Steady-state operation of the brushless cascaded doubly fed machine: a survey
Purpose - The purpose of this paper is to investigate the steady-state stability and features of the brushless cascaded doubly fed machine (BCDFM), which is made up of two wound-rotor induction machines: the power machine (PM) and the control one, with their rotors mechanically and electrically coupled. Design/methodology/approach - The machine modelling is first treated considering a Park reference frame linked to the rotating field of the PM. Then, a state representation related to small perturbations is established following the linearisation of the BCDFM model around a steady-state operating point. This allows the investigation of BCDFM steady-state stability, power flow and the torque-speed characteristics. Findings - It has been found that the electrical variables of the control machine greatly affect the BCDFM steady-state stability and characteristics. Research limitations/implications - The work should be extended considering a validation of the established results through experimental tests. Originality/value - The steady-state small perturbation of the BCDFM model has been introduced for the first time, which is the key of the machine steady-stability analysis and features investigation.
modelling electric machines torque stability (control theory) eigenvalues and eigenfunctions