High Withstand Research Articles

A cyclic durable all-solid-state battery constructed with LiBH4-based electrolyte with high ionic conductivity at room temperature

LiBH4 has been considered as a promising solid electrolyte for lithium-ion batteries. However, the low ionic conductivity at room temperature has been the biggest challenge of LiBH4 solid-state electrolyte (SSE) toward practical solid-state batteries. In this work, a ternary electrolyte is designed and prepared by milling LiBH4 with LiNH2 and interfacially decorated with g-C3N4. It is revealed that the soft dispersed phase of two-dimensional g-C3N4 can build an effective transportation network in the composite electrolyte, thereby decreasing the interfacial impedance and reducing the energy barrier for lithium ion diffusion. The optimized SSE, LiBH4-2LiNH2-g-C3N4-10 % (LBN-CN-10 %), exhibits an ionic conductivity of 1.5×10−3 S cm−1, five orders of magnitude higher than that of the LiBH4 electrolyte at 30 °C. The LiIn symmetric cell with LBN-CN-10 % electrolyte delivers a low polarization of ∼89 mV over 10,000 h. When assembling with Li4Ti5O12 cathode, the all-solid-state battery exhibits excellent cycling over 1000 cycles at 30 ℃, achieving a breakthrough in the lifetime of solid-state batteries with LiBH4 -based electrolyte. Moreover, the all-solid-state battery with LiNi0.8Co0.1Mn0.1O2 cathode also delivers a discharge plateau at 3.0 V, revealing the high voltage withstanding of LBN-CN-10 % electrolyte. This work provides new options for the development and practical application of room-temperature hydride all-solid-state batteries.

Study of operation mode and breakdown characteristics for multi-stage gas switch

Multi-stage gas switches (MSGSs) are widely used in megavolt pulsed power systems due to their advantages of high withstand voltage, fast establishing time and relatively high operating frequency. Multiple operation modes, which are induced by the different breakdown sequences at each stage, are found to affect the breakdown characteristics of the gas switch. Based on the theoretical analysis of the working principle, the classification of the operation mode and the factors determining the operation mode of the MSGS are proposed. Methods for investigating the output waveform for MSGS are established by simulating lumped parameters and studying the breakdown time sequence of individual stages. In comparison with the intended mode of operation, the disadvantages of the unintended modes of operation for MSGS, including error-breakdown and non-triggering mode, are revealed. For unintended modes, the distortion of the output waveform, which determines the efficiency of energy transmission through the switch and the increased delay time jitter, which determines the synchronization of the gas switch, are further investigated. The possibility of non-triggering and its mechanism on surface flashovers induced by drifting electrons are also analyzed. Based on this study, design principles and methods are proposed to ensure the intended operation of the MSGS.

Sandwich-structured SrTiO3/PEI composite films with high-temperature energy storage performance

Dielectric capacitors are widely used in aerospace and power systems due to their non-polluting, high power density and fast charge/discharge rates. Polyetherimide (PEI) exhibits excellent temperature tolerance, high withstand voltage and low dielectric loss. However, its relatively low dielectric constant restricts its energy storage density. In this paper, a sandwich-structured composite film with the outer layer of pure PEI and the middle layer of strontium titanate (SrTiO3)/PEI is prepared by the solution casting method. At room temperature, the composite film with 5 vol% two-dimensional (2D) SrTiO3 plates achieves an outstanding energy storage density of 19.46 J cm−3 and an ultra-high energy storage efficiency of 97.05% under an electric field of 630 MV m−1. Furthermore, this composite film exhibits a maximum energy storage density of 10.34 J cm−3 and an energy storage efficiency of 88.13% at 150 °C. Combined with finite element simulation results, it confirms that the synergistic effect of 2D SrTiO3 plates and sandwich-structured can effectively hinder the development of electric trees. This work presents a sophisticated approach to design and preparation of dielectric composites suitable for the applications of high-temperature energy storage.

