Due to nonlinear characteristics of boostconverter, some researches have employed nonlinear controller such as slidingmodecontrol. The robustness against parameter uncertainty and disturbance are the main reason why slidingmodecontrol is utilized to controlnonlinearsystem, including boostconverter. Many slidingmodecontrol methods [9-13] had been applied to boostconverter. However, in practical, this control method requires to be fully known some variables, such as input voltage, inductor current, output voltage, and resistance load. As consequences, many sensors are needed to be installed to acquire those variables as input control. Implementing those methods causes increasing cost production and adding more space and weight in real system. Therefore, to reduce the number of sensors, nonlinear disturbance observer [13-15] is designed to estimate some variables, such as inductor current, output voltage, resistance load, and input voltage generated from solar array. The nonlinear disturbance observer accurately generates the estimated value of resistance load and input voltage such that when the variations of those variables exist, the proposed controller is still able to overcome those disturbances. In slidingmodecontrol design, steady state error regulation needs to be considered. However, in , it is employed standard slidingsurface and only use equivalent control signal to regulate boostconverter. This can cause the output voltage response cannot track the varying desired output voltage and leads to steady state error. To enhance system performance, adaptiveslidingmodecontrol is applied to the boostconverter for overcoming parameter uncertainty and disturbance [16-17]. Steady state error can be eliminated by constructing PIslidingsurface, while ensuring slidingmode in finite time is employed reaching law dynamics and incorporates it to natural control signal. Therefore, nonlinearobserverbasedadaptiveslidingmodecontrol with PIslidingsurface is proposed for boostconverter. The main contribution of this paper is to improve the system performance of voltage regulation boostconverter using the combination of nonlinearobserver and adaptiveslidingmodecontrol by modifying the conventional slidingsurface into PI structure slidingsurface. In addition, the stability of proposed method is proven by using direct Lyapunov method.
Abstract— This paper presents a photovoltaic (PV) system with an adaptiveslidingmodecontrolbased maximum power point tracking (MPPT) algorithm. The goal of this work is to maximize power extraction from the photovoltaic generator. This aim is achieved by using an adaptiveslidingmode con- troller (ASMC) that drives a boostconverter connected between the PV generator and the load. The robustness and stability of the proposed controller are investigated against weather changes. Simulation results with real data, under MATLAB- SIMULINK, are given to demonstrate the effectiveness of the proposed approach.
The average generalized PI output feedback regulator as a steer for defining the switched implementation of the average slidingmode features through a sigma-delta modulation strategy has been addressed . The con- trol loop of a parallel connection of two non-identical paralleled positive output elementary super lift Luo con- verters using the SMC theory for current distribution control in continuous conduction mode . A droop me- thod has been proposed for the converter parallel operation, which adaptively controls the reference voltage of each module. The scheme improves the output voltage regulation and the current sharing of the conventional droop method . A robust controller for parallel dc-dc buck converters has been coined by combining the concepts of integral-variable-structure and multiple-sliding-surfacecontrol . Grid connected solar PVsystem with SEPIC converter compared with parallel boostconverterbased MPPT . Nonlinear back-stepping adap- tive controller has been proposed for the design of parallel DC-DC buck converters with uncertainties of load and power disturbance. The relationship between the control elements and circuit parameters has been deter- mined by simulation analysis. The relationship between current sharing difference and circulating current for two parallel connected dc-dc converters has been investigated . Although there may exist a trade-off be- tween current sharing difference and voltage regulation, the proposed droop index algorithm gives better per- formance and low voltage regulation. The detailed analysis and design procedure are explained for two dc-dc boost converters connected in parallel. The effectiveness of proposed method is verified using MATLAB simu- lation.
