Reduced-order Sliding Mode Controller Research Articles

Design and Analysis of Zeta Converter for Power Factor Correction Using Cascade PSO-GSA-Tuned PI and Reduced-Order SMC

This paper presents the design and analysis of a single-phase power factor correction (PFC) scheme using a DC–DC Zeta converter operating in continuous conduction mode. The presented DC–DC converter exhibits non-linearity due to switching elements that degrades the performance of the converter. Therefore, this paper proposes a non-linear cascade control of particle swarm optimization-gravitational search algorithm (PSO-GSA) tuned proportional-integral (PI) and sliding mode controller (SMC) in outer and inner loop, respectively, to improve the performance of the converter. The robustness of the controller is analysed by applying the load and line variations to the converter. The simulation results showed that the steady state performance indices such as integral absolute error and integral square error, and transient performance indices like settling time and peak overshoot are significantly enhanced for the proposed cascade control scheme compared to the PSO and root locus method of tuning the outer PI with the inner SMC controller. The proposed control scheme gives better performance in terms of power factor improvement, percentage reduction in total harmonic distortion, and efficient tracking of output voltage for change in reference voltage compared to other techniques presented. Further, the performance of the proposed scheme is tested for battery charging application of the solar photovoltaic system. The demonstrated simulation results are validated by implementing the DC–DC Zeta converter in real-time hardware set-up.

Design and Development of ROSMC-Based Single-Stage Z Source Inverter for Power Quality Enhancement in Hybrid Electric Vehicle Applications

This research work focuses on the design and analysis of the single-stage reduced order sliding mode control (ROSMC)-based Z-source inverter (ZSI) using sinusoidal pulse width modulation (SPWM) technique for improving the output power quality. To enhance the ZSI output voltage, the shoot-through (ST) mode is executed. Reduced 2nd order model of ZSI is derived from original 6th order model using moment matching method to reduce the sensor requirements and complexity in controller design. The closed loop control is accomplished using cascade control technique to investigate the system’s dynamic response. A Genetic Algorithm (GA)-tuned Proportional Integral (PI) controller is used for the outer voltage control. GA-tuned PI/ROSMC-based SPWM control technique has been attempted for inner current control. Sinusoidal reference signal is generated by the inner current control loop. Internal Model Control (IMC)-tuned Proportional Integral derivative (PID) controller is used to minimise the effect of Right Half-Plane zero, and it also produces required shoot-through duty ratio (STDR). Simulation results illustrate that the ROSMC-based SPWM technique provides superior performance than GA-tuned PI-based SPWM control technique. An experimental prototype model of 2 kW ZSI, ROSMC-based SPWM control is implemented using SPARTAN-6 field programmable gate array. The simulation results are substantiated with the hardware results.

Improved control strategy for Cuk converter assisted wind‐driven SEIG for DC nanogrid

In this study, the current mode control strategy for a Cuk converter assisted self-excited induction generator-based wind energy conversion system (WECS) for DC nanogrid is proposed. The sliding mode controller (SMC) is a non-linear controller and, is preferred because of good static and dynamic response for input -output disturbance rejections. However, the knowledge of all the state variables is required, which increases the number of sensors and control complexity. To reduce the number of sensors, reduced-order SMC (ROSMC) can be implemented. Conventionally design of the voltage loop in ROSMC does not consider the uncertainty of the control parameter. However, the accuracy of the control signal generated by the ROSMC also depends on how accurately the reference current is generated. Therefore, a genetic algorithm tuned PI controller is proposed to generate the ripple-free reference current. Artificial intelligence assisted ROSMC (AIROSMC) is proposed because of its advantages over SMC, which are a reduced number of sensors, improved dynamic response and easy implementation. The extensive simulation study is carried in MATLAB\Simulink for comparative analysis of fixed frequency SMC, two variable SMC, ROSMC, and AIROSMC. The harmonic spectrum analysis is carried out to justify the selection of DBR instead of the controlled rectifier.

Robust Position Control of SM-PMSM Based on a Sliding Mode Current Observer

This paper propose a reduced-order sliding mode controller based on a sliding mode observer applied to a Surface Mounted Permanent Magnet Synchronous Motor (SM-PMSM). The external disturbances are considered in the design of the controller in order to provide good results and accuracy of the system. Additionally, the corresponding observer is used to estimate the rotor position. Simulations and experiment results are shown to confirm the effectiveness of the proposed controller and observer.

