Constant Load Voltage Research Articles

Nonlinear Analysis and Closed-Form Solution for Overhead Line Magnetic Energy Harvester Behavior

Recently, much attention has been given to the development of various energy harvesting technologies to power remote electronic sensors, data loggers, and communicators that can be installed on smart grid systems. Magnetic energy harvesting is, perhaps, the most straightforward way to capture a significant amount of power from a current-carrying overhead line. Since the harvester is expected to have a small size, the high currents of the distribution system easily saturate its magnetic core. As a result, the operation of the magnetic harvester is highly nonlinear and makes precise analytical modeling difficult. The operation of an overhead line magnetic energy harvester (OLMEH) generating significant DC power output into a constant voltage load was investigated in this paper. The analysis method was based on the Froelich equation to analytically model the nonlinearity of the core’s BH characteristic. The main findings of this piecewise nonlinear analysis include a closed-form solution that accounts for both the core and rectifiers’ nonlinearities and provides an accurate prediction of OLMEH transfer window length, output current, and harvested power. Continuous and discontinuous operational modes are identified and the mode transition boundary is obtained quantitatively. The theoretical investigation was concluded by comparison with a computer simulation and also verified by the experimental results of a laboratory prototype harvester. A good agreement was found.

On the Maximum Power of Passive Magnetic Energy Harvesters Feeding Constant Voltage Loads Under High Primary Currents

On the Maximum Power of Passive Magnetic Energy Harvesters Feeding Constant Voltage Loads Under High Primary Currents

Efficient power conversion with four switch soft-switching boost integrated half-bridge dual-output series resonant converter

Soft switching reduces voltage and current stress during transitions, smoothing and quieting operations and reducing electromagnetic interference while also increasing efficiency and equipment lifespan. Circuit design, component selection, and switching frequency optimization affect power electronics soft switching. This paper proposes boost integrated half-bridge dual-output series resonant (BIHBDOSR) converter, a novel converter design and control method to increase series resonant converter performance by reducing storage element size, switch count, and switching losses. This methodology relies on soft-switching technologies like zero-voltage switching (ZVS) and zero-current switching (ZCS). These methods use class-D, class-E, series, parallel, and series–parallel resonant converter circuits to increase efficiency and minimize component stress. The proposed converter is ideal for constant voltage, constant power, and current-controlled loads with the output voltage being regulated by a closed-loop PI controller. The output voltages for two loads in the simulation depart from reference values. V01 changes from 14 to 20 V and V02 from 18 to 15 V at 300 ms owing to switching variances. The proposed converter utilizes gate driver circuits, resonant tank circuit, current sensor, FPGA board for closed-loop control, and current sensor for stability, ensuring converter stability. The proposed converter closed-loop control method modifies PWM signals to regulate both loads independently and ensure steady output voltage. Additionally, to validate the effectiveness of proposed converter, a 50-W driver circuit is designed, delivering two independent outputs of 20 W and 30 W. Frequency modulation (FM) and duty cycle control methods are employed to obtain the desired outputs.

A Power-Efficient Envelope-Detector-Less Amplitude-Shift-Keying Forward Telemetry for Wirelessly Powered Biomedical Devices.

This paper proposes an envelope-detector-less (EDL) amplitude-shift-keying (ASK) forward telemetry (FT) demodulator for wireless power/data transfer (WPDT) systems. The EDL ASK FT demodulator can substitute bulky and power-hungry components, which are an envelope detector and an analog comparator in the conventional ASK FT demodulator, with a digital controller, reducing both power dissipation and chip area. The proposed demodulator shares the gate control signals of pass transistors, which are used in an ac-dc regulator for wireless power reception, to maintain a constant load voltage while efficiently demodulating the forward telemetry data. Also, a proposed digital cleaner in the EDL demodulator refines this control signal into a wide pulse without suffering from resonant frequency noise, while a synchronizer can align its frequency with the data rate and resonant frequency. The 0.25-μm CMOS prototype chip of the proposed power-path-less EDL ASK FT demodulator, equipped with the ac-dc regulator, demonstrates a significant 38.2% reduction in power dissipation compared to the conventional ASK FT demodulator. Moreover, the EDL ASK FT demodulator occupies only 0.023-mm2 silicon area and achieves a low bit error rate (BER) less than 10-4 while maintaining a regulated voltage of 4.5 V on the load.

