Reduced Conduction Losses Research Articles

Minimizing conduction losses in multiple active bridge converters across wide voltage ranges using advanced dual‐duty modulation

AbstractMultiple port DC/DC converters have applications in many fields: hybrid energy storage systems where batteries are combined with supercapacitors, multi‐level and multi‐modular inverters that need multiple DC sources, and DC microgrids. Among these converters, the Multiple Active Bridge (MAB) is particularly attractive due to its high power ratings and galvanic isolation capabilities. This paper introduces an advanced dual‐duty modulation technique for MAB converters designed to significantly reduce conduction losses over a wide range of input voltages by minimizing the harmonics’ reactive power on the AC stage. Consequently, it can improve the converter's efficiency when dealing with non‐constant voltage sources such as batteries and supercapacitors. The overall control technique is based on the dq‐frame control method under the first harmonic approach (FHA). This method is verified through simulations and implemented in a 1000 W triple‐port prototype. In the simulation, conductive and switching losses are modelled, and the trade‐off between these loss types is discussed. The experimental results affirm an overall improvement in efficiency for certain scenarios involving non‐unit voltage conversion ratios.

Metadielectrics for high-temperature energy storage capacitors

Dielectric capacitors are highly desired for electronic systems owing to their high-power density and ultrafast charge/discharge capability. However, the current dielectric capacitors suffer severely from the thermal instabilities, with sharp deterioration of energy storage performance at elevated temperatures. Here, guided by phase-field simulations, we conceived and fabricated the self-assembled metadielectric nanostructure with HfO2 as second-phase in BaHf0.17Ti0.83O3 relaxor ferroelectric matrix. The metadielectric structure can not only effectively increase breakdown strength, but also broaden the working temperature to 400 oC due to the enhanced relaxation behavior and substantially reduced conduction loss. The energy storage density of the metadielectric film capacitors can achieve to 85 joules per cubic centimeter with energy efficiency exceeding 81% in the temperature range from 25 °C to 400 °C. This work shows the fabrication of capacitors with potential applications in high-temperature electric power systems and provides a strategy for designing advanced electrostatic capacitors through a metadielectric strategy.

Ultrahigh efficiency and energy density in tri-layered ferroelectric polymer composites utilizing ultralow loading of micro-sized plates

Ferroelectric-based composites have demonstrated tremendous potential in electrostatic capacitor owing to their exceptional dielectric characteristics. However, it is extremely challenging to attain desirable energy density (Ue) and above 95% efficiency (η) under low electric fields in the ferroelectric polymer-based composites because of the dominating electrical conduction loss. Herein, ferroelectric polymer composites consisting of SrTiO3@SiO2 plates/(PVDF-co-HFP) as the inner layer and polycarbonate (PC) as the outer polymer layers are elaborately proposed. The vital role of the multiple interlaminar interfaces (electrode/dielectric interface and interlayer interface) on the reduction of conduction loss and improvement of corresponding energy storage properties of the ferroelectric polymer is verified by experimental and theoretical simulations. The resulting composite with an ultralow loading of SrTiO3@SiO2 plates (0.5 vol%) displays a record high capacitive performance (∼8.73 J/cm3) at above 95% η under the low electric field of 280 MV/m1, indicating an enormous ∼118% increment of the maximal Ue over the commercial bench-mark biaxially oriented polypropylene (∼4 J/cm3) and far outperforming those of the polymer-based dielectrics reported to date. Along with fast discharge time (9 ns), this contribution presents a versatile and competitive technology for fabricating composites with exceptional energy storage capabilities operating under low electric fields.

Interface engineering of polymer composite films for high-temperature capacitive energy storage

Polymer film capacitors encounter challenges in harsh conditions of high temperatures and electric fields because of large conduction loss and degraded breakdown strength (Eb). Herein, an interface engineering strategy is proposed to fluorinate the interfaces between the polyetherimide (PEI) matrix and wide bandgap boron nitride nanosheets (BNNSs) fillers. The composite films exhibit high-performance capacitive energy storage with a remarkable energy density of 5.73 J/cm3 and an ultrahigh efficiency of 91.22 % in conditions of 575 kV/mm and 150 °C. By adopting interfacial fluorination, the band structure of BNNSs is tailored to achieve a type II band alignment with PEI, promoting the dual trapping for both electrons and holes. It highly suppresses leakage current and reduces conduction loss. Typically, introducing fillers can compromise the properties of interfacial layers, creating weak points that trigger breakdown. Conversely, fluorinated interfaces exhibit an increased Young’s modulus and a reduced dielectric constant. According to the electromechanical breakdown theory, the interfacial Eb is increased. The breakdown phase propagation along the interfaces is thereby impeded, ultimately resulting in a further increase in overall Eb, reaching up to 589 kV/mm at 150 °C. Fluorinated interface engineering addresses interfacial challenges posed by fillers, enabling high-temperature energy storage capability in PEI-based capacitors.

