Pulse Width Modulation Research Articles

Degradation Behavior of Galvanostatic and Galvanodynamic Cells for Hydrogen Production from High Temperature Electrolysis of Water

High temperature electrolysis of water using solid oxide electrochemical cells (SOEC) is a promising technology for hydrogen production with high energy efficiency and may promote decarbonization when coupled with renewable energy sources and excess heat from nuclear reactors. One of the challenges facing the commercial deployment of this technology is improving the cost competitiveness of hydrogen produced by electrolysis, which, among other factors, critically depends on the long-term durability of the SOEC system under relevant duty cycles. To extend the lifetime and optimize hydrogen production costs over projected lifetimes, fundamental knowledge of degradation mechanisms and rates as a function of operating conditions is a critical gap to close. Degradation mechanisms of solid oxide electrolysis cells are often coupled with each other and may vary based on cell overpotential and current, making them difficult to isolate and investigate effectively. Pulse Width Modulation (PWM) can be used to create a low-time scale variation under operating conditions that can identify non-linear degradation mechanisms between current and voltage. The short-term perturbations caused by PWM can help relieve stressors compared to cells running under constant (e.g., galvanostatic) conditions, even if the average current that the cell experiences over time is the same. In this work, water electrolysis cells were operated under dynamic conditions and compared with galvanostatic cells with respect to overall cell lifetime and degradation behavior. Specifically, the increases in overpotential and impedance are analyzed and compared between these two different operating modes to provide insights into the differences between average and instantaneous current.

Monolithic Integration of Organic Solar Cell and Secondary Battery with Shared Electrode As a Photo-Rechargeable Energy Device

The solar cell-secondary battery energy system has been widely used as decentralized power generation and energy-storage system to reduce reliance on fossil fuel-based generation and mitigate fluctuations in solar cell energy supply. This typically involves power conversion by connecting two energy devices through charge controllers such as maximum power point tracker (MPPT) and pulse width modulator (PMW), which are technically mature and ensure reliable energy conversion and storage within the system. In the era of the fourth industrial revolution, characterized by the hyper-connectivity and hyper-mobility of the internet of things and wearable devices, solar-based integrated energy systems are emerging as a promising independent power source. To make devices more cost-effective, miniaturized, and energy efficient, many researchers are developing integrated energy devices that directly connect two energy devices without relying on a charge controller, a so-called "monolithic" form. However, most integrated devices reported to date still utilize a simple four-electrode structure. While this may visually resemble a monolithic device, it is functionally and structurally limited in its integration capabilities. To maximize the benefits expected from monolithic integrated devices, such as reduced process costs, miniaturization, and increased efficiency, it is essential to implement energy devices with three-electrode structures that share core components such as the electrode of the devices. In this regard, studies have been reported to realize a three-electrode energy device by utilizing the anode (or cathode) of a solar cell, which is a power generation device, as the electrode of an energy storage device, but there is a limitation that the energy density per unit area is low due to the use of a supercapacitor as the storage device, and the overall efficiency of the integrated device is low.In this study, we report on the design and implementation of a three-electrode integrated energy device sharing an electrode to improve the performance (e.g., areal capacity, energy efficiency). This integrated device uses an organic solar cell as the power generation device and a silver-zinc secondary battery as the energy storage device, and they share a silver electrode with each other. The shared silver electrode acts as a multifunctional layer that simultaneously serves as the positive electrode of the solar cell, the electrical connection between the solar cell and the secondary battery, and the cathode active material of the secondary battery. On the device perspective, by using a secondary cell instead of a capacitor, we have significantly increased the areal capacity. In order to further improve the efficiency of the integrated energy device, we applied the following three design strategies to the battery design. First, through the composition design of active ions in the electrolyte, the operating voltage of the secondary battery was matched to the same level as the maximum output voltage of the solar cell. This allows the solar cell to operate at its maximum power conversion efficiency when it charges the battery. Second, we improved the fast-charging characteristics of silver-zinc battery by ensuring that the area near the silver electrode surface is supersaturated with silver anion species during battery operation. This allows the secondary battery to accept the high-power density supplied by the solar cell at a low overvoltage, improving the efficiency of the integrated device. Finally, by applying a gel electrolyte with an optimized ratio of electrolyte components (gelling agent, hardener, salt, and plasticizer), we prevented the failure of the solar cell due to the penetration of electrolyte components and ensured the stable operation of the secondary battery. In conclusion, the aforementioned design improvements enabled the high-performance silver-zinc battery to be recharged near the maximum power point of the solar cell, achieving the highest photo conversion-storage efficiency (PSE) of any organic solar cell-based integrated energy system to date. In this presentation, the design and implementation of a solar cell-battery integrated energy device in a three-electrode configuration sharing a silver electrode will be presented in detail. In addition, secondary battery design strategies will be discussed to maximize the efficiency of the integrated device during high-power charging from solar cells.

