An MRAS Observer-Based Speed Sensorless Control Method for Dual-Cage Rotor Brushless Doubly Fed Induction Generator

This article presents a model reference adaptive system (MRAS) speed observer based on the power winding (PW) active power and reactive power for dual-cage rotor brushless doubly fed induction generator (DCR-BDFIG). The mathematical relationship between the PW current and control winding (CW) current is derived first. Then, to reduce costs and to improve the reliability, a PW power-MRAS-based speed observer is designed with the stability analyzed. In the proposed speed observer, the PW power is selected as the reference model since it is relatively readily available and smooth due to the clamped PW voltage under grid-connected condition. In addition, only the CW current is required to be measured for the estimated PW power of the adaptive model, being simple and easy implemented. Finally, combining the proposed speed observer and the grid-connected power control system, a complete speed sensorless control system for grid-connected DCR-BDFIG is designed and implemented to regulate the active power and reactive power independently. The detailed simulation and experiments are carried out, showing that the estimated rotor speed can track its real values with minor steady-state errors and fast transient responses. Both simulation and experiments verify the effectiveness of the proposed speed sensorless control method for DCR-BDFIG.