Adaptive Hysteresis Band Research Articles

O Splines-Based Fixed-Frequency Integral Sliding-Mode Controller for PFC Rectifier

This paper proposes a fast-response sliding mode controller (SMC) for a semi-bridgeless boost converter under large and quick load fluctuations to ensure tight output voltage regulation and unity power factor correction (PFC) at the line side. In this sense, a novel approach for estimating the reference current profile is presented focusing on the real-time phasor estimation via the O-splines of the discrete-time Taylor-Fourier transform (DTTFT). This method allows for improving the computational efficiency and dynamic performance of the estimations of amplitude, frequency and phase of the network voltage used for the generation of the reference current profile. Several aspects of the controller design are discussed, including the choice of the sliding surface, the existence and stability conditions, and the implementation of an adaptive hysteresis band to fix the switching frequency and reduce zero-crossing distortion. Experimental results of a GaN-based prototype validate the theoretical predictions, exhibiting a PF close to 1 and a total harmonic distortion lower than 3.2% in presence of load changes of up to 50% and changes in the output voltage set point. Several comprehensive experimental comparisons between the proposed framework and the most widely used methods recently reported in the literature are accomplished in terms of transitory and steady-state responses. The robustness of the proposed control approach is experimentally demonstrated under sag conditions and a wide operating range of the input voltage.

Constant switching frequency‐based delta‐sigma modulation of single‐phase AC–AC zeta converter

SummaryDirect pulse width modulated (PWM) AC–AC converters, derived from their DC–DC counterparts, serve as promising media for AC–AC power conversion because they offer benefits, such as single‐stage power conversion, absence of bulky DC links, and small footprint. In this study, a single‐phase ( ) AC–AC zeta converter was analyzed under buck, boost, and buck‐boost operations. Delta‐sigma modulation (DSM) technique, known for its simple logic implementation, excellent reference‐tracking property, robust control, and fast transient response, was employed for the load voltage control of a AC–AC zeta converter. However, the conventional DSM technique relies on a fixed hysteresis band (FHB) for restricting the integrated (sigma) error (delta) between the reference and estimated control voltages within a narrow band, which causes the converter to operate at a variable switching frequency (VSF). Although VSF enhances the converter performance with low total harmonic distortion (THD) and high degree of flexibility over waveform quality, it poses serious implications such as higher switching losses, putting more strain on thermal management of switches. This paper presents a constant switching frequency‐based DSM technique based on an adaptive hysteresis band (AHB) for a AC–AC zeta converter. The converter is controlled using FHB‐DSM and AHB‐DSM techniques, and a comparison is drawn between the two in terms of various performance indices. In this comparison, FHB‐DSM serves as a benchmark and an optimum switching frequency based on AHB‐DSM technique is determined, which exhibits low switching losses while maintaining the same THD limits, dynamic response, and waveform quality as that of FHB‐DSM technique. The proposed strategy was validated by simulation studies in MATLAB/SIMULINK software. Furthermore, a real‐time simulator, OPAL‐RT (OP4510), was used to validate the study with real‐time implementation.

Advanced compensation scheme for enhancing photovoltaic power quality

With the photovoltaic (PV) system becoming highly popular in distribution network, there is also a growing concern regarding its adverse impacts over the power quality (PQ) of integrated system. This deterioration in PQ hassparked a new interest in the filtering techniques used in the power systemfor mitigating these problems. In contrast to conventional passive filters now active power filters (APFs) are being looked as the predominant solution.This paper presents a state-estimation based effective compensation strategy for enhancing performance of employed APF scheme. A novel control technique for PQ enhancement is proposed where Kalman filtering approach has been applied for generating the reference signals. Also, an adaptive hysteresis band technique has been applied here in the switching strategy. Thus an enhanced filter performance is achieved with reduced complexity and better elimination of distortions. Simulated results obtained in MATLAB/Simulink platform have been analyzed completely, where the superiority of filtering algorithm has been also demonstrated through leasttotal harmonic distortion (THD) achieved in source current among all the existing Kalman filters.

