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Second-order sliding-mode control of a Buck converter
Abstract
Results on second-order sliding-mode control algorithms are applied to a linear Buck converter in regulation tasks. As usual in SOSMC, chattering, an undesired consequence of sliding control mode, is highly reduced. A basic requirement for the method to be applicable is to find appropriate bounds for the state variables (current and voltage), as well as for the input control. The proposed method has proved to be robust in face of line and load perturbations.
... Second-order SM control algorithm has been applied to buck converter for reduction of chattering [14]. Two types of SM-control for boost and buck-boost converters: one using the method of stable system center [15] and the other using sliding dynamic manifold are discussed [16]. ...
... Considering the system operating over the sliding region, the sliding function satisfies the condition shown in (14). ...
El objetivo de esta investigación es mejorar la respuesta dinámica del sistema de convertidor DC-DC con incertidumbres en los parámetros internos. La metodología de control por modo deslizante en las obras existentes se basa en un sistema de control proporcional-integral-derivativo (PID). El presente trabajo aborda diversas cuestiones en un enfoque unificado para el diseño y la aplicación de la modulación de ancho de pulso (PWM) basado en control digital por modos deslizantes adaptativos (CMD), técnica de control para el controlador buck para los teléfonos móviles que funcionan en modo continuo de conducción (MCC) y el modo de conducción discontinua (MCD). El controlador está programado para controlar la ganancia de la condición de carga de salida y cambiar adaptativamente los parámetros de control para dar un rendimiento dinámico óptimo correspondiente a las variaciones de carga. Además, la estabilidad se verifica analíticamente utilizando el criterio de estabilidad de Lyapunov y se prueba que el sistema es global y asintóticamente estable. Finalmente, la eficacia del método propuesto se verifica mediante la simulación y experimentación. Se obtiene una respuesta estable en estado estacionario con ondulación reducida.
... Buck converters as a part of DC-DC converters can be modeled as variable structure systems controlled by a discontinuous control input [3]. Thus, SMC method has been considered to be very appropriate and applied to control buck converters [3], [4]. ...
... Buck converters as a part of DC-DC converters can be modeled as variable structure systems controlled by a discontinuous control input [3]. Thus, SMC method has been considered to be very appropriate and applied to control buck converters [3], [4]. However, a major disadvantage of applying SMC to power converter is that their dynamics and steady state performances is affected by load variations [5], [6]. ...
This paper proposes a control method for buck converters using an adaptive sliding mode control (SMC) with simple adaptive control (SAC). The controller is designed to monitor the output voltage of the buck converter, and to use it and its derivations to adaptively change the control parameters to keep the output voltage error minimal corresponding to any loading variations. The role of SAC is to construct an equivalent control input of adaptive SMC. To construct a corrective control input, this paper applies the method using the sign function with a modified sliding surface. Thus the states of the buck converter are not required by the controller. Furthermore, this proposed method is applied based on pulse-width-modulation (PWM). Computer simulations have been carried out to verify the idea.
... Moreover, in [10] a solution employing open-loop control for transient and closed-loop for steady state has been proposed, although without a formal proof of stability. Second order sliding mode strategies have been discussed for buck converters in order to directly control the voltage, in [11] based on the theory in [12] and in [13] based on the use of the twisting algorithm [14]. However, none of the above papers presents detailed conditions for the existence of a solution in the Buck converter. ...
... The parameters δ and T are not given an explicit expression in the Theorem, but they may be reduced by reducing [19], while the parameter α depends on the initial conditions. The above theorem, differently from [11] or [13], results into a high-gain PID control law, with known robustness properties. The interesting feature is its ability to predict both the output and the input variables, that turns out to be very useful when constraints on the control variable have to be taken into account. ...
Different sliding mode controls for DC/DC converters control are considered. Classical Buck, Boost and bidirectional Buck/Boost plants are presented for control application. A unified approach is adopted based on the mathe- matical tools of first- and second-order sliding mode output con- trol. Set-up and ancillary conditions, as condenser pre-charging, are discussed and justified on a rigorous mathematical basis. Numerical simulations show the effectiveness of the proposed novel control strategy in terms of disturbance rejection and fast tracking of the output reference. Direct implementation with hysteretic controllers or PWM are possible.
