Energy Storage Elements Research Articles

Bioelastic state recovery for haptic sensory substitution.

The rich set of mechanoreceptors found in human skin1,2 offers a versatile engineering interface for transmitting information and eliciting perceptions3,4, potentially serving a broad range of applications in patient care5 and other important industries6,7. Targeted multisensory engagement of these afferent units, however, faces persistent challenges, especially for wearable, programmable systems that need to operate adaptively across the body8-11. Here we present a miniaturized electromechanical structure that, when combined with skin as an elastic, energy-storing element, supports bistable, self-sensing modes of deformation. Targeting specific classes of mechanoreceptors as the basis for distinct, programmed sensory responses, this haptic unit can deliver both dynamic and static stimuli, directed as either normal or shear forces. Systematic experimental and theoretical studies establish foundational principles and practical criteria for low-energy operation across natural anatomical variations in the mechanical properties of human skin. A wireless, skin-conformable haptic interface, integrating an array of these bistable transducers, serves as a high-density channel capable of rendering input from smartphone-based 3D scanning and inertial sensors. Demonstrations of this system include sensory substitution designed to improve the quality of life for patients with visual and proprioceptive impairments.

Current Compensation for Faulted Grid-Connected PV Arrays Using a Modified Voltage-Fed Quasi-Z-Source Inverter

Large-scale photovoltaic (PV) systems are being widely deployed to meet global environmental goals and renewable energy targets. Advances in PV technology have driven investment in the electric sector. However, as the size of PV arrays grows, more obstacles and challenges emerge. The primary obstacles are the occurrence of direct current (DC) faults and shading in a large array of PV panels, where any malfunction in a single panel can have a detrimental impact on the overall output power of the entire series-connected PV string and therefore the PV array. Due to the abrupt and frequent fluctuations in power, beside the low-PV systems’ moment of inertia, various technical problems may arise at the point of common coupling (PCC) of grid-connected PV generations, such as frequency and voltage stability, power efficiency, voltage sag, harmonic distortion, and other power quality factors. The majority of the suggested solutions were deficient in several crucial transient operating features and cost feasibility; therefore, this paper introduces a novel power electronic DC–DC converter that seeks to mitigate these effects by compensating for the decrease in current on the DC side of the system. The suggested solution was derived from the dual-source voltage-fed quasi-Z-source inverter (VF-qZSI), where the PV generation power can be supported by an energy storage element. This paper also presents the system architecture and the corresponding power switching control. The feasibility of the proposed method is investigated with real field data and the PSCAD simulation platform during all possible weather conditions and array faults. The results demonstrate the feasibility and capability of the proposed scheme, which contributes in suppressing the peak of the transient power-to-time variation (dP/dt) by 72% and reducing its normalized root-mean-square error by about 38%, with an AC current total harmonic distortion (THD) of only 1.04%.

Renewable Energy-Based Electric Drive with a Novel Control Technique for Smooth Power-Sharing

Energy management between different power sources, which are used to feed Electric vehicles (EVs) is one of the complex scenarios. Normally, power management is done based on the Electric vehicle load requirements. In this work, three different energy sources are considered, in that one is an active energy source and two are passive energy storage elements. The Photo Voltaic (PV) based energy source is considered an active element, on the other hand, the Battery sand supercapacitor (SCap) is treated as a passive type of element. To manage the power flow between two energy sources, a novel control technique is adopted by considering the speed and current of the electric motor as major input parameters known as the Measurement of the parameter-based controller (MPBC). The Measurement of a parameter-based controller is used to control the pulse signals of the Bidirectional converters connected at the battery and supercapacitor ends, and the required pulse signals can be generated by the Conventional Proportional Integral (PI) controller. The main circuit is implemented with a novel hybrid controller which is used to provide controlled pulse signals to the bidirectional converters connected to the battery and supercapacitor. Finally, the MATLAB/Simulink model was developed with the novel hybrid controller and examined the performance at different load conditions of the motor by considering three different states of power delivered by the PV array.

Adaptive Frequency-Based Power Management for Off-Grid Hybrid Photovoltaic Converters

The intermittency in photovoltaic systems (PV) can lead to power quality issues, especially in off-grid applications. In these cases, adding an energy storage element helps to cope with the intermittency to provide adequate power to the local load. In this scenario, combining Li-Ion batteries and supercapacitors as a hybrid energy storage system (HESS) is powerful due to the battery's high energy density and the supercapacitor's high power density. The HESS demands adequate power management to operate adequately. This paper proposes an adaptive frequency-based power management for a Li-Ion battery and supercapacitor HESS applied to an off-grid PV converter. The main idea of this strategy is to guarantee a smoother current in the battery and reduce the power dissipation in the HESS. The smoother battery current transition helps avoid excessive battery stress and improves lifespan. The proposed strategy is compared with two other strategies. The results show that the proposed approach is more efficient in reducing the HESS' power dissipation and providing smooth current variations to the battery.

