OVERCURRENT LIMIT IN THE CONTROL OF THREE-PHASE MACHINES FED BY INVERTER

摘要

A method and a structure operate a three-phase machine, which is fed by a three-phase converter, using a stator flux regulator and either a slip frequency regulator or a torque regulator. A torque-forming fundamental-frequency current component of the stator current is limited by limiting a setpoint value that is supplied to the slip frequency regulator or to the torque regulator to a maximum slip frequency value maximum torque value. The flux-forming fundamental-frequency current component of the stator current is limited by limiting the speed at which a setpoint value supplied to the stator flux regulator changes to a maximum value. The maximum slip frequency value or maximum torque value is calculated on the basis of a prescribed maximum current value for a stator current fundamental-frequency magnitude of the stator current and on the basis of a filtered actual value of the flux-forming fundamental-frequency current component of the stator current.