A loosely coupled transformer structure with anti‑offset capability based on uniform magnetic field

Yufei Zhou,Yu Yan,Dongdong Li,Yang Luo 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.8

Inductively coupled power transfer (ICPT) technology is widely used in wireless charging systems because of its safety, convenience, and reliability. However, the loosely coupled transformer, the most significant part of an ICPT system, has misalignment conditions in practical applications, which have a negative effect on the efficiency of the ICPT system. This paper proposes a new loosely coupled transformer structure, where the primary side is composed of two hybrid winding D coils and a solenoid coil, and the secondary side consists of a D coil and a solenoid coil, which is referred to as a “double-D solenoid coil–D solenoid coil” (DDS–DS). The hybrid winding D coils, which are composed of multiple layers of windings, can construct a uniform magnetic field at the operational air gap. The S coil is added to the primary and secondary sides of the transformer to build a mutually perpendicular energy channel with the D coils, which compensates the coupling valley without introducing cross-coupling. Therefore, the DDS–DS structure can construct a wide uniform magnetic field and effectively improve the anti-offset capability of the system. Finally, an experimental prototype is established, and the effective charging width reaches 78% of the transmitting coil's width with a 50 mm operational air gap, which verifies that the structure has good anti-offset capability.

The Misaligned Coupling Improvement of Loosely Coupled Transformer with Multi-Receivers for IPT System

Zhou Yufei,Li Dongdong,Wang Yingying,Hong Feng,He Xueru,Liu Shuai,Sun Xiangfeng 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4

The low coupling coeffi cient (CC) of loosely coupled transformer (LCT) can greatly aff ect the effi ciency of inductive power transfer (IPT) system. In order to improve the coupling coeffi cient and misaligned tolerance of LCT, this paper proposes a transformer structure with multiple independent small receiving coils. Respectively in ideal alignment and misalignment mode, the distribution of magnetic force lines and the variation law of CC of independent small receiving coils are analyzed. According to the relationship between the coupling coeffi cient matrix and the mutual inductance, the eff ective coupling coeffi cient (ECC) is deduced, and its variation with the misalignment distance is also analyzed. The ECC of the LCT with multi-receiver (MR) structure is almost unchanged. For the multiple loads' characteristics of receivers, by adopting S/P compensated topology, a 500 W outputs prototype of IPT system is established. The experimental results show that the ECC is improved and tolerance performance to lateral and rotational misalignment of proposed MR structure has good characteristics.

Design Methodology of LLC Resonant Converters for Single-stage Power Factor Correction Application

Zhou Yufei,Liu Shuai,Ren Jiaqi,Wu Qibin,Hong Feng,Shen Ang,Xu Wei 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5

This paper proposes a new design methodology for LLC resonant converter with single-stage power factor correction (PFC) function. By designing the achievable gain of resonant tank at a certain point of the AC voltage higher than the required gain, its gain will satisfy the requirement of the whole AC line voltage cycle and lead to a good single-stage PFC design. By adjusting switching frequency and changing voltage gain along with the AC voltage, the converter can realize PFC with high effi ciency. The proposed converter inherits the advantages of the traditional LLC resonant converter, including soft switching of power switches across the whole load range, buck-boost power conversion ability which benefi ts the optimization of the down-stream DC-DC converter. Gain characteristic and design consideration for PFC purpose are analyzed in detail. Experimental results are presented to show its validity and feasibility.

Full-bridge resonant converter with hybrid control for wide input voltage range applications

Zhou, Yufei,He, Xin'an,Sheng, Lunhui The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

This paper proposes a hybrid control strategy for a full-bridge resonant converter. In the applications with a wide input voltage, a resonant converter with variable frequency control (VFC) has to modulate the converter operating in a wide switching frequency range to satisfy gain requirements, which results in some problems such as difficulty in optimizing the design of magnetic components, increased power loss and deteriorated electromagnetic interference. By use of VFC, primary-side phase shift control and secondary-side phase shift control, the frequency variable range can be greatly reduced and the conversion efficiency can be increased, which make the converter appropriate for a wide input voltage range. With this hybrid control strategy, the converter can automatically convert to the corresponding control mode according to variations of the input voltage and load, which has a good transient performance. The working principle, gain characteristics and design considerations of a hybrid controlled CLL resonant converter are introduced in detail. Experimental results are shown to demonstrate its validity and feasibility.