The switch mode DC-DC converters are some of the simplest circuit which converts power level of DC power effectively. It has wide application in modern computer, DC motor drive, power system, automotive, aircrafts etc. the commonly used control methods are pulse width modulation (PWM), voltage modecontrol, PWM current modecontrol with proportional (P), proportional integral (PI), and proportional integral derivative (PID) controller. But this control method cannot perform satisfactory under large load variation so non liner control technique is in picture. The dc-dc converters, which are non-linear and time variant system, and do not lend themselves to the application of linear control theory, can be controlled by means of sliding-mode (SM) control, Which is derived from the variable structure controlsystem theory (VSCS). Variable structure systems are systems the physical structures of which are changed during time with respect to the structure control law. The instances at which the changing of the structure occurs are determined by the current state of the system. Due to the presence of switching action, switched-mode power supplies (SMPS) are generally variable structured systems. Therefore, SM controllers are used for controlling dc-dc converters. Though SM control compiles of various advantages, SM controlled converters suffers from switching frequency variation when the input voltage and output load are varied. Hence there are many control methods which have been developed for fixed switching frequency SM control such as fixed frequency PWM basedslidingmode controllers, adaptive SM controller, digital fuzzy logic SM controller, etc. In case of adaptivecontrol, adaptive hysteresis band is varied with parameter changes to control and fixate the switching frequency. But, these methods require more components and are unattractive for low cost voltage conversion applications.
performance. This cascade control is employed at the low hierarchy level in order to control the boostconverter. This level also uses a feedforward control which eliminates all the demerits of feedback control. As a result, the speed and performance of the overall system improves, if feedforward control together with feedback action is employed. Differential flatness is used at the high hierarchy level which ensures that the system is controllable or not. If the system is controllable, then the system is said to be stable. DC motor is placed in the high hierarchy level. The low hierarchy level ensures that the converter output voltage is equal to the one required to drive the DC motor whereas the high hierarchy level is designed to complete the velocity tracking task developed for the DC motor.
In this paper, a nonlinearslidingsurface has been proposed. It is shown that the error states converge to an arbitrarily small region centred at the origin within a finite time and thereafter asymptotically converge to the equilibrium point. A nonlinearslidingmodecontrol law has been developed using an improved version of the exponential reaching law. The method is applied for control of a robot manipulator system. The residual set defined by the slidingmode has been determined. The simulation results show that the proposed method has more precise tracking, faster convergence, and stronger robustness against system uncertainty and external disturbances than an existing approach. Due to the smooth control signal, the proposed approach reduces the chattering effectively and has a wider range of applications. Future work will focus on application of the results experimentally and in industry.
The main aim of this project is to revise and define the automatic steering con- trol of passenger cars for general lane-following maneuver. A 2-DOF controller based on H loop-shaping methodology is used by lateral vehicle controlsystem is success- fully designed . The 2-DOF controller supplies good lane-keeping and lane-change abilities on both curved and straight road segments. Moreover, it provides a com- putationally efficient algorithm and does not require explicit knowledge of the vehicle uncertainty. But, the test results show that the higher the vehicle’s speed, the less stable the vehicle system.
The robustness to the uncertainties becomes an important aspect in designing any controlsystem. Slidingmodecontrol (SMC), originally studied by Utkin , is a robust and simple procedure for the control of linear and nonlinear processes based on prin- ciples of variable structure control (VSC). It is proved to be an appealing technique for controlling nonlinear systems with un- certainties. Figure 1 shows the graphical representation of SMC using phase-plane, which is made up of the error (e(t)) and its derivative ( e(t)). It can be seen that starting from any initial con- ˙ dition, the state trajectory reaches the surface in a finite time (reaching mode), and then slides along the surface towards the target (slidingmode).
The fuzzy logic controller integrates the fuzzy approximation theory and the SMC have been developed. Moreover, adaptive fuzzy slidingmodecontrol (AFSMC) schemes have been proposed [6–11]. The adaptive fuzzy controller incorporated with a SMC is developed. In other words, the adaptive fuzzy logic systems are utilized to approximate the unknown system functions in designing the SMC of nonlinearsystem. In order to improve the performance of AFSMC, an adaptive fuzzy logic control combining linearization feedback and SMC is considered in this paper. It is proved that the closed-loop system is globally stable in the Lyapunov sense, if all the signals are bounded and the system output can track the desired reference output asymptotically with uncertainties.