Realizing enhanced energy storage performance of Na0.47Bi0.47Ba0.06TiO3-based relaxors with weak coupling behavior by manipulating phase fraction

Lead-free dielectric capacitors have attracted considerable attention as the core energy storage element of pulsed power systems due to their advantages of fast charging capability, high power density and environmental friendliness. However, the low recoverable energy storage density (Wrec) and narrow operating temperature range have become the bottleneck technical problems limiting its practical application. In this work, a class of weakly coupled relaxor ferroelectrics with excellent Wrec (9.06 J/cm3) and energy storage efficiency (η ∼ 85.3 %) were designed and prepared by manipulating phase fraction. Moreover, the materials exhibit excellent temperature stability with regard to energy storage, with a change in Wrec and η of less than 8 % over a wide temperature range (25 °C − 200 °C). The introduction of Sm(Mg0.5Hf0.5)O3 (SMH) enhances the insulating properties while refining the grains, effectively increasing the breakdown field strength (Eb) of the material. The emergence of weakly coupled nano-microdomains has the effect of suppressing the nonlinear polarization response of the material, which in turn results in a high polarization difference (ΔP). The preceding work presents a universal strategy for the future design and preparation of BNT-based lead-free dielectric capacitors with high energy storage properties (ESP) and good temperature stability.

Balancing the Mechanical and Electrochemical Properties of Multifunctional Composite Electrolyte for Structural Batteries

The pursuit of energy-efficient for electric vehicles and aircraft has driven the exploration of structural batteries. In the material-level design of structural batteries, electrode and electrolyte materials act as both load-bearing structures and energy storage elements. During these developments, carbon fibers with excellent mechanical and electrical conductive properties were used as electroactive materials and current collectors. However, most of these systems are combined with electrolytes without mechanical integrity (such as liquid or gel-type electrolytes), thus limiting the load-carrying performance of the battery. Currently the development of electrolytes for structural batteries remains challenging because the parameters enhancing electrochemical properties are often in contradiction with that for mechanical properties. In response to this challenge, the present study proposes a multifunctional composite electrolyte with balanced mechanical and electrochemical properties, which uses polyvinylidene fluoride (PVDF) as the matrix and metal-organic frameworks (MOF) modified glass fabric (MOF@GF) as the reinforcement. This study systematically investigates the following factors on mechanical and electrochemical properties of the composite electrolytes. Firstly, MOF with high specific surface areas and metal open sites onto the surface of glass fibers establishes a robust ion transporting network. With 20% MOF modified glass fiber and resin content 89%, the electrolyte exhibits high ion conductivity (1.74 × 10-3 S cm−1). In addition, by carefully controlling the resin content, a key parameter for fiber-reinforced composites, a delicate balance between mechanical strength and ionic conductivity can be achieved. Furthermore, interfaces were investigated, including glass fiber-MOF and MOF-PVDF interfaces, revealing the importance of effectively transfers stress and maintains structural integrity. Finally, these findings were combined to create a structural lithium metal battery that utilizes carbon fiber (CF) as the positive electrode and lithium metal as the anode. The resulting battery exhibits ultra-high tensile strength while maintaining a moderate capacity, ensuring normal operation under high voltage stress. This breakthrough discovery not only enhances the understanding of multifunctional composite electrolytes, but is also expected to promote further research and applications in the field of structural batteries. The promise of enhanced system electrolytes opens new avenues for lightweight design, space efficiency and expanded energy storage capabilities in electric vehicles and aircraft. Figure 1 . SEM images of (a) bare glass fiber. (b) MOF grown in-situ on glass fiber. (c) Single fiberglass within polymer matrix. (d) Cross section of the composite polymer electrolyte membrane. Figure 1

Emission Spectra of Ammonia Laminar Flames in Spherically Propagating Flames and a Modified McKenna Burner