Realization of ultracapacitor as sole energy storage device in induction motor drive electric vehicle with modified state timing based field weakening control algorithm

This article employs the concept of realizing an electric vehicle (EV) driven by an induction motor (IM) with an ultracapacitor (UC) as a sole energy storage device for a short distance range in city drive. In battery-driven EVs, the performance of batteries will extensively degrade during frequent start, stop, acceleration and deceleration of the vehicle. However, UC can withstand that circumstance without any degradation. High charge/discharge efficiency, high power density, high temperature withstand capabilities and quick charging capability allows UC to run the EV for an extended range, including the regenerative braking technique. Apart from source, EVs also require efficient drive control for a smooth vehicle operation in the entire driving range. To achieve the vehicle characteristics, it is preferred to operate the propulsion drive in the field weakening (FW) region over the constant torque region. This paper also proposes a Modified State Timing SVPWM Based Control Algorithm for the FW region operation of IM for EV applications. The proposed algorithm is designed to overcome the torque ripple issue of the conventional SVPWM Based Control Algorithm in the FW region. The reduction in torque ripple is achieved by imposing current and voltage limits on the motor d and q axis by considering a maximum modulation index of 1.2732 and with an additional current loop for mitigating the transients in the torque due to sudden variation of the load. The simulation/hardware studies show a smooth operation of UC-driven EV for an entire driving range with a 78.57 percent improvement in torque ripple in the FW region by the proposed algorithm compared with the conventional FW control algorithm. The real time Lab prototype of UC driven EV has been developed and the proposed algorithm has been validated in real-time using the STM32F407VGTx ARM Cortex M4 microcontroller.

Controlling Dielectric Film Defects to Increase the Breakdown Voltage of Conductive Polymer Solid Capacitors.

Aluminum solid polymer capacitors are promising devices for the increased demand for power electronics applications. Nonetheless, the low breakdown voltage of commercially available catalysts (∼100 V) limits their applications. In this study, a hydroxide-film-covered high-purity aluminum was anodized at 700 V in boric acid at 85 °C, and the effect of a second hot water immersion (posthydration treatment) after anodizing on the breakdown voltage was studied as a possible future treatment to enhance the withstand voltages of solid electrolytic capacitors. The dielectric breakdown voltage of the anodized aluminum with a PEDOT:PSS coating was ∼500 V, being ∼200 V less than the anodizing voltage; however, the dielectric breakdown voltage was increased above 700 V by introducing the posthydration treatment due to the formation of a nanovoid layer above the dielectric alumina film. Our research suggests that the highly dispersed nanovoids incorporated with PEDOT:PSS avoid the current concentration at some local regions, effectively increasing the dielectric breakdown voltage. The posthydration treatment increased the leakage current by introducing physical defects in the dielectric film. However, the leakage current was reduced by a voltage sweep below the breakdown voltage after the PEDOT:PSS coating or a second anodizing process before the coating, keeping the breakdown voltage above 600 V. A promising processing route to obtain aluminum solid capacitors with high withstand voltage (600 V) found in our research is, first, dipping in hot water; second, anodizing at 700 V; then a second hot water treatment; and a second anodizing at 400 V, which keeps the capacitance invariable with a breakdown voltage enhanced.

Development of green ternary-blended-geopolymers for multifunctional engineering applications

Many industrial-wastes/clays, such as ground granulated blast-furnace slag (GGBFS), fly ash (FA), cement kiln dust (CDK), and metakaolin (MK), are employed in developing geopolymeric materials used in the construction sector. Accordingly, this work aims to find a green approach to benefit from the synergistic impacts of the precursors in developing ternary-blended geopolymers (TBGs; GGBFS/FA/CKD and GGBFS/MK/CKD) having multifunctional engineering applications. Five mixes were prepared: the control specimen (100 % GGBFS, S0) and the others contained different portions from GGBFS, FA, MK, and CKD. All mixes were cured in high humidity for up to 28-days. The impact of the TBGs’ mix-design on the fresh properties (workability and setting time), compressive-strength, pore-structure parameters, firing resistivity (200–900 °C), high dose gamma-radiation withstanding (1000–3000 kGy), and anti-microbial activity (against Aspergillus-oryzae, Aspergillus-fumigatus, Bacillus-Cereus and Salmonella-typhi) were investigated. Moreover, the phase composition (X-ray diffraction (XRD) and thermogravimetric analysis (TGA/DTG)) and microstructure (scanning electron microscope (SEM/EDX)) were studied. The obtained results demonstrated that CKD greatly impacts the lowering of workability and shortening of setting time due to high fineness/alkali-content in contrast with FA and MK. The obtained strength values by TBGs after 28-days ranged from 46.3 to 52.2 MPa. TBGs have significant strength retention and resistance to higher temperatures and higher doses of gamma-radiation compared to control due to the formation of highly-stable zeolitic phases. The S0 specimens cannot inhibit the growth of Salmonella-typhi in variance with TBGs that inhibit the growth of all micro-organisms owing to the presence of Fe2O3 and TiO2 in the matrix.

