Modified Sliding Mode Control Research Articles

Modified sliding mode control for seamless integration of P.V. energy in A.C. grid

Solar energy is a potentially abundant and reliable source of renewable energy. While it can undoubtedly increase grid reliability and efficiency, the inverted voltage generated from P.V. sources may introduce distortion into the A.C. grid. The proposed control mechanism, modified sliding mode control (MSMC), can seamlessly integrate the inverter output generated by obtaining D.C. voltage from the boost converter linked with the P.V. output. This research confirms the validity of the proposed method by comparing its results with a similar system that is only integrated through filters and with a system with a P.I. control technique. The simulation proves the effectiveness of seamlessly integrating the Photovoltaic (P.V.) source into the A.C. grid.

A direct vector control based on modified SMC theory to control the double-powered induction generator-based variable-speed contra-rotating wind turbine systems

The current and active power ripples are two of the biggest drawbacks of the direct vector control (DVC), as these ripples cause several problems in the electric power generation system from contra-rotating wind turbines (CRWTs) systems. But the DVC technique has multiple advantages that make it among the most widely used techniques in the field of renewable energies for its ease to implementation and simplicity. In this work, a modified sliding mode controller (MSMC) was proposed and applied in the DVC strategy. The combination of the DVC and MSMC controller leads to a more robust control scheme, thus reducing the current, torque, active power, and reactive power ripples of the double-powered induction generator (DPIG). The designed DVC-MSMC strategy is used to improve the performance of the DPIG-based CRWT system. Simulation results done in Matlab software show the effectiveness and robustness of the proposed technique.

Direct Power Control Based on Modified Sliding Mode Controller for a Variable-Speed Multi-Rotor Wind Turbine System Using PWM Strategy

A robust and improved control scheme of a variable speed multi-rotor wind turbine (MRWT) system with a doubly fed asynchronous generator (DFAG) is displayed in this work. In order to improve the performances and effectiveness of the traditional direct power control (DPC) strategy of the DFAG, a new kind of sliding mode controller (SMC) called modified SMC (MSMC) is proposed. The most important advantage of the DPC-MSMC strategy is to reduce the power ripples and improve the quality of the currents provided to the grid. In addition, to control the rotor inverter, a pulse width modulation (PWM) technique is used. The proposed DPC-MSMC strategy was modeled and simulated using MATLAB/Simulink software. The simulation results showed that the ripples in stator currents, active and reactive powers and torque were considerably reduced for the proposed DPC-MSMC strategy compared to the traditional DPC. Additionally, the proposed DPC-MSMC method works excellently to reduce the total harmonic distortion (THD) of the stator current in the case of variable wind speed. On the other hand, a robustness test against parametric variations showed and confirmed the robustness of the proposed technique compared to the classical method.

Modified sliding mode control for a universal active filter-based solar microgrid system

This manuscript presents a larger signal model by combining the universal active filter (UAF) and the solar system with a vector switching operation (VSO) in a novel γθ frame. The detailed modelling of the S-UAF using VSO and modified sliding mode control (MSMC) is proposed for achieving better power quality (PQ) operation. MSMC-based novel γθ frame is used to estimate the accurate reference signals for SHAF during dynamic state conditions such as sag/swell, change in irradiance, fault and sensitive load condition. SEAF control is based upon the conventional dq control strategies and it adjusts the load voltage during dynamic conditions. SHAF is used to balance the grid side current and reduces the harmonic distortion by injecting the appropriate current in quadrature with the load current and facilitates fast transient response during sudden load change by providing better tracking capability and reduction in the switching losses. To validate the proposed controller and S-UAF approach with different test conditions, it is tested in MATLAB/Simulink environment and the related results are discussed.

Improving the performance of parallel robots by applying distinct hybrid control techniques

AbstractDuring the last two decades, parallel robots have become more ubiquitous, employed in a great variety of sectors, from food to aerospace industries. In fact, they are much more efficient than their serial counterparts in terms of performing fast motions and consuming less energy. However, due to their mechanical complexity, they present a highly complex non-linear dynamics, which makes the modelling and control tasks difficult. Aiming to improve the performance and robustness of the control laws already used to control this type of mechanisms, this paper proposes two hybrid control techniques. The first hybrid control is derived from the combination of a pure PD control with a modified Sliding Mode control. The second hybrid control, in its turn, combines a pure Computed Torque with the altered Sliding Mode control. The proposed modifications in the Sliding Mode control aim to achieve a considerable reduction of the tracking errors and chattering. A stability analysis of the proposed control techniques and an experimental validation are carried out, comparing the performance of the pure and hybrid control laws in a 5R parallel mechanism. Moreover, simulations are also conducted to evaluate the behaviour of a 3-dof spatial parallel robot, when performing a 3D-path. Analysing the simulations and the experimental results, it is possible to observe a significant reduction of the path tracking and steady-state errors in both hybrid control strategies.

