Jorge Rivera

Hybrid Control of Induction Motors via Sampled Closed Representations

In this paper, a controller for induction motors is proposed. A continuous feedback is first applied to obtain a discrete-time model in closed form. Then, on the basis of these exact sampled dynamics, a discrete-time controller ensuring speed and flux modulus reference tracking is determined, making use of the sliding mode technique. The resulting controller is hence hybrid, in the sense that it contains both continuous and discrete-time terms. It is shown how to implement such a hybrid controller using the so-called exponential holder, which is the only device to be implemented analogically, together with an analog integrator. Moreover, a discrete-time reduced-order observer is designed for rotor fluxes and load torque estimation. The performance of the proposed controller is finally studied by simulation and experimental tests.

DISCRETE-TIME SLIDING MODE CONTROL OF AN INDUCTION MOTOR

Abstract A discrete-time sliding mode with block control aided design is applied to a nonlinear discrete-time induction motor model where the load torque is considered as unknown perturbation. With full state measurements, both rotor speed and rotor flux amplitude tracking objectives are satisfied. Then, a reduced order observer is implemented where speed and current measurements provide the observation for the unreachable fluxes and load torque. The simulations predict the system to be robust with respect to external load torques.

Discrete time sliding mode control with application to induction motors

This work deals with a sliding mode control scheme for discrete time nonlinear systems. The control law synthesis problem is subdivided into a finite number of subproblems of lower complexity, which can be solved independently. The sliding mode controller is designed to force the system to track a desired reference and to eliminate unwanted disturbances, compensating at the same time matched and unmatched parameter variations. Then, an observer is designed to eliminate the need of the state in the controller implementation. This design technique is illustrated determining a dynamic discrete time controller for induction motors.

Robust Trajectory Tracking for an Electrohydraulic Actuator

Various robust control techniques, such as integral-block, sliding-mode, and H-infinity controls, are combined to design a controller, forcing an electrohydraulic actuator which is driven by a servovalve to track a chaotic reference trajectory. This approach enables one to compensate the inherent nonlinearities of the actuator and reject matched external disturbances and attenuate mismatched external disturbances. The capabilities of the approach are illustrated in a simulation study.

Robust Nested Sliding Mode Regulation with Application to Induction Motors

In this work a robust nested sliding mode block control is designed for a class of nonlinear systems with unknown matched and unmatched perturbations. It is well known that sliding mode is robust against matched perturbations. In order to enhance this robustness property, a novel nested sliding mode procedure is proposed. The performance of the designed controller has been tested considering an induction motor with unknown load torque and varying stator and rotor resistances, where the only information are the estimation of the upper bounds with respect to the nominal values.

ABS + active suspension control via sliding mode and linear geometric methods for disturbance attenuation

This paper deals with the control of an Anti-lock Brake System (ABS) assisted with an active suspension. The main objective is to track the slip rate of a car and ensure a shorter distance in the braking process. For the ABS subsystem an integral nested sliding mode controller based on the block control principle is designed. On the other hand, for the active suspension subsystem a sliding mode controller based on regular form and linear geometric techniques is proposed. Both closed-loop subsystems are robust in presence of matched and unmatched perturbations. To show the performance of the proposed control strategy, a simulation study is carried on, where results show good behavior of the ABS with active suspension under variations in the road.

Second order sliding mode sensorless torque regulator for induction motor

In this paper the torque and the square of the rotor fluxes magnitude using a second order sliding mode (SM) controller for an induction motor, is proposed. The main contribution of the control scheme presented here is the output regulation as well as the asymptotically stabilization of the zero dynamics. The sliding manifold is designed such that the speed zero dynamics become asymptotically stable on this manifold. To enforce the SM motion on the designed manifold a super-twisting SM algorithm is used. This algorithm permits to reduce chattering that is inherent in standard sliding mode control and to improve accuracy. The rotor fluxes and speed are estimated by means of an adaptive observer, whereas the estimate of the load torque is obtained via design of a robust differentiator. The effectiveness of the designed observer-control scheme is confirmed via simulation.

Discontinuous Output Regulation of the Pendubot

Abstract In this work we address the problem of nonlinear output regulation of an underactuated system by means of discontinuous control actions, in particular, the sliding mode output regulator problem in the case of error feedback is considered for the Pendubot system. The theory is revisited for nonlinear systems presented in the so-called Regular form. Simulations are carried out to verify the effectiveness of the discontinuous method.

Discrete-time modeling and control of a boost converter by means of a variational integrator and sliding modes

Abstract This work deals with the discrete-time modeling of a boost DC-to-DC power converter by means of a discrete Lagrangian formulation based on the midpoint rule integration method. Then in the basis of this model, a discrete-time sliding mode regulator is designed in order to force the boost circuit to track a DC-biased sinusoidal signal. Simulations and experimental tests are carried on where the great performance of the proposed methodology is verified.

Super-twisting sensorless control of linear induction motors

In this work, a sensorless control scheme is presented for linear induction motors. The secondary fluxes are algebraically calculated by first determining the primary fluxes, then, a super-twisitng observer for secondary fluxes is designed in order to retrieve the back-EMF components by means of the equivalent control method. Based on these components, the linear velocity is determined and used in a linear velocity and load force observer, where the estimated variables along with primary current and voltage measurements are used to control the linear induction motor for the tracking of a reference linear velocity signal and a square secondary flux modulus, all by means of a super-twisting controller. Simulations show that the proposed observer based controller scheme performs well when tracking a time varying linear velocity signal.