Electrical tree modelling in dielectric polymers using a phase-field regularized cohesive zone model

Electrical treeing is a leading cause to the eventual breakdown of dielectric polymers under high voltages. This paper presents a simulation scheme developed based on the phase-field regularized cohesive zone model (PF-CZM) for electrical tree modelling. By using the electrical analog of the crack propagation, the localized breakdown is modelled by the evolution of surface energy, and the electrical treeing is driven by the competition between the surface energy and the stored energy following the laws of thermodynamics. The microscopic Weibull distribution of the dielectric breakdown strength is the key factor resulting in the fractal structures of the electrical tree. The model developed is mesh independent and length-scale insensitive when the mesh size is no greater than 2.5μm. The validity of the model was confirmed through experiments, which strengthens its credibility. Three types of composites are designed and compared. The results indicate that the epoxy resin enhanced with 5 vol% silica and 1 vol% graphene sheet has a 3.5 % longer dielectric breakdown time and a 29.2 % higher thermal conductivity than the pure epoxy resin. Overall, the model provides a valuable tool for understanding the physics of electrical treeing and designing new dielectric materials with high withstand voltages.

Driving Cycle Design Optimization of Less-Rare-Earth PM Motor Using Dimension Reduction Method

In this paper, a driving cycle design optimization approach using the dimension reduction method is proposed for a less-rare-earth permanent magnet (LRE-PM) motor. In order to improve the efficiency of driving cycle optimization, the k-means clustering method, sensitivity analysis, and principal component analysis are utilized to reduce the dimensions of operating points, design parameters, and optimization objectives respectively. Furthermore, based on multi-objective genetic algorithm, improved motor performances of the whole driving cycle can be realized, including relatively high output torque, low torque ripple, low motor loss, and high demagnetization withstand capability. In addition, motor performances over the driving cycle before and after optimization are compared in detail. Finally, a prototype motor is built and tested. Both simulation and experimental results indicate that motor performances can be improved efficiently and comprehensively, which provides a potential research path for high-efficiency driving cycle optimization.

A wide input range, external capacitor-less LDO with fast transient response

A high voltage, external capacitor-less low-dropout regulator (HVLDO) with transient enhancement loop is presented in this work. The proposed HVLDO is designed with high withstand voltage laterally-diffused MOS (LDMOS) transistors and a transient enhancement loop is proposed to properly inject/sink current to/from the gate and output nodes of the power transistors to achieve fast transient response and high stability. Fabricated in 0.5µm SOI BCD process, the HVLDO occupies an active area of 0.29mm2. Operating with an input voltage ranging from 5.2 to 20V, it supplies an output voltage of 5V and a maximum load of 100mA. For all load conditions, this design has the power supply rejection of -49dB@100kHz, the phase margin over 68.4deg and achieves a temperature coefficient of 13.15ppm/°C. Measurement results show that this design has a line regulation of 0.88mV/V and a load regulation of 0.22mV/mA. The proposed HVLDO features fast line transient response of 60/20mV@9.8V/µs, fast load transient response of 30/70mV@100mA/µs, and recovery time of 2µs without external capacitors. Compared with the prior art, this work achieves the best transient FOM of 12.19fs.

Study on Directivity of Underwater Circular Transducer Array

At present, in the detection and identification of underwater noise sources, one of the most commonly used transducer arrays is the circumferential transducer array. The circumferential transducer array is symmetrical in space and has high withstand voltage capability and small sound pressure fluctuation in the horizontal beam. Its directivity is an important index that affects the performance of the array. This paper focuses on the directivity maps of circular arrays with different sizes and numbers of elements. From the graph, it is concluded that the undulation of the directivity graph of the circular array is directly related to the array element spacing. The smaller the array element spacing is, the smaller the undulation is, and vice versa. The directivity formula and law can provide technical guidance for the design of a uniform circular transducer array.

High-Power Microwave Limiters Using Recess-Free AlGaN/GaN Schottky Barrier Diodes

In this letter, a thin-barrier AlGaN/GaN Schottky barrier diode (SBD) is proposed and implemented in a three-stage high-power RF limiter module. Benefited from the thin-barrier epitaxy, a recess-free process in the Schottky region is allowed to avoid the plasma damage, resulting in low ON-resistance of 5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> and high withstand voltage characteristics. In addition, the proposed SBDs have achieved a low junction capacitance of 0.35 pF at 0 V bias and a turn-on voltage of 0.5 V. With the optimized SBD and well-designed matching circuits, the limiter has reached a high power capacity of over 10 W in continuous wave (CW), 20 W in pulse mode, and a fast recovery time of 30 ns at a frequency of 3.5 GHz, exhibiting better characteristics than traditional limiters. Both simulation and measured results agree with each other. It indicates that the AlGaN/GaN-based SBD is promising for high-power and high-frequency limiters.

