Hysteresis Band Research Articles

Using Hysteresis Band Method for the Control of Three-Phase STATCOM Connected to a Transport Network

The transit of reactive power through the electric transport lines due to the inductive loads, creates problems of instabilities on the electrical networks. Transport networks are increasingly vulnerable to instability of voltage due to industrialization and/or population growth. The managers of these networks are therefore seeking effective solutions to these problems. STATCOM is one of the devices of the family of shunt FACTS used for reactive energy compensation. It generally offers better features compared other FACTS devices and conventional reactive compensation devices. This work aims to apply the STATCOM controlled by the current control method by hysteresis bands for the maintenance of the voltage in an electric transport network. The transport network is modeled as a transport line in MATLAB/SIMULINK and its characteristics are compared to the system without STATCOM.

Using Hysteresis Band Method for the Control of Three-Phase STATCOM Connected to a Transport Network

The transit of reactive power through the electric transport lines due to the inductive loads, creates problems of instabilities on the electrical networks. Transport networks are increasingly vulnerable to instability of voltage due to industrialization and/or population growth. The managers of these networks are therefore seeking effective solutions to these problems. STATCOM is one of the devices of the family of shunt FACTS used for reactive energy compensation. It generally offers better features compared other FACTS devices and conventional reactive compensation devices. This work aims to apply the STATCOM controlled by the current control method by hysteresis bands for the maintenance of the voltage in an electric transport network. The transport network is modeled as a transport line in MATLAB/SIMULINK and its characteristics are compared to the system without STATCOM.

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.

Investigating sine-band hysteresis control of photovoltaic-grid connected inverter

<p>In this paper, an optimization of PV grid connected system is investigated. This is achieved by considering the application of artificial intelligence in the DC side to realize maximal power extraction, and using a sine-band hysteresis control in the AC side of the system, to generate a sine current/voltage suitable for grid connection IEEE929-2000 standards. The overall system has been simulated taking into account environmental effects and standards constraints in order to achieve best performance. The choice of sine band hysteresis control was selected considering its implementation simplicity. The algorithm runs fast on a low-cost microcontroller allowing to avoid any delay that can cause a phase shift in the system. An experimental setup has been realized for tests and validation purposes. Both simulation and experimental results lead to satisfactory results which are conform to the IEEE929-2000 standards.</p>

An Improved Open-Phase Fault-Tolerant DTC Technique for Five-Phase Induction Motor Drive Based on Virtual Vectors Assessment

The multiphase machine (MM) drives are best suitable for safety-critical applications due to its inherent fault-tolerant capability. The fault-tolerant operation of MM drives is challenging and necessary for applications such as off-shore ship propulsion, highway electric vehicles, and more electric aircraft. A two-level voltage source inverter fed five-phase induction motor (FPIM) drive has been considered for the postfault performance assessment. In this article, an improved fault-tolerant direct torque control (DTC) technique is proposed for the FPIM drive based on virtual vector (VV)s assessment under the open-phase fault condition. The theoretical analysis is carried out to investigate the impact of VVs on the change in torque as well as flux response at different speeds and loading conditions. Based on this analysis, a modified lookup table, flux, and torque hysteresis bands are designed to improve the functioning of the fault-tolerant DTC of FPIM drive. The FPIM drive performance is analyzed and tested experimentally with an open-phase fault. Studies have confirmed the reliability and superiority of the proposed DTC controller over existing postfault solutions. In addition, the robustness of the FPIM drive at steady-state and dynamic operating conditions is evaluated from the given results, including the transition from pre-to-post fault operation.

