A DC motor velocity control in feedback systems usually requires a velocity sensor, which increases the controller cost. Additionally, the velocity sensor used in industrial applications presents several disadvantages such as maintenance requirements and signal conditioning. In this work, we propose a robust velocity control scheme applied to a DC motor based on estimation strategies using a sliding-mode observer. This means that measurements with mechanical sensors are not required in the controller design. The proposed observer estimates the rotational velocity and load torque of the motor. The controller design applies the exact-linearization technique combined with the super-twisting algorithm to achieve robust performance in the closed-loop system. The controller validation was carried out by experimental tests using a workbench, which is composed of a control and data acquisition Digital Signal Proccessor board, a DC-DC electronic converter, an interface board for signals conditioning, and a DC electric generator connected to an adjustable resistive load. The simulation and experimental results show a significant performance of the proposed control scheme. During tests, the accuracy, robustness, and speed response on the controller were evaluated and the experimental results were compared with a classic proportional-integral controller, which uses a conventional encoder.

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The wind power systems of variable velocity using a doubly-fed induction generator dominate large-scale electrical generation within renewable energy sources. The usual control goal of the wind systems consists of maximizing the wind energy capture and streamlining the energy conversion process. In addition, these systems are an intermittent energy source due to the variation of the wind velocity. Consequently, the control system designed to establish a reliable operation of the wind system represents the main challenge. Therefore, emulating the operation of the wind turbine by means of an electric motor is a common strategy so that the controller design is focused on the induction generator and its connection to the utility grid. Thus, we propose to emulate the dynamical operation of a wind turbine through a separately excited DC motor driving by a sensor-less velocity controller. This controller is synthesized based on the state-feedback linearization technique combined with the super-twisting algorithm to set a robust closed-loop system in the presence of external disturbances. A robust velocity observer is designed to estimate the rotor velocity based on the armature current measuring. Furthermore, a robust differentiator is designed for estimating the time derivative of the velocity error variable, achieving a reduction in the computational calculus. Experimental tests were carried using a separately excited DC motor coupled with a dynamometer to validate the proposed wind turbine emulator.

Hoy en día, la mejora de la calidad de la energía ha tomado mucha relevancia debido al crecimiento sostenido de la demanda de carga eléctrica para ser abastecida con altos estándares y eficiencia. Los consumidores de energía tienen la posibilidad de mejorar sus características de carga para evitar una excesiva infraestructura de generación y distribución por parte de las empresas proveedoras energía. En este trabajo se propone un compensador estático de potencia reactiva para mejorar el factor de potencia y contribuir a una mejor regulación de voltaje en la red eléctrica. El compensador está compuesto por la red eléctrica, un filtro LCL, un inversor trifásico y un bus de CD. A partir del modelo en el marco dq, el compensador de potencia reactiva se sintetiza para regular la potencia reactiva y el voltaje del bus de CD de un inversor. La ley de control super-twisting se aplica para proporcionar robustez al desempeño del sistema y cancelar las perturbaciones externas las cuales son originadas por un flujo de potencia activa al controlar la velocidad angular de un motor de inducción con seguimiento de un tren de pulsos arriba de la velocidad de sincronismo, y se acopla en la flecha un generador de inducción que inyecta energía eléctrica a la red eléctrica, como carga del motor. Este trabajo presenta resultados experimentales que validan la robustez del sistema de control aplicado al compensador estático de potencia reactiva.