Controlled electric motor arrangement for a tension mechanism

Field-oriented control method for an electric drive comprising a plurality of electric motors, for implementing a tension mechanism, for load cable and/or gearing means (1, 3), using measurements of a polyphase motor actual current (U, V, W), the measured values of which 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, and the quadrature and direct current components from the actual current are subjected to a comparison with predetermined quadrature and direct current components (isq_ref, isd_ref) of a current command value, with the following steps:

• a) two synchronous motors (M1, M2) are used as electric motors
• b) the magnet wheels or rotors of the two synchronous motors (M1, M2) are rotated or oriented toward one another and are then mechanically coupled in such a way that between their magnetic flux linkages (ψm1, ψm2) or other magnetic fluxes an angular offset (V) 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 (m_ref) output by a controller (7), from which a quadrature current component (isq_ref) for the current command value is derived
• e) a direct current component (isd_ref) for the current command value is derived from the predetermined tension torque control value (m_ref) with sign reversal.