Data‐driven predictive control of perturbed buck converters using a modified iterative feedback tuning algorithm

AbstractThe most challenging aspect of utilizing model predictive controllers (MPCs), particularly those involving power electronic applications, is the extraction of a model that accurately represents the behavior of the studied system. Concerning the use of power electronic applications, as long as an MPC is used, adjusting the controller parameters brings difficulties. In addition, as the number of elements increases, it becomes harder to get the best control law out of the model. To do away with the need for model extraction, this study presents an offline data‐driven approach in conjunction with the MPC that can optimally adjust the MPC parameters based on the iterative feedback tuning (IFT) algorithm called the iterative feedback predictive controller (IFPC). The proposed method eliminates concerns regarding selecting an optimal number of algorithm iterations, thereby reducing operating costs, by introducing a modified IFT called feedback‐based IFPC (FIFPC) while simultaneously achieving optimal MPC parameters. The proposed method is applied to a constant voltage load (CVL) connected less‐than‐ideal buck converter, that is, one with perturbed filter elements and variable loads. A robust stability analysis (RSA) is performed under normal operating conditions to investigate the robustness behavior of the proposed controller. Simulation studies are presented to evaluate the proposed controller under different scenarios, such as step and abrupt load changes and measurement noise, compared with the well‐known model‐based and data‐enabled predictive controller (DeePC) approaches in the MATLAB/Simulink environment.

Single-Phase Robust Charger with High Power Quality for Electric Vehicle Application

The widespread use of electric vehicles (EVs) necessitates the development of a robust charging infrastructure. The goal of this research paper is to create a high-quality, single-phase charger for electric cars. The purpose of this design is to provide a charger that is both fast and efficient but also protects against power quality problems including harmonics, power factor correction, and voltage variations. A single-phase–single-stage improved power quality EV charger for small and medium power applications has been designed and simulated. A single DC-DC converter is utilized for constant charging and improved power quality operation. The charger presented exhibits improved power quality as sinusoidal current is drawn from the utility grid supply with the total harmonic distortion (THD) in compliance with the IEEE 519 and IEC 61000-3-2 standards. In order to charge the battery of an electric vehicle, most two-stage converters first use a boost converter for power factor correction (PFC), and then they use a DC-DC converter that can accept any input voltage. These two-stage conversions are inefficient and use more parts than necessary. This work proposes a PFC converter based on a single-stage switching inductor Cuk converter, which has the advantages of high step-down gain, low current stress, high efficiency, and a small number of components. The suggested converter’s operational analysis and design equations are performed in continuous current mode. The proposed converter is the subject of extensive mathematical modelling, analysis, simulation, and experimentation presented in this study. With both constant voltage (CV) and constant current (CC) loads, the proposed converter’s performance is analysed with regard to power quality indices like voltage total harmonic distortion (THD), current THD, and total power factor. Additionally, in CV mode and CC mode, the suggested converter’s dynamic performance with battery charging is evaluated in relation to the extensive supply changes. The developed charger presents a reliable and efficient solution for EV charging, fostering the transition to a cleaner and more sustainable transportation system.

Stabilization of constant power loads and dynamic current sharing in DC microgrid using robust control technique

DC microgrids are appealing in distribution networks due to their high efficacy, stability, and ease of incorporation with renewable energy resources. In order to maintain system reliability, load sharing is crucial, because disturbances such as the constant power load (CPL), constant voltage load (CVL), uncertainty parameters, and variations in input voltage may result in instability. The conventional droop control method has been frequently employed to regulate the DC microgrid. However, under significant disturbances, conventional droop control is not suitable for achieving both accurate current sharing and acceptable voltage regulation. To tackle these limitations, this paper introduces a robust control for sharing load current and regulating DC bus voltage in a DC microgrid feeding a CPL and CVL. The proposed approach is split into two loops. The main loop, which is based on an RST controller, is used to regulate the current load sharing between two parallel boost DC/DC converters, handle the instability issue caused by disturbances, and improve system reliability. The DC bus voltage is adjusted using the secondary loop built using the proportional-integral (PI) controller. The key benefits are precise voltage regulation, load power sharing, and good reliability. Aside from that, the RST controller has great resilience, quick dynamic response, and strong stability for significant load fluctuations. The feasibility and efficacy of the proposed approach are confirmed by time-domain simulation results, and hardware-in-the-loop (HIL) testing under various scenarios. The obtained findings show that the suggested control strategy is capable of ensuring proportionate power-sharing while dealing with DC voltage instability under CPL, CVL, uncertainty parameters, and input voltage fluctuations.

