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Pattern recognition receptors (PRRs) sense ligands in pattern-triggered immunity (PTI). Plant PRRs include numerous receptor-like proteins (RLPs), but many RLPs remain functionally uncharacterized. Here, we examine an Arabidopsis thaliana RLP, RLP53, which positively regulates immune signaling. Our forward genetic screen for suppressors of enhanced disease resistance1 (edr1) identified a point mutation in RLP53 that fully suppresses disease resistance and mildew-induced cell death in edr1 mutants. The rlp53 mutants showed enhanced susceptibility to virulent pathogens, including fungi, oomycetes, and bacteria, indicating that RLP53 is important for plant immunity. The ectodomain of RLP53 contains leucine-rich repeat (LRR) motifs. RLP53 constitutively associates with the LRR receptor-like kinase SUPPRESSOR OF BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE (BAK1)-INTERACTING RECEPTOR KINASE1 (SOBIR1) and interacts with the co-receptor BAK1 in a pathogen-induced manner. The double mutation sobir1-12 bak1-5 suppresses edr1-mediated disease resistance, suggesting that EDR1 negatively regulates PTI modulated by the RLP53-SOBIR1-BAK1 complex. Moreover, the glycosylphosphatidylinositol (GPI)-anchored protein LORELEI-LIKE GPI-ANCHORED PROTEIN1 (LLG1) interacts with RLP53 and mediates RLP53 accumulation in the plasma membrane. We thus uncovered the role of a novel RLP and its associated immune complex in plant defense responses and revealed a potential new mechanism underlying regulation of RLP immune function by a GPI-anchored protein.

The resting metabolic rate (RMR) predictive equations suitable for Tibetan adolescents in Tibet, China, were developed to provide a reference for their reasonable energy intake.We measured RMR by indirect calorimetry and body composition by bioelectrical impedance analysis in 325 Tibetan adolescents aged 13-18 years in Tibet, China. Stepwise regression analysis was used to develop the predictive equations. Pearson correlation analysis, paired sample t test, bias rate, concordance correlation coefficient (CCC) and Bland-Altman were used to verify the validity of the predictive equations.The RThe existing predictive equations cannot accurately predict the RMR of Tibetan adolescents in Tibet, China. In this study, the age segmentation predictive equations with age, sex, and fat free mass (FFM) as independent variables were more valid. The predictive equations were as follows: RMR (kcal/day) = 50.1 × FFM (kg) - 202.8 × Sex (F: 0; M: 1) - 72.1 × Age + 930.3, 13-15 years; RMR (kcal/day) = 58.4 × FFM (kg) - 441.1 × Sex (F: 0; M: 1) - 702.2, 16-18 years.

This article offers a detailed analysis of pseudo-phase transitions of Ising and Baxter-Wu models in two-dimensional finite-size lattices. We carry out Wang Landau sampling to obtain the density of states. Using microcanonical inflection point analysis with microcanonical entropy, we obtain the order of the psuedo-phase transitions in the models. The microcanonical analysis results of the second-order transition for the Ising model and the first-order transition for the Baxter-Wu model are consistent with the traditional canonical results. In addition, the third-order transitions are found in both models, implying the universality of higher-order phase transitions., 13 pages, 5 figures

A series of novel anthranilic diamides analogues(9a–9t) containing trifluoroethoxyl pyrazole moiety was designed and synthesized and their insecticidal bioactivities against Mythimna separata(Walker, M. separata) and Plutellaxylostella (P. xylostella) were evaluated. The structures of the title compounds were confirmed by 1H NMR, 13C NMR and HRMS. Preliminary insecticidal activities showed that some of the title compounds possessed good to excellent bioactivities towards M. separata and P. xylostella. Compounds 9c and 9t exhibited 100% mortality rate against M. separate at 0.2 mg/L. For the P. xylostella, the synthesized compounds(9c–9e, 9i and 9o) showed 70%, 80%, 75 %, 65% and 60% insecticidal activities at 1×10−6 mg/L, respectively, higher than that of chlorantraniliprole(0). Based on excellent insecticidal activities, the mode of the action was tested by the calcium-imaging technique, the results of which demonstrated that the novel compounds shared the same target with chlorantraniliprole. The binding pose of the most active compound 9t in RyRs of P. xylostella was predicted by molecular docking, which showed that compound 9t interacted with the residues Glu140(A) and His147(A) via hydrogen bond.

