Variable Structure Control Strategy Research Articles

Performance Evaluation of Variable Structure and Linear Control Strategies for Grid Connected PMSG Wind Energy System under Different Operating Conditions

Performance Evaluation of Variable Structure and Linear Control Strategies for Grid Connected PMSG Wind Energy System under Different Operating Conditions

A New Variable Structure Control Scheme for Mismatched Uncertain Large Scale Systems

In this paper, a new decentralized adaptive output feedback variable structure control scheme is designed for mismatched uncertain large-scale systems where the exogenous disturbance is unknown. The proposed approach uses output information completely in sliding surface and controller design. Therefore, conservatism is reduced and robustness is enhanced. Furthermore, the reduce order system in sliding mode is asymptotically stable under certain conditions. Finally, a numerical example is used to demonstrate the efficacy on the method.

RETRACTED ARTICLE: Chattering-free variable structure controller design via fractional calculus approach and its application

The chattering phenomenon in variable structure control (VSC) is always given to attention long time. This paper proposes a novel type of control strategy combining the fractional calculus with second-order sliding mode control called second-order fractional variable structure control for a class of nonlinear systems. A novel adaptation law is assigned for reaching the controller part of the sliding mode control to eliminate the chattering phenomenon in spite of the small and large uncertainties in the system. The applied adaptation law acts like a saturation function technique in a thin boundary layer near the sliding surface so that the stability of the system is guaranteed. The proposed chattering-free VSC displays better tracking performance, higher degree of robustness to parameter variations, and lower control effort need. The simulation utilizing the nonlinear models of inverted pendulum and interconnected twin tank system are examined to verify the effectiveness of the proposed control strategy, and its advantages are shown in the results. Finally, the physical application of the proposed VSC strategy is demonstrated through an instance of a typical hexapod robot.

Soft variable structure controller design for singular systems

A novel soft variable structure control (SVSC) scheme is addressed for a class of singular systems under I-controllable in this paper. The structural features of SVSC with differential equations are investigated. The stability of singular systems based on SVSC scheme is guaranteed by an equivalent characterization theory, and then a soft variable structure controller is designed. The concrete algorithm of SVSC with differential equations is proposed. The developed SVSC law for singular systems is carried out for the purpose of achieving rapid regulative rate, and shortening arrival time. Moreover, system chattering can be attenuated in the process of approaching to the equilibrium state. Finally, a simulation example is provided to verify the feasibility of the proposed scheme.

Multi-phase robust position control scheme for synchronous reluctance motor

In the recent years the synchronous reluctance motor (SynRM) has received much attention due to its desirable controllability and simple structure. In this paper, in order to improve the position control performance of a three phase SynRM, a control scheme is proposed. In the proposed controller design, the smooth operation of the traditional linear controllers and the robustness of variable structure controllers have been considered. The proposed controller eliminates the drawbacks of traditional linear control schemes and conventional variable structure control scheme, such as high frequency chattering at the same time. Yet, their advantages such as smooth operation and robustness are preserved as a big merit. The experimental results clearly demonstrate the superiority of the proposed controller over conventional control schemes.

Multiphase Robust Position Control Scheme for Synchronous Reluctance Motor

In the recent years the synchronous reluctance motor (SynRM) has received much attention due to its desirable controllability and simple structure. In this paper, in order to improve the position control performance of a three phase SynRM, a control scheme is proposed. In the proposed controller design, the smooth operation of the traditional linear controllers and the robustness of variable structure controllers have been considered. The proposed controller eliminates the drawbacks of traditional linear control schemes and conventional variable structure control scheme, such as high frequency chattering at the same time. Yet, their advantages such as smooth operation and robustness are preserved as a big merit. The experimental results clearly demonstrate the superiority of the proposed controller over conventional control schemes.

Study on maximum power point tracking of photovoltaic array in irregular shadow

Abstract Traditional maximum power point tracking (MPPT) methods can hardly find global maximum power point (MPP) because output characteristics curve of photovoltaic (PV) array may have multi local maximum power points in irregular shadow, and thus easily fall into the local maximum power point. To address this drawback, Considering that sliding mode variable structure (SMVS) control strategy have such advantages as simple structure, fast response and strong robustness, and P&O method have the advantages of simple principle and convenient implementation, so a new algorithm combining SMVS control method and P&O method is proposed, besides, PI controller is applied to reduce system chattering caused by switching sliding surface. It is applied to MPPT control of PV array in irregular shadow to solve the problem of multi-peak optimization in partial shadow. In order to verity the rationality of the proposed algorithm, the experimental circuit is built, which achieves MPPT control by means of the proposed algorithm and P&O method. The experimental results show that compared with the traditional P&O algorithm, the proposed algorithm can fast track the global MPP, tracking speed increases by 60% and the relative error decreased by 20%. Moreover, the system becomes more stable near the MPP, the fluctuations of output power is greatly reduced, and thus make full use of solar energy.