New Modulation Technique in Smart Grid Interfaced Multilevel UPQC-PV Controlled via Fuzzy Logic Controller

The use of sensitive electronic devices has increased recently; hence, power quality has become an important factor in electrical power systems. The various disturbances occurring in the electrical network (harmonics, voltage swells, sags, etc.) may lead to technical-economic damage that negatively impacts the quality of the supplied power. Therefore, the use of the Unified Power Quality Conditioner (UPQC) is a promising solution to limit such damage. In this paper, a nine-level structure of the proposed standardized power quality conditioner is analyzed. The conditioner is connected between a photovoltaic system (UPQC-PV) and a smart grid. Then, a new approach to generate switches for the switches of both the series and parallel converters is proposed. This modulation technique relies on an adaptive hysteresis band (AHB) that is determined via a fuzzy logic controller in order to obtain the required modified output voltage with minimum distortion. Simulation results, using MATLAB/Simulink, of different disturbance scenarios that may occur in the network are presented to verify the accuracy of the proposed fuzzy-logic-based AHB control system. Compared with the conventional SPWM, it is found that the proposed AHB modulation technique significantly improves the power quality in terms of producing less total harmonic distortion in both the voltage and current waveforms.

Proportional Hysteresis Band Control for DC Voltage Stability of Three-Phase Single-Stage PV Systems

Ensuring the stability of DC-link voltage in grid-connected photovoltaic (PV) systems plays a critical role in their reliable and continuous operation. DC voltage fluctuation and, in the worst case, DC voltage collapse will dramatically hamper real and reactive power delivery to the grid. This is more the case in single-stage inverters with no DC-DC boost stage, and the DC voltage has a varying nature. This paper proposes a new control approach for ensuring DC-link voltage stability in single-stage PV systems. The proposed control strategy is based on an adaptive hysteresis band controller (HBC), supplementing the conventional control blocks. This strategy offers the capability to prevent fast discharge of DC-link capacitor and keeps it within acceptable limits by quickly modifying phase shift applied to inverter PWM through quick calculations. Results show that the approach greatly improves PV system performance, in various operating modes. The proposed control scheme is implemented in the real-time simulator, OPAL-RT, OP5600 to verify its applicability and effectiveness in real time.

A Two-Step Control Approach for Torque Ripple and Vibration Reduction in Switched Reluctance Motor Drives

The objective of this work is to reduce the torque ripple and vibration in Switched Reluctance Motor (SRM) drives. To achieve such a goal, a two-step approach is proposed. In the first step, the reference current is profiled using an optimization method, aimed to reduce the torque pulsation. In the second, the optimum current profile is applied to the SRM through an adaptive hysteresis band controller to actively cancel the radial vibration. The proposed technique uses an optimization procedure based on the Field Reconstruction Method (FRM) and Non-Derivative Optimization Method to find the optimal current profile that mitigates the torque pulsation, however, the investigation has shown that the proposed excitation leads to a higher radial vibration, which has been mitigated by using an adaptive hysteresis band controller. The theoretical basis for the proposed approach is initially presented, followed by system modeling and simulation. In addition, experimental verification has been conducted using an 8/6 SRM to show the feasibility of the proposed approach. The proposed method alleviates the acoustic noise and torque pulsation in SRM and offers an effective step towards the prevalent use of SRM in a wide range of applications.

Grid Connected Unsymmetrical Two-Phase Induction Generator System Using Time-Based Unbalanced Space Vector PWM and Adaptive Hysteresis Band Current Control

Wydawnictwo SIGMA-NOT wydaje czasopisma fachowe informujące swoich czytelników o najnowszych osiągnięciach naukowych i nowoczesnych rozwiązaniach technicznych w Polsce i na świecie, popularyzuje problemy techniczne oraz poszerza wiedzę i kulturę techniczną.

Adaptive hysteresis band current control of grid connected PV inverter

In this paper, adaptive hysteresis band current controller is implemented to control the current injected into the grid. Initially it was implemented by B.K Bose for control of the machine drive. Now it is implemented for the grid connected PV inverter, to control the current injected into Grid. It is well suitable for the distribution generation. The adaptive hysteresis band controller changes the bandwidth based on the modulating frequency, supply voltage, input DC voltage and slope of the reference current. Consequently, the controller generates pulses to the inverter. It is advantageous over the conventional hysteresis controller, as the switching frequency is maintained almost constant. Thereby quality of grid current is also improved. It is verified in time domain analysis of simulation using MATLAB.

English

Recently the use of sensitive electronic devices has increased, and the quality of energy has become an important factor in electrical power systems, where disturbances occurring in the network (harmonics, swell, voltage sag, etc.) affect consumers and lead to technical-economic damages. One of the most prominent solutions to address energy quality problems is the UPQC (Unified Power Quality Conditioner). In this paper, the unified power quality conditioner used to improve the electrical power quality in the distribution networks was discussed, where the Park transformations are used to obtain the required reference signals, and also the use of adaptive hysteresis band to generate the electronic switch pulses in both serial and shunt switches, where the pulse width is determined by dependence on fuzzy logic. The studied system was validated by simulating different distortion cases and comparing the results when using the Sinusoidal Pulse Width Modulation (SPWM) to control the two switches. The results showed improvement in the electrical power quality through the use of an adaptive hysteresis band controller, and that appeared by reducing the total distortion factor (THD%), which resulted in improving the shape of both the voltage and current waveforms.