Background: Since there is little knowledge about the 24-hour movement behaviors of Chinese children and adolescents, the purposes of this study were to investigate the proportion of Chinese children and adolescents meeting the 24-Hour Movement Guidelines and to further evaluate its relationship with overweight and obesity. Methods: A total of 440 children and adolescents aged 7–18 years from 7 cities in China were selected to measure physical activity using accelerometers, and sleep (SLP) and screen time (ST) using questionnaires. The data were analyzed with the independent T-test, Mann–Whitney U test, Cox–Stuart test, chi-square test, and logistic regression. Results: The proportion of Chinese children and adolescents meeting the overall 24-Hour Movement Guidelines was 7.3%. Boys (11.8%) were higher than girls (3.4%) (p < 0.001) and showed a downward trend with age (Ptrend = 0.03). The rates of overweight and obesity among children and adolescents who met the ST, MVPA + ST, ST + SLP, and MVPA + SLP + ST guidelines were 39%, 15%, and 36%, and 25% did not meet any guidelines. The rates of overweight and obesity among those who met 1, 2, and 3 guidelines were lower than the rate among those who did not meet any guidelines (odds ratio (OR) = 0.51, 95% confidence interval (CI): 0.22–1.17; OR = 0.32, 95% CI: 0.13–0.77; OR = 0.23, 95% CI: 0.07–0.81) and showed a decreasing trend (Ptrend = 0.006). Conclusions: The proportion of Chinese children and adolescents meeting the overall 24-Hour Movement Guidelines was low. The rate of overweight and obesity among children and adolescents who met the overall 24-Hour Movement Guidelines was the lowest compared with the rates among those who met any one or two. There was a dose–response relationship between the number of guidelines met and the overweight and obesity rate.

Cardiorespiratory fitness (CRF) is a core element of healthy physical fitness. Foreign attention to CRF in adolescents at different altitudes is high, while less research has been conducted on Chinese adolescents. In order to compare the CRF of Chinese Tibetan adolescents with their Han counterparts born and raised at high altitude and Chinese Han adolescents at sea level. A total of 2748 participants, including Chinese Tibetan adolescents, Chinese Han adolescents born and raised at high altitudes, and Chinese Han adolescents at sea level aged 12–18 years old, were obtained using convenience sampling and random cluster sampling. The method of the 20 m shuttle run test (20 m SRT) test was used to derive VO2max by equation. One-way ANOVA and LSD methods were conducted, and effect sizes were calculated to compare the CRF of the three types of adolescents. Regression analysis was used to analyze the relationship between altitude and VO2max. The VO2max scores of Chinese Tibetan adolescents and Chinese Han adolescents at sea level were higher than Chinese Han adolescents born and raised at high altitudes. For both boys and girls, the VO2max scores of Chinese Tibetan adolescents exceeded Chinese Han adolescents at sea level after the age of 16 years old. Regression analysis showed that altitude was inversely associated with VO2max. The pace of lung growth may distinguish Chinese Tibetan adolescents from Chinese Han adolescents born and raised at high altitudes. The results of the study suggest that we should focus on the changes in CRF in adolescents at different altitudes and should adopt different CRF interventions for adolescents at different altitudes.