ABSTRACT Ammonia (NH3) has received significant attention recently as a promising carbon-free, low-cost, and safe candidate as a chemical energy storage element and/or fuel alternative. As for any new fuel, fundamental aspects of the combustion process, such as the detailed chemical kinetic pathways of NH3 oxidation, flame propagation and stability, and emissions, are to be understood to predict its combustion behavior in practical systems. One aspect of improving our understanding of the combustion behavior of NH3 is to explore the emission spectra of spherically expanding and/or Bunsen-type flames under controlled laboratory conditions. In this study, flame spectra from NH3-containing mixtures were obtained utilizing two different experimental flame configurations, namely a spherically propagating flame and a modified Mckenna burner flame. Two different fuel mixtures were investigated. The first was an oxy-ammonia mixture consisting of NH3 + (25% O2 +75% N2) with the goal of studying neat ammonia. The second mixture consisted of H2:NH3:N2 with a ratio of 45:40:15 by volume. Several excited-state species within the UV-visible spectral region were identified. For instance, NO* emission features were found between 220 and 280 nm. In addition, OH* emission was detected around 310 nm, and an NH* feature was seen around 337 nm. Moreover, a broadband intensity was reported over the visible range (400 ~ 800 nm), where several NH2* features were also detected. The effect of the mixture on the flame spectra was investigated by examining the two different mixtures utilizing the same experimental apparatus (spherical flame in this case), and it was shown that the mixture has an effect on the presence of NH2* features, which was also backed by chemical kinetics predictions for the NH2* mole fraction profiles. It was shown (from kinetics) that the oxy-ammonia mixture produced more NH2* than the H2:NH3:N2 mixture by up to 113%. Additionally, the effects of the flame configuration were also investigated by studying the same mixture (the H2:NH3:N2 mixture in this case), and it was revealed that the spectra produced using the modified Mckenna burner had less noise, and all features were easily identified. Lastly, laminar flame speeds of the oxy-ammonia mixture were measured using the spherical flame apparatus. The laminar flame speed followed the expected pattern, peaking near a 1.1 equivalence ratio with a measured flame speed of 22.7 cm/s.

Viability of hybrid and alkali-activated slag materials for thermal energy storage: Analysis of the evolution of mechanical and thermal properties

Technological progress is needed to develop renewable energies. Improvements should be especially focused on the energy storage element to help correct the mismatch between energy supply and demand. In concentrated solar power (CSP) plants, ordinary concrete made of Portland cement (PC) has been proven to be a good thermal energy storage (TES) medium. However, the substantial environmental impact of PC manufacturing makes it necessary to develop new materials. Thus, in this work, alternative alkali-activated mortars (AAM) and hybrid materials (HM) have been developed using blast furnace slag to replace PC. This has been done in order to study their stability at high temperature (up to 500 °C) and their viability to operate as TES, undergoing thermal cycles between 200 °C and 400 °C, as they would in CSP technologies. Studying the mechanical and thermal properties after the thermal treatments has revealed that the alternative materials offer improved mechanical properties as well as very good thermal conductivity and storage capacity values. In particular, the best results in terms of mechanical properties were achieved by the AAM system, where the compressive strength value is increased with respect to the reference PC sample by 195% after exposure to 500 °C and by almost 97% after 20 thermal cycles between 200 °C and 400 °C. Furthermore, in terms of thermal properties, the AAM system showed a 31% increase in thermal conductivity after thermal exposure compared to PC. In addition, both AAM and HM systems demonstrated substantial improvements in specific heat and thermal storage capacity, outperforming PC by up to 46% during CSP-like thermal cycles. These promising results open new doors to the study of these alternative materials, such as TES, as they are more suitable than PC from an operational point of view.

Effective Charging of Commercial Lithium Cell by Triboelectric Nanogenerator with Ultrahigh Voltage Energy Management.

It is an increasingly mature application solution that triboelectric nanogenerator (TENG) supplies power to electronic devices through its power management system (PMS). However, the previous PMS is able to manage a limited voltage magnitude and the energy storage elements are limited to capacitors. This work proposes an ultrahigh voltage PMS (UV-PMS) to realize the charging of commercial lithium cells (LCs) by TENG. The design of UV-PMS enables energy management of TENGs with ultrahigh open-circuit voltages up to 3500V and boosts the peak charging current from 30.9µA to 2.77mA, an increase of 89.64 times. With the introduction of UV-PMS, the effective charging capacity of LC charged by a TENG at a working frequency of 1.5Hz for 1h comes to 429.7µAh, making a 75.3 times enhancement compared to charging by TENG directly. The maximum charging power comes to 1.56mW. The energy storage efficiency is above 97% and the overall charge efficiency can be maintained at 81.2%. This work provides a reliable strategy for TENG to store energy in LC, and has promising applications in energy storage, LC's life, and self-powered systems.