Normalized Error-Based PI Controller and Its Application to the DC–DC Buck Converter

In this article, the structure of the normalized error-based proportional-integral (PI) controller is presented and its application to the DC–DC buck converter is discussed. The main motivation is to overcome the drawbacks of saturation and the limited range of controller gains offered by the traditional PI controller. Initially, the theoretical structure and advantages of an improved PI controller are shown. Next, the problem of regulation of the step-down DC–DC converter is addressed using the proposed controller. The objective is to keep the load voltage constant even when the converter parameters vary. The averaged state-space model of the converter is presented and a detailed stability analysis based on the Lypunov indirect method is carried out. The results show an improved range of controller parameters when the proposed controller is employed. Finally, some simulation results are shown to illustrate the effect of controller parameter variations on the output response. These results also verify the ability of the proposed controller to handle the changes in the load, input voltage, and reference voltage of the converter. Moreover, a comparative simulation study validates the superior transient response of the proposed normalized error-based PI controller over the traditional PI controller.

Artificial ecosystem optimized neural network controlled unified power quality conditioner for microgrid application

Unified power quality conditioner is chiefly employed to offer power quality improvement, especially in grid connected mode of operation in microgrid applications. This article proposes an artificial ecosystem optimized neural network for control of photovoltaic system and battery powered UPQC for microgrid applications. The intelligent routine implemented by the proposed controller helps tune parameters such as the error between load voltage references and measured load voltage signals so that the optimal performance of the system can be reached as its exploratory and exploitation capabilities are leveraged in controller design. A prototype of a three-phase system with a dually powered conditioner is tested and validated in MATLAB-Simulink environment in a variety of dynamic scenarios that are commonly present in a contemporary distribution network, such as grid voltage changes, grid inaccessibility, variation in photovoltaic power output, and nonlinear load. It is shown that the proposed controller, being aware of the instantaneous values of grid voltages, was able to adequately compensate in magnitude and phase under all dynamic scenarios to maintain the load voltage constant at the nominal value and sinusoidal. When the system switches automatically from grid-connected mode to islanded mode due to a grid fault, it was observed that the controller prioritizes delivering uninterrupted power to critical loads and enables fast discharge from the battery. The total harmonic distortion percentages of grid currents and load voltages are found to be within the limits as per IEEE-519 standards.

Easy-to-install battery storage based residential power supply with contactless power transfer

Solar energy with battery storage has enormous potential for residential power supply applications. However, the installation is often complicated with lots of wiring. The wireless power transfer (WPT) interface can greatly reduce the complicated wiring part, facilitating easier installation, with additional benefits like electrical isolation, lower maintenance cost, better reliability. However, rigorous proof-of-concept of WPT for LV household power supply still remains to be largely unexplored. This work fills the research gap by presenting application of contactless power transfer system with battery storage for the solar-powered low-voltage (LV) power supply. Various resonant topologies for inductive power transfer (IPT) are studied, and a complete theoretical model of an LCL compensated IPT system integrated with a battery energy storage system is presented. The voltage and current characteristics are investigated to understand the operation of the proposed integrated IPT system at LVDC level. The setup is first realized and analysed in details in simulation using MATLAB/Simulink. Hardware experiments proves the feasibility of the contactless power transfer capability at the high efficiency of the integrated IPT battery system. The results show that the proposed system can maintain a constant load voltage of 48 V for a load variation of around 25%, with an efficiency of 92% at 85 kHz switching frequency.

Evaluation and Suppression of Oscillations in Inductive Power Transfer Systems With Constant Voltage Load and Pulse Skipping Modulation

This paper identifies how Constant Voltage Load (CVL) characteristics cause Inductive Power Transfer (IPT) systems to exhibit a poorly damped oscillation mode. When operated with pulse skipping strategies such as Pulse Density Modulation (PDM), the skipped voltage pulses can excite this mode and cause severe oscillations that do not appear in systems with a constant resistance load (CRL). The critical mode is identified from a linearized state-space model of the system and two control approaches are proposed for attenuating the oscillations in current amplitude and power flow. Firstly, the influence of the operating frequency on the critical eigenvalue is analyzed and it is shown how slightly off-resonant operation can increase the damping of the oscillation mode. Secondly, an active damping method based on sending current feedback control is studied. The active damping is based on Phase Shift Modulation (PSM) with limited phase shift angles applied to the PDM signal when oscillations are detected. The effectiveness and feasibility of the proposed methods are validated by simulations and experimental results from a small-scale laboratory prototype.

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.