Mitogen-activated protein kinase (MAPK) cascades are highly conserved signaling modules that regulate plant immune responses. The Arabidopsis thaliana Raf-like MAPK kinase kinase ENHANCED DISEASE RESISTANCE1 (EDR1) is a key negative regulator of plant immunity that affects the protein levels of MKK4 and MKK5, two important MAPK cascade members, but the underlying mechanism is poorly understood. Here, genome-wide phosphorylation analysis demonstrated that the E3 ligase KEEP ON GOING (KEG) is phosphorylated in the edr1 mutant but not the wild type, suggesting that EDR1 negatively affects KEG phosphorylation. The identified phosphorylation sites in KEG appear to be important for its accumulation. The keg-4 mutant, a previously identified edr1 suppressor, enhances susceptibility to the powdery mildew pathogen Golovinomyces cichoracearum. In addition, MKK4 and MKK5 protein levels are reduced in the keg-4 mutant. Furthermore, we demonstrate that MKK4 and MKK5 associate with full-length KEG, but not with truncated KEG-RK or KEG-RKA, and that KEG ubiquitinates and mediates the degradation of MKK4 and MKK5. Taken together, these results indicate that MKK4 and MKK5 protein levels are regulated by KEG via ubiquitination, uncovering a mechanism by which plants fine-tune immune responses by regulating the homeostasis of key MAPK cascade members via ubiquitination and degradation.

In order to find a new variety of ryanodine receptor(RyR) regulator with greater biological activity, a series of anthranilic diamide derivatives possessing pyrrole structure was designed and synthesized in this study. The pyrrole derivatives were evaluated for their insecticidal activity against Mythimna separata and Plutella xylostella. As indicated by the preliminary biological activities, compounds 12h–12j and 12l–12n exhibited a remarkable insecticidal activity against M. separata at 0.25 mg/L. Compared to control chlorantraniliprole, compound 12j exhibited more excellent insecticidal activity at 0.1 mg/L. Meanwhile, compounds 12c, 12h, 12i, 12j, 12l, and 12m were selected to test the insecticidal activity against P. xylostella, which led to the desirable insecticidal activity at 1×10−3 mg/L. Notably, compound 12l demonstrated 47% insecticidal activity at 5×10−6 mg/L over the control. In addition, the biological mechanism of action of compound 12j was investigated by means of insect electrophysiology experiment.

Objective: Cardiorespiratory fitness (CRF) reference data for Tibetan (Zang ethnicity) children and adolescents at high altitudes in Tibet of China are lacking. The present study aimed to develop sex- and age-specific 20mSRT norms for Chinese Tibetan children and adolescents at high altitudes. Method: A total of 4667 participants from Lhasa (3650 m), Nagqu (4500 m), and Amdo (4700 m) were selected by a stratified random cluster sampling method in two stages. The 20 m SRT test was used to estimate cardiorespiratory fitness. The 20 m SRT norms were developed by the lambda, mu, and sigma method (LMS). Results: The 20 m SRT laps, completed stages/minutes, and the speed at the last complete stage of Chinese Tibetan children and adolescents aged 7–18 years increased with age. Conclusion: Given the importance of CRF for children and adolescents’ health, the government should strengthen the monitoring of the CRF of Tibetan children and adolescents in high-altitude areas, strengthen physical education curriculum reform, and increase the level of physical activity in order to improve the level of CRF in children and adolescents.

An iron-catalyzed hydrofluorination of unactivated alkenes has been developed. The use of a multidentate ligand and the fluorination reagent N-fluorobenzenesulfonimide (NFSI) proved to be critical for this reaction, which afforded various fluorinated compounds in up to 94 % yield.

A series of (R)-2-phenyl-4,5-dihydrothiazole-4-carboxamide derivatives containing a sulfur ether moiety were synthesized and characterized on the basis of NMR and elemental analysis (EA). The crystal structure of (R)-N-(2-methyl-1-(methylthio)propan-2-yl)-2-(4-nitrophenyl)-4,5-dihydrothiazole-4-carboxamide (13d) was determined to show R configuration. The bioasssy results indicated that most title compounds displayed good and broad spectrum antifungal activities against several phytopathogenic fungi. The structure activity relationships were discussed. Based on the antifungal activity of title compounds against Phytophthora capsici, a CoMSIA calculation was performed to establish a 3D-QSAR model, which revealed that electrostatic and hydrophobic fields were the two most significant factors for antifungal activity. According to the established 3D-QSAR model, structure optimization was carried out to find (R)-N-((R)-1-(methylthio)propan-2-yl)-2-(p-tolyl)-4,5-dihydrothiazole-4-carboxamide (15h) with excellent activity against Phytophthora capsici, thus emerging as a new lead compound for novel antiphytopathogenic fungus agent development.