Robust non‐linear control design for systems governed by Burgers' equation subjected to parameter variation

In this study, a robust sliding mode controller is proposed for dynamic systems governed by Burgers' equation with Neumann boundary conditions in the presence of parameter variations. The main objective is to design a reduced-order model based controller at a nominal value of the system parameter that stabilises the full-order model while being robust with respect to model uncertainties in the obtained reduced-order model. The model uncertainties resulted from the variation of the parameter ν are discussed under two categories; first, the error arising from the change in the states of the full-order model, and second, the error associated with the estimated proper orthogonal decomposition basis functions at the nominal value of ν 0 . In this work, the boundedness of the error functions is studied and an estimation of these bounds is obtained in terms of the reduced-order model and matrices of the full-order system that are known a priori. Next, the bounds on the error functions are used to design a reduced-order sliding mode controller that guarantees the stability of the full-order model obtained via a finite element approximation of the Burgers' equation for a trajectory tracking problem.

Dynamics and control of underactuated spacecraft formation reconfiguration in elliptic orbits

Feasibility of underactuated formation reconfiguration in elliptic orbits without radial or in-track thrust is investigated in this paper. For either underactuated case, by using a linear time-varying dynamical model of spacecraft formation, controllability and feasibility analyses are conducted, based on which the preconditions on reconfigurable formations are then derived. With the inherent coupling of system dynamics, the reduced-order sliding mode control technique is employed to design a closed-loop underactuated controller for either case. To ensure the stability of the closed-loop system, the conditions imposed on the controller parameters are derived, and the parameter adaptation laws are then solved analytically. Meanwhile, the explicit relationships between the steady accuracies of system states and the controller parameters are obtained via a Lyapunov-based approach. Numerical examples are simulated in a J2-perturbed environment to validate the theoretical analyses. The results indicate that by using the proposed control schemes, underactuated reconfiguration in elliptic orbits is still feasible even in the absence of radial or in-track thrust and in the presence of unmatched disturbances.

Analysis of multiple oscillations in a sampling reduced-order sliding mode control in frequency domain

The phenomena of oscillations in sliding mode control system usually cause potential damage or danger in engineering applications. This paper focuses on the estimation and adjustment of oscillation parameters (frequency and amplitude) using an improved describing function method and the characterization of the influence of the reduced-order sliding surface coefficients on the performance of the nonlinear system. The model of series connection of the zero-order holder and switching function is established in frequency domain. The improved describing function method could intuitively estimate the number, stability and parameters of oscillations for the coupled nonlinear system by its amplitude-phase characteristics and pole placement. The stability, parameters and attraction zones of three oscillations in a fourth-order plant are analyzed and simulated. The analytical results show that the reduced-order sliding mode controller possesses complex and colorful nonlinear behaviors. Besides, a coefficient tuning method is presented to eliminate the undesired oscillation which may lead to poor precision or break the stability. The simulations demonstrate that appropriate tuning on sliding surface may greatly improve the efficiency and robustness of the sliding mode control system.

Dynamics and control of voltage multiplier cells integrated boost converter

This paper presents a reduced order sliding mode controller based on hysteresis modulation for a boost converter with single voltage multiplier cell (VMC) operating in continuous conduction mode. Although VMC integrated boost converter improves the static gain without extreme duty cycle, it increases the number of components which in turn increases the order of the system. Due to complexity in control of higher order converters, a reduced order sliding mode controller is suggested in this study to reduce the number of sensors. Both static and dynamic performances are improved by considering only two control parameters, the input inductor current and the output capacitor voltage of the VMC integrated boost converter. The robustness of SMC over line variation, load variation and parameter variations are revealed through simulation and compared with conventional PI controller. Inrush current of the VMC integrated boost converter is observed to be high and a startup control with an auxiliary diode is incorporated. A prototype model of a 100 W boost converter with single VMC controlled by SMC is designed and implemented to validate the simulated results. A VMC integrated boost converter with SMC approach offers high voltage gain at reduced duty cycle with improved dynamic characteristics.

Full-order sliding mode control for high-order nonlinear system based on extended state observer

In this paper, a full-order sliding mode control based on extended state observer (FSMC+ ESO) is proposed for high-order nonlinear system with unknown system states and uncertainties. The extended state observer (ESO) is employed to estimate both the unknown system states and uncertainties so that the restriction that the system states should be completely measurable is relaxed, and a full-order sliding mode controller is designed based on the ESO estimation to overcome the chattering problem existing in ordinary reduced-order sliding mode control. Simulation results show that the proposed method facilitates the practical application with respect to good tracking performance and chattering elimination.

