Search

Aiming at the problem caused by the fact that traditional on-board charging systems (OBC) usually use a single form of AC input, this research suggests a suitable isolated OBC for single-phase and three-phase power sources. It adopts a two-stage structure. The front stage can switch between different input modes. Using a single-phase AC input mode, the front stage is a totem pole bridgeless cascade Boost circuit for power factor correction (PFC). It can be switched to a three-phase six-switch PFC circuit in a three-phase AC input mode. A full-bridge LLC resonant converter serves as the rear stage. The system adopts a double closed-loop control strategy and a mixed control mode that consists of pulse width modulation (PWM) and pulse frequency modulation (PFM). In either the single-phase or three-phase AC input mode, the front stage PFC circuit can output a 700 V DC bus voltage, and keep the input current and input voltage in phase. It is possible to achieve soft switching in the rear stage resonant converter, and to output a wide range of voltage to charge the power battery. According to a theoretical analysis, a system simulation model is built and an experimental prototype of the OBC is produced. The accuracies of the simulation and the theoretical analysis are confirmed by experimental findings.

To address the challenge of acquiring detailed insulation status for long-length submarine cables, this article proposes a branch parameter identification method without manual thresholds, based on an extended Debye model (EDM) and the polarization depolarization current method. First, depolarization current is used to construct a Hankel matrix, and the singular values and incremental sequences of information entropy are acquired by step. Subsequently, the matrix pencil (MP) algorithm is employed to determine the branches with the highest amplitudes, which are successively removed from the original signal. The number of branches is confirmed by minimizing the variance of the information entropy increment sequences according to the characteristics of white noise. Simulation results demonstrate that the proposed method achieves high accuracy even at SNR =30 dB. Moreover, the proposed method remains accurate even when there are significant differences in branch amplitudes. Finally, the proposed method is applied to four in-service submarine cables, and the results are corroborated through comparisons with data obtained from the frequency domain reflection (FDR) method and temperature-measuring optical fiber; thus, validating the effectiveness of the proposed method.

Moisture at the insulation interface is the main cause for electrical breakdown and insulation failure of cable accessories. However, it is still unclear how the presence of moisture affects the discharge development and interfacial breakdown process. This paper clarifies the reasons for the breakdown failure of cable accessory insulation interfaces under the effect of moisture. First, the moisture and breakdown characteristics of faulty cable accessories in the field are presented. Second, the discharge evolution characteristics during the breakdown process of dry and wet interfaces are experimentally described. Then, the effect mechanism of moisture on the development of interfacial breakdown is explained by combining product analysis and electric field analysis. Finally, the proposed breakdown mechanism of insulation interface under the effect of moisture are verified through a field case. The experiment results show that the discharge develops in stages and generates gases during the breakdown of the insulation interface, and there exist multiple discrete arc discharges with random paths during the breakdown of the wet interface. The severe electric-field distortion and its dynamic movement caused by the gas bubble areas formed in the wet interface are the main reasons for the increase in randomness of interface discharge and the decrease in breakdown strength. Through current impulse detection and generated gas analysis, it is expected to provide new solutions for early fault detection for cable accessories.

Effectively controlling ice recrystallization (IR) during the frozen storage of food remains highly challenging. Inspired by the structural characteristics of antifreeze proteins in nature, silk fibroin (SF) derived from silk fibers has been developed. Through dual validation using the “splat” assay and “sucrose sandwich” assay, the IR inhibition activity of SF at various concentrations was confirmed, revealing that its regular alternating hydrophilic/hydrophobic domains endow SF with the potential to inhibit the axial growth of single ice crystal and significantly reduce the average maximum crystal size by approximately 67%. Additionally, the quality stability of frozen muscle foods treated with SF was comprehensively evaluated. In stark contrast to traditional commercial antifreeze agents (4% sucrose and 4% sorbitol), prepared steaks with the addition of 2% SF maintained rich juiciness and excellent color acceptability over a three-month frozen storage period. Thus, SF holds promise as a potential protective agent for frozen muscle foods, enhancing their quality during storage.