... Either it being a DC-DC converter or it being an inverter, the SMC has been used widely in the literature. Kim et al. applied the SM to control the inverter switches in order to force the followed current in the grid to pursue a generated reference current; the simulation and experimental results of this single-stage grid-connected PV system shown that the proposed controller can reduce current overshot and contribute to the optimal design of power devices [28]- [35]. ...
p> In this paper, a straightforward method for locating the controller in a PV-based bootstrap converter system is presented. Recent developments in control strategies and power electronics have made it possible to create PV-based DC-to-AC converters for AC drives that are connected to 3-phase loads. High voltage gain is intended to be produced by the bootstrap converter (BSC). The BSC's purpose is to control load voltage. This study compares the time specification performance of the proportional resonant controller (PRC) and the sliding mode control (SMC) for photovoltaic systems with bootstrap three phase inverter (PV-BSTPI). For the delicate loads, steady voltage is typically more important. The BS-TPI system incorporates a closed loop control to fast achieve constant voltage. Choosing the best control approach is the aim. It is observed that the steady state error of SMC is 1.67 which is better when compared to PRC. </p
... Existence refers to the existence of a sliding surface in a system. Reachability refers to the ability of points outside the sliding surface of a system state to move to the sliding surface within a finite time [35][36][37][38][39]. Stability refers to the ultimate stability of the system state under model control. ...
In response to the era background of “comprehensive electrification” and “dual carbon plan” of electric vehicles, DC/DC converters have a good performance in terms of weight, volume, and efficiency and are widely used in fields such as solar power generation, UPS, communication, computers, and electric vehicles. At present, the DC bus voltage is an important indicator for measuring the safe and stable operation of high-voltage DC power systems in electric vehicles. Therefore, regulating the stability of bus voltage through converters has good economic benefits for the sustainable development of electric vehicles in terms of maintenance costs and effective energy management. In order to solve the problem of bus voltage resonance instability caused by negative impedance characteristics of constant power load in an electric vehicle DC power system, a sliding-mode control design strategy of three-phase interleaved bidirectional converter under constant power load was proposed. Firstly, a GPI observer was designed to estimate the state and concentrated disturbances of the system. Then, the estimated value was introduced into the controller for feedforward compensation, thereby achieving fast-tracking of the output voltage to the reference voltage. Finally, the simulation results show that the controller can effectively maintain the influence of disturbances and better improve tracking characteristics and robustness to disturbances and uncertainties.
... Among HOSMC, second order SMC is more common and has been used on the converters. Second-order sliding mode (SOSM) controller, based sub-optimal algorithms, is designed for buck converter in [6], which has proved to be robust against perturbations. In [7,8], twisting and super-twisting algorithms are used to devise SOSMC for buck converter. ...
This study aims to control the switching frequency of synchronous buck (SR-buck) converters using the second-order sliding mode controller by prescribed control law. The relation between position of the switching line and the switching frequency is discussed at stable state. On-resistance of MOSFET and ESR of inductor and capacitor are taken into account. A hysteresis method is proposed to change the position of switching line to control the switching frequency, and the equation of calculating hysteresis width is deduced. The differentiator with the discrete super-twisting is designed. Numerical simulation results under rated working condition, load disturbance, voltage perturbation, and switching frequency variation have been presented. Switching frequency variation is discussed and can be controlled accurately when the working condition is fixed. It validates the effectiveness and feasibility of the method proposed in this study.
... In addition to expanding the sliding mode control theory for power converters, performance evaluation and comparison with other control methods are presented. In 2002, Secondorder sliding mode controller was applied to reduce vibration problem for buck converter by Fossas and Ras [24]. ...
This paper presents a simple and systematic approach to design second order sliding mode controller for buck converters. The second order sliding mode control U+0028 SOSMC U+0029 based on twisting algorithm has been implemented to control buck switch mode converter. The idea behind this strategy is to suppress chattering and maintain robustness and finite time convergence properties of the output voltage error to the equilibrium point under the load variations and parametric uncertainties. In addition, the influence of the twisting algorithm on the performance of closed-loop system is investigated and compared with other algorithms of first order sliding mode control such as adaptive sliding mode control U+0028 ASMC U+0029, nonsingular terminal sliding mode control U+0028 NTSMC U+0029. In comparative evaluation, the transient response of the output voltage with the step change in the load and the start-up response of the output voltage with the step change in the input voltage of buck converter were compared. Experimental results were obtained from a hardware setup constructed in laboratory. Finally, for all of the surveyed control methods, the theoretical considerations, numerical simulations, and experimental measurements from a laboratory prototype are compared for different operating points. It is shown that the proposed twisting method presents an improvement in steady state error and settling time of output voltage during load changes.