Power converter is among the core components of the direct-drive wind turbines. The lifespan of semiconductor modules is essential for reliability evaluation of the power converter, but it is substantially influenced by output power fluctuation and intermittency of the turbine. This paper proposes a fast method for lifespan evaluation of semiconductor modules under various operation conditions. This method makes full use of wind speed and temperature information throughout the year, and considers the impact of low-frequency, fundamental-frequency, and ambient temperature fluctuations on the lifespan of the semiconductor module. By utilizing equivalent average model instead of the switching model for thermal effect calculation, the computation burden is significantly reduced, and satisfying calculation speed is guaranteed. A 1.2 MW wind turbine is utilized as a benchmark for lifespan evaluation, and the effectiveness of this method is validated.

Fluorinated organic compounds represent a growing and important family of commercial chemicals. Introduction of fluorine into active ingredients has become an effective way to develop modern crop protection products. Given the particular properties of fluorine and high efficiency and selectivity of diamide insecticides, we designed and synthesized 27 anthranilic diamides analogues containing fluoro-sustituted phenylpyrazole. A preliminary bioassay indicated that most target compounds exhibited good biological activity against Mythimna separata and Plutella xylostella. Compound IIIf containing a 2,4,6-trifluoro-substituted benzene ring showed 43% insecticidal activity against M. separata at 0.1 mg L-1, while the control chlorantraniliprole was 36%. The activity of IIIe against P. xylostella at 10-5 mg L-1 was 94%, compared with that of the control being 70%. Thus, introduction of fluorine into diamide insecticides was useful for increasing activity. Insect electrophysiology studies showed that the calcium concentration in the nerve cells of third M. separata larvae was elevated by IIIf, which further confirmed that ryanodine receptor (RyR) was its potential target.

Fractional frequency transmission system (FFTS), also known as low-frequency ac transmission system, is a promising solution to offshore wind power integration. The ac/ac converter is the most important equipment in FFTS. The modular multilevel matrix converter (M3C) is widely regarded as the next-generation ac/ac converter, but its complex control remains a problem. A novel control strategy is proposed featuring its decoupling algorithm in this paper. Different from previous research, the proposed current control regulates current components of different frequencies separately in star-figure subconverters under their synchronous rotating frames (SRFs), where the current is transformed to dq -axis dc signals for a better performance. A novel algorithm named “cross-SRF decoupling algorithm” is proposed to overcome the tight coupling between the circulating currents of two different frequencies. The effectiveness of the proposed control strategy has been verified by the simulation results obtained from a 110 kV, 400 MW M3C system implemented in MATLAB /Simulink.

In order to search for the new ryanodine receptor (RyR) regulator, a series of 35 novel fluoro-substituted compounds introduced 1-(2-chloro-4,5-difluorophenyl)-1H-pyrazole moiety containing modified pyrazole heterocycle were designed and synthesized. Then, they were tested for the insecticidal activities against Mythimna separata and Plutella xylostella in our greenhouse. After a systematic biological screening, it was found out that IVc showed 50% larvicidal activities against Mythimna separata at 0.1 mg L−1, equivalent to that of chlorantraniliprole (36%, 0.1 mg L−1). The activity of IVc against Plutella xylostella was 90% at 10−5 mg L−1, whereas the chlorantraniliprole was 70% at the same concentration. Then, insect electrophysiology experiments were conducted to study the pattern of action of IVc and IVe. It was confirmed by the experimental results that both compounds could lead to the release of calcium from the endoplasmic reticulum of neurons as classical anthranilic diamide insecticides.

