Sliding Mode Voltage Controller Research Articles

Robust and efficient control strategy for single-phase two-stage PV grid-tied system with improved power quality

In the last couple of decades, the integration of photovoltaic (PV) systems with the utility grid has gained significant attention due to its potential to harness renewable energy and contribute to sustainable power generation. However, the integration of the PV system into the grid leads to issues related to power quality and system stability under varying solar irradiation, dc offset, and distorted grid conditions. Therefore, this paper focus on the robust and efficient control of a single-phase, two-stage PV grid-tied system to improve power quality and stable system operation under abnormal grid conditions. These objectives can be achieved using the synchronization method, dc link voltage control, and grid current control. The hybrid PLL is proposed in this paper for synchronization and to mitigate the effect of dc offset and lower-order harmonics in the estimated phase and frequency. Further, the sliding mode voltage controller and integral sliding mode current controller are proposed for dc link voltage regulation and grid current tracking. The stability of voltage and current control loops is analyzed using the Lyapunov stability theory. Furthermore, the proposed schemes are validated using MATLAB simulation and experimental analysis. The proposed approach outperforms conventional methods and exhibits better disturbance rejection capability under both dynamic and steady-state conditions, making it a robust and efficient control strategy for grid-tied systems.

Implementation and performance analysis of a novel sliding mode controller for bidirectional DC to DC converter in aircraft application

Purpose The purpose of this paper is to implement a closed loop regulated bidirectional DC to DC converter for an application in the electric power system of more electric aircraft. To provide a consistent power supply to all of the electronic loads in an aircraft at the desired voltage level, good efficiency and desired transient and steady-state response, a smart and affordable DC to DC converter architecture in closed loop mode is being designed and implemented. Design/methodology/approach The aircraft electric power system (EPS) uses a bidirectional half-bridge DC to DC converter to facilitate the electric power flow from the primary power source – an AC generator installed on the aircraft engine’s shaft – to the load as well as from the secondary power source – a lithium ion battery – to the load. Rechargeable lithium ion batteries are used because they allow the primary power source to continue recharging them whenever the aircraft engine is running smoothly and because, in the event that the aircraft engine becomes overloaded during takeoff or turbulence, the charged secondary power source can step in and supply the load. Findings A novel nonsingular terminal sliding mode voltage controller based on exponential reaching law is used to keep the load voltage constant under any of the aforementioned circumstances, and its performance is contrasted with a tuned PI controller on the basis of their respective transient and steady-state responses. The former gives a faster and better transient and steady-state response as compared to the latter. Originality/value This research gives a novel control scheme for incorporating an auxiliary power source, i.e. rechargeable battery, in more electric aircraft EPS. The battery is so implemented that it can get regeneratively charged when primary power supply is capable of handling an additional load, i.e. the battery. The charging and discharging of the battery is carried out in closed loop mode to ensure constant battery terminal voltage, constant battery current and constant load voltage as per the requirement. A novel sliding mode controller is used to improve transient and steady-state response of the system.

Mitigation of Uncertainty in an Islanded Microgrid Using Robust Voltage Controller

In microgrid, a severe problem occurs in terms of voltage oscillations due to mismatch between synchronizing and damping torque. In this study, a centralized nonlinear sliding mode voltage controller proposes to minimize the rotor and DC voltage oscillations issue in an islanded microgrid. The linear matrix inequality (LMI) technique has been applied for bounding the state error. Lyapunov criteria is utilized for assurance of asymptotic convergence and LMI optimization approach is used for obtaining the controller parameters. The proposed controller is able to tackle the parametric uncertainties of diesel generator, oscillations of rotor and voltage fluctuation as well as the closed-loop system responses also improves both transient responses and steady state responses simultaneously. The simulation results authenticate that the proposed controller confirms speedy recovery of nominal frequency without any oscillations and reduced the limitation of chattering notably without any loss in control accuracy. The performance and robustness of the proposed controller is also compared with conventional controllers.