... To increase the operating and conversion efficiency of solar cells a maximum power point tracking (MPPT) algorithm is used[5]. There are various MPPT control techniques available to attain maximum efficiency[6][7][8]. In the absence of sun or when it is cloudy/rainy outside the solar panels won't generate the enough quantity of power and that is why it is connected to the grid. ...
... The transfer function obtained though these dynamic models help to design the PID for this application [6]. Sliding Mode Control (SMC) provides an effective and robust means of controlling nonlinear multi-input converters [7][8][9]. An analysis with sliding mode provides a simple analysis tool to obtain equivalent continuous system representation of such time varying systems like DC-DC converters. ...
... The inverter of the PV system supplies non-linear and critical step changing loads. The above load deforms the desired sinusoidal output voltage of inverter [5]. For all types of loads, the total harmonic distortion (THD) of the inverter output voltage should be below 5%. ...
This paper presents the small signal stability (SSS) analysis of a standalone photovoltaic (PV) system with battery as backup source for power management between the source and the load. The stability of this system needs to be analysed for its proper and smooth operation. Lead-acid battery is commonly used in high power PV applications due to its low cost and availability in large size. Three independent control loops are proposed to control the standalone PV system; MPPT control loop to extract maximum power from PV module under varying solar irradiation, battery control loop for bidirectional power flow between battery, dc-link through buck-boost converter to maintain constant dc input voltage, and inverter control loop for maintaining tight voltage regulation and achieving fast dynamic response under sudden load fluctuations. State-space modeling of the standalone system is discussed for the SSS analysis. The stability of the above control loops are verified by using Bode diagram. Finally the proposed method is applied to 2 kW, 110 V, 50 Hz two-stage single-phase standalone PV system. The simulation and the experimental results are presented to validate the proposed control strategy and its stability.
... But we have to trade-off the efficiency for longer charging and discharging cycles. The inverter shown in Fig. l supplies non-linear and critical step changing loads, which are responsible for distorted sinusoidal output voltage waveform [8]. The total harmonic distortion (THD) of inverter output voltage as per the IEEE standard 1547 should be below 5%. ...
This paper presents modeling and control of a
standalone photovoltaic (PV) system in which a battery is used as
a backup source for power management between the source and
the load. Lead-acid battery is commonly used in high power
PV applications due to its low cost and availability in large
size. The modeling of PV system and lead-acid battery by using
the corresponding equivalent circuits are discussed here. Three
independent control loops are proposed to control the standalone
PV system; MPPT control loop for extracting maximum power
from PV module under different solar irradiation, battery control
loop for bidirectional power flow between battery and dc-link
through buck-boost converter to keep the input dc voltage
constant, and inverter control loop for maintaining good voltage
regulation and achieving fast dynamic response under sudden
load fluctuations. The stability of the above control loops are
verified by using Bode diagram. Finally the proposed method is
applied to 2 kW, 110 V, 50 Hz, two- stage single-phase standalone
PV system. The simulation and the experimental results are
presented to validate the theoretical analysis, effectiveness and
feasibility of the proposed control strategy.
... N OWADAYS, single-phase pulsewidth modulation (PWM)-based inverter (see Fig. 1), which is used in uninterruptible power supply (UPS), should supply nonlinear and critical step loads. Since the inverter output impedance is not zero, these loads can deform the sinusoidal output voltage of the inverter [1]- [3]. According to the IEEE Standard 1547, the total harmonic distortion (THD) of the output voltage must be less than 5%, especially for nonlinear load. ...
Sliding mode control (SMC) is recognized as robust controller with a high stability in a wide range of operating conditions, although it suffers from chattering problem. In addition, it cannot be directly applied to multiswitches power converters. In this paper, a high performance and fixed switching frequency sliding mode controller is proposed for a single-phase unipolar inverter. The chattering problem of SMC is eliminated by smoothing the control law in a narrow boundary layer, and a pulsewidth modulator produces the fixed frequency switching law for the inverter. The smoothing procedure is based on limitation of pulsewidth modulator. Although the smoothed control law limits the performance of SMC, regulation and dynamic response of the inverter output voltage are in an acceptable superior range. The performance of the proposed controller is verified by both simulation and experiments on a prototype 6-kVA inverter. The experimental results show that the total harmonic distortion of the output voltage is less than 1.1% and 1.7% at maximum linear and nonlinear load, respectively. Furthermore, the output dynamic performance of the inverter strictly conforms the standard IEC62040-3. Moreover, the measured efficiency of the inverter in the worst condition is better than 95.5%.