Using a Monte Carlo simulation and the single histogram reweighting technique, we study the critical behaviors and phase transitions of the Baxter-Wu model on a two-layer triangular lattice with repulsive interlayer interactions. Via the finite-size analysis, we obtain the transition temperatures and critical exponents at different interlayer coupling strengths. The reduced energy cumulants and the histograms reveal pseudo-first-order phase transitions, and the critical exponents derivate from the standard Baxter-Wu model if the coupling is weak. As the increase of the coupling, the behavior of the pseudo-first order transition disappears and the critical exponents are in accordance with the ones known for the 2D 4-state Potts model.

In order to design a high-efficiency, cost-effective, high-power driver for supplying multiple light-emitting diode (LED) strings in parallel, a novel single-stage bridgeless, soft-switched integrated AC-DC converter is proposed. The proposed converter can be derived by integrating the totem-pole bridgeless boost power factor correction (PFC) circuit and half-bridge LLC resonant converter. Therefore, the number of semiconductors in the line-current path can be significantly minimized, and the power losses in the secondary rectifier diodes and the primary switches can be dramatically reduced. Moreover, the twin-bus concept can be adopted to achieve the quasi-single-stage power conversion of the total LED driver with multiple LED strings load. In addition, this circuit allows removing the bulky electrolytic capacitors with short lifetime by increasing the bus voltage ripple, and thus, the long lifetime is another advantage of the proposed LED driver. The detailed operation principles and design considerations for the proposed converter are analyzed and discussed. The feature of the proposed solution was demonstrated using a 100-W hardware prototype with six LED strings. The experimental results showed the converter achieves full-range ZVS for primary switches and the efficiency of 94.5% under the 120 V input voltage.

This paper presents a hybrid switch that parallels a power MOSFET and an insulated-gate bipolar transistor (IGBT) as the main switch of a zero-voltage switching (ZVS) inverter. The combination features the MOSFET conducting in the low-current region and the IGBT conducting in the high-current region, and the soft switching avoids the reverse recovery problem during the device turn-on. A custom hybrid switch module has been developed for a variable-timing-controlled coupled-magnetic-type ZVS inverter with a nominal input voltage of 325 V and the continuous output power of 30 kW for a traction motor drive. Experimental results of the hybrid-switch-based inverter with the total loss projected by temperature indicate that the inverter achieves 99% efficiency at the nominal condition and demonstrate ultrahigh-efficiency operation over a wide load range. At 375-V input, the maximum measured efficiency through temperature projection and loss separation analysis is 99.3%.

Fractional frequency transmission system (FFTS) is a promising solution to offshore wind power integration. The back-to-back modular multilevel converter (MMC) and modular multilevel matrix converter (M3C) are universally regarded as two promising ac/ac converter candidates of the next generation. This paper performs a detailed comparison between back-to-back MMC and M3C with special emphasis on their total capacitor and semiconductor ratings. The arm current and capacitor ripples are first analyzed, then comparison results of a 220 kV, 500 MW case is given. In terms of peak-current-based and RMS-current-based total semiconductor ratings the M3C is 42.56 % and 22.97 % larger respectively, while its total capacitor rating is merely 33.15% of the back-to-back MMC. The better candidate can be determined according to the quantitative comparison results and the latest prices of semiconductors and capacitors.

Modular multilevel matrix converter (M3C) is a competitive frequency converter option to be used in fractional frequency transmission system (FFTS). However, the previous literatures about M3C seldom study its harmonic issue and arm capacitor parameter selection principle. This paper analyzes the harmonic components of the electrical quantities of M3C by circular iteration and provides the principle of the arm capacitor parameters selection. Finally, the validity of the analysis is confirmed by simulation in PSCAD/EMTDC.

A novel soft-switching hybrid converter combining the phase-shift full-bridge (FB) and half-bridge (HB) LLC resonant converters' configuration with shared zero-voltage switching (ZVS) lagging leg is proposed to ensure the switches in the lagging leg operating at fully ZVS condition. The dual outputs of the proposed hybrid FB-HB converter are connected in series and the whole dc-output voltage can be regulated by the PWM phase-shift control within the desired voltage range. A resonant circuit is used in the secondary side of the FB converter to reset the primary current during the freewheeling period, as well as to transfer more input energy and clamp secondary rectifier voltage. The proposed converter is attractive for hybrid electric vehicle/electric vehicle on-board charger applications. The principle of operation, the validity, and performance are illustrated and verified on a 3.7-kW experimental circuit. Experimental results show that the proposed converter can get good efficiency curves at different operation points, and the maximum efficiency is 98.30%.

