Stator flux oriented control of a cascaded doubly-fed induction machine

A cascaded doubly-fed induction machine (CDFM) is a connection of two wound rotor induction machines. In comparison to a single doubly-fed induction machine (SDFM) brushes are obsolete. Due to recent developments in brushless doubly-fed machine design, there is a renewed interest in associated control. Theoretical and experimental studies of a stator flux oriented control method for a CDFM are presented. The use of vector control principles to control torque, speed, active and reactive power is investigated. It is found that the additional closed rotor circuit of the CDFM introduces a cross coupling between the d-axis and the q-axis. Nevertheless, the cross coupling effect remains small in relation to the overall control concept so that the control of the CDFM resembles that of the SDFM.