A Review on Coupled Inductor-Based High Step-Up DC-DC Converters for Renewable Energy Sources

Renewable energy sources are increasingly being embraced due to their environmental advantages, characterized by clean energy production, including solar energy, fuel cells, and wind turbines. High step-up DC-DC converters are commonly employed in conjunction with these sources to elevate their unregulated output voltage to a high and regulated level. This is especially true for converters based on coupled inductors, which are able to achieve high voltage with a low duty cycle. This paper provides a comprehensive review on the coupled inductor-based high step-up DC-DC converters. This review involves five widely used topologies, namely stacked converters, cascaded converters, multi-winding converters, interleaved converters, and integrated converters. It is evident that the researchers proposing these converters aim to enhance the overall efficiency of the renewable energy system by achieving a high voltage gain with a low duty cycle, thereby reducing conduction losses, mitigating stress on switches, alleviating voltage spikes across the main switches, and recycling the leakage energy. However, it is noteworthy that some of the proposed circuit designs are complex and involve a high number of components resulting in increase in cost and size of packaging. Additionally, some proposed circuits could not effectively achieve the aforementioned objectives. This paper serves as a valuable resource for researchers, offering an overview of the latest developments in the high step-up converters based on coupled inductor, which may help them to identify potential research gaps.

Power converters analyzed in energy storage systems to enhance the performance of the smart grid application

This paper implements and compares the existing power supply converters for an energy storage system to determine the best suited for the smart grid application. A survey of different DC-DC converters is carried out to analyze the battery's overall performance. The main objective is to identify this application's most appropriate energy storage device. The advantages of this technology have high efficiency and reliability, which can connect various energy sources and reduce conduction losses in the power converters. Through the converter control, reference currents are imposed to charge the battery. The battery nominal voltage needs to change to see which type of converter is the most suitable and robust. Simulation results show that the operating ranges of boost-buck, buck-boost, and buck-boost converters with negative output voltage enhance the efficiency of battery and renewable energy sources and compared the DC converters to know the functional voltage for the energy storage system. The power converter's efficiency and control facility will allow us to link the energy storage system with the power grid. The overall installation is established using MATLAB/Simulink software.

Performance evaluation of bridgeless isolated SEPIC-Luo converter for EV battery charging using PI and ANN controller

Electric vehicle (EV) rechargeable battery packs that employ traditional power factor correction (PFC) circuit design have performance limitations due to their substantial conductivity loss that ensures at the input of a diode bridge rectifier (DBR). This study suggests a bridgeless (BL) isolated single ended primary inductance converter (SEPIC) - Luo converter to address the problem. As a result, the input current exhibits a power factor operation of unity throughout the charging process. DBR elimination and current conduction through a remarkably small number of circuits both significantly reduce conduction losses. The use of an artificial neural network (ANN) and proportional integral (PI) controller enhances the converter's performance with a stable DC link voltage. The suggested converter overall operation is thoroughly described in terms of variety of operating modes and simulation-based effectiveness. Here, with the assistance of the hysteresis current controller (HCC), the input current disruptions are reduced. Constant current and voltage management is used to successfully charge the EV battery, resulting in improved efficacy and inherent PFC. By utilizing simulation outcomes achieved from MATLAB, the performance of proposed BL isolated SEPIC-Luo in boosting the power quality of EV charger system is examined.