... The method does not resort to asymptotic state observers and efficiently extends the sliding mode control methodology to traditional input-output, frequency domain, descriptions of the given switched plant. The underlying design task reduces to a rather simple average output feedback control scheme and it is found to be related, in an asymptotic manner, to higher order sliding motions extensively treated on the existing literature [5], [6], [7], [8], [9], [10]. The proposed approach is based on a crucial observation regarding the switched control interpretation of the Generalized Proportional Integral (GPI) controller design for the smooth regulation of the average model of the given linear controllable plant. ...
In this article, we propose a state-free discontinuous feedback controller design approach for the asymptotic sliding mode control of a large class of linear switched systems. The method is devoid of state measurements and efficiently extends the sliding mode control methodology to traditional input-output descriptions of the plant. The approach is based on regarding the average Generalized Proportional Integral (GPI) controller design as a guide for inducing the sliding mode features through the switching controller. Throughout, it is assumed that the available output signal coincides with the system's flat output, an output capable of completely differentially parameterizing all the variables in the system (inputs, original outputs and state variables) and exhibits no zero dynamics. Encouraging simulation results are presented in connection with the tutorial example. Experimental results are also presented for the trajectory tracking problem on a popular DC-to-DC switched power converter of the “buck” type.
DC-DC buck converters are widely used in industrial applications. Practically, there are parametric uncertainties, external disturbances and nonlinear unmodeled dynamics affecting the control performance of the DC-DC buck converters. Worse still, the current sensor may fail to work normally in practice. Taking the factors aforementioned into account, this paper proposes a universal finite-time observer (UFTO) based second-order sliding mode controller with only output voltage measurement in a simple structure for buck converters subject to mismatched disturbances. Firstly, a universal finite-time observer is designed to give the estimations of unmeasurable states including the current inductor and lumped disturbances. Secondly, introducing the estimations, a second-order sliding mode controller is proposed and a rigorous stability of the whole system is presented. Under the proposed finite-time controller, the system obtains a better convergence property and a better disturbance rejection ability comparing with the asymptotic control method. Moreover, the controller has a simple structure, providing convenience for engineers. As a by-product, only voltage sensor is needed, which reduces the cost and improves the fault tolerant ability for the system. Simulation and experimental results are investigated to validate the effectiveness of the proposed control approach.
Using non-uniformly distributed heat input on thin aluminum foil the cap sealing process takes care of two activities – sealing and wax removal. Presence of more than one indirectly controlled spatial outputs being controlled by single heat input makes the process as under actuated. The performance of such system is optimal when energy delivered to and utilized by foil take place most efficiently. Though better topologies and power devices have emerged the most influential contribution for such systems has been the use of litz-wire in high-frequency magnetic components. Sharp reduction in high-frequency power loss has enabled simple low-power cooling arrangement. Here, energy utilization is improved when the coil head ensures multi-zone heating at single frequency on a thin moving foil whose thickness is negligible compared to its skin depth. Connecting multisegment air-cooled coil in parallel reduces no-load loss as its ac resistance is reduced. It, however, invites two problems, particularly, at no-load – the quality factor is large and damping factor is small. No-load oscillations tend to be more and undamped voltage across tank capacitor is high. This article demonstrates how introduction of robust control concept such as SOSM can resolve this weakness and help the system achieve its near optimal performance.
This paper aims to investigate an extended state observer based control (ESOBC) approach for DC-DC buck converters subject to the unknown load resistance disturbance, which is mismatched according to the average model of buck converter. Different from the existed methods, a disturbance compensation control method is proposed in this paper. Extended state observer (ESO) is employed to estimate the load disturbance and a composite controller which contains a disturbance compensation item is employed to eliminate effects of the disturbance based on its estimates. The simulation studies for the proposed method demonstrate the effectiveness of tracking performance in the presence of mismatched disturbances.
