Turker

A Robust Predictive Current Controller for PMSM Drives

High-performance current control is required to obtain a smooth output torque in permanent-magnet synchronous motor (PMSM) drives. In this manner, a new discrete-time robust predictive current controller is presented for PMSM drives. Controller and current prediction schemes are designed based on the dead-beat structure. The dead-beat control has good transient response, but it suffers from parametric uncertainties and unmodeled dynamics. In order to provide robustness, a discrete-time integral term is added to the dead-beat current prediction. The stability analysis is carried out considering the prediction error dynamics, nonlinear uncertain model of PMSM, and the integral action as the states of the overall system. The designed robust predictive controller is tested through numerical simulations and experiments. The proposed controller is easy to implement and suitable for high-performance PMSM applications.

Stabilisation of a class of 2-DOF underactuated mechanical systems via direct Lyapunov approach

This paper represents an alternative stabilisation procedure for a class of two degree-of-freedom underactuated mechanical systems based on a set of transformations and a Lyapunov function. After simplifying dynamic equations of the system via partial feedback linearisation and coordinate changes, the stability of the system is provided with Lyapunov’s direct method. Proposed control scheme is used on two different examples and asymptotic convergence for each system is proven by means of La Salle’s invariance principle. The designed controller is successfully illustrated through numerical simulations for each example.

A stabilizing controller for PVTOL aircraft

A stabilizing controller structure is proposed for planar vertical take off and landing (PVTOL) aircraft. In order to achieve almost global asymptotic stabilization, the coupling coefficient, ε, is assumed to be in the interval 0 ≤ ε <; 1. Stability analysis is performed based on a Lyapunov function and asymptotic convergence is proven by means of La Salles invariance principle. The proposed controller is implemented by numerical simulations on PVTOL aircraft and results are presented.

Exact Model Knowledge and Direct Adaptive Controllers on Ball and Beam

This paper presents analysis and implementation of Exact Model Knowledge (EMK) and Direct Adaptive control schemes on the 4th order ball and beam system in which the dynamics of the ball position and the dynamics of the beam angle are cascaded. For the controller analysis the error dynamic equations for ball position and the beam angle are derived for both cases. Following, experimental studies are conducted based on the proposed control approaches and it is presented that constant and sinusoidal references for the ball position are tracked asymptotically.

Stabilization of uncoupled PVTOL aircraft based on a Lyapunov function

In this paper we present a stabilization procedure for PVTOL (planar vertical take off and landing) aircraft with zero coupling coefficient that is defined as the effect of rolling moment on lateral acceleration. A stabilizing control structure has been designed via Lyapunov’s direct method including almost the whole state space and its asymptotic convergence has been proven using La Salle’s invariance principle. Simulation results have illustrated the effectiveness of proposed control algorithm.

A discrete-time controller for the reduction of commutation torque ripple in BLDCM drives

In this paper, a control strategy for the current loop of brushless DC motor (BLDCM) drives is proposed to reduce the commutation torque ripple. The proposed method consists of two different controllers based on dead-beat structure. Two different electrical model of BLDCM for conducting and commutation periods are considered by the controllers that are switched in conducting and commutation periods. In addition, a model based prediction is utilized to predict the beginning and ending of the commutation periods. Then, this information is used to modify the reference phase voltages in order to reduce commutation torque ripple. The characteristics of the proposed controller are evaluated by numerical simulations and satisfactory results are obtained.

Stabilization of a Class of 2-DOF Underactuated Mechanical Systems Via Lyapunov's Direct Approach

Abstract We study a class of 2-DOF underactuated mechanical systems(UAMS) where the objective is to obtain a design framework for stabilization. We propose a stabilization procedure via Lyapunovs direct approach to a class of UAMS employing partial feedback linearization and a change of coordinates. Asymptotic stability of unstable equilibrium point has been achieved in a large region of attraction and we make use of La Salles theorem to prove it. Designed controller scheme has been successfully illustrated through simulations on two different UAMS namely the pendulum on a cart and the inertia wheel pendulum.

A discrete-time current controller for permanent magnet synchronous motor drives

A discrete-time current controller is presented for the current loop of the permanent magnet synchronous motor drives. Firstly, the difference equations of current errors are obtained for constant reference values. Then, a dead-beat controller is designed to drive the dq-axes currents to the desired values. Discrete-time integral action with an anti-windup scheme is added to the dead-beat structure to achieve a better steady-state behaviour. In order to improve the transient properties of the controller, a current prediction scheme based on dead-beat structure is also introduced to the controller. Finally, the proposed controller is implemented through numerical simulations to illustrate the effectiveness for both transient and steady-state responses.

Design and implementation of an adaptive backstepping controller for a magnetic levitation system

Dynamics of magnetic levitation systems contain high order nonlinearities and uncertainties on the physical parameters. Despite of these uncertainties and nonlinearities, the main purpose of this study is to drive the position tracking error of the ball to zero. In order to achieve this, an adaptive backstepping controller is designed. After deriving the error dynamics and designing the adaptive backstepping controller, adaptation rules are defined for the uncertain model parameters and the gravitational acceleration in the system model. Numerical simulations are performed for different working conditions to test the designed controller and the adaptation rules. In addition to this, the viability of the proposed controller is verified through experimental studies and satisfactory results are obtained.

A switching adaptive current controller for BLDCM drives

A switching adaptive controller is proposed to control the phase currents in brushless DC motor (BLDCM) drives. After deriving the error dynamics, the conduction and commutation periods of the drive is taken into account separately, and two different controllers are designed for each operation region of the current loop of BLDCM drives. All the system constants in the dynamical model of the drive are considered uncertain, and adaptation rules are derived for these unknown parameters. The stability of the closed-loop system is shown by a common Lyapunov function, and the convergence of the current error to zero is proved as well. Various numerical simulations are performed for different working conditions to test the viability of the designed controller.