A regulatory power split strategy for energy management with battery and ultracapacitor

Electric vehicle batteries face fast degradation due to the high frequency of charging/discharging cycles and great peak power demands. Lifetime, continuity of supply and power density of these batteries affect the performance of electric vehicles (EVs). Hybrid energy storage systems (HESS) offers a feasible solution by incorporating other energy storage elements like ultra-capacitor (UC) along with battery. Their combination provides higher efficiency and better performance in terms energy/power density. UC can behave like a power buffer when the EV is accelerating and regenerating. The HESS needs a controller that can split the available power between different sub systems as per demand. This paper presents a regulatory control strategy useful in HESS with battery and UC for the speed regulation of a brushless DC (BLDC) motor using a 3-port bidirectional DC-DC converter. The regulatory control strategy monitors the state of charge (SOC) of UC and a fuzzy logic controller regulates the power flow between HESS and the motor. Simulation in MATLAB validates the efficacy of the strategy. Simulation results and hardware evaluation confirm that the regulatory control scheme is effective in splitting the available power according to the load demand and achieves better energy efficiency.

Optimal scheduling of energy routers based on distributed CAES systems

Abstract With the rise of renewable energy, distributed energy, and other different forms of energy, the architecture and function of the energy router are relatively perfect, for the topology of the energy router itself, different forms of energy in the energy router flow, conversion to realize the large-scale use of distributed energy equipment has also gradually become a hot spot of research. However, there are fewer studies on the energy router with a distributed CAES system to participate in the optimal scheduling of energy for integrated energy systems. Therefore, this paper is based on the operational domain model of an energy router with a distributed CAES system and analyzes the physical characteristics and coupling relationship of non-energy storage components, takes air pressure, temperature, and oil volume as state variables, takes charging, power generation, and heating power as external interfaces, and utilizes internal interface variables such as air quality and flow rate to realize energy storage, flow, and other internal interface variables to realize the communication between energy storage and non-energy storage elements, and finally determine the operation domain of the system. Secondly, the feasible domain of the energy router based on the distributed CAES system is portrayed, and the optimization of the system parameters is guided with the help of the relative distance by establishing the electric and thermal power constraints and the storage state constraints. Finally, the effectiveness of the feasible domain analysis method in the energy router of a distributed CAES system is verified by taking a northern region as an example.

Analysis of the Methods for Realization of Low-Power Piezoelectric Energy Harvesting Circuits for Wearable Battery-Free Power Supply Devices

This paper presents a comprehensive review of the design and implementation methods of low-power piezoelectric energy harvesting circuits, which in the last few years have gained an extremely large range of applications like the power sources of wearable electronic devices, such as biometrical sensors. Before examining the electronic circuitries of the self-supplied power devices, an overview of the structure, equivalent electrical circuits, and basic parameters of the piezoelectric generators and MEMSs as energy harvesting elements is presented. The structure of energy storage elements (parallel-plate capacitors and thin-film supercapacitors), suitable for this type of application, is also presented. The description of these components from an electrical point of view allows them to be easily workable when connected to the various power conversion electronic circuits. Based on an overview of the structure and the principles of operation, as well as some analytical expressions for energy efficiency evaluation, a comprehensive comparative analysis is presented. Depending on the advantages and disadvantages of the known circuit configurations, the basic electrical and design parameters are systematized in tabular form. Practical realizations of piezoelectric power conversion circuits are also presented in graphic form, ensuring the optimal value of energy efficiency and compactness in the construction of the devices.

Wave energy converter with mechanical motion rectifier, motion regulator, and energy storage element.

In this work, a novel design of an oscillating body-type Wave Energy Converter (WEC) is proposed with an efficiency of 48.73 %. Innovative features of the new design include the integration of Mechanical Motion Rectifier (MMR), Motion Regulator (MR), Energy Storage Element (ESE), and Electric Generator (EG) with the operation controlled by a microcontroller, limit switches, and linear actuator. Lab experiments conducted with a prototype ensured a peak voltage of 8.1 V and peak power of 4.3 W. Experimental and MATLAB theoretical simulation results demonstrated the average power of 55.2-148.3 mW for a wave height of 50-125 mm. In comparison to the conventional operation, where the electric generator is directly driven by wave motion, the proposed design will ensure higher peak power and better energy utilization characteristics of the generated voltage waveform. Simulation results are presented with the incorporation of non-circular gears that ensure modification of the voltage waveform for better energy utilization.