This paper demonstrates a second order sliding mode control for a voltage source inverter. A super twisting control algorithm (STA) is used to control the output ac voltage of the voltage source inverter circuit. Using the algorithm tracking of the output voltage is observed with small steady state error. The controller is found to be robust against sudden changes in the load. The output voltage waveform carries less harmonic content. The frequency response analysis shows good stability properties. PSCAD/EMTDC version 4.2 is used for simulation studies. A comparison is also brought about between the classical sliding mode control and the proposed second order sliding mode controller.
The studies presented in this thesis concern the thermal modeling, sizing and control of a stack composed of supercapacitors and DC/DC converter that feeds the auxiliaries or traction motors of the trolleybus in the case of electrical microcuts. In the first part, we were interested in the sizing of the storage system for an application concerning the recovering braking energy of a trolleybus. Direct and inverse models of the kinematic chain were studied in order to define a design strategy based on the Ragon. The second part concerns the reliability of the storage system. The aim is to evaluate the stresses on supercapacitors during cycling and to predict the aging of the components. Toachieve this goal, we have developed and validated an electrothermal model of the stack. This model was then coupled to aging laws allowing taking into account the major parametric variation of the system. The results show the impact of the dispersion of temperatures inside the stack on the life time of each supercapacitors in the storage system. Finally, the control of the static converter (Buck/Boost converter) combined with supercapacitors is analyzed. A theoretical study was conducted to synthesize PI and sliding mode controller applied to a boost converter. This control laws has been validated on a test bench consisting of a reversible converter, a DC power supply, a resistive load and eight supercapacitors. The experimental results show the advantage of sliding mode control in terms of robustness and reactivity compared to a classical PI control.
In this paper, second-order sliding-mode (SOSM) control approach is applied to synchronous buck dc-dc converters. The proposed SOSM controller can stabilize synchronous buck dc-dc converters using a simple digital state machine structure, without requiring current sensing or an integral term in the control loop. The SOSM controller results in fast step-load and start-up transient responses, and is robust against parameter uncertainties. Fast transients and current limitation during start up can be accomplished by adjusting one controller parameter. Furthermore, a hysteresis method is introduced to control the switching frequency. The proposed approach is verified by experimental results on a 1.25 V, 10 A prototype.
This study presents a reduced state feedback sliding-mode current controller (RSFSMCC) for a voltage source inverter (VSI)-based higher-order circuit. The proposed controller consists of an inner current loop and an outer voltage loop. The reference for the inner input inverter current is generated from the outer voltage loop through a proportional plus integral controller. The stability of the system is ensured by using feedback of only two state variables, that is, input inverter current and output capacitor voltage of the VSI circuit. A reduced state feedback analysis is used to obtain the gain matrix for the higher-order circuit. The tracking control convergence criterion of the system is examined through the eigen values of the resultant state matrix derived for the VSI circuit. The frequency response plot shows that the proposed RSFSMCC is robust with good stability margins. The simulation results show that the output voltage well tracks the reference voltage with reduced steady-state error for both linear and non-linear loads. The simulation results obtained in power systems CAD/electromagnetic transients including DC (PSCAD/EMTDC) v4.2.1 software are verified through the experimental results conducted on a single-phase VSI circuit using field programmable gate array implementation of the RSFSMCC.
Maintaining good voltage regulation and achieving fast dynamic response under sudden load fluctuation are extremely important in distributed generation (DG) as well as uninterrupted power supply (UPS) systems. This paper presents a fixed frequency hysteresis current (FFHC) controller, which is implemented on the basis of sliding mode control (SMC) technique and fixed frequency current controller with a hysteresis band. The controller retains the benefit of hysteretic current control having fast dynamic responses and mitigates the drawback of the variable switching frequency. These have been verified and compared with the carrier based pulse width modulated (PWM) voltage controller under the same load fluctuation. The proposed method is then applied to 6-KVA, 220V, 50Hz islanded 1-Φ voltage source inverter (VSI) system. The results show that the dynamic response is quite faster than that of widely used PWM-controlled inverter systems. Moreover, the total harmonic distortion (THD) of inverter output voltage is 2.14% at standard nonlinear load IEC62040-3.