Stability analysis and stabilization of Cuk converter with constant power load

AbstractAs one of the important energy conversion systems in renewable energy power generation, the two‐stage DC‐DC converter cascaded system composed of source converter and load converter has been widely used in industrial applications. Different from the constant voltage load of the traditional DC‐DC converter, the load converter in the cascaded converter, as the constant power load of the source converter, has an obvious impact on the stability of the source converter. In this paper, the cascaded system composed of Cuk converter as source converter and buck‐boost converter as load converter is studied. Analyses results show that with increasing of power load, a Floquet multiplier of monodromy matrix belongs to the converter cascaded system traverses the unit circle from outside to inside along negative real axis and will suddenly jump out of the unit circle when the power load reaches a specific value. Correspondingly, the entire system gradually moves from period‐doubling bifurcation state to period‐1 limit cycle and then suddenly jumps to chaos state. With application of monodromy matrix theory and sinusoidal voltage compensation method, stability boundary of the system is extended and nonlinear behaviors are stabilized. Finally, simulation and experimental results verify the feasibility of analytical technique and conclusions.

SOFC cathode material of La1.2Sr0.8CoO4±δ with a fibrous morphology: Preparation and electrochemical performance

Using soluble salts as metal-ion sources and polyacrylonitrile (PAN) as a polymer matrix, La1.2Sr0.8CoO4±δ cathode material with a fibrous morphology is prepared by electrostatic spinning, and microstructural characteristic of this material is investigated by field-emission scanning microscopy and X-ray diffraction. Electrochemical performance of the material in solid-oxide fuel cells is then tested. The results demonstrate that phase-pure La1.2Sr0.8CoO4±δ fibrils with tetragonal structure can be prepared from fresh silky precursors using electrospinning after annealing at high temperature. Compared to the conventional cathode material that possesses a plain granular structure, La1.2Sr0.8CoO4±δ fibrils exhibit superior electrochemical performance. At a temperature of 800 °C, the area specific resistance with this fibrous cathode is as low as 0.043 Ω cm2, and maximum power density with the corresponding single-cell is 716 mW cm−2, demonstrating the fast electrode kinetics in the O2 reduction reaction. Comparatively, the area specific resistance with the plain cathode is 0.062 Ω cm2, and the maximum power density with the corresponding single-cell is only 642 mW cm−2. Under a constant voltage load of 0.6 V at a fixed temperature of 750 °C, the power output from a single-cell with the fiber-structured cathode maintains between 615 mW cm−2 and 585 mW cm−2 even after 15 h of running time, showing a slower fading rate and a more stable electrochemical performance than the plain cathode.

CLOSED LOOP BIDIRECTIONAL BUCK-BOOST CONVERTER FOR BATTERY

Charging and discharging batteries A DC bus (with a constant voltage), a battery, a common load, and a bidirectional two-switch Buck-Boost DC-DC converter are used here.1- The control of battery charging as well discharging is based on using PI controllers 2- The other is for battery current regulation. The presented case study includes two modes of operation: 1-Charging mode: automatically activated when the DC bus is connected and the control objective i.e.: set point (of the PI closed loop) becomes the full voltage of the battery. 2-Discharging mode: automatically activated when the DC bus is NOT connected and the control objective (of the PI closed loop) becomes load voltage to maintain the constant load voltage during discharging. In control topology, a distinct control as well as pulse width modulation (PWM) system is created for each mode of operation using the voltage feedback control strategy. This method of charging and discharging can be used in a vehicle to grid and grid to a vehicle (here vehicle is considered as battery source/ DC source because of the same operation. Renewable energy can be used as a source to reduce pollution. The other mode of charging and discharging can be done with the help of solar as renewable resources to charge the battery. These are the way by which the closed loop buck-boost converter are been used for the battery operation.

Standalone PV-based single-phase split-source inverter using model-predictive control

This paper proposes the control of single-phase split-source inverter (SSI) for a standalone PV application using model-predictive control scheme. The PV system under investigation consists of PV modules, single-phase SSI, battery bank for energy storage, and DC-DC bidirectional converter to allow for bidirectional power flow with the batteries. Maximum power is extracted from the PV array using PI-based incremental conductance method. Both the maximum power point tracking of the PV modules and the synthesis of the sinusoidal output load voltage are achieved using the SSI. The control of the bidirectional converter is carried out using PI controllers to regulate the DC-link voltage. Selection of the controllers parameters is achieved using Harris Hawks optimization technique. Simulation results show that the system has succeeded in producing a constant DC-link voltage and well-regulated AC load voltage with low THD under various operating conditions. Experimental results verify the system performance.