Efficiency optimization of variable‑frequency controlled power factor correction converters

Yufei Zhou,Xueru He,Shuai Liu,Feng Hong,Jiaqi Ren,Dongdong Li 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.6

More attention is being paid to energy effi ciency and harmonic reduction. Thus, power factor correction (PFC) is widely used in power supplies. However, under the condition of light load, the single-stage LLC PFC converter has the problems of low effi ciency and output voltage misaligned, such as other PFC topologies. Aiming at the problems that occur under light load conditions, this paper proposes a least-pulse delta (Δ)–sigma (Σ) modulation (LPΔ–Σ modulation). Under diff erent loads, the system can automatically select the appropriate pulse density and reduce the energy transfer to the secondary side by uniformly turning off the driving signals, which stabilizes the output voltage and improves the system effi ciency. Meanwhile, LPΔ–Σ modulation is more benefi cial for improving the PF value when compared with the burst mode under light load conditions. Experimental results show that LPΔ–Σ modulation based on the traditional dual-loop control can eff ectively stabilize the output voltage and improve effi ciency. When compared with the existing burst control scheme, it reduces the output voltage ripple and eff ectively improves the PF.

Feasibility of a Clinical-Radiomics Model to Predict the Outcomes of Acute Ischemic Stroke

Zhou Yiran,Wu Di,Yan Su,Xie Yan,Zhang Shun,Lv Wenzhi,Qin Yuanyuan,Liu Yufei,Liu Chengxia,Lu Jun,Li Jia,Zhu Hongquan,Liu Weiyin Vivian,Liu Huan,Zhang Guiling,Zhu Wenzhen 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.8

Objective: To develop a model incorporating radiomic features and clinical factors to accurately predict acute ischemic stroke (AIS) outcomes. Materials and Methods: Data from 522 AIS patients (382 male [73.2%]; mean age ± standard deviation, 58.9 ± 11.5 years) were randomly divided into the training (n = 311) and validation cohorts (n = 211). According to the modified Rankin Scale (mRS) at 6 months after hospital discharge, prognosis was dichotomized into good (mRS ≤ 2) and poor (mRS > 2); 1310 radiomics features were extracted from diffusion-weighted imaging and apparent diffusion coefficient maps. The minimum redundancy maximum relevance algorithm and the least absolute shrinkage and selection operator logistic regression method were implemented to select the features and establish a radiomics model. Univariable and multivariable logistic regression analyses were performed to identify the clinical factors and construct a clinical model. Ultimately, a multivariable logistic regression analysis incorporating independent clinical factors and radiomics score was implemented to establish the final combined prediction model using a backward step-down selection procedure, and a clinical-radiomics nomogram was developed. The models were evaluated using calibration, receiver operating characteristic (ROC), and decision curve analyses. Results: Age, sex, stroke history, diabetes, baseline mRS, baseline National Institutes of Health Stroke Scale score, and radiomics score were independent predictors of AIS outcomes. The area under the ROC curve of the clinical-radiomics model was 0.868 (95% confidence interval, 0.825–0.910) in the training cohort and 0.890 (0.844–0.936) in the validation cohort, which was significantly larger than that of the clinical or radiomics models. The clinical radiomics nomogram was well calibrated (p > 0.05). The decision curve analysis indicated its clinical usefulness. Conclusion: The clinical-radiomics model outperformed individual clinical or radiomics models and achieved satisfactory performance in predicting AIS outcome

Enhanced Antibacterial Effect of Polypyrazole-Graphene Oxide Composite

Bin Yang,Yufei Wang,Longqiang Xiao,Xiaowen Hu,Guofu Zhou 한국고분자학회 2017 Macromolecular Research Vol.25 No.1

Besides excellent physical performances, graphene oxide (GO) has been widely acknowledged as a potential antibacterial material. Chemical modification of GO was taken out with polypyrazole by facile amidation in the presence of dicyclohexylcarbodiimide (DCC) and then generated polypyrazole-graphene oxide (FGO) nanohybrid. FGO nanohybrid showed smooth and multilayer structures by scanning electron microscopy. The value of static water contact angle of FGO is 103o, suggesting FGO was a hydrophobic material. Thermo gravimetric analysis of FGO showed a 65% mass loss up 50 to 600 oC, suggesting that FGO is a thermal stability material. Inactivation efficiency test of nominal Escherichia coli cells showed that the viability greatly decreased to 7% after 4 h incubation with FGO under 37 oC, indicating an outstanding antibacterial ability of FGO much better than that of polypyrazole and GO.

Parallel Gene Loss and Acquisition Among Strains of Different Brucella Species and Biovars

Zhijun Zhong,Yufei Wang,Jie Xu,Yanfen Chen,Yuehua Ke,Xiaoyan Zhou,Xitong Yuan,Dongsheng Zhou,Yi Yang,Ruifu Yang,Guangneng Peng,Hai Jiang,Jing Yuan,Hongbin Song,Buyun Cui,Liuyu Huang,Zeliang Chen 한국미생물학회 2012 The journal of microbiology Vol.50 No.4