Sliding-Mode Direct-Voltage Control of Voltage-Source Converters With LC Filters for Pulsed Power Loads

This article proposes a direct-voltage controller, based on sliding modes, for regulating the output voltage of voltage-source converters (VSCs) equipped with LC filters. Grid-forming VSCs used in microgrids with pulsed loads must provide fast dynamic response and strong rejection of load perturbations. The new voltage control scheme uses a single-stage sliding-mode voltage controller with state feedback. The typical two-loop cascaded topology using a current controller in the inner loop and a voltage controller in the outer loop is not employed. The sliding-mode control (SMC) contains three components: 1) a feedforward effort that sets the ideal operating point, 2) a switching control law based on SMC, and 3) a sliding-mode equivalent control. The sliding variable is defined with proportional-derivative (PD) dynamics, and thus, it provides inherent active damping properties. The SMC improves the robustness with respect to load perturbations and modeling errors, whereas the equivalent control adds damping and reduces the response time to large load transients. The article describes the design and gain selection, and provides a simulation-based sensitivity analysis for this scheme. Two variants are tested in standalone operation: with and without the P term of the PD component. Experimental results show that, in both cases, the response to pulsed loads is very fast (about 1 ms) and accurate.

High performance DC/DC buck converter using sliding mode controller

<span>This paper investigated the performance of the sliding mode control technique for dc/dc converter using frequency response method. The applications of the step down type switching regulator) buck converter (are found in the devices that use batteries as power source like laptop, cell phones, electric vehicle, and recently, it has also been used in the renewable energy processing, as a maximum output power can be achieved at higher efficiency. In order to optimize the efficiency and for convenient power management, the issues like power on transients, the effect of load variation, Switching and Electromagnetic interference (EMI) losses has to be overcome for which controllers are used. In the proposed method, pulse width modulation (PWM) based on proportional-integral-derivative sliding mode voltage controller (PID SMVC) is designed for a buck converter and the response for appropriate control parameters has been obtained. The system stability has been examined and analyzed from the performance characteristics, which shows clearly that the buck converter controlled by the sliding mode controller has fast dynamic response and it’s very efficient for various applications.</span>

A Sliding Surface-Regulated Current-Mode Pulse-Width Modulation Controller for a Digital Signal Processor-Based Single Ended Primary Inductor Converter-Type Power Factor Correction Rectifier

To efficiently supply wide-range DC voltage from a pulse-width modulation (PWM) rectifier, this paper presents a single-phase, full-wave, diode-bridge, single-ended primary-inductor converter-type (SEPIC-type) power-factor-correction (PFC) rectifier in continuous conduction mode with a sliding surface-regulated current-mode PWM controller. According to the switched-mode operation of the rectifier, a fourth-order switch model of the SEPIC is derived. From the fourth-order model, a simplified state-averaged model which approximately describes the dynamic behaviors of both the output voltage and inductor current is proposed. Then, from the simplified state-averaged model, the sliding surface-regulated current-mode PWM controller for the SEPIC-type PFC rectifier is proposed. The sliding surface-regulated current-mode PWM controller comprises a sliding-mode voltage controller in outer loop for robust control of the output DC-voltage and a sliding-mode current controller in inner loop for phase-synchronized control of the inductor current. For experimental studies, implementation of the proposed control algorithm in a DSP controller and a laboratory prototype of the SEPIC-type rectifier with the DSP-based PWM controller were carried out. Experimental results from the DSP controller-applied SEPIC-type rectifier are illustrated to confirm the validity of the proposed controller for practical applications.

Study of a control strategy for grid side converter in doubly- fed wind power system

The grid side converter is an important part of the excitation system of doubly-fed asynchronous generator used in wind power system. As a three-phase voltage source PWM converter, it can not only transfer slip power in the form of active power, but also adjust the reactive power of the grid. This paper proposed a control approach for improving its performance. In this control approach, the dc voltage is regulated by a sliding mode variable structure control scheme and current by a variable structure controller based on the input output linearization. The theoretical bases of the sliding mode variable structure control were introduced, and the stability proof was presented. Switching function of the system has been deduced, sliding mode voltage controller model has been established, and the output of the outer voltage loop is the instruction of the inner current loop. Affine nonlinear model of two input two output equations on d-q axis for current has been established its meeting conditions of exact linearization were proved. In order to improve the anti-jamming capability of the system, a variable structure control was added in the current controller, the control law was deduced. The dual-loop control with sliding mode control in outer voltage loop and linearization variable structure control in inner current loop was proposed. Simulation results demonstrate the effectiveness of the proposed control strategy even during the dc reference voltage and system load variation.