The oxygen evolution reaction (OER) performance of ruthenium-based oxides strongly correlates with the electronic structures of Ru. However, the widely adopted monometal doping method unidirectionally regulates only the electronic structures, often failing to balance the activity and stability. Here, we propose an “elastic electron transfer” strategy to achieve bidirectional optimization of the electronic structures of Sr, Cr codoped RuO2catalysts for acidic OER. The introduction of electron-withdrawing Sr intrinsically activates the Ru sites by increasing the oxidation state of Ru. Simultaneously, Cr acts as an electron buffer, donating electrons to Ru in the presence of Sr in the as-prepared catalysts and absorbing excess electrons from Sr leaching during the OER. Such a bidirectional regulation feature of Cr prevents overoxidation of Ru and maintains its high oxidation state during the OER. The optimal Ru3Cr1Sr0.175catalyst exhibits a low overpotential (214 mV @ 10 mA cm–2) and excellent stability (over 300 h).

The corrosion and ablation of the water-blocking buffer layer of high-voltage cables are accompanied by the production of various gases. By selecting characteristic gases and analyzing the corresponding relationship between their concentration and the corrosion/ablation stages, it is possible to evaluate the status of the buffer layer. This article analyzes the time-varying characteristics of gas concentration during the corrosion and ablation of water-blocking buffer layers, reveals the mechanisms of gas production, and proposes a method for evaluating the status of the buffer layer based on characteristic gas analysis. Results indicate that both the corrosion and ablation processes of the buffer layer produce H2, CH4, and CO2, but the ablation process generates additional gases including C2H6, C2H4, C2H2, and CO. The H2 concentration is positively correlated with the amplitude of applied voltage, water content, and surface pressure and saturates after a period of generation. On this basis, the mechanism of H2 production during the corrosion stage and the decomposition of polyethylene terephthalate (PET) accompanied by hydrocarbon gas production during the ablation stage of the buffer layer are investigated. By detecting the concentration of H2 in the cable, the overall damage level of the buffer layer can be determined. Additional detection on C2H6, C2H4, C2H2, and CO gases can determine whether the buffer layer is in a corrosion state. Finally, the effectiveness of evaluating the status of the buffer layer by characteristic gas analysis is proved on new and on-site 110-kV cables.

During operation within nuclear power plants (NPPs), the insulation of cross-linked polyethylene (XLPE) cables can progressively degrade due to radiation exposure, potentially resulting in insulation failure. This article explores the influence of various radiation doses on the aggregate structure and interfacial polarization characteristics of XLPE. Samples are subjected to $\gamma $ -ray irradiation at varying doses, followed by a series of tests to scrutinize alterations in aggregate structure and polarization characteristics. The study’s findings indicate that as the radiation dose escalates, XLPE experiences a 7.87% decline in crystallinity. Contrarily, both crystallite size and crystal plane spacing exhibit an increase exceeding 20%. These outcomes suggest that while the crystalline region of XLPE becomes less dense, it remains intact. The reduction in XLPE’s mechanical properties following the irradiation unfolds through three discernible stages. Among these, the rapid degradation primarily results from the disruption of molecular chains responsible for interconnecting lamellar structures, thereby heightening the likelihood of crystal slippage. In addition, oxidation and chain fragmentation yield an augmented presence of oxygen-containing groups with more substantial electric dipole moments, subsequently amplifying the interfacial polarization phenomenon.

A deep understanding of the main factors affecting the insulating properties of polymers is essential for the progress of insulation components in various applications, including electric vehicles, electronic devices, and information technology. In this study, we used polybutylene terephthalate (PBT) samples with varying degrees of crystallinity as a model material to investigate the influence of aggregation structure on its electrical performance. The results revealed that increasing the crystallinity of PBT led to a simultaneous increase in the surface flashover voltage. We identified the amorphous region as the weak link in the aggregation structure of PBT. Compared to the amorphous region, the crystalline region exhibited superior resistance to charged ion bombardment, a higher degree of compactness, higher bulk resistivity, and lower surface resistivity. A comprehensive understanding of the relationship between the aggregation structure and electrical performance of polymers is fundamental for developing practical high‐performance insulation components. This study provides valuable guidance for controlling the electrical performance of polymers with high‐performance insulating properties, and is thus of great significance to the electrical aging field.