Adaptive Passivity-Based Control of a DC–DC Boost Power Converter Supplying Constant Power and Constant Voltage Loads

This article presents a robust passivity-based control (PBC) strategy to mitigate the instability effect of the dc–dc boost power converter supplying a constant power load and a constant voltage load in dc microgrid systems. The control robustness of the PBC against both line and load variation is significantly improved by adding the nonlinear disturbance observer (NDO). Using the disturbance estimation technique, this observer works in parallel with the PBC strategy to compensate the disturbances of the system through a feed-forward compensation channel. Based on the dissipation property, the PBC strategy ensures the system stability, whereas the NDO guarantees global trajectory tracking to the reference voltage during disturbances. This control strategy not only ensures large-signal stability of the system, but also provides a fastest recovery performance during disturbances of the system as compared with other PBC strategies. The hardware-in-loop and real-hardware experimental results are provided to verify the control robustness of the proposed control strategy.

Design of a maximum power point tracking-based PID controller for DC converter of stand-alone PV system

Stand-alone photovoltaic system (PV) produces a variance in the output voltage under variable irradiation and temperature, and variable load conditions, resulting in control challenges. The research scope is to maintain a constant output load voltage despite variations in input voltage or load. The use of a DC converter ensures that the output voltage of such systems remains constant regardless of changes in the production voltage and load. The control on a DC boost converter is employed to solve this problem. This paper presents the design of a maximum power point tracking-based (MPPT) DC converter controller for such a system. The MPPT-based PID has been proposed as a control approach and implemented to the system DC converter. Incremental Conductance (IC) algorithm has been employed as an MPPT in association with an optimized PID. The Particle Swarm optimization technique (PSO) has been used to optimize the proposed PID through selected cost function. The PV system with the loaded converter is modeled and simulated using the MATLAB/Simulink environment. The system performance is displayed using a family of curves under different operating conditions and disturbances.

Maximum power extraction of hybrid photovoltaic ‐battery system with nonisolated single‐input and dual‐output DC‐DC converter: An efficient RFAMAO approach

The DC-DC converter is more significant for the integration of photovoltaic (PV) and battery. The design of the power converter is high complexity, because of the nonlinear characteristics, like supply voltage variations, switches, load current variations, and parasitic component fluctuation. This article proposes an efficient approach for increasing the maximum power of PV system and system efficiency. The proposed approach is the consolidation of Random Forest Algorithm (RFA) and Mexican Axolotl Optimization (MAO), hence it is called RFAMAO approach. The proposed approach utilized the single-input and dual-output boost converter to implement the maximum power point tracking of the system that improves the lesser voltage input power source, controllable higher voltage direct current bus and middle voltage output terminals. RFA is used to deal with the uncertainty caused by climate change. MAO is utilized to tune the control parameter of the system. The voltage-mode controlling strategy among the PV, battery, and standalone DC load depending on Digital Signal Processing and Control Engineering (DSPACE) is utilized for uninterruptible power flow management and constant DC load voltage maintenance. The proposed approach is implemented in MATLAB/Simulink, and its efficiency is compared with existing approaches. The oscillation around maximum power point (MPP) for case 1 of RFAMAO, modified shuffled frog leaping algorithm with fuzzy logic (MSFLA-FLC), fuzzy logic, and perturb and observe (P&O) is 2.69, 7.31, 20.54, and 29.12 W. The oscillation around MPP for case 2 of RFAMAO, MSFLA-FLC, fuzzy logic, and P&O is 2.57, 8.34, 18.56, and 27.65 W.

Three-Port Power Electronic Interface With Decoupled Voltage Regulation and MPPT in Electromagnetic Energy Harvesting Systems

In conventional electromagnetic energy harvesting systems, a two-port ac–dc rectifier is utilized to process the harvested power. However, it is difficult to achieve voltage regulation and maximum-power-point-tracking (MPPT) simultaneously. To resolve this issue, this article proposes a three-port power-electronic-interface (PEI) dedicated to this application. A battery port is introduced to buffer the redundant energy. A bidirectional dc–dc converter is utilized to tightly regulate the load side voltage. To capture the maximum power for the harvester, a simple MPPT method is proposed for this PEI. The power tracking of ac source can be simplified by dealing with the power of the battery port. The regulations of power and output voltage are fully decoupled with different control degree-of-freedoms. Moreover, when the harvester is in idle mode, the load can be powered by the battery via the bidirectional dc–dc converter independently. A 24-mW rated laboratory prototype, which processes the power flow among a 0.6 V, 100 Hz ac source, a 1.2 V battery, and a 3.3 V constant voltage load is developed and tested. The proposed concept is validated by experimental results.