A simplified method for dynamic control of brushless doubly-fed machines

Brushless doubly-fed machines (BDFM) have shown promise for adjustable speed drives applications, when they enable a reduction in converter rating and system cost. While scalar control methods are immediately applicable for low performance general purpose drives, the dynamic performance is far from optimum. A rotor flux oriented controller has been developed and exhibits good dynamic performance at the expense of using a shaft position encoder. The paper illustrates a simplified control algorithm which is based on the field oriented controller, but eliminates rotor position sensing. Simulation and experimental results illustrate the performance of the proposed control strategy and show the improvement over conventional scalar methods.