Method and apparatus for operating an asychronous motor fed by a current-source inverter during power failure

摘要

In order to maintain the flux in an asynchronous machine supplied by an intermediate-link converter in the event of a network disturbance, the converter is initially blocked at the beginning of the network disturbance. After the intermediate-link current has decayed, the timing of the free-running converter on the machine side and the ignition of two series-connected controlled rectifiers of the converter on the network side are effected. The flux still present in the machine induces in the stator circuit closed in this manner a machine current which is controlled by a supplemental current controller in an operation slightly on the generator side, whereby, at the expense of the kinetic energy of the synchronized machine, a current through the circuit is generated which is required for covering the dielectric losses and for maintaining the desired flux.