Comparative analysis of control strategies impact on power losses in IGBT power modules with a multiphysics‐circuit coupling method

AbstractPower losses in semiconductor devices present a significant impediment to advancing power electronics systems for achieving higher frequencies, improved efficiency, and greater integration. A major challenge lies in directly coupling power losses with various control strategies, considering the variations in manufacturers, packaging, and process structures within the power electronics field. This paper introduces a field‐circuit coupling simulation methodology of the insulated gate bipolar transistor (IGBT) within the Simulink/COMSOL environment, using a conventional three‐phase six‐switch voltage source inverter (VSI) IGBT module as a case study. A composite transfer function interconnects the electrical and thermal aspects, enabling bidirectional coupling between IGBT temperature and losses. This study aims to comprehensively compare the effects of various control strategies, namely, single‐vector, dual‐vector, and three‐vector current model predictive control (CMPC) and space vector pulse width modulation (SVPWM), on the losses and temperature of IGBT power modules. The findings emphasize that losses are significantly influenced by the selection of weighting factor coefficients and power factor settings under the same CMPC control strategy with a fixed switching frequency. Additionally, the selection of control strategies, such as CMPC and SVPWM, substantially impacts power losses in power electronic devices.

Design and implementation of single DC-link based three-phase multilevel inverter with CB-PWM techniques

Simulation and implementation of a single DC-link-based three-phase inverter are investigated in this article. The primary focus is on designing a single DC-link three-phase inverter for high power applications. Unlike conventional inverters that require 600 V to generate 400 V (RMS) at the output, the proposed system achieves this with only 330 V, facilitated by a 12-terminal 1:1 transformer. The system employs Proportional Integral (PI) and Neural Network (NN) controllers to optimize performance. Various Carrier-Based Pulse Width Modulation (CB-PWM) techniques, including Phase Disposition (PD), Phase Opposition Disposition (POD), and Alternative Phase Opposition Disposition (APOD), are implemented and evaluated based on Total Harmonics Distortion (THD) concerning the Modulation Index (MI) of the inverter. The proposed inverter achieves a THD reduction to 4.8%, demonstrating superior performance compared to recent studies. The system’s performance is validated through extensive MATLAB/Simulink simulations and practical implementation using XILINX FPGA software, confirming the efficacy of the proposed design.

A Finite-Time Control Design for the Discrete-Time Chaotic Logistic Equations

Finite-time control theory has been widely used as a mathematical tool to design robust controllers. By manipulating the finite-time convergence proof of this theory, we developed a new control design appropriately tuned for the finite-time control of the chaotic logistics system. In this experimental setup, the logistic equation is programmed into a PIC microcontroller, and a part of the controller was conceived using analog electronics. Because the system to be controlled is in the discrete-time domain, and the finite-time stability proof is stated in the continuous-time representation, our finite-time control approach is a good example for designing control algorithms in both time domain schemes. Hence, our experimental results support our main contribution. Pulse width modulation (PWM) is the format used to translate digital signals into the continuous-time field. Therefore, the main contribution of this article is the theoretical foundations for creating a recent controller that satisfies the convergence criterion in finite time and its construction using an 8-bit microcontroller. All this contributes to the chaotic logistical map.