Design and implementation of reduced‐order sliding mode controller plus proportional double integral controller for negative output elementary super‐lift Luo‐converter

This study presents a simple sliding surface design of variable frequency-based reduced-order sliding mode controller (ROSMC) plus proportional double-integral controller (PDIC) for the negative output elementary super-lift Luo-converter (NOESLLC) operated in continuous conduction mode (CCM). Owing to the time-varying switched mode operation, the dynamic characteristics of the NOESLLC is non-linear and the developed ROSMC plus PDIC aims at improving the dynamic performance along with the inductor current and the output voltage regulation of the NOESLLC. The developed ROSMC is well suitable to the inherently variable-structured NOESLLC when represented in the reduced-order state-space average-based model. The designed PDIC eliminates the steady-state error and also excellent start-up response of NOESLLC despite of line and load variations. The performance of the developed controller is verified for its robustness to perform over a wide range of operating conditions through both in MATLAB/Simulink models as well as in the laboratory prototype with the comparative study of a typical ROSMC plus proportional-integral-controller. Simulation and experimental results are showed that ROSMC plus PDIC can achieve proficient output voltage and inductor current regulation at various working conditions.

Analysis and design of reduced‐order sliding‐mode controller for three‐phase power factor correction using Cuk rectifiers

In this study, the analysis and design of reduced-order sliding-mode controller (ROSMC) for power factor correction (PFC) in a three-phase system is presented. A new and systematic technique for the selection of sliding surface co-efficients to implement ROSMC is attempted. The front end is a three-phase diode rectifier followed by DC–DC Cuk converter modules with the common DC output. Instantaneous symmetrical component theory is used for reference current generation. The control strategy uses three inner ROSMC current controllers for source current shaping and an outer voltage loop using proportional integral controller for load voltage regulation. The proposed method offers simple control strategy, fast transient response and power factor close to unity. To validate the proposed method, a prototype controlled by dSPACE 1104 signal processor is set up. Simulation and experimental results indicate that the proposed system offers regulated output voltage for wide load variations and power factor close to unity.

Design and implementation of reduced-order sliding mode controller for higher-order power factor correction converters

This study discusses a simple sliding surface design approach of a reduced-order sliding mode controller (ROSMC) for power factor correction, wherein a new and systematic technique for the selection of sliding surface co-efficients to implement ROSMC is attempted. Pade's approximation technique is used to obtain the reduced-order model. A prototype of front-end AC–DC converter followed by DC–DC Cuk converter controlled by ROSMC using a dSPACE signal processor is set up for 60 W. Experimental results are presented to validate the simulation results. Simulation and experimental results reveal that ROSMC control can achieve good output voltage regulation and also provide improved robustness in shaping the input current in the presence of load variations.

ℋ︁∞ sliding mode observers for uncertain nonlinear Lipschitz systems with fault estimation synthesis

AbstractThis paper presents a scheme to design robust sliding mode observers(SMO) with ℋ︁∞ performance for uncertain nonlinear Lipschitz systems where both faults and disturbances are considered. We study the necessary conditions to achieve insensitivity of the proposed sliding mode observer to the unknown input(fault). The objective is to derive a sufficient condition using linear matrix inequality(LMI) optimization for minimizing the ℋ︁∞ gain between the estimation error and disturbances, while at the same time the design method guarantees that the solution of the LMI optimization satisfies the so‐called structural matching condition. The sliding motion affects only a part of the system through a novel reduced‐order sliding mode controller. Furthermore, the so‐called equivalent control concept is discussed for fault estimation. Finally, a numerical example of MCK chaos demonstrates the high performance of the results compared with a pure SMO. Copyright © 2010 John Wiley & Sons, Ltd.

Reduced order sliding mode control for pneumatic actuator

A new position control algorithm, based on sliding mode control, has been developed for a pneumatic cylinder. In the proposed pneumatic system, commercially available two-way on-off solenoid valves have been used. The inherent robustness property of the sliding mode controller makes it easier to select the switching gains of the controller. Moreover, approximate dynamic modeling of the system makes the controller simple. Since in sliding mode control, the states remain on the sliding surface, the motion of the piston is very smooth. This suggests the potential of pneumatic cylinders as actuators for robot manipulators. The controller is hybrid in nature, consisting of an error amplifier, data conversion devices and an 8088 microprocessor along with various digital circuit accessories. Only one feedback device (potentiometer) is used. Velocity is calculated from the sampled position signals. >