パワーモジュールの絶縁基板における三重点の電界強度と絶縁破壊電圧に関する研究

Silicon carbide (SiC) devices exhibit several advantages such as high withstand voltage, high temperature operation, and low losses compared to conventional Si devices. However, in order to take full advantage of SiC devices, it is necessary to improve the characteristics of the power module package. In particular, the electrical insulation properties of the package depend on the insulating substrates. In this study, we focused on the difference in the electric field strength distribution when the front and back copper foils are moved horizontally relative to the aluminum nitride substrate.

Self-Powered Gate Drive Circuits With Optical Signal Isolation for In-Vehicle Marx Circuit of Ozonizer

Reducing the cost of a Marx circuit as a high-voltage power supply for nitrogen oxide (NOx) decomposition for diesel vehicles is required. The Marx circuit with MOSFETs has an advantage in size compared to the Marx circuit with gap switches. However, the Marx circuit with MOSFETs needs gate drive circuits on the gate of each MOSFET. The gate signal and drive power must be supplied to each gate with isolation in a low-cost way. However, the transformer for the isolation with high withstand voltage, such as 10 kV or more, is typically high cost because of the low demand. This article proposes the self-powered gate drive circuit using the charging path of the Marx circuit. The proposed gate drive circuit only requires a low withstand voltage because the power for the MOSFET on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> th stage is supplied from the ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n -1$ </tex-math></inline-formula> )th stage via a low-voltage transformer. Besides, the gate signal is transmitted through pairs of LEDs and photodiodes instead of high-cost optical fibers. The proposed gate drive circuits are developed and implemented into a prototype of the Marx circuit with an output voltage of 4 kV. From the experiments, it is demonstrated that the proposed drive circuits provide both drive power and gate signal.

Study on the high impulse current withstand properties and failure mechanism of ZnO varistors with different Bi2O3 content

Study on the high impulse current withstand properties and failure mechanism of ZnO varistors with different Bi2O3 content

Pre-Ball-Milled Boron Nitride for the Preparation of Boron Nitride/Polyetherimide Nanocomposite Film with Enhanced Breakdown Strength and Mechanical Properties for Thermal Management.

Modern electronics not only require the thermal management ability of polymer packaging materials but also need anti-voltage and mechanical properties. Boron nitride nanosheets (BNNS), an ideal thermally conductive and high withstand voltage (800 kV/mm) filler, can meet application needs, but the complex and low-yield process limits their large-scale fabrication. Herein, in this work, we prepare sucrose-assisted ball-milled BN(SABM-BN)/polyetherimide (PEI) composite films by a casting-hot pressing method. SABM-BN, as a pre-ball-milled filler, contains BNNS and BN thick sheets. We mainly investigated the thermal conductivity (TC), breakdown strength, and mechanical properties of composites. After pre-ball milling, the in-plane TC of the composite film is reduced. It decreases from 2.69 to 2.31 W/mK for BN/PEI composite film at 30 wt% content; however, the through-plane TC of composites is improved, and the breakdown strength and tensile strength of the composite film reach the maximum of 54.6 kV/mm and 102.7 MPa at 5 wt% content, respectively. Moreover, the composite film is used as a flexible circuit substrate, and the working surface temperature is 20 ℃, which is lower than that of pure PEI film. This study provides an effective strategy for polymer composites for electronic packaging.

Interfacial polarization suppression of P(VDF-HFP) film through 2D montmorillonite nanosheets coating

Polymer based dielectrics with excellent high electric field withstanding capability are of great significance for enhancing the power density and payload efficiency for both electrical and electronic systems. However, polymer-metal interface is prone to defect formation, leading to the dielectric aging and the initialization of electrical breakdown failure. A facile Montmorillonite (MMT) coating is self-co-assembled on the surface of P(VDF-HFP) high-k film to form hundreds of 2D nanosheets layers to impede the charge injection over the metal-polymer interface. The MMT coating increases the breakdown strength of the P(VDF-HFP) co-polymer film from 405 to 452 MV/m. The high field conduction study reveals a highly enhanced Schottky injection barrier that blocks the charge injection from electrodes to polymer bulk, leading to significantly suppressed charge injection and conduction loss in polymer. In addition, the introduction of MMT layered coating leads to prominent suppression of interfacial polarization loss, a phenomenon known as the blocking capacitance, which would otherwise stem from the accumulated charges of polymer-metal interface, by one order of magnitude, as demonstrated by the dielectric response analysis by using the Dissado-Hill model over a broad range of temperature and frequency. The superior charge injection and interfacial polarization suppression via the application of MMT coating impart the P(VDF-HFP) co-polymer film with higher breakdown strength, and provides an effective approach to develop high performance polymer dielectrics by interfacial engineering. This work provides insights into the understanding of the enhancement mechanism of 2D coating.

