Proposed Sliding Mode Controller Research Articles

Design of sliding mode controller with improved reaching law through self-learning strategy to mitigate the torque ripple in BLDC motor for electric vehicles

Brushless Direct Current (BLDC) motors and their evolution in electric vehicles (EVs) garner attention for their streamlined operation and control methods, enhancing driving range while reducing energy consumption. The primary objective is integrating sliding mode control to enhance BLDC motor capabilities, efficiently regulating speed and torque. The proposed sliding mode (SM) controller mitigates torque ripple and improves dynamic performance amidst fluctuating loads. Speed stabilization and torque control involve comparing reference and predicted speeds, with error feedback integrated into the SM controller. Integrating real-time rules and numerical data with an ANN (Artificial Neural Network)-Fuzzy self-learning algorithm empowers the SM controller to anticipate and mitigate error rates in the BLDC motor, efficaciously modulating motor torque with minimal ripple. Extensive MATLAB/Simulink model-in-loop (MIL) and hardware-in-loop (HIL) simulations demonstrate SM controller superiority over conventional PID, Fuzzy, and PID-Fuzzy controllers, with a rise time of 0.01 s, steady-state error of 0.001 %, settling time of 0.02 s, and peak overshoot of 0.066 %. Moreover, the experiment results show an impressive 29.41 % reduction in torque ripple and the development of efficiency maps to attain the maximum efficiency of 96.12 %. This initiative substantiates that the proposed SM controller to enhance BLDC motor efficiency and EV driving range across real-time conditions.

Grid-integrated single phase solar PV system employed with single switch high gain boost converter

• This paper deals with a grid-integrated single phase solar photovoltaic system (GISPSPS) employed with a single switched based high gain boost converter. The significant contributions in this paper are; • The dynamic model of HGBC including effective series resistance (ESR) of passive elements is developed for improving accuracy with slight increase in complexity of model. Then its stability analysis is carried out under different solar irradiations (i.e. 300, 500, 800 and 1000 W/m 2 ) using an eigenvalue plot. • The HGBC control is obtained using the sliding mode control (SMC) for PPE under change in solar irradiations. In proposed SMC only two sensing signals PV panel voltage and current (i.e. v pv and i pv ) are needed for PPE in comparison to three sensing signals PV panel voltage, current and DC link voltage (i.e. v pv , i pv and v dc ) require in SMC of ref. [10] . • The control of FBVSC is obtained by a F i OGI controller. The F i OGI provides noise-less extraction of synchronization signal, under presence of DC offset and noise in grid voltage. However, FOGI used in ref. [10] exhibits poor performance under presence of noise in grid supply voltage. This paper presents a grid-integrated single phase solar photovoltaic (PV) system (GISPSPS) with its modeling, design and control. The GISPSPS consists of a single switch based high gain boost converter (HGBC) and full bridge voltage source converter (FBVSC). The HGBC, boost the low PV panel voltage and extracts the optimum PV power. The HGBC allows high voltage conversion ratio and possesses less voltage stresses on power devices. The optimum PV power is extracted via a sliding mode control (SMC) strategy that generates the switching signal for the switch of HGBC. The FBVSC delivers PV power to the single phase utility grid, as well as load connected at point of interfacing (POI). A fifth order generalized integrator (F i OGI) is developed for FBVSC control to ensure harmonic suppression and DC offset rejection capability during extraction of fundamental grid voltage. Experimental validation of proposed GISPSPS and its control is also verified.

Improvement of PMSG-Based Wind Energy Conversion System Using Developed Sliding Mode Control

In recent years, regulating a wind energy conversion system (WECS) under fluctuating wind speed and enhancing the quality of the electricity provided to the grid has become a hard challenge for many academics. The current research provides a better control strategy to decrease the occurrence of chattering phenomena. Combined with the Maximum Power Point Tracking (MPPT) strategy and a pitch angle control, the control is possible to increase the performance and the efficiency of the Permanent Magnet Synchronous Generator (PMSG) based Wind Energy Conversion System. This study attempts initially to regulate the generator and the grid side converter to track the wind speed reference established by the MPPT algorithm. And secondly, to relieve the chattering problem associated with the conventional sliding mode control (CSMC), the proposed sliding mode control (PSMC) is based on a novel smooth continuous switching control. Besides, the suggested sliding mode control stability is confirmed using Lyapunov’s stability function. The complete system was evaluated in the MATLAB/Simulink (MathWorks, Natick, MA, USA) environment using a 2 MW PMSG’s power, under random fluctuations in the wind speed to show the suggested approach’s efficiency and robustness, which was then compared to the CSMC and other common approaches available in the literature. The simulation results reveal that the recommended sliding mode control approach delivers good speed, accuracy, stability, and output current’s ripple.

