circular path and the second sensors are arranged with radial symmetry on a second circular path, wherein in each case a sensor of the first type is arranged adjacent to a sensor of the second type. The invention further relates to a method for measuring a current by means of such a current-measuring device, wherein in order to determine the current intensity at least one of the sensors of the first type is evaluated, if the measurement values of at least two sensors of the first type lie within the measurement range and otherwise at least one sensor of the second type is evaluated.