A High Step-Up Resonant Converter Based on Current-Fed Voltage Multiplier Technique

An extendable non-isolated resonant dc-dc converter based on current-fed voltage multiplier (VM) technique is proposed in this paper for high step-up applications. These VM cells capacitors participate in a resonant network; therefore, no additional elements are required to provide a resonant tank circuit to realize soft switching conditions for power switches. Zero voltage switching (ZVS) and zero current switching (ZCS) conditions are realized here for switches and diodes, respectively. Consequently, MOSFETs dominant switching losses and the diodes reverse recovery problems are well overcome. Furthermore, the input source current waveform is continuous. Also, using the VM cells reduces the power devices voltage stresses. Accordingly, low voltage rating devices can be used, which reduce conduction losses and cost, and improve the converter efficiency. Also, by using more VM cells, the proposed converter can be used for high-voltage applications, without using extremely high duty cycle values to regulate the output voltage. The operation principles, steady-state analysis, design guidelines, and main characteristics of the proposed converter are given here, in detail. Finally, an 800 W prototype converter, with 80–100V input voltage and 2 kV output voltage, has been implemented to validate the given analyses, simulation results, as well as to show the proposed converter main advantages.

Paralleled Variable Inductor Phase-Shifted Full-Bridge Converter With Full-Load Range ZVS and Low Duty Cycle Loss

This paper presents a new phase-shifted full-bridge topology using a new variable inductor. In this topology, a variable inductor is connected in parallel with a near-ideal transformer. The ZVS of the switches is achieved over the full load range using the parallel current provided by the variable inductor. And the adjustable parallel current reduces conduction losses. Under the orthogonal DC magnetic potential, the variable inductor has similar characteristics to the saturated inductor, which is beneficial to reduce the conduction loss caused by the parallel current. Since the topology has no series inductor and the leakage inductor is extremely small, the proposed converter has the advantages of extremely small duty cycle loss, larger transformer turns ratio, smaller primary current stress, smaller secondary voltage stress, and smaller output current ripple, which are beneficial to improve the efficiency and frequency of the converter. An experimental platform was established. Theoretical analysis and experimental verification were carried out.

Constructing a dual gradient structure of energy level gradient and concentration gradient to significantly improve the high-temperature energy storage performance of all organic composite dielectrics†

The severe electrical conduction loss at elevated temperature is the initial factor for the degradation of energy storage performance of polymer dielectric films, thus it urgently needs to develop highly heat-resistant polymer capacitive films for meeting the advancing electrical and electronic applications. For reducing conduction loss and improving the high-temperature energy storage performance of dielectrics, the current approaches are focusing on preventing carriers mobility at elevated temperature and high electric field. In this study, the molecular semiconductor ITIC (ITIC is an organic molecular semiconductor 2,2′-[[6,6,12,12-Tetrakis(4-hexylphenyl)-6,12-dihydrodithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene-2,8-diyl]bis [methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis[propanedinitrile] abbreviation) with high electron affinity was filled into the blends of polyether imide (PEI) and polyethersulfone (PESU). The energy level gradient was constructed due to the different energy bandgap structures among ITIC, PESU and PEI. In addition, the concentration structure gradient was constructed due to the concentration of ITIC which varies along the thickness direction. The results demonstrate that the dual gradients of energy level and concentration can effectively inhibit carrier migration and lower conduction loss, thus significantly improving the electric breakdown strength and energy storage performance at high temperature. The energy storage densities (Ue) of 5.14 J/cm3 and 3.6 J/cm3 at 150 °C and 200 °C, respectively were achieved in PEI/PESU blends with 9 layers of ITIC gradient and 0.25 % ITIC in the outer layer. This study puts forward a novel structural design combining the energy levels gradient with concentration gradient to optimise the high-temperature energy storage properties of all-organic dielectric films.

High step up DC–DC converter with low conduction losses and reduced switching losses

AbstractThis article presents a novel high step up converter based on the active switch inductor (ASL) technique for renewable energy source applications. The coupled inductor technique provides an opportunity to increase the gain. The proposed converter exploited the leakage inductors to provide zero current switching (ZCS) turn‐on for both switches. Therefore, there is no need for an auxiliary circuit, which simplifies the structure. Also, all diodes turn off under ZCS, which eliminates the reverse recovery problem and results in reduced switching losses. The energy of the leakage inductor is recycled, and the voltage spike on the switches is limited. In addition, all semiconductor voltage stresses are clamped below the output voltage. Hence, components with lower on‐resistance can be utilized to reduce conduction loss. Because of the reduction in power loss, the efficiency rises to 97.2% at 250 W output power. It also benefits from the current sharing of the interleaved structure. The operating principles, design considerations, and comparison to other topologies are discussed. To verify the effectiveness of the proposed converter, a prototype converter with 250 W of output power, 50 V of input voltage, 500 V of output voltage, and 100 kHz of switching frequency is implemented.