Intelligent Solar System for Effective Renewable Energy

Photovoltaic (PV) systems are gaining popularity as a sustainable and renewable energy solution. Charge controllers play a crucial role in maximizing the energy harvested from PV panels and ensuring efficient battery charging. This study presents a comprehensive comparison between Pulse Width Modulation (PWM) and Maximum Power Point Tracking (MPPT) charge controllers, analyzing their performance, efficiency, and suitability for different PV system configurations. The analysis begins with an overview of PWM charge controllers, which regulate the charging process by rapidly switching the PV panel voltage on and off. PWM controllers are known for their simplicity, affordability, and reliability. However, their fixed voltage operation limits their ability to extract maximum power from the PV panels, especially in scenarios with varying solar irradiance and temperature conditions. In contrast, MPPT charge controllers employ advanced algorithms to continuously track the maximum power point (MPP) of the PV panels. By dynamically adjusting the operating voltage and current, MPPT controllers can optimize the power transfer from the PV panels to the battery bank. This capability results in higher energy harvesting, especially in situations with partial shading or non-ideal operating conditions.

Design and testing of an intelligent variable-rate spraying system based on LiDAR-guided application

Traditional plant protection machinery cannot apply pesticides according to the actual growth demand of crops, which causes a lot of pesticide waste and serious environmental pollution. Based on this, an intelligent variable-rate application system based on 3D LiDAR (light detection and ranging) scanning and PWM (pulse-width modulation) control for maize canopy was developed in this paper. After completing the performance testing, the system was mounted on a lightweight high-clearance self-propelled sprayer by remote controlling with an operating width of 6.0 m, and a ground gap of 2.0 m. And the actual operational performance of the sprayer showed that the prediction error of LiDAR for plant height was within 10%, which illustrated the accuracy of the detection system and the reliability of the variable application based on the plant height change. And the variable-rate system could adjust the spray volume in real-time according to the plant height change. The penetration rate of the upper, middle, and bottom layers maintained a relatively stable state (upper > middle > bottom) at variable-rate application and could reach the normal application level. This study can provide new ideas for efficient pests and diseases control of high stalk crops, especially suitable for small fields, and gives a reference for the structural design of new precise variable-rate application machinery and performance optimization of efficient application technology.

A Wirelessly Powered Scattered Neural Recording Wearable System.

This paper introduces a wirelessly powered scattered neural recording wearable system that can facilitate continuous, untethered, and long-term electroencephalogram (EEG) recording. The proposed system, including 32 standalone EEG recording devices and a central controller, is incorporated in a wearable form factor. The standalone devices are sparsely distributed on the scalp, allowing for flexible placement and varying quantities to provide extensive spatial coverage and scalability. Each standalone device featuring a low-power EEG recording application-specific integrated circuit (ASIC) wirelessly receives power through a 60 MHz inductive link. The low-power ASIC design (84.6 μW) ensures sufficient wireless power reception through a small receiver (Rx) coil. The 60 MHz inductive link also serves as the data carrier for wireless communication between standalone devices and the central controller, eliminating the need for additional data antennas. All these efforts contribute to the miniaturization of standalone devices with dimensions of 12×12×5 mm3, enhancing device wearability. The central controller applies the pulse width modulation (PWM) scheme on the 60 MHz carrier, transmitting user commands at 4 Mbps to EEG recording ASICs. The ASIC employs a novel synchronized PWM demodulator to extract user commands, operating signal digitization and data transmission. The analog frontend (AFE) amplifies the EEG signal with a gain of 45 dB and applies band-pass filtering from 0.03 Hz to 400 Hz, with an input-referred noise (IRN) of 3.62 μVRMS. The amplified EEG signal is then digitized by a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) with a peak signal-to-noise and distortion ratio (SNDR) of 55.4 dB. The resulting EEG data is transmitted to an external software-defined radio (SDR) Rx through load-shift-keying (LSK) backscatter at 3.75 Mbps. The system's functionality is fully evaluated in human experiments.

