High-power drive using a wound rotor induction motor and two current controlled inverters

New configurations for high-power and high-performance motor drives suitable for steel rolling mills are presented. Three-level inverters, using 6 inch GTOs, can deliver 10,000 kVA output. In the case of drives rated more than several thousands kW, this capacity is still insufficient. Usually, for such drives, two three-level inverters have been combined using bulky, expensive inter-phase reactors. To solve these problems, a new configuration using wound-rotor induction motors and two inverters, is proposed. In this configuration, the outputs of the two inverters are combined directly within the machine. The novel features that can thus be obtained are explained.