# US 2018/0026564 A1 · Control device for an asynchronous machine and method for operating an asynchronous machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026564 A1 - Document ID: US20180026564A1 - Status: Published application - Kind: A1 - Application number: 15/551,652 - Filed: 2016-01-13 - Published: 2018-01-25 - Earliest claimed: 2015-02-27 - Assignees: Robert Bosch GmbH - Applicants: Robert Bosch GmbH - Inventors: Martin HENNEN - Web page: https://patentgrep.com/patent/US20180026564A1 ## CPC - H02P 21/05: specially adapted for damping motor oscillations, e.g. for reducing hunting - H02P 23/08: Controlling based on slip frequency, e.g. adding slip frequency and speed proportional frequency - H02P 1/00: Arrangements for starting electric motors or dynamo-electric converters (starting of synchronous motors with electronic commutators H02P6/20, H02P6/22; starting dynamo-electric motors rotating step by step H02P8/04; vector control H02P21/00) - H02P 21/09: Field phase angle calculation based on rotor voltage equation by adding slip frequency and speed proportional frequency - H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence) - H02P 2207/01: Asynchronous machines - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract The invention relates to a method for operating an asynchronous machine comprising the steps: determining an operating point trajectory for the asynchronous machine for a plurality of desired torques of the asynchronous machine by calculating 2-tuples from longitudinal current values and cross current values in a synchronously rotating coordinate system of the asynchronous machine; calculating a slip frequency of the asynchronous machine for each of the 2-tuples calculated from longitudinal current values and cross current values; determining a current rotor speed of the asynchronous machine; calculating an excitation frequency of the asynchronous machine by summation of the calculated slip frequency and the current rotor speed weighted with the number of pole pairs of the asynchronous machine; and comparing the calculated excitation frequency of the asynchronous machine with at least one predetermined resonance frequency value of the asynchronous machine. The determined operating point trajectory is thereby corrected by changing the ratio between longitudinal current value and cross current value at a constant desired torque for each of the 2-tuples for which the calculated excitation frequency corresponds to the at least one resonance frequency value. ## Claims ### Claim 1 A method (20) for operating an asynchronous machine (1), the method comprising: determining (21) a working point trajectory for the asynchronous machine (1) for a plurality of desired torques of the asynchronous machine (1) by calculating 2-tuples from longitudinal current values and cross current values in a synchronously rotating coordinate system of the asynchronous machine (1); calculating (22) a slip frequency of the asynchronous machine (1) for each of the 2-tuples calculated from longitudinal current values and cross current values; determining (23) a present rotor speed of the asynchronous machine (1); calculating (24) an excitation frequency of the asynchronous machine (1) by summation of the calculated slip frequency and the present rotor speed weighted with the number of pole pairs of the asynchronous machine (1); comparing (25) the calculated excitation frequency of the asynchronous machine (1) with at least one predetermined resonance frequency value of the asynchronous machine (1); and correcting (26) the determined working point trajectory by changing the ratio between longitudinal current value and cross current value at a constant desired torque for each of the 2-tuples for which the calculated excitation frequency corresponds to the at least one resonance frequency value. ### Claim 2 (depends on 1) The method (20) as claimed in claim 1, wherein the determination (21) of the working point trajectory includes: minimizing the phase current, which is obtained by vector addition of the longitudinal current and the cross current, for each of the plurality of desired torques of the asynchronous machine (1). ### Claim 3 (depends on 1) The method (20) as claimed in claim 1, wherein the at least one predetermined resonance frequency value of the asynchronous machine (1) includes a characteristic frequency in a gearbox connected to the asynchronous machine (1), a resonance frequency excited by air-gap forces in the asynchronous machine (1), and/or the harmonic components thereof. ### Claim 4 (depends on 3) The method (20) as claimed in claim 3, wherein the predetermined resonance frequency values of the asynchronous machine (1) are determined using speed-dependent measurements of airborne noise. ### Claim 5 (depends on 1) The method (20) as claimed in claim 1, wherein the change in the ratio between longitudinal current value and cross current value includes an increase in the phase current, which is obtained by vector addition of the longitudinal current and the cross current, at a constant desired torque. ### Claim 6 A control device (2) for an asynchronous machine (1), comprising: a control module (7) configured to determine a working point trajectory for the asynchronous machine (1) for a plurality of desired torques of the asynchronous machine (1) by calculating 2-tuples from longitudinal current values and cross current values in a synchronously rotating coordinate system of the asynchronous machine (1), calculating a slip frequency of the asynchronous machine (1) for each of the 2-tuples calculated from longitudinal current values and cross current values, and calculating an excitation frequency of the asynchronous machine (1) by summation of the calculated slip frequency and a present rotor speed weighted with the number of pole pairs of the asynchronous machine (1); and a comparison module (8) coupled to the control module (7) and configured to compare the excitation frequency of the asynchronous machine (1) calculated by the control module (7) with at least one predetermined resonance frequency value of the asynchronous machine (1), and correcting the working point trajectory determined by the control module (7) by changing the ratio between longitudinal current value and cross current value at a constant desired torque for each of the 2-tuples for which the calculated excitation frequency corresponds to the at least one resonance frequency value. ### Claim 7 (depends on 6) The control device (2) as claimed in claim 6, further comprising: a speed detection module (6) coupled to the control module (7) and configured to detect the present rotor speed of the asynchronous machine (1). ### Claim 8 (depends on 6) The control device (2) as claimed in claim 6, further comprising: a reference value memory (9) coupled to the comparison module (8) and configured to store predetermined reference frequency values of the asynchronous machine (1). ### Claim 9 (depends on 8) The control device (2) as claimed in claim 8, wherein the predetermined resonance frequency values include a characteristic frequency in a gearbox connected to the asynchronous machine (1), a resonance frequency excited by air-gap forces in the asynchronous machine (1), and/or the harmonic components thereof. ### Claim 10 (depends on 6) The control device (2) as claimed in claim 6, wherein the control module (7) is configured to determine the working point trajectory for the asynchronous machine (1) by minimizing the phase current, which is obtained by vector addition of the longitudinal current and the cross current, for each of the plurality of desired torques of the asynchronous machine (1). ### Claim 11 (depends on 1) An electric drive system (10), comprising: an asynchronous machine (1); an inverter (3) coupled to the asynchronous machine (1) and configured to provide a polyphase current supply for the asynchronous machine (1); and a control device (2), comprising a control module (7) configured to determine a working point trajectory for the asynchronous machine (1) for a plurality of desired torques of the asynchronous machine (1) by calculating 2-tuples from longitudinal current values and cross current values in a synchronously rotating coordinate system of the asynchronous machine (1), calculating a slip frequency of the asynchronous machine (1) for each of the 2-tuples calculated from longitudinal current values and cross current values, and calculating an excitation frequency of the asynchronous machine (1) by summation of the calculated slip frequency and a present rotor speed weighted with the number of pole pairs of the asynchronous machine (1), and a comparison module (8) coupled to the control module (7) and configured to compare the excitation frequency of the asynchronous machine (1) calculated by the control module (7) with at least one predetermined resonance frequency value of the asynchronous machine (1), and correcting the working point trajectory determined by the control module (7) by changing the ratio between longitudinal current value and cross current value at a constant desired torque for each of the 2-tuples for which the calculated excitation frequency corresponds to the at least one resonance frequency value; the control device coupled to the inverter (3) and configured to control the inverter (3) according to the method as claimed in claim 1 for operating the asynchronous machine (1).