Soft variable structure controller design for constrained systems based on S-class functions

A soft variable structure control (SVSC) strategy based on S-class functions is addressed in this paper. Firstly, the definition of SVSC strategy is given, the structure of SVSC system under constrained control input is analyzed, and S-class functions with smoothness, strict monotonicity, and saturation are presented. Secondly, the sufficient condition on the stability of SVSC system is obtained by Lyapunov stability theory. A soft variable structure controller based on S-class functions is developed aiming at optimizing the smoothness problem of the SVSC systems based on variable saturations, and the chattering problem of sliding mode control (SMC) systems. Then, the concrete algorithm on SVSC strategy based on sigmoid functions is obtained. Finally, a simulation example is carried out to verify the feasibility and effectiveness of the SVSC strategy, and compared with SMC strategy, high regulation rate is achieved, settling time is shorted, and the system chattering can be reduced by the proposed strategy.

Variable Structure Control Strategy Research on Regenerative Braking for a Brushless DC Motor Driven Electric Bus Cruising Downhill

To use regenerative braking to act as an auxiliary brake to maintain the constant speed of a brushless DC motor driven electric bus (BDCMEB) on downhill based on the feature of double-loop control structure of the control method for electric vehicle traction motor and the variable structural characteristics of PWM Control System for brushless DC Motor. A double-manifold variable structure control method to control regenerative braking is proposed for the bus cruising downhill. The impact of lead-acid battery's charge acceptance ability over a long charging period on the regenerative braking force of a driving motor is analyzed. Dynamic model of the bus on long downhill is established. A double-manifold variable structure controller is designed for the DCMEB on long downhill. The simulation result shows that the control system maintains enough stability and strong robustness. It may be achieved for the bus to maintain a constant speed downhill only by regenerative braking on a smaller slope. But the dynamic process is very slow. When deceleration or a constant speed is desired on a larger slope, only by electro mechanical parallel braking can the bus track the target speed precisely and quickly.

Multivariable adaptive variable structure disturbance rejection control for DFIG system

A novel variable structure and disturbance rejection control strategy for a wind turbines equipped with a double fed induction generator based on stator‐flux‐oriented vector control is presented. According to estimation of maximum power operation points of wind turbine under stochastic wind velocity profiles and tracking them using traditional offline gain, scheduling and innovative adaptive online method is necessary. To demonstrate the effectiveness of the proposed control strategy, the estimation of maximum operating power point of wind turbine and tracking it under stochastic wind velocity profiles has been considered as a test case. Simulation results show the validity of the proposed technique. © 2014 Wiley Periodicals, Inc. Complexity 21: 50–62, 2016

High-Order Terminal Sliding Mode Control for Brushless Doubly-Fed Machines

A novel sliding-mode variable structure(SMVS) control strategy is proposed to reduce the ripples of flux and torque of brushless double-fed machines(BDFM) based on direct torque control system. In order to ensure the constant switching frequency for the inverter, two hysteresis regulators in the conventional direct torque control system system are substituted by the SMVS controllers of flux and torque，nonsingular terminal sliding modes are designed to make the motor power reach the given values in a finite period of time. and the high-order sliding mode method is adopted to estimate the chattering phenomenon of the conventional sliding mode. Meanwhile, to obtain the parameters of High-order terminal sliding mode control, a method of fuzzy neural network is presented. The simulation results show that the nonsingular high-order terminal sliding-mode control can improve the robustness and dynamic response of the system.

The Application of Sliding Mode Control in Current Source Converter

Current source converter is a variable structure system due to its switching nature, so that it can easily cause the output current waveform distortion and can not be accurately track the reference current. To solve the above problems, this paper proposes a new variable structure control strategy with fan-shaped sliding domain in the current source converter control system. In the control strategy, the paper deduces the switching surface and switching control law of SMVSC, and calculates the sliding existence domain based on the mathematical model of current source converter. Finally, the simulation results show that the control scheme can make current source converter have better output current waveform, fast tracking the reference current, and strong anti-interference ability. Therefore, the control scheme is correct, effective and feasible.

Sliding Mode Variable Structure Control and Real-Time Optimization of Dry Dual Clutch Transmission during the Vehicle’s Launch

In order to reflect driving intention adequately and improve the launch performance of vehicle equipped with five-speed dry dual clutch transmission (DCT), the issue of coordinating control between engine and clutch is researched, which is based on the DCT and prototype car developed independently. Four-degree-of-freedom (DOF) launch dynamics equations are established. Taking advantage of predictive control and genetic algorithm, target tracing curves of engine speed and vehicle velocity are optimally specified. Sliding mode variable structure (SMVS) control strategy is designed to track these curves. The rapid prototyping experiment and test are, respectively, conducted on the DCT test bench and in the chassis dynamometer. Results show that the designed SMVS control strategy not only effectively embodies the driver’s intention but also has strong robustness to the vehicle parameter’s variations.