Adopting noble metals on non-noble metals is an effective strategy to balance the cost and activity of electrocatalysts. Herein, a thorough analysis of the synergistic OER is conducted at the heterogeneous interface formed by Ir clusters and NiCo2O4based on DFT calculations. Specifically, the electrons spontaneously bring an egoccupancy of interfacial Ir close to unity after the absorbed O, providing more transferable electrons for the conversion of the absorbed O-intermediates. Besides, the diffuse distribution of electrons in the Ir 5dorbital fills the antibonding orbital after O is absorbed, avoiding the desorption difficulties caused by the stronger Ir–O bonds. The electrons transfer from Ir to Co atoms at the heterogeneous interface and fill the Co 3dband near the Fermi level, stimulating the interfacial Co to participate in the direct O–O coupling (DOOC) pathway. Experimentally, the ultrathin-modulated NiCo2O4nanosheets are used to support Ir clusters (Ircluster-E-NiCo2O4) by the electrodeposition method. The as-synthesized Ircluster-E-NiCo2O4catalyst achieves a current density of 10 mA cm–2at an ultralow overpotential of 238 mV and works steadily for 100 h under a high current of 100 mA cm–2, benefiting from the efficient DOOC pathway during the OER.

The study evaluated the stability of an oligopeptide (Lys-Arg-Gln-Lys-Tyr-Asp, KRQKYD) and its transport mechanism by simulating gastrointestinal digestion and a model of human intestinal Caco-2 monolayer cells in vitro. In this study, the effects of environmental factors (temperature, pH and NaCl concentration) and simulated gastrointestinal digestion on the stability of KRQKYD were evaluated by indicators of the levels of alanine transaminase (ALT), aspartate transaminase (AST) and malondialdehyde (MDA) in an alcohol-induced hepatocyte injury model. The results showed that KRQKYD still maintained satisfactory hepatocyte-protective activity after treatment with different temperatures (20−80 °C), pH (3.0−9.0), NaCl concentration (1 %−7 %) and simulated gastrointestinal digestion, which indicated that KRQKYD showed good stability to environmental factors and simulated gastrointestinal digestion. Furthermore, the intact KRQKYD could be absorbed in a model of Caco-2 monolayer cells with a Pappvalue of (9.70 ± 0.53) × 10−7cm/s. Pretreatment with an energy inhibitor (sodium azide), a competitive peptide transporter inhibitor (Gly-Pro) and a transcytosis inhibitor wortmannin did not decrease the level of transepithelial KRQKYD transport, indicating that the transport mechanism of KRQKYD was not associated with energy dependent, vector mediated and endocytosis. The tight junction disruptor cytochalasin D significantly increased the level of transepithelial KRQKYD transport (P< 0.05), suggesting that intact KRQKYD was absorbed by paracellular transport.

In the context of the increasing scale of bridges and the increasing service life of bridges, it is very important to carry out efficient, accurate and intelligent bridge operation and maintenance. In recent years, advanced equipment, technology and intelligent algorithms have developed rapidly. It is necessary to apply advanced equipment and algorithms to bridge operation and maintenance business to facilitate the digitalization and intelligence of bridge operation and maintenance. To grasp the research progress on the bridge intelligent operation and maintenance, this paper summarizes the research progress in recent years from the aspects of intelligent detection equipment and technology, intelligent monitoring equipment and technology, intelligent data analysis, intelligent evaluation and early warning, and intelligent repair and maintenance. According to the review, more and more smart devices have been used to replace human beings to detect dangerous and hidden bridge components. At the same time, image processing, radar and other technologies have been used to analyze component damage more objectively and quantitatively. To solve the shortcomings of traditional sensors such as short life and low robustness, more non-contact measurement methods have been proposed. Scholars have proposed various intelligent algorithms to process the massive amount of bridge health monitoring data to improve the quality of the data. To achieve the rapid perception of bridge status and timely early warning of structural abnormalities, different from traditional theoretical calculations, scholars have tried to use data-driven methods to intelligently evaluate and early warning of bridge structural status. In terms of intelligent repair and maintenance, more intelligent algorithms have been used to optimize structural maintenance strategies and determine the best maintenance time by integrating multi-source heterogeneous data. All these provide strong support for the automation, digitization and intelligence of bridge operation and maintenance.

AC–DC converter has the advantages of high power density, stable output, easy to control, etc., and is widely used in many industrial fields. In this paper, the two-stage isolated AC–DC converter is the object of study, and the converter consists of a front-stage Boost PFC converter and a rear-pole LLC resonant converter. The small signal perturbation analysis method and the extended function method are used to construct the equivalent mathematical models of the PFC converter and the LLC resonant converter, and analyze their input and output characteristics and frequency response characteristics. The control strategy based on particle swarm algorithm optimized PI is proposed, and the PSO algorithm optimized PI loop control system is designed on this basis. Simulation software is used to compare the performance indexes of PSO optimized PI control method, and an experimental platform is built to verify it. The results show that the isolated converter can not only meet the requirement of sinusoidal input current on the grid side, but also realize the electrical isolation and ensure the output voltage stability. The PSO algorithm is also introduced to automatically adjust the PI parameters according to the operating state of the converter, so that a faster regulation speed can be obtained during the startup of the converter and the sudden change of the load, and the system as a whole has a better dynamic characteristic and steady state characteristic, and the simulation analysis and experimental sessions verify the correctness of the circuit design and the effectiveness of the control strategy.