Coordinated Power Sharing in Islanding Microgrids for Parallel Distributed Generations

Optimal power sharing between parallel inverters and the demand load in microgrids is challenging and particularly critical for power grids in islanding operation. This paper introduces a novel control approach for managing parallel distributed power sources in the presence of variable load in islanding regime. The proposed scheme is based on the modified sliding mode control (MSMC) which is combined with the optimal Riccati control method to achieve convergence at the slip level with higher accuracy. The mathematical principles of the network equations are derived and its stability is obtained using the Lyapunov function. The MSMC simulation results are discussed in relation to the conventional droop method, while the laboratory evaluation was carried out to characterize its dynamic and static response. The results show that the proposed scheme control is able to manage the distributed power generation for static and dynamic load scenarios, and as such, guarantying microgrid frequency stability.

A Modified Sliding Mode Control for Circulating Current Control and Voltage Balancing in Modular Multilevel Converter

A Modified Sliding Mode Control for Circulating Current Control and Voltage Balancing in Modular Multilevel Converter

Performance of the adaptive sliding mode control scheme for output voltage control of the DC/DC buck converter system

In this work, the DC output voltage of a step-down DC/DC buck converter system has been controlled using different schemes of sliding mode controllers (SMCs) such as classical sliding mode controller (CSMC), modified sliding mode controller (MSMC) and the adaptive sliding mode controller (ASMC). As the DC/DC buck converter is a nonlinear and time-variant system, the application of linear control techniques for controlling this type of converters is not always suitable. Therefore, the SMCs are used here due to their characteristic features of maintaining the overall system stability with acceptable performance in the absence or presence of the parameters uncertainty and external disturbance. The simulation results obtained using MATLAB/Simulink software show the advantages of using ASMC in terms of reducing the settling time, the chattering value in the control action and the steady state error but the hitting time is increased when compared with the CSMC. Besides, the simulation results show the advantages of using ASMC in terms of reducing the settling time and the chattering value, but the steady state error and the hitting time are increased when compared with the MSMC. Since the buck converter is a fast response system, the performance of the ASMC is better than that of the CSMC and MSMC in terms of reducing the settling time and the chattering value in the control action.

Robust Control for a Two DOF Robot Manipulator

In this paper, we present robust control techniques applied on a manipulator robot system: modified sliding mode control (MSMC) and backstepping control (BSC). The purpose is to evaluate SMC and BSC performances, taking into account the model uncertainties. Then, the obtained results of MSMC technique are compared with those of the adaptive sliding mode. Both methods have comparable simulation results which show a good quality of robustness. However, simulation results prove that the modified SMC is more robust, mostly under the effect of external variations and uncertainties.

High Accuracy Power Sharing in Parallel Inverters in an Islanded Microgrid Using Modified Sliding Mode Control Approach

Increasing the penetration level of distributed generation (DG) units in micro grids which feeds the large loads in parallel connections creates the concept of power sharing phenomena in recent researches. In island mode of micro grid the voltage and the frequency control are done using the high inertia inverter. Therefore, the internal control loop is executed in such way to avoid all of DGs not to be overloaded. consequently, the reactive power-sharing error is eliminated and the voltage is also kept constant within the permissible range. This paper, presents a modified control method based on sliding mode approach. The proposed control method is tested using several different disturbances and three scenarios. Also, the fractional order calculus is applied to proposed control strategy to increase the convergence speed and the system accuracy. finally, the proposed method is compared to other well-known controlling approaches while the achieved results confirms the superiority of proposed one.

Vibration Reduction of the Nonlinearly Tufted Carpet Yarn by a Modified Sliding Mode Control Method

The yarn vibration causes the yarn tension value to fluctuate, causing a change in the amount of yarn feed, thus causing a deviation of the carpet pile height from the predetermined value. To solve this problem, the sliding mode control algorithm is used to design the sliding mode function and the sliding mode control law. And four variables in the yarn vibration system are controlled by the MATLAB software. For solving the chattering problem of the control law, the sliding mode control law is improved. The fuzzy sliding mode control algorithm based on the quasisliding mode is adopted. The results show that the sliding mode control algorithm is effective, but the sliding mode control force needs to be switched at high frequency and there is severe chattering. The fuzzy sliding mode control algorithm based on quasisliding mode is adopted to achieve better control effect with a smaller force. In addition, the control force does not have high‐frequency switching, and the change is relatively stable, which reduces the chattering phenomenon of sliding mode control.

Optimization of Modified Sliding Mode Control for an Electro-Hydraulic Actuator System with Mismatched Disturbance

Optimization of Modified Sliding Mode Control for an Electro-Hydraulic Actuator System with Mismatched Disturbance

Optimization of Modified Sliding Mode Control for an Electro-Hydraulic Actuator System with Mismatched Disturbance

Optimization of Modified Sliding Mode Control for an Electro-Hydraulic Actuator System with Mismatched Disturbance

Neural network-based nonlinear sliding-mode control for an AUV without velocity measurements

ABSTRACTFor an autonomous underwater vehicle (AUV), a nonlinear sliding-mode control based on linear-in-parameter neural network (NSMC-NN) is proposed to deal with the unknown dynamics and the external environmental disturbances and a first-order robust exact differentiator is introduced considering unknown velocities of an AUV. The sliding-mode surfaces of NSMC-NN can enter into the boundary layers after a period that depends on the design parameters. To demonstrate the feasibility of the proposed controller, simulation studies applying Omni-Directional Intelligent Navigator (ODIN) are carried out, compared with proportional–integral–derivative (PID) and the modified sliding-mode control (MSMC). The simulation results show that the presented control method can achieve the effective control performance.