Delta-Sigma Modulation Based Common-Mode Voltage Elimination in Direct Matrix Converter

The direct matrix converter (DMC) offers a compact and robust solution over typical ac–dc–ac converter, by enabling direct ac–ac power conversion without any energy storage requirements. Moreover, it offers enhanced source current quality, innate bidirectionality and power factor correction capabilities. Its industrial suitability is further advocated by the elimination of common-mode voltage through the DMC topology. Space vector modulation and model predictive control based approach to common-mode voltage elimination in matrix converter, are previously proposed. This article proposes the delta-sigma modulation for common-mode voltage elimination in matrix converter, which is computationally less cumbersome and performs better as compared to previously documented methods. This method utilizes only six most optimum states of DMC that yield zero common-mode voltage, and performs load voltage and source current control by computing each error variable (delta), integrating it (sigma) and further minimizing it within a hysteresis band. Source current control necessitates load current estimation, which is done through predictive model of the load, hence eliminating load current sensors.

Nonlinear Model Predictive Control for the Energy Management of Fuel Cell Hybrid Electric Vehicles in Real Time

This article proposes an energy management system (EMS) for a fuel cell (FC) hybrid electric vehicle. The EMS is based on nonlinear model predictive control (NMPC) and employs a recurrent neural network (RNN) for modeling a proton exchange membrane FC. The NMPC makes possible the formulation of control objectives not allowed by a linear model predictive control (MPC), such as maximum efficiency point tracking of the FC, while the RNN can accurately predict the FC nonlinear dynamics. The EMS was implemented on a low-cost development board, and the experiments were performed in real time on a hardware-in-the-loop test bench equipped with a real 3-kW FC stack. The experimental results demonstrate that the NMPC EMS is able to meet the vehicle's energy demand, as well as to operate the FC in its most efficient region. Moreover, a comparative study is performed between the proposed NMPC, a linear MPC, and hysteresis band control. The results of this comparative study demonstrate that the NMPC provides a better fuel economy and can reduce FC degradation.

Latest Advances in DTC Control of Induction Motors

In these days, developments in the area of Induction Motor control is increasing significantly. Considerable advancements have been taken place in the area of Direct Torque Control (DTC), which is capable of providing quick dynamic response with respect to torque and flux. This paper presents a detailed survey on various latest techniques of DTC control of Induction Motor such as DTC-SVM with hysteresis band, DTCSVM with Model Predictive Control, DTC with sliding mode control, DTC with Model reference adaptive system (MRAS) et cetera. The simulation results are discussed for DTC-SVPWM topology and results obtained proves that this method has reduced torque ripple

Fractal Approach Based Simplified and Generalized Sector Detection in Current Error Space Phasor Based Hysteresis Controller Applied to Multilevel Front-End Converters

The current error space phasor (CESP) based hysteresis controller employed for front-end converter requires two (inner and outer) hysteresis bands for vector selection and sector detection, respectively. As a result of this, the CESP moves out of the fixed (hexagonal) inner boundary many times in one fundamental cycle (and touches outer hysteresis band) to detect appropriate sector. This distorts the supply current waveform and increases the implementation complexity. To provide effective solution to the said issue, in this article, a fractal approach with a triangularization technique is proposed and analyzed to eliminate the outer hysteresis band and lookup table for sector change detection. The novelty proposed in this article is the integration of the fractal approach to CESP-based hysteresis controller, which reduces the complexity of the implementation of CESP-based hysteresis controller for any general multilevel front-end converter. The detailed analysis of the proposed technique for sector detections is presented considering the voltage space phasor structure of three-level and five-level converters. A generalized flowchart for any multilevel converter employing CESP-based hysteresis controller with proposed sector detection technique is developed and presented. Laboratory prototype is developed for a three-level flying capacitor front-end converter with an effective capacitor voltage balancing scheme. The experimental results are presented to validate the effectiveness of the proposed current controller in terms of unity power factor and low harmonic distortion in the line current under various practical conditions.

