Real-Time Maximum Torque per Ampere Control of Brushless DC Motor Drive With Minimum Torque Ripple

A nonlinear control scheme is proposed for realtime tracking of maximum torque per ampere trajectory of the surface-mounted brushless dc motorwith non-sinusoidal back electromotive force (back-EMF). The strategy employs the Lagrange's Theorem to obtain the optimum stator current, at which both torque ripple and corresponding current magnitude become minimized. A new maximum torque per ampere (MTPA) criterion is introduced. Forcing this criterion to zero guarantees MTPA realization. The input-output feedback linearization (IOFL) control scheme is employed to improve tracking of the applied optimum currents. In the suggested approach, the magnitude of the stator current vector is minimized effectively in each instant. The performance of the control system is validated through experimental results.