In this paper, a new cascade active-front-end converter based on dual-boost/buck converters is proposed for an intelligent universal transformer (IUT), which allows adjusting the power factor to control both the active and reactive powers between medium and low voltage levels. Compared to the traditional cascade H-bridge converter, it has much enhanced system reliability owing to no shoot-through problems and lower switching loss with the help of using power MOSFETs. In addition, a unified control scheme is proposed for active-reactive power control and individual voltage balancing control, which is modular and easy to implement. In the end, a laboratory three-unit cascade active-front-end converter based on the half-bridge dual-boost/buck converter is constructed and tested. The experimental results verified the feasibility and effectiveness of the proposed active-front-end converter and the unified control scheme for IUT.

In this paper, a novel electric power source structure optimization (EPSSO) scheme is proposed to achieve the sustainable development objectives of economic growth, electricity demand and environmental protection. Different from power generation expansion planning (PGEP), the proposed EPSSO method evaluates the optimal investment scheme for a long-term power generation expansion from the viewpoints of macro-economy. By adjusting the proportion of renewable power generating units at a more appropriate time, it can promote the efficiency of national capital with the constraint of CO2 emissions. The basic idea of this method is to combine the conventional objective function with the capital efficiency which is often used as a repressor of economic growth. At last, the genetic algorithm (GA) is used to solve the highly nonlinear combinatorial problem of EPSSO and a numerical case is present to demonstrate the feasibility of this scheme based on the background of China.

This paper focuses on the application of modular multilevel matrix converter (M3C) in fractional frequency offshore wind power system (FFOWPS). M3C is one of the direct ac-to-ac power converters capable of bidirectional power flow. It has many advantages compared with traditional cycloconverter, so it is more competitive and promising to be used in FFOWPS. This paper constructs an equivalent circuit of M3C to make the control of the lower frequency side (LFS) and power frequency side (PFS) of M3C mutually independent. A control scheme of M3C suitable for FFOWPS is proposed according to that equivalent circuit. Finally the validity and effectiveness of the control strategy are verified by simulation of a downscaled case.

This paper presents a 55-kW three-phase inverter based on soft-switching modules for hybrid electric vehicle drives at high-temperature conditions. The main switch of the module is composed of the hybrid switch, which is composed of parallel IGBT and MOSFET. Highly integrated soft-switching modules have been employed to achieve switching loss as well as conduction loss reduction. The operation principle of the proposed inverter is analyzed in detail. Experimental evaluations of the inverter have been conducted through both inductive load and motor-dynamometer load at coolant temperatures ranging from 25°C to 90°C. Efficiency measurement using power meter showed that the peak efficiency is around 99%, and it drops slightly at lower speed and higher temperature conditions. To ensure measurement fidelity, a double-chamber differential calorimeter system was designed and calibrated for the inverter testing. Through long-hour testing, the measured efficiencies consistently showed 99% and higher. The soft-switching inverter has been operated reliably and demonstrated high efficiency at different temperature and test conditions.

This paper presents a new type of cascade inverter based on dual buck topology and phase-shift control scheme. The proposed cascade dual buck inverter with phase-shift control inherits all the merits of dual buck type inverters and overcomes some of their drawbacks. Compared to traditional cascade inverters, it has much enhanced system reliability thanks to no shoot-through problems and lower switching loss with the help of using power MOSFETs. With phase-shift control, it theoretically eliminates the inherent current zero-crossing distortion of the single-unit dual buck type inverter. In addition, phase-shift control and cascade topology can greatly reduce the ripple current or cut down the size of passive components by increasing the equivalent switching frequency. A cascade dual buck inverter has been designed and tested to demonstrate the feasibility and advantages of the system by comparing single-unit dual buck inverter, 2-unit and 3-unit cascade dual buck inverters at the same 1 kW, 120 V ac output conditions.