Input Control of Photovoltaic Fed DC-DC Converter Based on a Dual Modeling Approach

The non-linear characteristic of photovoltaic (PV) sources with a clear dual nature on both side of their maximum power point complicates the interfacing converter design, especially in the case of maximum power point tracking MPPT. To overcome such constraint, in the current study, two distinct input controllers of the PV fed converter are used. The first one designed assuming a current fed topology, and the second assuming a voltage fed one. The probable oscillation in the neighborhood of the maximum power point is reduced by imposing a hysteresis band, to allow a soft transient from one region to the other one. The converter is modeled following a state-space averaging method, where the resulting transfer functions describe fully the converter internal dynamics. The control issue of the resulting dual model is discussed, and a frequency approach is used, where the system loop gain transfer function is shaped for the best possible performances. The validity of the modeling and the controllers design approach are finally tested by both model simulation and experimental tests under open and closed loop conditions.

SAPF for Power Quality Improvement Based on PSODE Optimization Algorithm

PQ phenomenon has gain an overwhelming attention in recent years for extensive use of complicated industrial processes. In the modern world, the usage of intelligent algorithms to enhance power quality is increasing gradually as the present day utility system as a linear model is unsatisfactory and ineffective. This paper emphasis on comparative analysis of PSODE with traditional PSO and DE for the harmonic reduction in source current with optimal tuning of proportional integral (PI) controller gain values. The SAPF is dominant among the power quality conditioners used to limit the current variations that are induced in the utility system because of nonlinear loads. The reference current generation is based on PQ theory. The instantaneous switching of voltage source inverter (VSI) is taken care by hysteresis band current controller (HBCC). The pro-effective simulations are implemented in the MATLAB/SIMULINK environment, which even supports the efficacy of the present day power system.

Improved Direct Torque Control strategy for Wide Range Speed Control of Induction Motor Drives

Induction Motor is popular option for most of the drives applications. It has simple construction but complex control. DC motor like decoupled control of induction motor drives similar to Field Oriented control is possible using Direct Torque Control (DTC) method which is very simple control strategy compared to vector control. The DTC strategy is very useful for automobile and traction applications using IM but due to use of hysteresis band controllers, DTC has problems of torque ripples, variable switching frequency and poor low speed performance. Because of these reasons, DTC is used in such applications for high speed range and not for the whole speed range. An improved DTC strategy suitable for wide range speed control is suggested in this paper which is based on a performance index calculated on the basis of what is the value of THD of stator current, value of operating speed and switching frequency. It uses new five level variable width torque hysteresis band controller and two level variable width hysteresis band flux controller along with new hybrid model for stator flux estimation. This improved strategy is designed to maintain simplicity of conventional DTC and give better performance than it. This new strategy is simulated using Matlab/Simulink

Analysis of Multiaxis Current Controller for Power System Friendly Front-End Converter Employing Two-Level and Three-Level Topologies

It is highly essential to develop a control technique that can be applied to conventional two-level as well as high-power multilevel front-end converters (FECs). Multiaxis current controlled, unity power factor (PF), regenerative FEC is described in this article. Current error space phasor is controlled by multiaxis current monitoring and its movement is confined within the prescribed hexagonal boundary. It is shown that the needed information on sector change detection can be derived from instantaneous values of supply voltages for the two-level FECs. However, similar approach cannot be extended for three-level FECs. Hence, sector change detection technique employing additional outer hysteresis band is proposed. With the help of experimental results, for steady state and dynamic conditions of FEC, it is demonstrated that the proposed current-controlled technique is equally applicable to two-level and three-level FECs. A three-level flying capacitor topology is considered, where voltage balancing of flying capacitors is guaranteed by effective utilization of redundant switching states. Results clearly depict the power system friendly nature of the presented scheme, i.e., unity PF, low total-harmonic distortion in supply current, good load and line regulations, and capacitor voltage balancing with regenerative capability of the converter. All the schemes are implemented on OPAL-RT hardware-in-loop platform.

