In this article, a comparison between the performances of an online algebraic estimator and a reduced order observer is established in the context of adaptive load torque estimation in a controlled unit power factor rectifier-DC motor system combination. A passivity-based output feedback controller was constructed to regulate the angular speed while correcting the power factor of the mono phase boost rectifier. The proposed controller allowed us to compare the results of both on-line estimation techniques. The experimental results show a superiority of the algebraic approach in which the angular velocity was maintained at the desired reference value by the adapted controller, even under severe load changes on the motor shaft, while the power factor was also kept at high values in the power supply system.

This article deals with the low‐speed sensorless trajectory tracking control of a permanent magnet synchronous motor (PMSM). The rotor position and angular speed are obtained through back electromotive forces (back‐EMF), using extended state observers (ESOs) in the alpha‐beta coordinates. Additionally, the estimation of the back‐EMF is used by an algebraic module to reconstruct online the position and speed using an off‐line estimation of the back‐EMF parameter Km^. The control law is derived using a robust recursive controller design methodology, namely; the backstepping design approach in the d‐q coordinates. Estimation schemes allow the adaptation of the angular position, angular speed, and the load torque parameters in the control law. With this adaptation, the controller achieves the necessary robustness to reduce the effects of endogenous and exogenous perturbations present in the PMSM system. The trajectory tracking task is achieved at low angular speed, with the presence of a load torque applied to the motor shaft. Experimental results at low‐speed and rated load/no‐load conditions are presented to demonstrate the effectiveness and robustness of the proposed scheme.

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