This paper presents a new type of three-phase voltage source inverter (VSI), called three-phase dual-buck inverter. The proposed inverter does not need dead time, and thus avoids the shoot-through problems of traditional VSIs, and leads to greatly enhanced system reliability. Though it is still a hard-switching inverter, the topology allows the use of power MOSFETs as the active devices instead of IGBTs typically employed by traditional hard-switching VSIs. As a result, the inverter has the benefit of lower switching loss, and it can be designed at higher switching frequency to reduce current ripple and the size of passive components. A unified pulsewidth modulation (PWM) is introduced to reduce computational burden in real-time implementation. Different PWM methods were applied to a three-phase dual-buck inverter, including sinusoidal PWM (SPWM), space vector PWM (SVPWM) and discontinuous space vector PWM (DSVPWM). A 2.5 kW prototype of a three-phase dual-buck inverter and its control system has been designed and tested under different dc bus voltage and modulation index conditions to verify the feasibility of the circuit, the effectiveness of the controller, and to compare the features of different PWMs. Efficiency measurement of different PWMs has been conducted, and the inverter sees peak efficiency of 98.8% with DSVPWM.

Fractional frequency transmission system (FFTS) is utilized to transmit large-scale and remote wind power. By adopting a lower frequency (50/3 Hz), FFTS could reduce the electric distance of transmission lines, thus lowering the transmission loss. In order to analyze the interconnected system of FFTS and main grid, the power flow calculation should be conducted. This paper introduces a new method to calculate the power flow of the interconnected system and analyzes the control strategy of reactive power of FFTS. Firstly, a quasi- steady model of the cycloconverter is elaborated. Secondly, the validity of the model is verified through power flow calculation and PSCAD/EMTDC simulation of a simplified system. Finally, an alternate iteration method for power flow calculation of the interconnected system is proposed. Based on the IEEE-30 system, the power factor control of FFTS is discussed considering various integration buses of wind power.

This paper presents a hybrid switch that parallels a power MOSFET and an IGBT as the main switch of a zero-voltage switching inverter. The combination features the MOSFET conducting in the low current region and the IGBT conducting in the high current region, and the soft switching avoids the reverse recovery problem during the device turn-on. A custom hybrid switch module has been developed for a variable-timing controlled coupled-magnetic type ZVS inverter with a nominal input voltage of 325 V and the continuous output power of 30-kW for a traction motor drive. Experimental results of the hybrid-switch based inverter with the total loss projected by temperature indicate that the inverter achieves 99% efficiency at the nominal condition and demonstrate ultrahigh efficiency operation over a wide load range. At 375-V input, the maximum measured efficiency through temperature projection and loss separation analysis is 99.3%.

This paper presents a new three-phase four-leg inverter based on dual-buck power cell. Compared to traditional standard three-phase four-leg inverters with two IGBT switches in one leg, the proposed inverter incorporates dual-buck power cell, which results in several benefits. First, the dual-buck power cell allows the use of power MOSFETs for higher switching speed and efficiency improvement. Second, with the help of unique operation of dual-buck power cell, the inverter reliability is enhanced because no dead time is needed for all four legs and shoot-through concerns are totally eliminated. A unified pulse width modulation (PWM) is introduced for the proposed inverter to reduce computational burden of real-time implementation by digital signal processor (DSP). Space vector PWM (SVPWM) and discontinuous space vector PWM (DSVPWM) are analyzed under the unified PWM scheme. A prototype of the proposed inverter is designed and tested with three-phase unbalanced load under different dc bus voltage and modulation index conditions to verify the feasibility and effectiveness of the topology and the unified PWM scheme.