Optimization of Torque Tracking Performance for Direct-Torque-Controlled PMSM Drives With Composite Torque Regulator

In this article, a composite torque regulator is proposed for optimizing the torque tracking performance in direct torque-controlled permanent-magnet synchronous motor drives. In the proposed composite torque regulator, two new variable hysteresis bands are designed and combined with two constant hysteresis bands. In the conventional direct torque control (DTC) scheme, the torque increasing rate and decreasing rate are changed with different speeds and loads. Thus, the average torque will deviate the reference torque seriously under some operation states. With torque deviation, the reference torque can hardly reflect the actual electromagnetic torque, and the torque tracking becomes more difficult and unsatisfactory in dynamic process. On the other hand, the time delay of one sampling period further deteriorates the precision of torque tracking. By introducing the proposed composite torque regulator, both torque deviation and the impact of time delay on the torque ripple can be eliminated. In addition, the advantages of the conventional DTC scheme, namely low switching frequency, fast dynamic response, simple structure, and independence of motor parameters, can be reserved in the proposed DTC scheme with a composite torque regulator. Experimental results are presented to verify the effectiveness of the proposed scheme and compare its performance with the conventional DTC scheme.

Design and Implementation of a Hysteresis Band Current Controller Three-Phase AC Chopper System

In this study, a three-phase alternative current (AC) chopper circuit was designed and simulated using a hysteresis band current controller (HBCC) method. The HBCC method is often preferred in switching control of AC choppers. The AC chopper circuit, which is both simulated and designed in this study, was composed of six IGBTs. The control of the switches in the circuit was provided by the pulse width modulation (PWM) method and this control in the design was realized by a digital signal processor (DSP) microcontroller. The aim of both the simulation and the design was to examine the output harmonics by ensuring the high quality and efficient operation of the AC chopper circuit. Controlled by the PWM method, this simulation was performed using the MATLAB program. The importance of HBCC in the process of reducing the harmonics in the current was shown in real-time.

Artificial Intelligence Based Vector Controller for Switched Reluctance Motor SRM

The prevalence of the Switched Reluctance Motors (SRMs) increments step by step because of its points of interest, for example, Simple structure, low cost, less weight, high effectiveness and high beginning torque when contrasted with regular motors. SRM is an electric motor which has invaluable highlights that qualifies it to be utilized in electric vehicle, aviation and industrial applications. In this paper, the switched reluctance motor is controlled using vector control by AI controller (fuzzy) so as to limit the torque ripples by directing torque inside indicated hysteresis band. AI Control of SRM encouraged through an irregular converter. The proposed AI controllers are executed in MATLAB/SIMULINK for specified SRM parameters. As indicated by the attained outcomes the SRM behavior is better when impelled by AI controller in contrast with usual controllers.

Optimization of harmonics with active power filter based on ADALINE neural network

Mostly the power quality issues in the distribution line system happen due to the presence of harmonics. Especially, the nonlinear loads such as power electronic converters, high-speed semi-conducting switches, and solid state drives were the major causes for harmonics in distorted power system signals. Moreover, the estimation of magnitude and the phase of this harmful harmonic interference are necessary. By taking in to consideration of all the above factors, this paper develops an efficient technique for harmonic estimation and detection of the renewable wind energy resources and elimination of these harmonics will also be done accordingly for getting desired output from wind energy. 8 bit inputs (4 + 4) are collected and used to generate the intended input set for ANN training. The proposed work develops an Adaptive Linear Neural Network (ADALINE) for the estimation of harmonics which is the novelty of this work. For making the harmonics content more negligible and to enhance the load power quality, an Active Power Filter (APF) is used. The novel control design is developed with a Pulse Width Modulation (PWM) control. In addition, feed forward networks (trained by back propagation algorithm) works like a hysteresis band comparator. An APF control design is developed with ADALINE network in which the load and current along with voltage will be analyzed and then the controller will be calculating the control signal by considering the reference compensation current. Afterwards, the power system is injected with compensating current. The simulation is carried out with Matlab-Simulink laboratory prototype is developed with Xilinux 3E Spartan FPGA board to verify the proposed control designs. The proposed work is compared with exiting method comprising Shunt Active Power Filters (SAPF) with ADALINE for the performance perspectives. This method was found to be effective in terms of many parameters such as load voltage, load current, voltage, reactive power, real power and especially THD value than those of the existing works which are considered.