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.

New adaptive hysteresis band width control for direct torque control of induction machine drives

This paper presents a new adaptive hysteresis band control approach used in direct torque control (DTC) of the induction motor (IM) drives with the switching tables for the generation of PWM signals. Constant Hysteresis Direct torque control (CHB-DTC) method used the torque and stator flux errors to generate the stator voltage reference and frequency vectors for controlling the three-phase induction motor. The CHB-DTC gives better torque transient performance but it has large steady state ripples. To reduce torque and stator current ripples in CHB-DTC controlled induction motor drives a new adaptive hysteresis band control (AHB) approach is proposed, where the hysteresis band is adapted in real time with the stator flux and torque errors variation, instead of fixed bandwidth. Both classical CHB-DTC method and the proposed adaptive hysteresis band DTC (AHB-DTC) fed three induction motor have been simulated using Matlab/Simulink. The simulation results at different operating conditions over a wide speed range demonstrate the validity, effectiveness, and feasibility of the proposed scheme. The measurements showed that torque ripples were significantly decrease with the new AHB-DTC technique and better speed response in step up or down compared to the CHB-DTC.

Experimental Evaluation of a Multifunctional System Single-Stage Pv-Shunt Active Filter Under Partial Shading Conditions

Distributed solar photovoltaic (PV) generation is becoming more popular. Similarly, the number of electronic loads has increased along with the need to improve power quality. The PV-Shunt Active Filter (PV-SAF) is a system capable of injecting the PV power generated in the electrical grid and eliminating harmonics of current and reactive power of the local installation load. In the single-stage topology, the PV array is connected directly to the SAF DC bus, without the need for an intermediate DC-DC converter. In this paper, a three-phase single-stage PV-SAF system is evaluated in partial shading conditions. For this, a Global Maximum Power Point Tracking (GMPPT) technique capable of quickly tracking the point of maximum power even in the presence of several peaks in the power-voltage curve of the PV array is proposed. A night-time mode is implemented for the system operation when there is no PV generation. The instantaneous power theory and the adaptive hysteresis band current controller are used to control the SAF currents. The results obtained through an experimental prototype show that the PV-SAF system with the control strategies adopted is capable of simultaneously injecting into the grid the maximum power of the PV system and compensating harmonics and reactive power.

Three-Phase Grid Connected Bi-Directional Charging System to Control Active and Reactive Power with Harmonic Compensation

Abstract The feasibility of integration of Battery Energy Storage System (BESS) with a three-phase AC grid is being investigated in this paper. A converter is an inevitable part of a modern DC generating system. The link between the grid and the BESS is established through a Voltage Source Converter (VSC). Therefore, the converter can be utilized to dispatch the DC generated power to the connected AC grid and at the same time provides reactive power compensation and load harmonic compensation throughout the day. The DC bus voltage control of the converter system is carried out to keep the power factor always at unity, irrespective of the charging state of the battery source. The charging and discharging of the connected battery energy storage system are carried out through a bidirectional DC-DC converter. Adaptive hysteresis band current control (AHCC) scheme is employed to produce the switching signals. Finally, its performance is compared with the traditional hysteresis band control technique.

Adaptive hysteresis band current control‐based power conditioner to improve the power quality of V/V railway supply system

Subsequent to the publication of this article by Beirami and Feshki Farahani,1 the authors would like to correct the affiliation of author Hassan Feshki Farahani. The correct affiliation details are as follows: 2Department of Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran

Estudio comparativo de técnicas PWM de banda de histéresis para el control de corriente en filtros activos de potencia paralelos

El presente artículo evalúa el desempeño de un filtro activo empleando tres diferentes técnicas de control de corriente de banda de histéresis: banda fija, banda adaptativa y con modulación por vector espacial. En la comparación se estudian las características de cada técnica y mediante simulación se evalúa su desempeño y operación. En todos los casos se emplea la teoría pq para el cálculo de las corrientes de referencia y se emplea un controlador proporcional para regular la tensión del bus de continua. De acuerdo con los resultados, las técnicas PWM evaluadas permiten una reducción del contenido armónico de la corriente de la red de alimentación de 31 % sin compensación, a un 6 %, considerando el filtro activo de potencia. La técnica de banda adaptativa de histéresis presenta el más bajo desempeño en la reducción de armónicos en las corrientes de la red. Además, se tiene que el método de banda fija de histéresis es el más recomendado para aplicaciones de filtros paralelo debido a que posee una estructura más simple que permite su implementación. Los resultados tambien muestran que la técnica de banda adaptativa de histéresis es la que presenta mayor reducción en las variaciones de la frecuencia de conmutación, requiriendo mayor número de operaciones, ya que requiere calcular el ancho de banda en cada iteración. Mientras que la técnica de modulación por vector espacial y banda de histéresis presenta frecuencias de conmutación altamente variables y mayor complejidad en su implementación.