systems with both packet dropouts and channel noises in the networked scenario. Literature  developed a distributed state estimation method based on MHE for a class of two- time-scale nonlinear systems. These works have contributed to the teleoperation systembased on network communication which enhanced robustness of the networked controlsystem. Advanced controllers, including slidingmode con- trollers (SMCs) and adaptive controllers, have recently been developed for teleoperation systems in order to obtain accu- rate trajectory tracking and faithful force feedback. One slidingmode approach, the three-modecontrol scheme, can implehent a position–position, force–force, or force–position scheme, and the results show good trajectory tracking per- forhance . However, it does not consider time delay. To solve the problem of the adverse effects of parametric uncertainties, an adaptiveslidingmodecontrol scheme was proposed by Motamedi et al. . The algorithm has been verified on a teleoperation system with a single degree of free- dom (DOF). Yang and Hua  proposed a novel nonsingular fast integral terminal slidingmode (NFITSM) for a teleoper- ation system, and practical experiments on one-DOF motion tracking have now been completed. A nonsingular terminal slidingmode and adaptive finite-time control method was proposed by Zhang et al. , and simulation results have verified the effectiveness of this method. These methods are useful attempts to design feedback controllers that improve the performance and stability of a teleoperation system.
This paper proposes the implementation of a fuzzy based robust sliding model control design to obtain voltage regulation in a boostconverter with high dc gain. The proposed controller has an inner loop based on sliding- modecontrol whose slidingsurface is defined for the input inductor current. The current reference value of the slidingsurface is modified by a fuzzy logic controller in an outer loop that operates over the output voltage error.Robustness is analyzed in depth taking into account the parameter variation related with the operation of the converter in different equilibrium points. Simulations and experimental results are presented to validate the approach for a 20–100-W boostconverter stepping-up a low dc voltage (15–25-V dc) to a 400-V dc level.
ABSTRACT:The main objective of this paper is to design a SM Controller for a buck converter to convert a dc input voltage to the required lower dc output voltage level for lower power application to solve the problem of voltage regulation and high power loss of the linear voltage regulator circuit. The converter uses a switching scheme which operates the switch MOSFET in cutoff and saturation region to reduce power loss across MOSFET. Then, the output voltage is controlled using SM Control technique to get the desired output voltage level. The design is based on low power application such as laptop charger, mobile charger etc. The circuit is simulated using MATLAB/SIMULINK software to obtain desired response.The SM control is a type of nonlinearcontrol introduced initially as a means for controlling variable structure systems. The main advantage of the SM control over other types of nonlinearcontrol methods is its ease of implementation. This makes it well suited for common DC–DC power regulation purposes. The SM control is naturally well suited for the control of variable structure systems. Characterized by switching, power converters are inherently variable structure systems. It is therefore; appropriate to apply SM control on power converters.
NVIRONMENTAL consequences of using fossil fuels and also depletion of these reserves in recent years have caused researches to be focused on renewable energies and interface converters. DC-DC converters are mostly used in these applications. In the last decade, lots of DC-DC converters have been proposed for various applications such as extracting maximum power from photovoltaic (PV) and fuel-cell (F.C) systems, portable devices, hybrid electric vehicles (HEV) and etc. [1-5]. Among DC-DC converters with different applications, BDCs have become necessary for HEV applications since energy storage systems are required for cold starting and battery recharging . BDCs are used in HEVs [6-9], uninterrupted power supplies (UPS) [10-12], F.Cs [12-16], PVs [17,18], battery chargers [19-21] and many other industrial applications. BDCs are also used in DC micro-grid. Regulation of DC bus voltage and uninterrupted power
The expression for the average voltage applied across the winding is given by (25). The dc signal output of F/Vconverter is given as one of the input to analog to digital (A/D) converter of the DSP processor to determine the actual speed of the motor. The reference speed is set through a potentiometer and voltage follower and it is given as another input to the A/D converter to determine the reference speed. There is also another provision to set the reference speed from watch window of code composer studio software. The function of the DSP processor is to compute the error and change in error, store these values, compute the Fuzzy controller output, determine the new duty-cycle for the switching devices and perform electronic commutation. The high speed digital buffer IC 74HCT244 is used to interface the DSP with the IGBT hybrid power module ICand the hall sensor circuit. The flowchart for the fuzzy controller program implemented in DSP is shown in Fig 6.