Photovoltaic (PV) inverter is the most important part for energy conversion, and the current research focus for PV inverter is high efficiency, high reliability, and low-output ac-current distortion. With considerable grid-connected PV installation in last few years, high penetration PV system is desired, which requires integrating PV inverter into grid regulation. New code in Germany already requires PV inverter providing system regulation and service for low voltage distribution system. One of obvious impact on PV inverter is reactive power generation requirement. Most state-of-the-art high-efficiency PV inverters that adopt single-stage topology only allow unity power generation but none of them are able to generate reactive power. This paper proposes a high-efficiency dual-buck full-bridge PV inverter for a wide range power factor operation. Additionally, a novel hybrid bipolar PWM method is proposed to achieve low ground leakage current and low output current distortion in the PV system. At last, simulation and experiment demonstrate that the proposed PV inverter system can provide a wide-range power factor operation with high efficiency, low ground leakage current, and low output current distortion.

This paper presents a new type of cascade inverter, named cascade dual-buck full-bridge inverter. Compared to cascade H-bridge inverter, the proposed inverter has several advantages. First, it eliminates the possibility of shoot-through problems, which is the major failure of traditional voltage source inverters. Second, it does not need dead time, which fully utilizes the pulse width modulated voltage and transfers total desired energy to the load. In addition, it can use high-voltage power MOSFETs without the complexity of soft-switching assisting circuits to improve the system efficiency. In this paper, several PWM techniques are analyzed and compared, including bipolar PWM, unipolar PWM and phase-shifted PWM, when applied to the proposed inverter. It has been found out that a hybrid PWM technique with the combination of the two out of the three PWMs mentioned above leads to better performance of the cascade dual-buck full-bridge inverter in terms of less output current ripple and harmonics, no zero-crossing distortion, and higher efficiency. A prototype of the proposed inverter has been built and tested to verify the feasibility and effectiveness of the topology and the hybrid PWM technique.

This paper evaluates three different 600V-level super junction (SJ) MOSFETs employed in zero-voltage soft-switching inverter applications. Inverter efficiency was measured and compared with the same inverter test setup by only changing different MOSFETs. Besides high efficiency requirement, better switching performance is also highly appreciated in various inverter applications. Comparison test was done on each super junction MOSFET to investigate its body diode reverse recovery and associated problems. Based on performance of both efficiency and reverse recovery related issues, a high voltage super junction MOSFET selection for softswitching inverter was suggested.

This paper presents a 55kW three-phase softswitching inverter for hybrid electric vehicle drives at high temperature conditions. Highly integrated softswitching modules have been employed to achieve switching loss as well as conduction loss reduction. Detailed experimental evaluations of inverter efficiency have been conducted through both inductive load and motor-dynamometer load at coolant temperatures ranging from 25°C to 90°C. Efficiency measurement using power meter showed that the peak efficiency is around 99%, and it drops slightly at lower speed and higher temperature conditions. To ensure measurement fidelity, a double chamber differential calorimeter system was designed and calibrated for the inverter testing. Through long-hour testing, the measured efficiencies consistently showed 99% and higher. The soft-switching inverter has been operated reliably and demonstrated high efficiency at different temperature and test conditions.

This paper presents a high efficiency three-phase soft-switching inverter for electric vehicle drives application. A 12kW three-phase soft-switching inverter using CoolMOS as the main device and IGBT as the auxiliary device has been designed and fabricated. The electric vehicle drive test system has been assembled with soft-switching inverter, induction motor and dynamometer. The soft-switching inverter has been tested with closed-loop torque direction control under speed reversal conditions. The measured efficiency of the inverter in a wide load range is above 98.5%. The calorimeter test at 12kW shows 98.8% efficiency.

High temperature inverter involves thermal management, packaging, semiconductor device, switching circuit, and control circuitry. This paper is to focus on the drivetrain inverter design consideration for electric and hybrid electric vehicles. Basic structure and switching characteristics of different insulated-gate-bipolar-transistors (IGBTs) will be discussed. The use of silicon carbide Schottky diode in parallel with silicon IGBT will also be evaluated and compared with pure silicon IGBT modules running under both hard- and soft-switching conditions. Experimental results of conduction and switching loss at different temperature conditions are used to predict the device loss and associated junction temperature for switching cases.