10‐1: Layout of 1.50‐inch, 3207‐ppi OLED Display with OSLSI/SiLSI Structure Capable of Division Driving Fabricated through VLSI Process with Side‐by‐Side Patterning by Photolithography

We fabricated a 1.50‐inch, 3207‐ppi OLED display with drivers capable of 32‐division driving, which is achieved by monolithically stacking OSFETs over SiFETs. Taking advantages of minute OSFETs with a high withstand voltage, Si‐OS connection regions were provided in subpixels to connect Si drivers and OS pixel arrays at given positions.

Experimental study on discharging current to reduce voltage stress during underwater shock wave generation

In food processing using underwater shock waves, the intensity of shock waves is determined by a discharging current from an output capacitor. In past studies, to realize efficient food processing, the underwater shock wave has been generated by charging a high voltage to the output capacitor with high withstand voltage characteristics. For this reason, the conventional method suffers from high manufacturing costs. Furthermore, the conventional method is dangerous due to high voltage requirements such as 3.5 kV. In this work, a low-cost and safe non-heat treatment technology using underwater shock waves is presented for food processing. Unlike the conventional methods, the proposed method generates underwater shock waves by using multiple large output capacitors with low withstand voltage characteristics. Therefore, the proposed method can achieve safe and low-cost non-thermal food processing, because the output capacitors do not need to be charged at high voltage. In the proposed method, the output voltage is about one-fourth that of the conventional methods. The effectiveness and reliability of the proposed technique are confirmed by several experiments using a laboratory experimental system. The experiment revealed that the proposed technique can process a target food at 865 V output, where the rise time of the high voltage generator is 126 s and the output capacitor is 3300 μF.

A hybrid current modulated DAB DC/DC converter for connecting PV modules to DC grid considering partial shading

The Maximum Power Point (MPP) voltage of a PV module can decrease significantly under partial shading conditions. Hence, high voltage gain converters are required to connect PV modules to DC grid. Generally, two-stage boost-based converters are preferred for their simplicity. However, they utilize a high number of semiconductors with high withstand voltages, and require an input filter inductance. In this paper, a hybrid current modulation that uses triangular (TRM) and trapezoidal (TZM) current modulations is proposed for Dual Active Bridge (DAB) converter to connect PV modules to DC grid. The proposed converter provides soft switching, low number of semiconductors, and reduces the breakdown voltages of input semiconductors compared with the two-stage Boost Full Bridge Isolated Converter (BFBIC). It also eliminates the input inductance and uses a 36% smaller core size than the total core size of BFBIC. The proposed converter is realized by an experimental prototype, and analyses are verified.

Multi-disciplinary Optimizations on Flexural Behavioural Effects on Various Advanced Aerospace Materials: A validated investigation

Generally, the importance of bending test has been employed to analyse the induction level of internal resistance of its larger face size of the test speciemens. Comparatively, stress induction is quite larger at the perpendicular face, where the bending load has been initiated its point of contact. Therefore the estimation of the location of maximum stress induction on bending test specimen must be analysed for the purpose to estimate the breaking point of test specimen, which supported a lot in the lifespan estimation of a component. In this work, three different composites are selected under the category of primary composites and thereby underwent the bending testing for the purpose of material refinement to tackle compressive load based applications. Three-Point flexural tests are conducted on the primary composites. The internal molecules bonds at peak loads are visulaized through SEM approach. Thus, the perfect inital and boundary conditions for computational strurtual analyses are found out. Ansys Workbench is an advancement tool, which is used in this work for composite generation and structural simulations. All the computational tests are effectively executed with the help of advanced coupling facility between different working environments. Finally, the numerical results are compared with experimental results and then suitable material is shortlsted based on high load withstand capacity. Additionally, the conventional analytical approaches are used to validate the flexural outcomes. Further, the advanced finite element analyses are expanded to advanced composites materials such as nanocomposites, shape memory alloys based composites, and sandwich composites. From the above all studies, the superior material is finalized based on the outcomes of this multi-inclusive investigations.