Design and experimental evaluation of higher order sliding mode control for vibration suppression of shape memory alloy actuated structure

Abstract This paper deals with the utilization of shape memory alloy actuators in controlling and suppressing the vibration of flexible cantilever beam based structure. Emphasis is placed on the design of higher order sliding mode control in particular super twisting controller for improved performance. The controller is evaluated for the damping of first mode vibration of the structure. Model identified by ARX method is used for simulation and real time experimentation. The experimental results obtained demonstrate the potential of nitinol as a viable means for damping the vibration of the structure. Additionally the variable structure control strategy provides robustness to model uncertainties and parameter variations, while effectively compensating for system nonlinearities, achieving superior damping capability.

자동피킹 시스템 구동용 선형 유도 모터 드라이브 설계 및 적분형 가변구조 제어 기반의 강인 위치 제어기 설계

고 정밀도와 고 속응성의 물류 이송을 위한 자동피킹 시스템 (Automatic Picking System; APS) 구동용 선형 유도 모터 드라이브의 설계 및 강인한 위치 제어 기법이 제안된다. 모델 불확실성에 대한 강인한 위치 제어기 설계를 위해서 적분형 가변구조 제어 기법이 고려된다. APS의 외란추력, 질량 및 마찰계수 등의 기계적 파라미터 변화는 위치 제어 성능에 직접적 영향을 주며 이러한 불확실성 하에서도 강인한 위치 응답 성능을 보유하는 위치 제어기가 설계된다. 선형 유도 모터의 모델을 위한 Simulink 라이브러리가 상태방정식으로부터 개발되며 이를 활용한 Matlab - Simulink 기반의 비교 시뮬레이션을 통해 제안된 방식이 강인한 위치 응답 성능을 가지며 고 정밀도와 고 속응성을 요구하는 APS에 적합함이 입증된다. To implement an automatic picking system (APS) in distribution center with high precision and high dynamics, this paper presents a design of a linear induction motor (LIM) drive and robust position controller based on integral variable structure control (IVSC) scheme. The force disturbance as well as the mechanical parameter variation such as the mass and friction coefficient gives a direct influence on the position control performance of APS. To guarantee a robust control performance in the presence of such uncertainty, a robust position controller is designed. A Simulink library is developed for the LIM model from the state equation. Through this model and comparative simulation based on Matlab - Simulink, it is proved that the proposed scheme has a robust control nature and is most suitable for APS.

A sliding sector approach to quantized feedback variable structure control

This paper is concerned with the quantized feedback quadratic stabilization problem for linear time-invariant systems. Sliding sector based quantized state feedback variable structure control schemes are established. The main benefit of the sliding sector technique is that it can avoid chattering caused by the utilization of variable structure control strategy. With the proposed discrete on-line adjustment of the quantization parameter, it is shown that the proposed sliding sector based sliding mode controllers can tackle state quantization and guarantee quadratic stability of the closed-loop system. Simulation results are given to verify the effectiveness of the proposed method.

Reliable piecewise control design for systems with actuator saturation and fault

This paper proposes a reliable piecewise control (RPC) law for input-saturated systems with norm-bounded external disturbances and faults, whose feature is that the following three goals can be simultaneously achieved: improving the disturbance attenuation performance, maximising the region of attraction, and totally removing the influence of the actuator fault. Here, the RPC law is developed to be dependent on several switching sets with the set invariance property, where the size of the most inner switching set is minimised and the size of the outer switching sets is maximised to fulfil the first two goals, respectively. Moreover, for the third goal, this paper introduces a norm-bounded representation method for the actuator fault and incorporates a variable structure control scheme into the RPC law.

Decentralized Variable Structure Control for Uncertain Large-Scale Time-Delayed Systems: A New Approach

In this paper, a novel decentralized variable structure control (DVSC) scheme is proposed for a class of large-scale time-delayed systems (LSSs) with mismatched interconnections and uncertainties. New invariance conditions are derived such that each subsystem in the switching surface is completely invariant to both delay interconnections and uncertainties. It also shows that the stability of each closed-loop subsystem is guaranteed. By constructing auxiliary function and applying matrix norm inequality technique, the developed DVSC law for the interconnected system is realized independently through the delay terms. Moreover, the chattering around the switching surface can be reduced by the proposed design approach. Illustrative example is given to verify the validity of the developed controller.

Efficiency Optimization of Asynchronism Motor Based on a Novel Reaching Law

To satisfy with the high-power control of the asynchronism motor control drive system, this paper devised a novel reaching law of sliding mode variable structure control strategy and analysed this control strategy for vector control system of asynchronism motor and the high-frequency chattering phenomenon in traditional sliding mode controllers. The simulation results demonstrate that the control strategy can ensure rapid dynamic speed response during the efficiency optimization at low loads and decrease chattering phenomenon effectively, greatly improve the robustness of asynchronism motor and improve control quality.

Research on Multivariable Model Reference Variable Structure Control

This paper studies the output-feedback variable structure control for MIMO (multi-input multi-output) linear systems with generalized relative degree one. A new variable structure control scheme is proposed within the framework of model reference control. Under the assumption that the high frequency gain matrix of the plant can be transformed to a main diagonal dominant matrix via full rank transformation, it is shown that all signals of the closed-loop system are globally uniformly bounded and meanwhile, the tracking error converges to zero exponentially. Simulation results are presented to illustrate the effectiveness of the proposed scheme.