The stacked structure thin film transistors (TFT) has caused the widespread attention to achieve high mobility and reliability simultaneously. To ensure the stacked structure TFT application to mass production, it is critical to reduce the number of mask‐count. In this paper, 8‐mask‐count stacked TFT‐array process using the first semiconductor layer overlapped with the source and drain layer directly, which is the first layer on the glass substrate, is studied. By adopting this novel process, the device mobility is 25.4 cm2/Vs, which is more than twice that of conventional top‐gate self‐aligned a‐IGZO device. Besides, the ΔVth under the positive bias stress of 30V and negative bias temperature illumination stress of ‐30V for 1 h is +0.41V and ‐0.13V, respectively, achieving the stability to the level of a‐IGZO TFTs.

ABSTRACTPARP (poly(ADP-ribose) polymerase) inhibitors have demonstrated promising clinical activity in multiple homologous recombination (HR) deficiency tumors. However, glioblastoma (GBM) patients have obtained little benefit from PARP inhibitors alone. PARP inhibition shows considerable promise when used together with other therapeutic agents. Thus, novel combination therapies may enhance PARP inhibitor efficacy and overcome resistance mechanisms in GBM. Herein, we report that concurrent treatment with the PARP inhibitor olaparib and XPO1 (exportin 1) inhibitor KPT330 showed synergetic anticancer effects on GBM cells. Mechanistically, in the nucleus, we show that KPT330 induced the nuclear retention of SQSTM1 (sequestosome 1) and further inhibited the ubiquitination of the DNA repair signal H2AX (H2A.X variant histone) mediated by olaparib, thus inhibiting DNA damage response and repair in GBM. Moreover, in the cytoplasm, KPT330 blocked the activation of autophagic flux caused by olaparib reagent, downregulated the expression of LAPTM4B (lysosomal protein transmembrane 4 beta) and induced the dysfunction of lysosomes, thereby preventing the degradation of autophagosome, and ultimately promoted cell death. Furthermore, in the LN229-luc mouse orthotopic xenograft model, combination treatment showed significantly increased antitumor efficacy compared to each monotherapy. These data illustrate the application prospects of combined oral administration of olaparib and KPT330 for the treatment of glioblastoma.AbbreviationsAO: acridine orange; ATM: ATM serine/threonine kinase; CHEK1: checkpoint kinase 1; CHEK2: checkpoint kinase 2; CI: combination index; DMSO: dimethyl sulfoxide; DSBs: double-strand breaks; GBM: glioblastoma; HR: homologous recombination; H2AX: H2A.X variant histone; IHC: immunohistochemistry; LAPTM4B: lysosomal protein transmembrane 4 beta; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PARP: poly(ADP-ribose) polymerase; RAD51: RAD51 recombinase; SQSTM1: sequestosome 1; SSBs: single-strand breaks; RNF168: ring finger protein 168; XPO1: exportin 1.

This article presents a novel polarization and depolarization current (PDC) system and calculation process of $\text {tan}\,\delta $ for long-length submarine cables. The effect of the current limiting resistor on $\text {tan}\,\delta $ was analyzed by the Debye model and found to be significant as the cable length increases. To eliminate this effect, a revised process was proposed for making the PDC method suitable for the insulation diagnosis of high-voltage (HV) submarine cables. Simulation results revealed that a sampling interval of 0.04 s is appropriate for $\text {tan}\,\delta $ calculation at 0.1 Hz. We also adjusted the picoammeter to the HV side compared with the traditional PDC test system. Finally, we carried out PDC tests on four in-service cables, which clearly show their insulation condition and verify the validity of the PDC method for insulation diagnosis of HV submarine cables.