Sliding Mode Controller for Electric Vehicles based on Switched Boost Converter

This paper proposes electric vehicle energy conversion of DC-DC by using switched capacitor step-up converter and the implemented system’s control techniques. In this system, the proposed switched boost capacitor converter is interfaced with a power source, attaining high power gain that could not be achieved by the existing systems like VSI and boost converter. In this proposed system, the large inductor is ignored and the capacitor that used for filtering purpose. Because of this, the system is directed to low cost and high density. The switched capacitor regulated converter is applicable for all the power conversion such as dc-ac, dc-dc. In this paper, the proposed Sliding mode controller (SMC) controls the BLDC motor in the vehicle’s inverter. The proposed system results are obtained and verified using MATLAB/Simulink.

A Sliding Surface for Controlling a Semi-Bridgeless Boost Converter with Power Factor Correction and Adaptive Hysteresis Band

This paper proposes a new sliding surface for controlling a Semi-Bridgeless Boost Converter (SBBC) which simultaneously performs Power Factor Correction (PFC) and DC bus regulation. The proposed sliding surface is composed of three terms: First, a normalized DC voltage error term controls the DC bus and rejects DC voltage disturbances. In this case, the normalization was performed for increasing system robustness during start-up and large disturbances. Second, an AC current error term implements a PFC scheme and guarantees fast current stabilization during disturbances. Third, an integral of the AC current error term increases stability of the overall system. In addition, an Adaptive Hysteresis Band (AHB) is implemented for keeping the switching frequency constant and reducing the distortion in zero crossings. Previous papers usually include the first and/or the second terms of the proposed sliding surface, and none consider the AHB. To be best of the author’s knowledge, the proposed Sliding Mode Control (SMC) is the first control strategy for SBBCs that does not require a cascade PI or a hybrid PI-Sliding Mode Control (PI-SMC) for simultaneously controlling AC voltage and DC current, which gives the best dynamic behavior removing DC overvoltages and responding fast to DC voltage changes or DC load current perturbations. Several simulations were carried out to compare the performance of the proposed surface with a cascade PI control, a hybrid PI-SMC and the proposed SMC. Furthermore, a stability analysis of the proposed surface in start-up and under large perturbations was performed. Experimental results for PI-SMC and SMC implemented in a SBBC prototype are also presented.

A Modified Hysteresis-Modulation-Based Sliding Mode Control for Improved Performance in Hybrid DC–DC Boost Converter

Sliding-mode (SM) control is a popular nonlinear control strategy for the dc-dc converters as it offers several advantages such as ease of implementation and robust performance against load and line variations. However, the main drawback of the traditional hysteresis-modulation-based SM controller is that its use in the regulation of the dc-dc converters results in a tradeoff between the overshoot and speed of the closed-loop output voltage response. This is due to the use of the traditional proportional-integral (PI) controller which is used to generate the reference inductor current of the controller. To overcome this problem, the traditional PI-based SM controller is modified such that the reference inductor current used in the sliding surface is now generated using an integral whose integrand is a function of the normalized output voltage error of the converter. A key feature of the integrand is that it is bounded by a user-defined constant. The modified SM control strategy is applied to a hybrid dc-dc boost converter. The expression of the equivalent control signal of the proposed SM controller is derived and the detailed stability analysis of the closed-loop controlled system is given. Also, experimental results are provided to show that the proposed SM controller gives an improved performance as compared to that obtained using the existing PI-based SM controller.

An Improved PWM-Based Sliding-Mode Controller for a DC–DC Cascade Boost Converter

This brief presents an improved pulse-width-modulation-based sliding-mode (SM) controller for the regulation of a 2-stage dc–dc cascade boost converter. The main drawback of the existing SM controller is that its use in the regulation of the high-order dc–dc converter results in a trade-off between the overshoot and speed of the transient output response. In order to overcome this problem, the sliding surface of the proposed SM controller is designed such that the integral action in the resulting equivalent control signal is based on the normalized output voltage error of the converter. Also, the derivative of the integrand is bounded by a user defined constant. The derivation of equivalent control signal of the proposed SM controller and the stability analysis of the closed-loop system are presented. Finally, an experimental comparative study involving the proposed and existing SM controllers is provided.