Modified Sliding Mode Control for Mismatched Uncertain Large-Scale Systems

In this paper, a modified sliding mode control is proposed to stabilize a class of large-scale systems with mismatched uncertainties, unknown exogenous disturbances and without the measurements of the states. Based on the Lyapunov method, appropriate linear matrix inequality stability conditions are derived to guarantee the stability of the system. Then, a modified adaptive sliding mode control law is proposed to guarantee the finite time reachability of the system states by using output feedback only. Final, a double-inverted pendulums system connected by a spring is simulated to demonstrate the efficacy of the proposed method.

Modified Sliding Mode Control for Mismatched Uncertain Systems with Unknown Disturbances

In this paper, a new sliding mode control law is developed for a class of mismatched uncertain systems with more general exogenous disturbances. First, we derive a new existence condition of linear sliding surface in terms of strict linear matrix inequalities such that the reduce-order sliding mode dynamics is is asymptotically stable. Second, we propose an adaptive sliding mode control law such that the system states reach the sliding surface in finite time and stay on its thereafter. Final, a numerical example is used to demonstrate the efficacy of the proposed method.

Design Modified Sliding Mode Controller with Parallel Fuzzy Inference System Compensator to Control of Spherical Motor

The increasing demand for multi-degree-of- freedom (DOF) actuators in a number of industries has motivated a flurry of research in the development of non-conventional actuators, spherical motor. This motor is capable of providing smooth and isotropic three- dimensional motion in a single joint. Not only can the spherical motor combine 3-DOF motion in a single joint, it has a large range of motion with no singularities in its workspace. The spherical motor, however, exhibits coupled, nonlinear and very complex dynamics that make the design and implementation of feedback controllers very challenging. The orientation- varying torque generated by the spherical motor also contributes to the challenges in controller design. This paper contributes to the on-going research effort by exploring alternate methods for nonlinear and robust controlling the motor. The robust sliding mode controller proposed in this paper is used to further demonstrate the appealing features exhibited by the spherical motor. In opposition, sliding mode controller is used in many applications especially to control of highly uncertain systems; it has two significant drawbacks namely; chattering phenomenon and nonlinear equivalent dynamic formulation in uncertain dynamic parameter. The nonlinear equivalent dynamic formulation problem and chattering phenomenon in uncertain system (e.g., spherical motor) can be solved by using artificial intelligence theorem and applied a modified linear controller to switching part of sliding mode controller. Using Lyapunov-type stability arguments, a robust modified linear fuzzy sliding mode controller is designed to achieve this objective. The controller developed in this paper is designed in a robust stabilizing torque is designed for the nominal spherical motor dynamics derived using the constrained Lagrangian formulation. The eventual stability of the controller depends on the torque generating capabilities of the spherical motor.

Study of Modified Sliding Mode Control Strategy for STATCOM with LCL Filter

This paper studies the control strategy of STATCOM with LCL filter. The STATCOM sixth orders differential equations in dq coordinate separate to two parts. Invert system theory deals with their uncoupling and nonlinearity. Then the sliding mode control strategy is used to the differential equations. Finally simulation results show validity and effectiveness of the design by comparing with PI controller.

Biological Systems Drug Infusion Controller Using FREN With Sliding Bounds

In this paper, a direct adaptive control for drug infusion of biological systems is presented. The proposed controller is accomplished using our adaptive network called Fuzzy Rules Emulated Network (FREN). The structure of FREN resembles the human knowledge in the form of fuzzy IF-THEN rules. After selecting the initial value of network's parameters, an on-line adaptive process based on Lyapunov's criteria is performed to improve the controller performance. The control signal from FREN is designed to keep in the region which is calculated by the modified Sliding Mode Control (SMC). The simulation results indicate that the proposed algorithm can satisfy the setting point and the robust performance.

Modified Sliding Mode Control for Wind-Excited Benchmark Problem

Among promising control strategies, the sliding mode control is particularly robust with respect to structural uncertainty. In this paper, a modified sliding mode control (MSMC) strategy using dynamic output feedback is presented and demonstrated for the wind-excited benchmark building equipped with an ATMD (active tuned mass damper) control device. The main advantage of the MSMC presented is its ability to systematically modulate the control effort through the introduction of a prefilter prior to the control force. For practical implementation of a MSMC using acceleration measurements at strategic locations, a Kalman.Bucy filter type of observer is designed based on the augmented system. Hence the sliding surface design is composed of the observer state, and the modulation of control forces can be achieved by forming an optimization problem with a linear quadratic objective function. As shown by the simulation results of the wind-excited benchmark building, the modified sliding mode controller indeed has the capability of systematically modulating the control force. Moreover, the remarkable performance of the MSMC demonstrates that the strategy presented is suitable for the wind-excited tall buildings.