Dual tri-isolated DC H-6 inverter with minimal power components design

Multilevel inverters have been forecasted in recent years for industrial and renewable energy applications due to its inherent characteristics of shaping the output voltage nearer to sinusoidal shape through concatenating several two/three level inverters using isolated DC sources or DC-link capacitors. However, the classical topologies used for synthesizing stepped voltage have several outwards like more number of DC sources or DC-link capacitors and switching devices used. In this paper, an effort has been sighted to bring a new topology for generating stepped voltage to overcome the above mentioned demerits. In addition to this, a new digital pulse width modulation (PWM) strategy is developed in-line with a new topology to eliminate the use of carrier and reference signals. The performance of the proposed topology and developed control strategy are evaluated in MATLAB/ Simulink platform and an laboratory prototype is constructed for experimental investigations to accord the simulation results.

PV system applied on the new PUC-NPC inverter

In this article, the authors present a new competitive Packed-U-cell and neutral point clamped (PUC-NPC) 9-level converter that utilizes a small number of power switches and passive components. Only seven switches are added to a single DC source. However, the proposed converter takes benefits of the neutral point clamped (NPC) converter’s capability to connect capacitors in series, all with a simple control that enables the algorithm associated to the proposed inverter operate correctly in an open loop operation. A technique of pulse width modulation (PWM) is employed to maintain capacitor voltage at desired values. The proposed inverter produces an almost sinusoidal waveform output voltage, as result, a perfectly sinusoidal charge current with minimal impact on the economy and energy consumption are optioned. The converter has been integrated with a photovoltaic system to minimize its impact on the electricity supply and enhance energy efficiency. In order to take a maximum power from the photovoltaic panel, authors employ a maximum power point tracking (MPPT) technique based on disturbance and observe (P and O). When combined with the proposed control technique, it offers a competitive system suitable for standalone use or as an energy source, eliminating the need for PI regulators or additional investments. The proposed 9-level converter has been validated through simulation, utilizing the MATLAB Simulink environment to model the proposed system. Dynamics of this later were verified by changing the load charge.

Comparative harmonic elimination techniques for supraharmonic reduction in microgrid

In order to reduce voltage distortion and supraharmonic (SH) emission in microgrid (MG) systems with electric vehicle (EV) charging stations, this research compares several harmonic elimination approaches. The increasing deployment of EVs has led to the integration of EV charging stations within MG systems, presents challenges in maintaining a high power quality (PQ). Voltage distortions and SH emissions are caused due to non-linear loads and the intermittent nature of EV charging, which have an effect on the performance and dependability of the MG. In order to solve these problems, multilevel converters (MLCs) are used to produce high-quality waveforms. MLCs use harmonic elimination methods to cut down on SH emissions, which improves the PQ overall. Sinusoidal pulse width modulation (PWM), selective harmonic elimination (SHE), space vector modulation (SVM), and random-PWM (RPWM) techniques are among the harmonic elimination methods compared and analyzed. The results will enable the selection of the most appropriate strategy for minimizing voltage distortion and SH emission in MG systems, while providing valuable insights into the effectiveness of each method.

An SNR-Enhanced 8-Ary (SNRE-8) Modulation Technique for Wireline Transceivers Using Pulse Width, Position, and Amplitude Modulation

An SNR-Enhanced 8-Ary (SNRE-8) Modulation Technique for Wireline Transceivers Using Pulse Width, Position, and Amplitude Modulation

A new multilevel inverter topology, controlled by the pulse width and height modulation (PWHM) technique, with a reduced number of switches

A new multilevel inverter topology, controlled by the pulse width and height modulation (PWHM) technique, with a reduced number of switches

Active power compensation circuit for resonance mitigation and harmonic reduction in microgrid system

The nature and behavior of capacitors, transformers, inductors, active compensators, and non-linear loads can produce power resonance. Unfortunately, the presence of a resonance phenomenon can have a negative impact on system stability and lead to catastrophic power system failures. Therefore, even when using modern or conventional techniques to enhance total harmonic distortion (THD) or improve input power factor (IPF), it is necessary to avoid resonance. An active power compensation circuit (APCC) is proposed and designed to function with two categories of linear/non-linear loads. The APCC has been implemented and regulated using an adjusted pulse width modulation technique. The aim of the suggested APCC is to minimize AC side distortions, improve the IPF, and mitigate harmonics resonance at the same time. The simulation results demonstrate that the proposed APCC investigates the aim function of this study by absorbing harmonics, correcting IPF, and eliminating resonance problems under both transient and steady-state operating conditions. The supply voltage and current THD values for the first power circuit type are reduced by 96.7 % and 96.3 %, respectively, at α=30°. Meanwhile, for the second power circuit, the THD is reduced by 91.92 % and 90.4 %. Also, the IPF changed for the first and second power circuits from 0.72 and 0.86 to almost unity. These results demonstrated the effective performance of the APCC circuit and controller in reducing power harmonics, eliminating power resonance, and modifying power factors.