The genus Brucella is divided into six species; of these, B. melitensis and B. abortus are pathogenic to humans, and B. ovis and B. neotomae are nonpathogenic to humans. The definition of gene loss and acquisition is essential for understanding Brucella’s ecology, evolutionary history, and host relationships. A DNA microarray containing unique genes of B. melitensis Type strain 16MT and B. abortus 9-941 was constructed and used to determine the gene contents of the representative strains of Brucella. Phylogenetic relationships were inferred from sequences of housekeeping genes. Gene loss and acquisition of different Brucella species were inferred. A total of 214 genes were found to be differentially distributed,and 173 of them were clustered into 15 genomic islands (GIs). Evidence of horizontal gene transfer was observed for 10GIs. Phylogenetic analysis indicated that the 19 strains formed five clades, and some of the GIs had been lost or acquired independently among the different lineages. The derivation of Brucella lineages is concomitant with the parallel loss or acquisition of GIs, indicating a complex interaction between various Brucella species and hosts.

Synthesis and Characterization of Novel Homopolyimides Containing Pyridine and Morpholine Groups for Gas Separation by Molecular Design and Simulation

Jing Ni,Jinling Li,Bowen Wei,Yufei Shi,Chanjuan Liu,Li Zhou,Xiaohua Huang 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

A novel 4-(4-(1-morpholinyl)phenyl)-2,6-bis(4-aminophenyl)pyridine (MPAP) diamine monomer was designed and synthesized by introducing non-coplanar morpholine groups and pyridine heterocyclic structures. By one-step homopolymerization of MPAP and different dianhydrides, three new polyimides (PIs) were synthesized. The obtained PIs are easily soluble in common organic solvents, such as NMP, DMAc, and CHCl3. Simultaneously, PIs have high thermal performance (Tg = 277–377 °C) and excellent thermal stability (Td,5% and Td,10% are 460–487 °C and 525–545 °C). They also have good optical transparency (λcutoff = 380–394 nm, λ80% = 469–482 nm) and hydrophobicity (θ = 87–92º). The free volume and gas adsorption are simulated by Materials Studio 2019 software, and the simulation results match the gas separation performance obtained from experimental test. They show good gas separation performance as well, especially PI-3 for the CO2/N2 (up to 23.26), O2/N2 (up to 5.02) and He/N2 (up to 59.78) separations, which is close to the 1991 Robeson upper bound.

Preliminary study of genome-wide association identified novel susceptibility genes for thyroid-related hormones in Chinese population

Huang Liang,Bai Fenghua,Zhang Yutian,Zhang Shanshan,Jin Tianbo,Wei Xingwei,Zhou Xiaoli,Lin Mei,Xie Yufei,He Chanyi,Lin Qi,Xie Tian,Ding Yipeng 한국유전학회 2022 Genes & Genomics Vol.44 No.8

Background: Thyroid hormones are critical regulators of metabolism, development and growth in mammals. However, the genetic association of thyroid-related hormones in the Chinese Han population is not fully understood. Objective: We aimed to identify the genetic loci associated with circulating thyroid-related hormones concentrations in the healthy Chinese Han population. Methods: Genotyping was performed in 124 individuals using Applied Biosystems™ Axiom™ PMDA, and 796,288 single nucleotide polymorphisms (SNPs) were available for the GWAS analysis. For replication, eleven SNPs were selected as candidate loci for genotyping by Agena MassARRAY platform in additional samples (313 subjects). The values of p < 5 × 10- 6 suggest a suggestively significant genome-wide association with circulating thyroid-related hormones concentrations. Results: We identified that rs11178277 (PTPRB, p = 4.88 × 10- 07) and rs7320337 (LMO7DN-KCTD12, p = 1.22 × 10- 06) were associated with serum FT3 level. Three SNPs (rs4850041 in LOC105373394-LINC01249: p = 3.55 × 10- 06, rs6867291 in LINC02208: p = 2.40 × 10- 06 and rs79508321 in WWOX: p = 3.35 × 10- 06) were related to circulating T3 level. Rs12474167 (LOC105373394-LINC01249, p = 1.65 × 10- 06) and rs1864553 (IWS1, p = 2.00 × 10- 06) were associated with circulating T4 concentration. The association with TGA concentration was for rs17163542 in DISP1 (p = 3.46 × 10- 06) and rs12601151 in NOG-C17orf67 (p = 2.72 × 10- 07). Two genome-level significant SNPs (rs2114707 in LINC01314, p = 1.69 × 10- 06 and rs12601151, p = 1.41 × 10- 07) associated with serum TMA concentration were identified. Moreover, rs6083269 (CST1-CST2, p = 3.36 × 10- 06) was a significant locus for circulating TSH level. In replication, rs12601151 in NOG-C17orf67 was still associated with serum TGA level (p = 0.012). Conclusions: The GWAS reported 11 new suggestively significant loci associated with circulating thyroid-related hormones levels among the Chinese Han population. These findings represented suggestively biological candidates for circulating thyroid-related hormones levels and provided new insights into the mechanisms of regulating serum TGA concentration.