In this chapter an adaptive sliding mode controller for the Furuta pendulum is proposed. The Furuta pendulum is a class of underactuated mechanical systems commonly used in many control systems laboratories due to its complex stabilization which allows the analysis and design of different nonlinear and multivariable controllers that are useful in some fields such as aerospace and robotics. Sliding mode control has been extensively used in the control of mechanical systems as an alternative to other nonlinear control strategies such as backstepping, passivity based control etc. The design and implementation of an adaptive sliding mode controller for this kind of system is explained in this chapter, along with other sliding mode controller variations such as second order sliding mode (SOSMC) and PD plus sliding mode control (PD TeX SMC) in order to compare their performance under different system conditions. These control techniques are developed using the Lyapunov stability theorem and the variable structure design procedure to obtain asymptotically stable system trajectories. In this chapter the adaptive sliding mode consist of a sliding mode control law with an adaptive gain that makes the controller more flexible and reliable than other sliding mode control (SMC) algorithms and nonlinear control strategies. The adaptive sliding mode control (ASMC) of the Furuta pendulum, and the other SMC strategies shown in this chapter, are derived according to the Furuta’s pendulum dynamic equations making the sliding variables, position errors and velocity errors reach the zero value in a specified reaching time. The main reason of deriving two well known sliding mode control strategy apart from the proposed control strategy of this chapter (adaptive sliding mode control) is for comparison purposes and to evince the advantages and disadvantages of adaptive sliding mode control over other sliding mode control strategies for the stabilization of the Furuta pendulum. A chattering analysis of the three SMC variations is done, to examine the response of the system, and to test the performance of the ASMC in comparison with the other control strategies explained in this chapter.
Switching frequency acts as a major role, while applying sliding mode control to dc-dc buck converter, switching frequency is affected by line and load variations. To reduce switching frequency deviation to line and load variations, an adaptive feed forward control is used, that varies hysteresis band according to the change of input voltage. Several methods of varying hysteresis band of the hysteresis modulator are possible. In this work adjusting the power supply is to be considered. An adaptive feedback control scheme that varies the control parameters (i.e. sliding coefficient) according to the change of output load is proposed. This paper presents a complete investigation into the problem and gives the effectiveness of the desired solutions. In this method implementing the proposed adaptive control strategies are discussed, simulation results gives that the adaptive control methods are capable of reducing the switching frequency variations, simulation have been done in MATLAB /Simulink to verify the results. KEYWORDS: Adaptive feedback control, adaptive feed forward control, buck converter, hysteresis modulation, pulse width modulation (PWM), sliding mode (SM) control.
This paper proposes a sliding mode controller for Pulse Width Modulation (PWM) based boost converter. The boost converter is modeled dynamic equations describing the converter are derived and sliding mode controller is designed. The performance of the controller is compared with conventional PID controller. Given a system with large variations of input voltage and load it is necessary to guarantee good performance of the system. Simulation results prove the robustness of converter with sliding mode controller when tested against step load changes and input voltage variations comparable to standard control techniques.
This paper examines the practical design issues of sliding mode controllers as applied to the control of DC-DC converters. A comprehensive review of the relevant literature is first provided. Major problems that prevent the use of sliding mode control in DC-DC converter for industrial applications and their possible solutions are discussed. Performance of sliding mode control is compared with that of conventional PWM control in terms of transient characteristics. It is shown that the use of sliding mode control can lead to improved robustness in providing consistent transient responses over a wide range of operating conditions
We present an analysis of the complex dynamics displayed by the classical buck converter, controlled with a Pulse-Width-Modulation technique. We show the conditions to make the circuit display a sliding mode and a null steady-state error. Also, some conditions for the existence of a periodic orbit with the same period as the modulation signal are established. Finally, taking the period of the modulation signal as a bifurcation parameter, we describe a situation where the controlled circuit exhibits chaotic behavior.
This paper presents a novel terminal sliding mode control for DC-DC buck converters. Since buck converters have high nonlinearity and uncertainty, a terminal sliding mode controller (TSMC) is proposed to achieve robust output voltage tracking. Different from traditional sliding mode control, a terminal sliding surface is introduced to assure finite convergent time of control errors on the surface. Furthermore, if the upper bound of uncertainty is known, the overall controlled system yields finite-time convergent stability. When considering highly unknown uncertainty, an adaptive fuzzy TSMC is derived to guarantee high robustness. In addition, this controller is implemented by a PSoC (Programmable system on chip) and results in expected performance.
