# US 2013/0278282 A1 · Monitoring and fault diagnosis of an electric machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278282 A1 - Document ID: US20130278282A1 - Status: Published application - Kind: A1 - Application number: 13/996,841 - Filed: 2011-12-08 - Published: 2013-10-24 - Earliest claimed: 2010-12-21 - Inventors: André Leppich; Markus Luft; Jürgen Rossmann; Alexander Stukenkemper - Web page: https://patentgrep.com/patent/US20130278282A1 ## CPC - G01R 31/282: {Testing of electronic circuits specially adapted for particular applications not provided for elsewhere (G01R31/2801 and G01R31/2851 take precedence)} - G01R 31/343: {in operation} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract In a method for monitoring a rotating electric machine (1) that is fed by a converter and for diagnosing faults of said rotating electric machine, a current signature (I1, I2, I3) of output signals of the converter is recorded, the current signature (I1, I2, I3) is transformed, and the transformed current signature (A) is evaluated in at least one frequency band in order to detect damage to the machine (1). ## Claims ### Claim 1 A method for monitoring and fault diagnosis of a rotating electric machine which is coupled with a converter, the method comprising: recording a current signature of output signals of the converter, carrying out a transformation of the current signature, and evaluating the transformed current signature in at least one frequency band in order to detect damage to the machine, wherein the transformation of the current signature comprises at least one fast Fourier transform using a filter function. ### Claim 2 (depends on 1) The method according to claim 1, wherein a transformed reference current signature is ascertained which represents a damage-free state of the machine, and the transformed current signature is compared during the evaluation with the transformed reference current signature. ### Claim 3 (depends on 1) The method according to claim 1, wherein in order to detect damage to the machine a frequency dependent tolerance band is predetermined in a value range of the transformed current signature and damage is concluded to have occurred if the transformed current signature lies outside the tolerance band in the case of at least one frequency. ### Claim 4 (depends on 2) The method according to claim 2, wherein the tolerance band is predetermined such that the transformed reference current signature lies within the tolerance band. ### Claim 5 (depends on 1) The method according to claim 1, wherein a damage-specific transformed current signature is ascertained for at least one damage type, and that during the evaluation the transformed current signature is compared with at least one damage-specific transformed current signature. ### Claim 6 (depends on 5) The method according to claim 5, wherein a damage-specific transformed current signature is ascertained at least for a broken rotor bar of a rotor of the machine or field asymmetry of the rotor or eccentricity of the rotor or a stator winding short-circuit of a stator of the machine or damage to a drive train of the machine. ### Claim 7 (depends on 1) The method according to claim 1, wherein all three phase currents are recorded for a three-phase converter current and the transformation of the current signature comprises the formation of a symmetrical component from the three phase currents. ### Claim 8 (depends on 1) The method according to claim 1, wherein the transformation of the current signature comprises an amplitude demodulation. ### Claim 9 (depends on 8) The method according to claim 8, wherein the amplitude demodulation is carried out with a Hilbert transform of the Fourier transformed current signature. ### Claim 10 (depends on 1) The method according to claim 1, wherein the machine is monitored continuously and automatically, and a fault report is automatically generated or an alarm is automatically triggered if damage to the machine is detected. ### Claim 11 (depends on 1) The method according to claim 1, wherein the machine is monitored continuously and automatically, and a fault report is automatically generated and an alarm is automatically triggered if damage to the machine is detected. ### Claim 12 A system for monitoring and fault diagnosis, comprising: a rotating electric machine coupled with a converter, means for recording a current signature of output signals of the converter, means for carrying out a transformation of the current signature, and means for evaluating the transformed current signature in at least one frequency band in order to detect damage to the machine, wherein the transformation of the current signature comprises at least one fast Fourier transform using a filter function. ### Claim 13 (depends on 12) The system according to claim 12, wherein a transformed reference current signature is ascertained which represents a damage-free state of the machine, and the transformed current signature is compared during the evaluation with the transformed reference current signature. ### Claim 14 (depends on 12) The system according to claim 12, wherein in order to detect damage to the machine a frequency dependent tolerance band is predetermined in a value range of the transformed current signature and damage is concluded to have occurred if the transformed current signature lies outside the tolerance band in the case of at least one frequency. ### Claim 15 (depends on 13) The system according to claim 13, wherein the tolerance band is predetermined such that the transformed reference current signature lies within the tolerance band. ### Claim 16 (depends on 12) The system according to claim 12, wherein a damage-specific transformed current signature is ascertained for at least one damage type, and that during the evaluation the transformed current signature is compared with at least one damage-specific transformed current signature. ### Claim 17 (depends on 16) The system according to claim 16, wherein a damage-specific transformed current signature is ascertained at least for a broken rotor bar of a rotor of the machine or field asymmetry of the rotor or eccentricity of the rotor or a stator winding short-circuit of a stator of the machine or damage to a drive train of the machine. ### Claim 18 (depends on 12) The system according to claim 12, wherein all three phase currents are recorded for a three-phase converter current and the transformation of the current signature comprises the formation of a symmetrical component from the three phase currents. ### Claim 19 (depends on 12) The system according to claim 12, wherein the transformation of the current signature comprises an amplitude demodulation. ### Claim 20 (depends on 19) The system according to claim 19, wherein the amplitude demodulation is carried out with a Hilbert transform of the Fourier transformed current signature.