Buck–Boost DC–AC converter based on coupled inductors

In this paper, a single stage buck–boost DC–AC converter based on coupled inductors is presented for renewable energy and electric vehicle applications. The proposed topology works with only three semiconductor switches, two diodes, and three coupled inductors to transfer input DC voltage to a high gain or low gain output AC voltage. A coupled inductor is used instead of normal inductors, which will reduce core and size requirements. The sinusoidal pulse width modulation strategy is used in this paper for controlling the main switch. There are many merits in the presented topology, like high gain up to five times of input voltage, compact size, less number of components, which results in reducing the overall cost, reducing switching loss, and increasing the converter efficiency. The simulation study is carried out using MATLAB/SIMULINK to simulate the operation of the proposed converter. Also, an experimental setup is built up to examine the actual operation of the proposed converter. There is a good agreement between simulation and experimental results which increases the validation and confidence of the model.

A distributed economic model predictive control-based FPPT scheme for large-scale solar farm

Increasing solar-photovoltaic-power penetration necessitates the implementation of flexible power point tracking (FPPT) in solar farms. However, coordinating multiple solar photovoltaic (PV) power generation systems (SPVPGSs) poses a significant challenge due to their inherent intermittency and varying dynamic characteristics, complicating FPPT implementation. To overcome this challenge, this paper proposes a distributed economic model predictive control (DEMPC) scheme to achieve FPPT, while simultaneously enhancing overall economic performance in solar farms. By integrating solar farm control and local control into one optimal control framework, this scheme eliminates the need for power allocation, PV voltage reference calculation, and pulse width modulation. Leveraging the SPVPGS model and soft power constraint, DEMPC controllers are designed to achieve the economic targets of solar farms, which cooperate through a communication network to realize FPPT and economic optimization. Additionally, the strong nonlinearity of SPVPGS causes a non-convex mixed integer nonlinear programming (MINLP) problem, solved by a MINLP algorithm using finite converter switching states. Simulations under step-changed irradiance and power reference, as well as urgent maintenance conditions, demonstrate that the DEMPC-based FPPT scheme significantly outperforms the traditional hierarchical model predictive control-based FPPT scheme, presenting both superior dynamic response and enhanced economic performance in FPPT implementation.

Diagnostics of unmanned aerial vehicle with recurrence based approach of piezo-element voltage signals

This work experimentally addresses damage calibration of an unmanned aerial vehicle in operational condition. A wide range of damage level and types are simulated and controlled by an electric motor via pulse width modulation in this regard. The measurement is carried out via established protocols of using a piezo-patch on one of the 8 arms, utilising the vibration sensitivity and flexibility of the arms, demonstrating repeatability of such protocol. Subsequently, recurrence analysis on the voltage time series data is performed for detection of damage. Quantifiers of damage extent are then created for the full range of damage conditions, including the extreme case of complete loss of power. Experimental baseline condition for no damage condition is also established in this regard. Both diagonal-line and vertical-line based indicators from recurrence analysis are sensitive to the quantitative estimates of damage levels and a statistical test of significance analysis confirms that it is possible to automate distinguishing the levels of damage. The damage quantifiers proposed in this paper are useful for rapid monitoring of unmanned aerial vehicle operations of connection.