Influence of chemical strains on the electrocaloric response, polarization morphology, tetragonality, and negative-capacitance effect of ferroelectric core-shell nanorods and nanowires

Using Landau-Ginzburg-Devonshire (LGD) approach, we proposed the analytical description of the influence of chemical strains on spontaneous polarization and the electrocaloric response in ferroelectric core-shell nanorods. We postulate that the nanorod core presents a defect-free single-crystalline ferroelectric material, and elastic defects are accumulated in the ultrathin shell, where they can induce tensile or compressive chemical strains. Finite-element modeling (FEM) based on the LGD approach reveals transitions of domain-structure morphology induced by chemical strains in the BaTiO3 nanorods. Namely, tensile chemical strains induce and support the single-domain state in the central part of the nanorod, while the curled domain structures appear near the unscreened or partially screened ends of the rod. The vortexlike domains propagate toward the central part of the rod and fill it entirely, when the rod is covered by a shell with compressive chemical strains above some critical value. The critical value depends on the nanorod sizes, aspect ratio, and screening conditions at its ends. Both analytical theory and FEM predict that the tensile chemical strains in the shell increase the nanorod polarization, lattice tetragonality, and electrocaloric response well above the values corresponding to the bulk material. The physical reason for the increase is strong electrostriction coupling between the mismatch-type elastic strains induced in the core by chemical strains in the shell. Comparison with earlier XRD data confirmed an increase of the tetragonality ratio in tensile BaTiO3 nanorods compared to the bulk material. Obtained analytical expressions, which are suitable for the description of strain-induced changes in a wide range of multiaxial ferroelectric core-shell nanorods and nanowires, can be useful for strain engineering of advanced ferroelectric nanomaterials for energy storage, harvesting, electrocaloric applications, and negative capacitance elements. Published by the American Physical Society 2024

α-MnO2 Cathode with Oxygen Vacancies Accelerated Affinity Electrolyte for Dual-Ion Co-Encapsulated Aqueous Aluminum Ion Batteries.

Aluminum batteries (ABs) are identified as one of the most promising candidates for the next generation of large-scale energy storage elements because of their efficient three-electron reaction. Compared to ionic electrolytes, aqueous aluminum-ion batteries (AAIBs) are considered safer, less costly, and more environmentally friendly. However, considerable cycling performance is a key issue limiting the development of AAIBs. Stable, efficient, and electrolyte-friendly cathodes are most desirable for AAIBs. Herein, a rod-shaped defect-rich α-MnO2 is designed as a cathode, which is capable to deliver high performance with stable cycling for 180 cycles at 500mAg-1 and maintains a discharge specific capacity of ≈100mAhg-1. In addition, the infiltrability simulation is effectively utilized to corroborate the rapid electrochemical reaction brought about by the defective mechanism. With the formation of oxygen vacancies, the dual embedding of protons and metal ions is activated. This work provides a brand-new design for the development and characterization of cathodes for AAIBs.

Design and implementation of a hybrid piezoelectric, radio frequency, solar, and thermal energy‐harvesting system for portable medical devices

AbstractToday, energy harvesting has developed into a technique from which various aspects are still hidden. By extracting energies from the environment and even the human body, and converting them into electrical energy, we can supply power to low‐consumption electronic devices. Energy harvesting works by inhibiting small amounts of ambient energies; otherwise, it is wasted in other forms such as heat, vibration, and light. In this paper, we aim to eliminate or minimize the dependence of portable electronic devices to the batteries, which have limited life times, service costs, handling, and environmental problems. This is accomplished via incorporating the hybrid energy‐harvesting techniques and designed to power (bio)medical devices in order to measure vital signs. In this circuit, by simultaneously harvesting RF, light, thermal, and solar (natural and artificial) energies, we were able to increase the reliability of continuous supply of electrical energy in energy‐harvesting systems by generating and storing maximum power from the environment. Supercapacitors are used as the energy storage elements so that there is no energy waste, and each system is constantly storing the electrical energy with the aid of a diode block. In addition, with the help of supercapacitors, this device is able to transmit a maximum of 420 mW to the load and the total efficiency is equal to 74%.