Power quality improvement in an AC network using artificial neural network and hysteresis band current controller

This paper demonstrates a study to improve the total harmonic distortion (THD) originated due to excessive use of power electronic (PE) equipment and non-linear loads. Shunt active power filter (SAPF) is used to mitigate the harmonics from the system because it has the capability of minimizing the harmonic problems initiated by non-linear loads. The instantaneous reactive power (IRP) p-q theory is used for the generation of reference signal and for the extraction of compensating components of the current. The proportional integral (PI) controller and artificial neural network (ANN) have been employed in the DC-link controller and for current errors adjustments. In this paper, both conventional hysteresis and adaptive hysteresis band current controller (HBCC) have been used for the generation of gate pulses for the SAPF, which reduces THD in the source current to a value within IEEE specified standards, without any phase error over the extensive range of adaptive HBCC strategy. Simulation results confirm that the SAPF with HBCC and ANN performs the harmonic mitigation efficiently and maintains power factor (PF) close to unity.

Adaptive hysteresis band current control-based power conditioner to improve the power quality of V/V railway supply system

Adaptive hysteresis band current control-based power conditioner to improve the power quality of V/V railway supply system

Adaptive fuzzy hysteresis band current control for reducing switching losses of hybrid active power filter

Although hysteresis band current control is an easy to implement and robust control method for industrial power electronics converters, it has also some disadvantages like variable and high switching frequency causing high switching losses. In this study, a novel adaptive fuzzy hysteresis band current control system is proposed by making use of fuzzy expressions of both hybrid active power filter (HAPF) current and integral of its harmonic components to reduce the switching losses of three-phase three-wire two-level HAPF. To reach this aim, a relation between switching frequency and integral of filter current harmonic components is formulised and used for defining a fuzzy hysteresis band. Moreover, the magnitude of the instantaneous current switched is also correlated to the switching losses; in this way, its fuzzy expression is also used for defining hysteresis band. Those fuzzy expressions are then utilised to constitute a dynamically changing hysteresis bandwidth. The proposed control system is finally optimised using EMTDC/PSCAD simulation environment and implemented in the field. The implemented HAPF system has been shown to successfully suppress all the interharmonic and harmonic current components produced by a steel melting facility occupying three induction melting furnaces and it has provided around 9% reduction in overall losses.

A Fuzzy adaptive hysteresis band controller for three phase four wire UPQC

Unified Power Quality Compensator (UPQC) is used to protect the sensitive loads in the distribution system from voltage and current disturbances. The compensation capability of UPQC depends on the control strategies used for shunt and series converters. Conventional adaptive hysteresis controller pulse width modulation technique had failed to track exactly during transient conditions and disturbances at load and source side. In paper fuzzy adaptive hysteresis controller is proposed for three phase four wire UPQC for compensating voltage sag/swell, current harmonics, voltage harmonics and neutral current compensation. Fuzzy adaptive hysteresis controller can effectively compensate the power quality problems during the transient conditions. A comparative simulation analysis of proposed and conventional methods are presented in this paper using MATLAB/SIMULINK tool.

Modeling & Analysis of a Novel Adaptive Hysteresis Band Controller for Boost and Buck Converter

In this paper, a new topology of Adaptive Hysteresis Band controller for Boost & Buck converter has been proposed, modeled and analyzed. The difficulties caused in Hysteresis Band (HB) controlled dc-dc converter have been eliminated using Adaptive Hysteresis Band (AHB) controller. This novel control topology can be able to maintain the switching frequency constant unlike HB controller. Thus the filter design for the converters will become easier with this controller. Again this control methodology is a robust one as it depends upon the system parameters where there was no possibility with HB controller. The Mathematical modeling of the controller is shown in this paper, further this has been simulated using Matlab /SIMULINK to generate pulse. The steady state analysis to find the parameters and the stability condition of the converter using the dynamic behavior is also portrayed in this paper. The simulation for a Boost and a Buck converter is also shown separately using AHB controller.