A novel ECG compression algorithm using Pulse-Width Modulation integrated quantization for low-power real-time monitoring

Cardiac monitoring systems in Internet of Things (IoT) healthcare, reliant on limited battery and computational capacity, need efficient local processing and wireless transmission for comprehensive analysis. Due to the power-intensive wireless transmission in IoT devices, ECG signal compression is essential to minimize data transfer. This paper presents a real-time, low-complexity algorithm for compressing electrocardiogram (ECG) signals. The algorithm uses just nine arithmetic operations per ECG sample point, generating a hybrid Pulse Width Modulation (PWM) signal storable in a compact 4-bit resolution format. Despite its simplicity, it performs comparably to existing methods in terms of Percentage Root-Mean-Square Difference (PRD) and space-saving while significantly reducing complexity and maintaining robustness against signal noise. It achieves an average Bit Compression Ratio (BCR) of 4 and space savings of 90.4% for ECG signals in the MIT-BIH database, with a PRD of 0.33% and a Quality Score (QS) of 12. The reconstructed signal shows no adverse effects on QRS complex detection and heart rate variability, preserving both the signal amplitude and periodicity. This efficient method for transferring ECG data from wearable devices enables real-time cardiac activity monitoring with reduced data storage requirements. Its versatility suggests potential broader applications, extending to compression of various signal types beyond ECG.

Advanced Multi-Sampling PWM Technique for Single-Inductor MIMO DC-DC Converter in Electric Vehicles

Amongst the various topologies of multi-input multi-output (MIMO) DC-DC converters, single-inductor MIMO (SI-MIMO) converters have the advantages of a reduced component count, a simpler structure, and low cost. These converters are suitable in electric vehicle (EV) applications involving variable ports, essential for performing different functions. Digital control in SI-MIMO converters is promising for enhancing transient performance due to its numerous benefits. However, delays in digital control, particularly computational and pulse width modulation (PWM) delays, can negatively impact the performance of DC-DC converters. Multi-sampling and double PWM update methods can mitigate these control delays, but they often necessitate complex control schemes, adding computational burden. In this work, an advanced multi-sampling PWM technique, integrating sample shift and multi-sampling, is proposed while employing a simple digital PID control scheme. The proposed method was tested for a shared-switch SI-MIMO converter with battery discharging and charging modes in the MATLAB/Simulink environment and compared with the conventional single- and multi-sampling PWM methods. The results demonstrated that the proposed method significantly improved the converter performance, surpassing the conventional single- and multi-sampling PWM methods. In the battery discharging mode, utilizing the proposed method, the output voltage achieved a settling time of 0.075 s in response to a step change in its reference, significantly outperforming multi-sampling, which yielded a settling time of 0.124 s, and single sampling, which exhibited an even longer settling time of 0.898 s. It also demonstrated a minimal overshoot of 0.06 volts compared to 1.5 volts with multi-sampling during the step change in the input voltage. Similarly, in the battery charging mode, upon a step change in the reference output voltage, the proposed method effectively minimized the overshoot of the output voltage to 0.845 volts compared to 1.175 volts with multi-sampling, and it decreased the inductor current settling time to 0.296 s from 0.330 s recorded under multi-sampling. These findings underscore the potential of the proposed method in enhancing the digital control performance of SI-MIMO DC-DC converters in electric vehicles.

Isothermal Amplification Using Temperature-Controlled Frequency Mixing Magnetic Detection-Based Portable Field-Testing Platform.

Sensitive magnetic nucleic acid (NA) detection via frequency mixing magnetic detection (FMMD) requires amplified NA samples for which a reliable temperature control is necessary. The feasibility of recombinase polymerase amplification (RPA) was studied within a newly integrated temperature-controlled sensor unit of a mobile FMMD based setup. It has been demonstrated that the inherently generated heat of the low frequency (LF) excitation signal of FMMD can be utilized and controlled by means of pulse width modulation (PWM). To test control performance in a point of care (PoC) setting with changing ambient conditions, a steady state and dynamic response model for the thermal behavior at the sample position of the sensor were developed. We confirmed that in the sensor unit of the FMMD device, RPA performs similar as in a temperature-controlled water bath. For narrow steady state temperature regions, a linear extrapolation suffices for estimation of the sample position temperature, based on the temperature feedback sensor for PWM control. For any other ambient conditions, we identified and validated a lumped parameter model (LPM) performing with high estimation accuracy. We expect that the method can be used for NA amplification and magnetic detection using FMMD in resource-limited settings.