Vector-controlled double-inverter-fed wound-rotor induction motor suitable for high-power drives

In this paper, the principle and the results of an experimental study concerning a new high-power inverter drive system are presented. One usual method of supplying large vector-controlled AC drives is by three-level inverters configured with 6-in 6-kV 6-kA gate-turn-off thyristors. These inverters can be adopted for drives that have ratings less than several thousand kilowatts. However, in the case of drives rated more than several thousand kilowatts, two inverters have been combined using interphase reactors. However, interphase reactors have problems of acoustic noise and high losses and, in addition, are bulky and expensive. To overcome these problems, a new configuration using a wound-rotor induction motor and two current controlled pulsewidth modulation inverters is proposed. In this configuration, the outputs of the two inverters are combined electromechanically in the machine and, as a result, novel features can be obtained.