Hemodynamics of ventricular-arterial coupling under enhanced external counterpulsation: An optimized dual-source lumped parameter model

Background and objectiveEnhanced external counterpulsation (EECP) is a mechanically assisted circulation technique widely used in the rehabilitation and management of ischemic cardiovascular diseases. It contributes to cardiovascular functions by regulating the afterload of ventricle to improve hemodynamic effects, including increased diastolic blood pressure at aortic root, increased cardiac output and enhanced blood perfusion to multiple organs including coronary circulation. However, the effects of EECP on the coupling of the ventricle and the arterial system, termed ventricular-arterial coupling (VAC), remain elusive. We aimed to investigate the acute effect of EECP on the dynamic interaction between the left ventricle and its afterload of the arterial system from the perspective of ventricular output work. MethodsA neural network assisted optimization algorithm was proposed to identify the ordinary differential equation (ODE) relation between aortic root blood pressure and flow rate. Based on the optimized order of ODE, a lumped parameter model (LPM) under EECP was developed taking into consideration of the simultaneous action of cardiac and EECP pressure sources. The ventricular output work, in terms of aortic pressure and flow rate cooperated with the LPM, was used to characterize the VAC of ventricle and its afterload. The VAC subjected to the principle of minimal ventricular output work was validated by solving the Euler-Poisson equation of cost function, ultimately determining the waveforms of aortic pressure and flow rate. ResultsA third-order ODE can precisely describe the hemodynamic relationship between aortic pressure and flow rate. An optimized dual-source LPM with three energy-storage elements has been constructed, showing the potential in probing VAC under EECP. The LPM simulation results demonstrated that the VAC in terms of aortic pressure and flow rate yielded to the minimal ventricular output work under different EECP pressures. ConclusionsThe ventricular-arterial coupling under EECP is subjected to the minimal ventricular output work, which can serve as a criterion for determining aortic pressure and flow rate. This study provides insight for the understanding of VAC and has the potential in characterizing the performance of the ventricular and arterial system under EECP.

Unified control of high gain DC-DC converter for PV-battery hybrid system in a standalone and DC-microgrid applications

This paper presents power management and control of standalone PV and battery integrated hybrid system using high gain converter suitable for the DC Microgrid applications. The necessity of high gain DC-DC converter is raised due to generation of low output voltage of PV system. The attractive features of high gain converter are high voltage gain, continuous input current and suitability for integration of multiple input sources. The perturb and observe algorithm is used for tracing the maximum power point from solar and intermittency of solar is compensated by energy storage element battery. In the suggested hybrid system, the battery charging is carried out from DC bus voltage through buck converter and discharging to the load through high gain DC-DC converter. In the proposed work, Simulink model of proposed system rated for 1.2 kW PV module, 120 V, 42 Ah battery is developed using Simulink of MATLAB software and results are obtained under different operating conditions. Scaled experimental model of proposed hybrid system is implemented in laboratory environment using STM32F407VGT6 microcontroller and results are validated.

Reduced sensor Lyapunov‐based control for active power decoupling circuit

SummaryThe double‐line frequency ripple power exists inherently in single‐phase power converters. To address this problem, active power decoupling (APD) technique is widely used. It diverts the ripple power into a small energy storage element by introducing passive and active power devices. This inevitably involves more voltage and current sensors for corresponding control, which raises the cost while decreasing reliability and power density. In this paper, a Lyapunov‐based methodology is proposed to achieve APD control without adding any sensor. According to the designed controller laws, the practical decoupling capacitor voltage will converge to its reference. The decoupling voltage reference is given by taking into account buffering the double‐line frequency ripple power. Afterward, the robustness against parameter perturbations of the proposed method is discussed. Finally, the experimental results verify the feasibility of the proposed control strategy.

Innovative Matrix-Type AC-AC Solid-State Transformer Eliminating Ripple Power with Double-Grid Frequency

Single-phase solid-state transformers (SSTs) have the advantages of a compact structure, higher reliability, and multiple functions, and have been widely studied. However, bulky energy storage elements and inherent ripple power with double-grid frequency issues are the main disadvantages of conventional single-phase SSTs. This paper presents a single-phase matrix-type AC-AC SST eliminating ripple power with double-grid frequency. The presented SST consists of a line-frequency-commutated rectifier without bulky DC-link capacitors, an LLC resonant converter, a buck converter, and a line-frequency-commutated inverter. The LLC operates efficiently with a fixed voltage gain, and the buck converter provides a voltage regulation function. As a result, high conversion efficiency, high power density, and potentially high reliability are achieved. A 1 kW SST prototype is developed and tested to validate the feasibility and functionality of the proposed methods.