Abstract—This paper studies the application of the slidingmodecontrol method to reduce the vibration of flexible structure with piezoelectric actuators and strain gage transducer in practical complex environment. The state- space dynamic model of the system was derived by using finite element method and experimental modal test. The structure is subjected to arbitrary, unmeasurable disturbance forces. Taking into account the uncertain random disturbance and measurement noise, Kalman filter is chosen as the state estimator to obtain the modal coordinates and modal velocities for the modal space control. A slidingmode controller is adopted due to its distinguished robustness property of insensitiveness to parameter uncertainties and external disturbances. The slidingsurface is determined by using optimization method, and the sliding controller is designed by applying Lyapunov direct method. That is, along the switching surface, the cost function of the states is minimized. A real-time controlsystem was built using dSPACE DS1103 platform, and vibration control tests were performed to experimentally verify the performances of the proposed controller. The results of experiment show the controller can effectively attenuate elastic vibration of the structure.
Abstract — This paper presents a time-varying slidingmodeadaptive controller in order to handle the stick-slip oscillation of nonlinear rotary drilling system. The time-varying slidingmode controller with strong robust has two time-varying sliding surfaces, one of them induced time-varying integral slidingmodecontrol can control the transient stage of the rotary drilling system and ensure the system remains the sliding condition whatever in usual or existing the parameter changes and disturbances to arrive at a controller capable of global stability. The herein developed controller is, a time-varying slidingmodeadaptive controller has tracking performance and identification of drilling parameters. Lyapunov principles have been carried out to verify the stability and robustness of system. The simulation results show that the controller has faster dynamic responses and suppress stick-slip in oil well drill string, can achieve global stability of rotary drilling system.
There has been a widespread interest in using advanced control techniques to improve the performance of vehicle suspension system. Performance of the suspension system has been greatly increased due to increasing vehicle capabilities. Several performance characteristics have to be considered in order to achieve a good suspension system. These characteristics deal with regulation of body movement, regulation of suspension movement and force distribution. Ideally the suspension should isolate the body from road disturbances and inertial disturbances associated with cornering and braking or acceleration . During the design of a suspension system, a number of conflicting requirements have to be met . The suspension must be able to minimize the vertical force transmitted to the passengers for passengers comfort. These objectives can be achieved by minimizing the vertical car body acceleration. Also, optimal contact between wheel and road surface is needed in various driving conditions in order to maximize safety . An early design for automobile suspension systems was focused on unconstrained optimizations for passive suspension system which indicate the desirability of low suspension stiffness, reduced unsprung mass, and an optimum damping ratio for the best controllability . Thus the passive suspension system, which
Numerous techniques have been proposed to eliminate this phenomenon in SMC, such as saturating approximation, integral slidingcontrol and boundary layer technique. To tackle these difficulties, fuzzy logic controllers (FLC) are often used to deal with the discontinuous sign function in the reaching phase of SMC . As well known, fuzzy logic control (FLC) is a knowledge-basedcontrol approach which can mimic human experience in controlling complex systems and has excellent capability to deal with nonlinear plants [21,22]. This method is a good choice for inferring the control gains of VSSM controller in wind turbines through fuzzy-rules-based inference. Meanwhile, the modeling error and the uncertain disturbance of wind power system can be estimated to obtain the appropriate switch gain through a fuzzy inference system with single input and single output. Many new algorithms have been proposed based on the integration of the fuzzy logic and the SMC . These approaches are similar in the aspect that they directly approximate the slidingmodecontrol law by fuzzy approximations. The main advantage of this control scheme is its ability to eliminate the chattering using a fuzzy slidingsurface in the reaching condition of the SMC . Recently, adaptive fuzzy SMC methods are also used for this purpose, which is shown to be quite effective . In contrast to a conventional feedback control algorithm, there is a fuzzy control algorithm consists of a set of heuristic decision rules that can be represented as a non-mathematical control algorithm. This algorithm proves to be very effective especially when the precise model of the system under control is not available or expensive to prepare. This combination (i.e., F-SMC) provides the mechanism to design robust controllers for nonlinear systems with uncertainty.
In spite of being a potential candidate, many factors associated with fuel cell application still prevent its commercialization. The high capital cost of fuel cell based electricity generation system due to high cost of fuel, catalyst, components etc, complex BOP (Balance of Plant) requirements, custom designed power conditioning unit, high operating and maintenance cost, sophisticated and advanced controller requirements to control the non-linearity of cell has limited its growth and development.