SEPIC-Boost-Based Unidirectional PFC Rectifier with Wide Output Voltage Range

A novel unidirectional hybrid PFC rectifier topology based on SEPIC and boost converters is proposed, which is applicable to various industrial applications such as electric vehicle charging stations, variable speed AC drives, and energy storage systems. Compared to other rectifiers, the proposed SEPIC-boost-based rectifier exhibits continuous current on the AC side, lower voltage stress on the active switches, a wider range of DC output voltage, no auxiliary DC-DC converters, and a high step-up static voltage gain operating with low input voltage and a low step-up static gain for the high-input-voltage operation. These traits allow the SEPIC-boost-based rectifier to utilize smaller input-side harmonic filtering inductors and adopt active switches with lower voltage ratings, resulting in reduced conduction losses. Additionally, the proposed rectifier features power factor correction and high boost/buck voltage-gain capabilities, simplifying control for electric vehicle charging and expanding its range of applications. In this paper, the operating principle of the novel topology is presented first, and then the mathematical model of the proposed rectifier is built. Based on this, the comparison between the proposed topology and conventional boost and SEPIC converters is given. Furthermore, the control strategy, including the high-power-factor control and the balancing control to the DC capacitor voltages, is discussed. Finally, to validate the accuracy of the proposed rectifier’s theoretical research, a 500-W SEPIC-boost rectifier system has been constructed in the laboratory, generating a 200/120 Vdc output voltage from a 155 Vpk/50 Hz power source.

A model predictive fault‐tolerant control strategy for non‐redundant T‐inverters with multiphysics‐circuit coupling loss analysis

SummaryThis paper presents a multiobjective optimal power prediction fault‐tolerant control (MO2PPC) approach for mitigating DC link neutral‐point voltage imbalance and current ripple problems in three‐level T‐type inverter (3LT2I). Additionally, an auxiliary thyristor is employed to isolate and reconstruct the faulty phase into an 8ST2I for ensuring uninterrupted operation during phase failure. A method called injected bias current‐MO2PPC (IBC‐MO2PPC) fault‐tolerant strategy is proposed for this structure. This approach eliminates the need for DC or AC current sensors to reconstruct the three‐phase current, thereby reducing neutral‐point oscillation caused by phase deficiency and ensuring full power output after failure. Additionally, nonfaulty phase power loss is compared and analyzed to verify the stability of this method following a phase fault. The internal losses and temperature distribution of an IGBT module in a bridge arm before and after a fault are verified through a multiphysics‐circuit model in COMSOL‐Simulink coupling simulation presented last. The model shows reduced conduction losses and overall lower temperature distribution in the IGBT module after fault reconstruction. Experiments and multiphysics simulations have demonstrated that this approach displays exceptional robustness and sustainability throughout the entire fault cycle.

Improved capacitive energy storage performance in hybrid films with ultralow aminated molybdenum trioxide integration for high-temperature applications.

Dielectric capacitors play a pivotal role in advanced high-power electrical and electronic applications, acting as essential components for electrical energy storage. The current trend towards miniaturization in electronic devices and power systems highlights the increasing demand for scalable, high-performance ultra-thin dielectric films with a high-temperature stability. While significant progress has been made in enhancing the discharged energy density (Ue) of dielectric polymers at elevated temperatures, such advancements have faced certain challenges. Herein, an innovative molecular engineering approach for the bonding of amine-functionalized molybdenum trioxide (A-MoO3) with the dianhydride monomer of polyetherimide (PEI) is presented, leading to a reduction in conduction loss and the substantial enhancement in storage energy density under high-temperature and high-field conditions. It is revealed that charge redistribution at the bonding sites induces a subtle variation in the potential energy, creating an in-built electric field between the PEI matrix and A-MoO3 based on density functional theory (DFT) analyses. The observed phenomenon leads to an increase in the electron barrier, effectively inhibiting the release of trapped electrons. Notably, at conditions of 200 °C and 100 Hz, the PEI/A-MoO3 hybrid film demonstrates a notable Ue at η > 90%, reaching up to 5.53 J cm-3, surpassing the performance of many current dielectric polymers and composites. Furthermore, the hybrid film's exceptional cycling durability, coupled with its ability to be fabricated into large-area, uniform-quality films, underscores its potential in the development of dielectric energy storage devices tailored for extreme environments.