This paper proposes a new adaptive sliding mode controller for buck converter operating in the continuous conduction mode. Through gain scheduling, the controller is designed to monitor the output loading condition, and adaptively changes its control parameters to give optimal dynamic performances corresponding to any loading variations. Simulations have been carried out to verify the idea. The results show faster transient response and reduced steady state error during over-loaded operation, and improved controller's reliability during underloaded operation, under the adaptive controller.
This paper examines the practical design issues of sliding-mode (SM) controllers as applied to the control of dc-dc converters. A comprehensive review of the relevant literature is first provided. Major problems that prevent the use of SM control in dc-dc converters for industrial and commercial applications are investigated. Possible solutions are derived, and practical design procedures are outlined. The performance of SM control is compared with that of conventional linear control in terms of transient characteristics. It has been shown that the use of SM control can lead to an improved robustness in providing consistent transient responses over a wide range of operating conditions.
Peak current control is a strategy widely used to control power electronic systems such as forward converters or two-level choppers. This strategy is characterized by constant switching frequency with good dynamic performance. This paper presents the application of this strategy to a multilevel voltage-source converter. The algorithm ensures that the converter output current follows the target reference, but it must be modified to include voltage-level selection within the multilevel converter. The principle of operation is introduced, and the implementation of the algorithm using a field-programmable gate array is demonstrated. Simulation and experimental results are presented to verify the control technique
The synthesis of a control algorithm that stirs a nonlinear system to a given manifold and keeps it within this constraint is considered. Usually, what is called sliding mode is employed in such synthesis. This sliding mode is characterized, in practice, by a high-frequency switching of the control. It turns out that the deviation of the system from its prescribed constraints (sliding accuracy) is proportional to the switching time delay. A new class of sliding modes and algorithms is presented and the concept of sliding mode order is introduced. These algorithms feature a bounded control continuously depending on time, with discontinuities only in the control derivative. It is also shown that the sliding accuracy is proportional to the square of the switching time delay.
This article presents an application of variable structure systems theory, and the associated sliding regimes (Utkin [1]-[4]) of the systems, 1) to study energy transfers between dynamic storage elements in lossless bilinear networks and 2) to obtain a feasible reformulation of the constant regulation problem in dc-dc switch-mode power converters (SPC's) usually treated by approximate state-space averaging techniques on pulse width modulation (PWM) control schemes. The approach exploits the geometric aspects of the problems and obtains an analysis and design methodology, based on the ideal sliding mode qualitative characteristics, which is intuitively clear, mathematically feasible, and devoid of approximations.
An adaptive feedback regulation scheme is proposed for the stabilization of average models of dc-to-dc power converters exhibiting unknown but constant resistive loads. The scheme is based on a dynamical feedback policy which suitably modifies the total energy of the closed-loop system while inducing appropriate damping injections on the desired stabilization error dynamics. The performance of the proposed adaptative regulators is tested through computer simulations including stochastic perturbation inputs. © 1998 John Wiley & Sons, Ltd.
A control system for power conditioning and uninterruptible power supply systems is presented. The design is based on the theory of variable-structure systems with sliding mode. Results of an analytical study and digital simulation of both the power and control systems are reported, showing good agreement. The high dynamics and the robustness of the implemented system, indicated by the simulation results, confirm the validity of the control scheme and suggest the possibility of adopting it for three-phase systems, variable frequency supplies, and measuring equipment.< >
Relying on the possibility of generating a second-order sliding
motion by using, as control, the first derivative of the control signal
instead of the actual control, a new solution to the problem of
chattering elimination in variable structure control (VSC) is presented.
Such a solution, inspired by the classical bang-bang optimal control
strategy, is first depicted and expressed in terms of a control
algorithm by introducing a suitable auxiliary problem involving a
second-order uncertain system with unavailable velocity. Then, the
applicability of the algorithm is extended, via suitable modifications,
to the case of nonlinear systems with uncertainties of more general
types. The proposed algorithm does not require the use of observers and
differential inequalities and can be applied in practice by exploiting
such commercial components as peak detectors or other approximated
methods to evaluate the change of the sign of the derivative of the
quantity accounting for the distance to the sliding manifold
Sliding Motions in Bilinear Scientific
- Z Sira-Ramirez
Z] Sira-Ramirez, H.. " Sliding Motions in Bilinear Scientific, 2000.
Sliding Mode Control in Elec-trom. Syst
- V Utkin
Utkin, V. et al.. Sliding Mode Control in Elec-trom. Syst., Taylor and Francis, London, 1999.