Robust Trajectory Tracking for Unmanned Aircraft Systems using a Nonsingular Terminal Modified Super-Twisting Sliding Mode Controller

Precision trajectory tracking problem for Unmanned Aerial Systems (UAS) is addressed in this work. A novel algorithm that combines a Nonsingular Modified Super-Twisting Controller with a High Order Sliding Mode Observer to enable an aerial vehicle tracking a desired trajectory under the assumption that i) its translational velocities are not available and ii) there are unmodeled dynamics and external disturbances. The proposed Sliding Mode Controller is based on a nonlinear sliding mode surface that ensures that the position and velocity tracking errors of all system’s state variables converge to zero in finite time. Moreover, the proposed controller generates a continuous control signal eliminating the chattering phenomenon. Finally, simulation results and an extensive set of experiments are presented in order to illustrate the robustness and effectiveness of the proposed control strategy.

A Fixed-Frequency Sliding Mode Controller for a Boost-Inverter-Based Battery-Supercapacitor Hybrid Energy Storage System

The boost-inverter-based battery-supercapacitor hybrid energy storage systems (HESSs) are a popular choice for the battery lifetime extension and system power enhancement. Various sliding mode (SM) controllers have been used to control the boost inverter topology in the literature. However, the traditional SM controllers for the boost inverter topology operate with a high and variable switching frequency which increases the power losses and system components design complexity. This can be alleviated by a pulse width modulation (PWM)-based fixed-frequency SM controller proposed in this paper. The SM controller is implemented using variable amplitude PWM carrier signals generated using the output capacitor voltage and inductor current measurements, thus eliminating the requirement of the output capacitor currents measurement. The battery-connected inductor reference currents for the SM controller are generated by a supercapacitor energy controller which is responsible for the HESS power allocation. First, the theoretical aspects of the SM controller, the operation and parameter selection of the supercapacitor energy controller, and the supercapacitor sizing for the HESS are discussed in the paper. Then, the proposed control system is experimentally verified, and it is shown that the HESS is able to satisfy the HESS output power requirements, while allocating the ripple current and the fast power fluctuations to the supercapacitor while maintaining operation of the supercapacitor within predefined voltage limits. The main advantage of the proposed SM controller, as compared with the traditional double-loop control method, is in eliminating possible DC current injection into the grid when the equivalent series resistance values of the boost inductors become unequal due to the tolerances and temperature variations.

Sliding-Mode Control of PWM Dual Inverter-Based Grid-Connected PV System: Modeling and Performance Analysis

This paper proposes a novel robust and adaptive sliding-mode (SM) control for a cascaded two-level inverter (CTLI)-based grid-connected photovoltaic (PV) system. The modeling and design of the control scheme for the CTLI-based grid-connected PV system is developed to supply active power and reactive power with variable solar irradiance. A vector controller is developed, keeping the maximum power delivery of the PV in consideration. Two different switching schemes have been considered to design SM controllers and studied under similar operating situations. Instead of the referred space vector pulsewidth modulation (PWM) technique, a simple PWM modulation technique is used for the operation of the proposed SM controller. The performance of the SM controller is improved by using an adaptive hysteresis band calculation. The controller performance is found to be satisfactory for both the schemes at considered load and solar irradiance level variations in simulation environment. The laboratory prototype, operated with the proposed controller, is found to be capable of implementing the control algorithm successfully in the considered situation.

Comparison of Sliding Mode Control and Fuzzy Logic control applied to Variable Speed Wind Energy Conversion Systems

wind energy features prominently as a supplementary energy booster. It does not pollute and is inexhaustible. However, its high cost is a major constraint, especially on the less windy sites. The purpose of wind energy systems is to maximize energy efficiency, and extract maximum power from the wind speed. In This case, the MPPT control becomes important. To realize this control, strategy conventional Proportional and Integral (PI) controller is usually used. However, this strategy cannot achieve better performance. This paper proposes other control methods of a turbine which optimizes its production such as fuzzy logic, sliding mode control. These methods improve the quality and energy efficiency. The proposed Sliding Mode Control (SMC) strategy and the fuzzy controllers have presented attractive features such as robustness to parametric uncertainties of the turbine, simplicity of its design and good performances. The simulation result under Matlab\Simulink has validated the performance of the proposed MPPT strategies.