Simulation Study of Two Torque Optimization Methods for Direct Torque-Controlled Induction Motors

The simplicity and excellent dynamic performance of Direct Torque Control (DTC) make Induction Motor (IM) drives attractive for many applications that require precise torque control. The traditional version of DTC uses hysteresis controllers. Unfortunately, the nature of these controllers prevents the optimization of the inverter voltage vectors inside the flux hysteresis band. The inverter voltage vector optimization can produce fast torque response of the IM drive. This research proposes two torque optimization methods for IM systems utilizing DTC. Analysis and Matlab simulations for the proposed optimization methods prove that the torque and, consequently, the speed responses, are greatly improved. The performances of the drive system controlled by the proposed optimization methods and the traditional DTC are compared. Conversely, the effects of the parameters on the proposed optimization methods are introduced. The proposed methods greatly improve the torque and speed dynamic performances against the traditional DTC technique. However, one of the proposed optimization methods is more sensitive to IM parameter variations than the other.

Model Predictive Control with Binary Quadratic Programming for the Scheduled Operation of Domestic Refrigerators

The rapid proliferation of the ‘Internet of Things’ (IoT) now affords the opportunity to schedule the operation of widely distributed domestic refrigerator and freezers to collectively improve energy efficiency and reduce peak power consumption on the electrical grid. To accomplish this, the paper proposes the real-time estimation of the thermal mass of each refrigerator in a network using on-line parameter identification, and the co-ordinated (ON-OFF) scheduling of the refrigerator compressors to maintain their respective temperatures within specified hysteresis bands commensurate with accommodating food safety standards. A custom model predictive control (MPC) scheme is devised using binary quadratic programming to realize the scheduling methodology which is implemented through IoT hardware (based on a NodeMCU). Benefits afforded by the proposed scheme are investigated through experimental trials which show that the co-ordinated operation of domestic refrigerators can i) reduce the peak power consumption as seen from the perspective of the electrical power grid (i.e., peak load levelling), ii) can adaptively control the temperature hysteresis band of individual refrigerators to increase operational efficiency, and iii) contribute to a widely distributed aggregated load shed for demand side response purposes in order to aid grid stability. Importantly, the number of compressor starts per hour for each refrigerator is also bounded as an inherent design feature of the algorithm so as not to operationally overstress the compressors and reduce their lifetime. Experimental trials show that such co-ordinated operation of refrigerators can reduce energy consumption by ~30% whilst also providing peak load levelling, thereby affording benefits to both individual consumers as well as electrical network suppliers.

A Modified Flux Regulation Method to Minimize Switching Frequency and Improve DTC-Hysteresis-Based Induction Machines in Low-Speed Regions

Direct torque control (DTC) suffers from flux droop owing to the long zero-voltage vectors at low motor speeds. Previous studies were able to attain flux regulation by imposing the continuous switching of forward and reverse active-voltage vectors by causing torque overshoots in the torque hysteresis bands (THBs). This led to an excessive increase in the switching frequency and larger torque and current ripples, thus reducing the drive efficiency. In this paper, a modified flux regulation method is proposed for the classical DTC using a single THB when flux droop occurs in a low-rotor-speed range. The proposed method can protect the DTC from flux droops at low speeds by reducing the duration of zero-voltage vectors and minimizing the number of reverse-voltage vectors. In addition, the proposed strategy is efficient in reducing torque and current ripples while operating at low motor speeds. Furthermore, a significant reduction in the switching frequency is obtained. The effectiveness of the proposed strategy is confirmed by simulation and experimental results.