# US 8,569,982 B2 · Method of determining the position of the drive mechanism of an electric machine, such as a motor, from the current supplied, and arrangement for carrying out the method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,982 B2 - Document ID: US8569982B2 - Status: Granted - Kind: B2 - Application number: 13/002,460 - Filed: 2009-07-03 - Published: 2011-07-28 - Granted: 2013-10-29 - Earliest claimed: 2008-07-03 - Assignees: Kollmorgen Europe GmbH - Applicants: Jan Achterberg - Inventors: Jan Achterberg - Web page: https://patentgrep.com/patent/US8569982B2 ## CPC - G05B 9/03: with multiple-channel loop, i.e. redundant control systems - H02P 21/18: Estimation of position or speed - H02P 2203/05: Determination of the rotor position by using two different methods and/or motor models - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A method and arrangement for determining the position of the drive mechanism of an electric machine from the current supplied thereto. Determination of the position is effected over two independent channels by measuring the three-phase current of the electric machine or motor, converting the measured values to the current space vector, calculating the angle of the current space vector within one electrical revolution, and determining the position of the motor. A current command, the field of which acts in the direction of the flux or field of the drive mechanism or rotor, is added within the motor stator. ## Claims ### Claim 1 A method of determining the position of a drive mechanism of an electric machine from the current supplied to the machine, including the steps of: effecting determination of the position of the electric machine over two paths or channels that are independent of one another to obtain two position values and thereafter combining the two position values and cross checking them with respect to a safe manner of operation or positioning of the drive mechanism, including the steps of: determining the position of the electric machine from two current channels by measuring a three-phase current of the electric machine to obtain measured values, IA, IB, converting the measured values to a current space vector, calculating the angle of the current space vector within one electrical revolution, and determining the position of the drive mechanism, wherein a current command, a field of which acts in the direction of a flux or field of the drive mechanism, is added within the electric machine. ### Claim 2 (depends on 1) A method according to claim 1, wherein said electric machine is a motor that includes a stator. ### Claim 3 (depends on 2) A method according to claim 2, wherein said drive mechanism is a rotor, and wherein said motor is a servomotor having permanent magnetic generation of the magnetic field of the rotor. ### Claim 4 (depends on 3) A method according to claim 3, wherein the angle of the current space vector serves for a determination of a position of the rotor. ### Claim 5 (depends on 3) A method according to claim 3, wherein the angle of the current space vector serves for a determination of a change in position over time, and hence of a speed of the rotor, or collectively of the position. ### Claim 6 (depends on 3) A method according to claim 3, wherein the field of the current command acts in the direction of the flux or field of the rotor, and is added within the stator. ### Claim 7 An arrangement for an improved measurement of the position of a drive mechanism of an electric machine from the current supplied to the electric machine, wherein the measurement is effected over two paths or channels that are independent of one another to obtain two measured values, and wherein thereafter the two measured values are combined and are cross checked with respect to a safe manner of operation or positioning of the drive mechanism, comprising: a circuit configured for determination of the position of the drive mechanism in one of the channels; a sensor disposed in the circuit and configured to measure a three-phase current of the electric machine to obtain measured values; a converter following said sensor in the circuit and configured to convert the measured values of the three-phase current to a current space vector; a computing unit following said converter in the circuit and configured to calculate the angle of the current space vector within one electrical revolution and to determine the position of the drive mechanism; and a current regulator having an addition or summing unit configured to add, within the electric machine, a current command having a field that acts in the direction of a flux or field of the drive mechanism. ### Claim 8 (depends on 7) An arrangement according to claim 7, wherein the electric machine is a servomotor having a stator and having permanent magnetic generation of the magnetic field of the stator, and wherein the drive mechanism is a rotor. ### Claim 9 (depends on 8) An arrangement according to claim 8, wherein the angle of the current space vector serves for a determination of a position of the rotor in the servomotor. ### Claim 10 (depends on 8) An arrangement according to claim 8, wherein the angle of the current space vector serves for a determination of a change in position, and hence of a speed, of the rotor in the servomotor, or of a position of the rotor. ### Claim 11 (depends on 8) An arrangement according to claim 8, wherein said addition or summing unit is configured to be controlled such that the current command, the field of which acts in the direction of the rotor flux or rotor field, is added within the stator when the current that generates a torque is low in comparison to a rated current. ### Claim 12 (depends on 8) An arrangement according to claim 8, wherein the current command, the field of which acts in the direction of the rotor flux or rotor field, is added within the stator when a speed of the rotor is low in comparison to a rated speed. ### Claim 13 (depends on 8) An arrangement according to claim 8, wherein the current command, the field of which acts in the direction of the rotor flux or rotor field, is added within the stator when the current space vector moves about the value zero. ### Claim 14 (depends on 8) An arrangement according to claim 8, wherein the current command, the field of which acts in the direction of the rotor flux or rotor field, is added within the stator when due to regulation of the servo loops of the servomotor, the current space vector jumps back and forth.