Method and device for detecting short-circuits in the stator core of electric machines

2:

• The method recited in claim 1, wherein the at least two detectors are disposed above one another substantially in a radial direction with respect to the rotor axis.

3:

• The method recited in claim 1, wherein each detector is an electrical coil and each detector is disposed so as to primarily measure a field component of the magnetic field that is tangential to a cylindrical inner surface of the stator bore and perpendicular to a direction of the rotor axis.

5:

• The method recited in claim 1, wherein the at least two signals is used as a reference signal.

6:

• The method recited in claim 1, wherein the evaluating includes representing an absolute value and phase difference of the at least two signals in a polar coordinate graph corresponding to a multiplicity of measurement points.

7:

• The method recited in claim 1, wherein determining at least one of a relative magnitude and relative phase angle is performed directly in the pickup device by subtraction.

8:

• The method recited in claim 7, wherein the at least two sensors are identical coils connected in series, in opposition.

9:

• The method recited in claim 7, wherein the at least two sensors are identical coils connected in series so as to generate a differential voltage, and further comprising amplifying the differential voltage in the pickup device.

10:

• The method recited in claim 7, wherein the at least two sensors are identical coils connected in series in a same direction, and wherein a voltage of the coils is tapped off by a trimming resistor.

11:

• The method recited in claim 10, wherein the trimming resistor is adjusted electronically and the voltages is supplied to an amplifier.

12:

• The method recited in claim 7, where the at least two sensors includes at least three sensors disposed one above the other, and connected so as to form respective pairs connected to each other in opposition.

13:

• The method as recited in claim 7, further comprising simultaneously evaluating a single one of the at least two signals.

15:

• The device recited in claim 14, wherein the at least two detectors are disposed above one another substantially in a radial direction with respect to the rotor axis.

16:

• The device recited in claim 14, wherein the at least two detectors are connected in series in a same direction, the at least one of the relative magnitude and relative phase angle of the at least two signals being determined directly in the pickup device by subtraction.

17:

• The device recited in claim 16, wherein the at least two detectors are identical electrical coils.

18:

• The device recited in claim 16, further comprising an amplifier disposed in the pickup device and being configured to amplify a differential voltage generated by series circuit of the at least two sensors.

19:

• The device recited in claim 14, wherein the at least two sensors are electrical coils connected in series in opposition, and further comprising an electronically adjustable trimming resistor disposed in the pickup device and configured to tap off a voltage of the series-connected coils, and an amplifier configured to receive the tapped-off voltage.