Robust Control of PMSG-based Wind Turbine under Grid Fault Conditions

This paper presents modeling of a direct-driven permanent magnet synchronous generator – based wind turbine and proposes a new controller for Back-To-Back (BTB) converters to enhance Low Voltage Ride Through (LVRT). The LVRT is implemented without any additional devices during grid fault conditions. In this structure, the Proportional-Integral (PI) controllers of Machine Side Converter (MSC) and Grid Side Converter (GSC) are replaced by Sliding Mode (SM) controllers. The MSC controls dc-link voltage and the GSC controls Maximum Power Point Tracking (MPPT) by regulating turbine-generator speed. This control strategy implements different grid code requirements such as Danish grid code. The proposed SM controller in comparison with the PI controller can eliminate dc-link voltage oscillations and reduce the converter voltage and current stresses. Simulation results verify the robustness and effectiveness of the proposed strategy. Hence, by using SM controller, there is no need for additional equipments to enhance LVRT in PMSG-based wind turbines and cost and complexity are significantly reduced.

A Digital Current Control of Quasi-Z-Source Inverter With Battery

This paper presents a fixed frequency operating sliding mode (SM) current control method with fast response and improved stability. Different from the conventional SM control with variable switching frequency, the fixed-frequency SM controller is proposed to control the modulation index and shoot-through duty ratio of the voltage-fed quasi-Z-source inverter (qZSI), which will not increase the passive components and filter design difficulty. A large-signal dynamic model of the system has been established, which can be used for the system stability control in a wide operating range. By using linear approximation, the system small-signal model is also obtained to analyze the control system stability and transient response. Compared with the conventional current mode controller, the proposed SM controller can achieve faster response, lower current ripple and better stability for qZSI when the supply and load variation is large. Experimental results are presented to demonstrate the validity of the theoretical design and the effectiveness of the proposed controller.

The Variable-Bandwidth Hysteresis-Modulation Sliding-Mode Control for the PWM–PFM Converters

This paper proposes the sliding-mode (SM) control method for the pulsewidth modulation -pulse frequency modulation (PWM-PFM) converters, in which both the duty cycle and the switching frequency are utilized as control parameters. Being different from the conventional PWM-PFM modulator, the proposed method utilizes a direct hysteresis modulation (HM) SM controller to perform the PWM, and, meanwhile, employs a quasi-indirect SM controller to control the bandwidth of the HM, so as to realize the PFM. With the proposed method, the control circuit is of low cost and is simple but the transient and steady responses are still satisfactory. The design, simplification, and implementation of the proposed SM control method are illustrated by using a typical single-switch-double-buck converter in this paper. The experimental results agree well with the analysis and show the validity of the proposed method.

Dead-beat and reaching-law-based sliding-mode control of perishable inventory systems

Dead-beat and reaching-law-based sliding-mode control of perishable inventory systemsIn this paper we consider the problem of efficient control of inventory systems with perishable goods. In the analyzed setting the deteriorating stock at a distribution center used to fulfill unknown, time-varying demand is replenished with delay from a supply source. The challenging issue is to achieve the high service level with minimum costs when the replenishment orders are procured with lead-time delay spanning multiple review periods. On the contrary to the typical heuristic approaches, we apply formal methodology based on discrete-time sliding-mode (SM) control. The proposed SM controller with the sliding plane selected for a dead-beat scheme ensures that the maximum service level is obtained in the system with arbitrary delay and any bounded demand pattern. In order to account for the supplier capacity limitations in the systems with input constraints, we also develop an alternative control strategy based on reaching law. Both controllers achieve a given service level with smaller holding costs and reduced order-to-demand variance ratio as compared to the classical order-up-to policy.

Digital Sliding-Mode Controller For High-Frequency DC/DC SMPS

Digital control technique is becoming an attractive alternative for high-frequency switching mode power supply (SMPS). This paper introduces a fully synthesizable digital sliding-mode (SM) controller for high-frequency dc/dc SMPS. The proposed SM controller is associated with a digital pulsewidth modulation (DPWM) block to operate at constant and high switching frequency compared to already published approaches. The digital SM controller is experimentally validated by means of field-programmable gate array in a 4-MHz step-down converter with 10-bit analog-to-digital conversion (ADC) and 11-bit DPWM. Measured dynamic performances are superior to conventional digital controllers for dc/dc SMPS.