Model reference adaptive sliding mode control using RBF neural network for active power filter

Abstract In this paper, a model reference adaptive sliding mode (MRASMC) using a radical basis function (RBF) neural network (NN) is proposed to control the single-phase active power filter (APF). The RBF NN is utilized to approximate the nonlinear function and eliminate the modeling error in the APF system. The model reference adaptive current controller in AC side not only guarantees the globally stability of the APF system but also the compensating current to track the harmonic current accurately. Moreover, a sliding mode voltage controller based on an exponential approach law is designed to improve the tracking performance of DC side voltage. Simulation results demonstrate strong robustness and outstanding compensation performance with the proposed APF control system. In conclusion, MRASMC using RBF NN can improve the adaptability and robustness of the APF system and track the given instructional signal quickly.

Sliding mode voltage control strategy for capturing maximum wind energy based on fuzzy logic control

A sliding mode voltage control strategy is proposed in this paper to capture the maximum electrical energy from wind. This control strategy mainly includes a fuzzy logic controller and a sliding mode voltage controller. The fuzzy logic controller is designed to derive the optimum DC-side voltage, while the sliding mode voltage controller is employed to track the derived optimum voltage with minimum steady-state error and hence to capture the maximum wind energy. This paper illustrates how major issues in the design and implementation of the two controllers can be handled effectively. Comparative experimental results demonstrate that significant performance improvements in maximum wind energy capture can be achieved by using the proposed control strategy.

PWM Based Quasi Sliding Mode Control of Buck Converter

This paper presents the sliding mode control technique with PD type of feedback controller and the design and analysis of a fixed-frequency pulse width modulation based quasi sliding mode voltage controller with PID type of feedback controller for buck converter. A practical design approach that aims at systematizing the procedure for the selection of the control parameters is presented. The robustness of the controller is discussed with line variation and load variation analysis. In addition, a simple method of implementing the proposed adaptive control strategy is discussed to reduce the line variations. Simulation results show satisfactory performance of the proposed switching converter.

PWM based Quasi Sliding Mode Control of Buck Converter

This paper presents the sliding mode control technique with PD type of feedback controller and the design and analysis of a fixed-frequency pulse width modulation based quasi sliding mode voltage controller with PID type of feedback controller for buck converter. A practical design approach that aims at systematizing the procedure for the selection of the control parameters is presented. The robustness of the controller is discussed with line variation and load variation analysis. In addition, a simple method of implementing the proposed adaptive control strategy is discussed to reduce the line variations. Simulation results show satisfactory performance of the proposed switching converter. Keywords: Hysteresis Modulation (HM), Pulse Width Modulation (PWM), Quasi Sliding Mode (QSM), Sliding Mode Control (SMC)

Design and Stability Analysis of a Fuzzy Adaptive SMC System for Three-Phase UPS Inverter

This paper proposes a combined fuzzy adaptive sliding-mode voltage controller (FASVC) for a three-phase UPS inverter. The proposed FASVC encapsulates two control terms: a fuzzy adaptive compensation control term, which solves the problem of parameter uncertainties, and a sliding-mode feedback control term, which stabilizes the error dynamics of the system. To extract precise load current information, the proposed method uses a conventional load current observer instead of current sensors. In addition, the stability of the proposed control scheme is fully guaranteed by using the Lyapunov stability theory. It is shown that the proposed FASVC can attain excellent voltage regulation features such as a fast dynamic response, low total harmonic distortion (THD), and a small steady-state error under sudden load disturbances, nonlinear loads, and unbalanced loads in the existence of the parameter uncertainties. Finally, experimental results are obtained from a prototype 1 kVA three-phase UPS inverter system via a TMS320F28335 DSP. A comparison of these results with those obtained from a conventional sliding-mode controller (SMC) confirms the superior transient and steady-state performances of the proposed control technique.

On the Practical Design of a Sliding Mode Voltage Controlled Buck Converter

This paper presents a simple and systematic approach to the design of a practical sliding mode voltage controller for buck converters operating in continuous conduction mode. Various aspects of the design, including the associated practical problems and the proposed solutions, are detailed. A simple and easy-to-follow design procedure is also described. Experimental results are presented to illustrate the design procedure.