A Battery-to-3.4 V Hybrid Buck-Boost Converter With Always Reduced Conduction Loss

A Battery-to-3.4 V Hybrid Buck-Boost Converter With Always Reduced Conduction Loss

Investigation of WBG based Power Converters used in E-Transportation

Nowadays, Uses for transportation are evolving in the direction of getting more electrified due to rising fuel costs and environmentally hazardous pollutants due to which The grid’s need for power is increasing dramatically. As the only solution for this is to diminish the power consumption of Electric Vehicles (EV). Enhanced component efficiency can lead to improved electric vehicle performance. Wide band gap (WBG) semiconductors, in particular silicon carbide (SiC) and Gallium Nitride (GaN), are ideal candidates of choice to address the recent growing demand in both high efficiency and great power density converters about electric vehicles. Due to their the capacity to switch at a high frequency, high temperature, high voltage, reduced size and reduced conduction losses makes them superior than Si semi-conductors. WBG devices have some properties which include rapid electron mobility, high breakdown field, and big band gap low on-state resistance and capacitance, lower co-efficient of thermal expansion (CTE) and high stability. This paper includes a study on WBG devices, their properties, and the increased efficiency of power converters i.e DC-DC boost converter and single-phase full bridge inverter using LTSpice simulation tool.

Reduced Conduction Loss ZVS Control for Buck-Type Active Filter Operating as Decoupling Circuit

Reduced Conduction Loss ZVS Control for Buck-Type Active Filter Operating as Decoupling Circuit

Hybrid interleaved DC‐DC step‐up converter based on coupled inductor

SummaryIn this paper, a high voltage gain hybrid interleaved DC‐DC converter (HIC) with quadratic voltage gain is proposed that is suitable for renewable energy systems. The hybrid technique is used in this converter to increase the output voltage. The proposed DC‐DC converter utilizes the interleaved boost converter on the input side, and the input current is shared with a low ripple that lengthens the lifetime of the renewable power source. In addition, the proposed converter has low voltage stress across the components that can be adopted to reduce conduction losses and the cost of the elements. In addition, the proposed converter share ground between the input and output and has high efficiency. The operation modes of the proposed converter are analyzed, and its equations are calculated. Then, the elements of the proposed converter are designed in continuous conduction mode. A comprehensive comparison of the proposed converter with other recently presented existing converters is discussed to show the advantages and disadvantages of the proposed structure. Finally, to verify the performance of the proposed converter and the obtained relations, a 400 W prototype is built to demonstrate the effectiveness of the proposed converter.

Practical Dead-Time Control Methodology of a Three-Phase Dual Active Bridge Converter for a DC Grid System

An effective dead-time control strategy for the three-phase dual active bridge (3P-DAB) converter of a distribution system is studied to reduce the switching losses of power switches and improve the under-light-load power conversion efficiency. Because of the advantages of a dual-active bridge converter, such as an inherent zero-voltage switching (ZVS) capability without any additional resonant tank and a seamless bi-directional power transition, this is an attractive topology for bi-directional application. The 3P-DAB converter is apt for high-power applications such as aircraft due to an interleaved structure, which can reduce conduction losses. However, the design of the dead time depends on engineering experience and empirical methods. In order to overcome the conventional practicality of the dead-time design method, the effective control of dead time is proposed based on the theoretical analysis. In this paper, the overall explanation of the 3P-DAB converter is shown with operation principles. In addition, the dead-time effect of the 3P-DAB converter is examined and the practical variable dead-time control strategy is studied. Finally, experimental results validate the proposed variable dead-time control strategy using a 25 kW prototype 3P-DAB converter.

A Novel Isolated High-Step-Up Interleaved Converter for Renewable Energy Systems

In this paper, an isolated high step-up interleaved converter for renewable energy systems is proposed. The input-parallel configuration introduced by two energy storage inductors, which can disperse the input current, reducing conduction losses and also improve the conversion efficiency. In order to improve the voltage gain and recover the energy stored in the leakage inductance, the auxiliary step-up structure is utilized in the proposed converter, that including an auxiliary inductor, an auxiliary capacitor, a voltage multiplier capacitor and two switches which serve to exchange the energy stored in auxiliary capacitors and inductors. On the secondary side, a voltage-doubler circuit is used to extend the voltage gain. Finally, a 48V-input, 400V-output and the rated power of 500 W prototype is implemented to verified the effectiveness of the proposed converter. The experimental results shows that the maximum efficiency is 95.97%, and the efficiency of full-load is 93.27%.