Importance

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Abstract

A field-oriented control method for an electric drive comprising a plurality of electric motors, for implementing a tension mechanism, especially for load cable and/or gearing means, using measurements of a polyphase motor actual current. The measured values are transformed into a direct current component and a quadrature current component, based upon a magnetic rotor field or flux angle, in a rotor flux-based d,q coordinate system. The quadrature and direct current components from the actual current are subjected to a comparison with predetermined quadrature and direct current components of a current command value. The method has the following steps: a) two synchronous motors are used as electric motors; b) the magnet wheels or rotors of the two synchronous motors are rotated or oriented toward one another and are then mechanically coupled in such a way that between their magnetic flux linkages or other magnetic fluxes an angular offset is formed; c) the two synchronous motors are each supplied with or traversed by the same phase currents, from a shared power converter; d) for a pretension torque, a command or reference value is predetermined, and is superposed on a motor torque control value output by a controller, from which a quadrature current component for the current command value is derived; e) a direct current component for the current command value is derived from the predetermined tension torque control value with sign reversal.

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First Claim