Online MTPTA and MTPIA Control of Brushless Doubly Fed Induction Motor Drives

This article proposes a nonlinear controller for brushless doubly-fed induction motor (BDFIM) drives on the basis of input-output feedback linearization (IOFL). In the proposed control approach, first, the maximum torque per inverter ampere (MTPIA) control strategy is considered by applying a fifth-order (reduced-order) model of BDFIM. By realizing the MTPIA, the control winding (CW) current magnitude is minimized under the constraint of constant torque. The realization criterion of MTPIA approach is independent of torque level and CW frequency. To fairly share the current between stator windings and minimizing the total current magnitude for a given torque, the MTPIA idea should be extended. Since, the power winding (PW) of BDFIM is not controllable, obtaining this purpose is a challenge. Therefore, to solve this problem, the model-based maximum torque per total ampere (MTPTA) control is introduced for BDFIM drives and the conditions for realizing this strategy are determined. It should be noted that the total amperes refer to the sum of the PW and the CW current magnitudes. In addition, using the fifth-order model of BDFIM, a nonlinear controller is developed based on IOFL technique which is capable to force the deviation from realization criterion of both proposed strategies to zero while the torque is controlled with high accuracy. The overall stability of the proposed controller is proven using the Lyapunov control theory. The validity of the proposed approach is finally verified by simulation and experimental results.