Frequency-domain reflection (FDR) stands as an effective technique for localizing cable defects. To address the issue of the significant influence of window functions and interference problems on the defect location accuracy of traditional FDR, this article proposes a cable defect location method based on multiresolution singular value decomposition (MRSVD) and stochastic subspace identification (SSI). Notably, this method eliminates the need for window function selection and effectively filters out interference signal subspaces, thereby enhancing defect location accuracy. First, the reflection coefficient spectrum (RCS) of the power cable is studied by using transmission line theory, which confirms that the RCS can be used to locate cable defects. Then, the principles of MRSVD, SSI, and density-based spatial clustering of applications with noise (DBSCAN) algorithm are introduced. By estimating the parameters of complex exponential decay oscillation functions in the RCS and removing relevant interference, a new cable fault location spectrum is proposed. Finally, the proposed method is applied to fault location in a 200-m simulated cable model and a 500-m real cable. The results demonstrate that the proposed fault location spectrum accurately locates faults in the cable with fewer interference problems, significantly improving the accuracy of the FDR method in locating cable defects.

Due to the great diversity of loads in low-voltage systems, the detection based on characteristic parameters of the current often confuses series arc faults (SAFs) with complex loads. To address this issue, an SAF detection method is proposed based on the inevitable dc component. First, comprehensive analyses, as well as observations, are made on the electrode-arcing-current asymmetry (EACA) to demonstrate that an inevitable dc component is inevitably induced during an SAF. Then, a dc-related dominated index and several asymmetry-related supplemental indices are gathered to form a feature set with strong generality. Afterward, a specific scheme is developed based on the uni-period state evaluation and the multiperiod fault judgment to reduce the false detection, where the eXtreme gradient boosting (XGBoost) algorithm is employed as a classifier. After that, experiments are made to verify the proposed method’s validity. Finally, with monitored samples used to construct an ultrageneral testing set, simulations are conducted to prove its superiority in generality.

Accurate detection of tumor biomarkers in blood is crucial for diagnosing and treating tumor disease. In this study, a metal enzyme-linked immunosorbent assay (MeLISA) was fabricated for the ultrasensitive and naked-eye detection of tumor biomarker alpha-fetoprotein (AFP) in clinical serum samples. Herein, novel copper metal–organic frameworks and gold platinum nanoparticle composites (Cu-MOFs@AuPtNPs) were synthesized for the first time by an in situmethod, which showed an enormous specific surface area and excellent peroxidase (POx) mimicking properties. Cu-MOFs@AuPtNPs linked with antibodies targeting AFP served as a signal nanoprobe to amplify the detection signal. Additionally, the specificity of MeLISA was significantly enhanced through a conventional antigen–antibody reaction and efficient blocking of non-specific sites with BSA. Under optimal conditions, the sandwich-type MeLISA exhibited a wide range from 0.001 to 1000 ng mL−1(R2= 0.997) and a low detection limit of 0.86 pg mL−1(S/N = 3) with acceptable stability, selectivity, and reproducibility. It is noteworthy that the suggested MeLISA performed exceptionally well in detecting clinical serum samples, which were visible to the naked eye and did not require complex platforms. To sum up, the innovative MeLISA based on Cu-MOFs@AuPtNPs provides an alternative method for early cancer diagnosis, particularly in economically backward areas where simple diagnostic apparatus is extremely desirable.

The time-frequency-domain reflectometry (TFDR) method has found its extensive application in location detection of power cable defects. Traditionally, it adopts Wigner-Ville distribution (WVD) to analyze time-frequency of cable signals, resulting in numerous cross terms in the location spectrum of defects, thereby inducing defect misjudgment. To address it, this article proposes a synchrosqueezing transform (SST)-based method to accurately locate the cable defects, which takes SST as the new kernel function for time-frequency analysis instead of WVD. Moreover, the modulation criteria of the test signal are defined to effectively and flexibly test the power cables with different lengths. Due to the characteristics of compression and rearrangement of the time-frequency spectrogram, SST suppresses the cross-term interference, thus improving the spectral peak resolution of locating the cable defects. Finally, the feasibility and effectiveness of the SST-based method are verified by building a simulation model of power cable and field tests, respectively.

Highly dispersed iron oxide has been rapidly and precisely loaded onto the Zr6nodes of a stable metal–organic framework (MOF), UiO-66, viaan atomic layer deposition (ALD) process to form novel Fe–O–Zr metal cluster sites. By varying the number of ALD cycles, three Fe-decorated UiO-66 materials (denoted as Fe@UiO-66-xc, x= 1, 2, 3) were synthesized. A series of photoelectrochemical measurements, including UV-vis diffuse reflectance spectroscopy, state photoluminescence spectroscopy, and transient photocurrent response, indicate that Fe@UiO-66-1c prepared by a single deposition cycle exhibits improved visible-light absorption ability and enhanced photo-generated charge carrier separation efficiency due to metal-to-metal charge transfer. Moreover, Fe@UiO-66-1c shows excellent photocatalytic activity for aerobic oxidation of N-aryl tetrahydroisoquinolines. This material also exhibits good stability and is capable of cycling the reaction six times and maintaining the crystal structure with a low leaching rate of iron ions. The study explores the application of the atomic layer deposition process in the preparation of advanced photocatalytic materials.

In this paper, a two-stage on-board charging system based on IPOP LLC resonant converter is proposed. The front stage uses a three-phase VSR, which can realize the PFC function and provide a stable DC voltage to the rear stage. The rear stage adopts IPOP LLC resonant converter, low output current ripple, output a wide range of DC voltage, the soft switch over the full load range, and the system efficiency is high. Voltage current double closed-loop control is used for the front stage converter and outputs stable DC voltage. The rear stage converter adopts variable frequency voltage regulation control and phase shift current sharing control, which reduces the volume of the filter capacitor and improves the overall performance and power density of the on-board charging system. A 3.3 kW system simulation model is built to prove the correctness of the theoretical analysis and parameter design method.

Graph Neural Networks (GNNs) are vulnerable to data poisoning attacks, which will generate a poisoned graph as the input to the GNN models. We present FocusedCleaner as a poisoned graph sanitizer to effectively identify the poison injected by attackers. Specifically, FocusedCleaner provides a sanitation framework consisting of two modules: bi-level structural learning and victim node detection. In particular, the structural learning module will reverse the attack process to steadily sanitize the graph while the detection module provides the “focus” – a narrowed and more accurate search region – to structural learning. These two modules will operate in iterations and reinforce each other to sanitize a poisoned graph step by step. As an important application, we show that the adversarial robustness of GNNs trained over the sanitized graph for the node classification task is significantly improved. Extensive experiments demonstrate that FocusedCleaner outperforms the state-of-the-art baselines both on poisoned graph sanitation and improving robustness.

Multiple line outages that occur together show a variety of spatial patterns in the power transmission network. Some of these spatial patterns form network contingency motifs, which we define as the patterns of multiple outages that occur much more frequently than multiple outages chosen randomly from the network. We show that choosing N-k contingencies from these commonly occurring contingency motifs accounts for most of the probability of multiple initiating line outages. This result is demonstrated using historical outage data for two transmission systems. It enables N-k contingency lists that are much more efficient in accounting for the likely multiple initiating outages than exhaustive listing or random selection. The N-k contingency lists constructed from motifs can improve risk estimation in cascading outage simulations and help to confirm utility contingency selection.

Cable joints are the weak links in cable lines and prone to frequent failures. A decreased breakdown strength (BDS) of composite insulation composed of silicone rubber (SiR) and crosslinked polyethylene (XLPE) is a main reason of these failures. This study proposes a prematurely swelling (PS) method where monomers with crosslinkable groups are first permeated within SiR and then interconnected using a crosslinker at the interface. To assess the bonding strength at this junction, the authors employed an interfacial BDS test to evaluate and study interfacial BDS performance, along with optical microscopy (OM) and polarization–depolarization current (PDC) devices. By applying a crosslinked coating that penetrates the interface, significant improvements in interfacial electrical performance were achieved. The results indicate that this practical and straightforward approach greatly diminishes interface polarization, enhancing the sample’s interfacial BDS performance by 124% compared to uncoated samples. Both the insulation performance and the mechanical performance were significantly enhanced.

A two-stage bidirectional DC/DC converter for electric vehicles is proposed in this paper. The converter has the features of bidirectional power flow and a wide input voltage range, which can realise output voltage stability. The front stage adopts a bidirectional CLLLC resonant converter with good characteristics of soft switching in both forward and reverse directions and adopts open-loop fixed frequency control to realise efficient power transmission. The rear stage adopts an interleaved parallel bidirectional buck/boost converter to reduce the current ripple and increase the transmission power and adopts the duty cycle secondary distribution method to achieve current equalisation and regulate the output voltage based on the voltage and current double closed-loop control. Bidirectional DC/DC converter's principle analysis and parameter calculation are completed, and the correctness and feasibility of the theoretical analysis are verified by simulation results.