Impacts of using wide bandgap transistors on electronics and motors

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mathieu Gerber ◽  
Guillaume Callerant ◽  
Christophe Espanet ◽  
Farid Meibody-Tabar ◽  
Noureddine Takorabet
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Wide Bandgap ◽  
Switching Frequency ◽  
Switching Speed ◽  
Content Type ◽  
Parasitic Element ◽  
Fast Switching ◽  
Electronic Model ◽  
The Impact

Purpose The purpose of this paper is to study the high-frequency impacts of fast switching wide-bandgap transistors on electronic and motor designs. The high-frequency power converters, dedicated to driving high-speed motors, require specific models to design predictively electronic and motors. Design/methodology/approach From magnetic and electric models, the high-frequency parasitic elements for both electronics and motor are determined. Then, high-frequency circuit models accounting for of parasitic element extractions are built to study the wide bandgap transistors commutations and their impacts on motor windings. Findings The results of the models, for electronics and motors, are promising. The high-frequency commutation cell study is used to optimize the layouts and to improve the commutation behaviours and performances. The impact of the switching speed is highlighted on the winding voltage susceptibility. Then, the switching frequency and commutation rapidity can be both optimized to increase the performance of motor and electronics. The electronic model is validated by experimentations. Research limitations/implications The method can be only applied to the existing motor and electronic designs. It is not taken into account in an automized global high-frequency optimizer. Originality/value Helped by magnetic and electric FEA calculations where the parasitic element extractions are performed. The switching frequency and commutation rapidity can be both optimized to increase the performance of motor and electronics.

Impacts of high-speed railway on the industrial pollution emissions in China

Kybernetes ◽  
2020 ◽  
Vol 49 (11) ◽  
pp. 2713-2735 ◽  
Author(s):  
Xiaomin Fan ◽  
Yingzhi Xu ◽  
Yongqing Nan ◽  
Baoli Li ◽  
Haiya Cai
Keyword(s):  
Environmental Effects ◽  
Industrial Pollution ◽  
High Speed ◽  
Assessment Method ◽  
Economic Effects ◽  
High Speed Railway ◽  
Central Cities ◽  
Content Type ◽  
Pollution Emissions ◽  
The Impact

Purpose The purpose of this paper is to analyse the impact of high-speed railway (HSR) on industrial pollution emissions using the data for 285 prefecture-level cities in China from 2004 to 2016. Design/methodology/approach The research method used in this paper is the multi-period difference-in-differences (DID) model, which is an effective policy effect assessment method. To further address the issue of endogeneity, the DID integrated with the propensity score matching (PSM-DID) approach is employed to eliminate the potential self-selection bias. Findings The results show that the HSR has significantly reduced industrial pollution emissions, which is validated by several robustness tests. Compared with peripheral cities, HSR exerts a greater impact on industrial pollution emissions in central cities. In addition, the mechanism test reveals that the optimised allocation of inter-city industries is an important channel for HSR to mitigate industrial pollution emissions, and this is closely related to the location of HSR stations. Originality/value Previous studies have paid more attention to evaluating the economic effects of HSR, however, most of these studies overlook its environmental effects. Consequently, the impact of HSR on industrial pollution emissions is led by using multi-period DID models in this paper, in which the environmental effects are measured. The results of this paper can provide a reference for the pollution reduction policies and also the coordinated development of economic growth and environmental quality.

scholarly journals Examining partial proportional odds model in analyzing severity of high-speed railway accident

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jing Wang ◽  
Yinghan Wang ◽  
Yichuan Peng ◽  
Jian John Lu
Keyword(s):  
High Speed ◽  
Proportional Odds Model ◽  
Impact Factors ◽  
Proportional Odds ◽  
High Speed Railway ◽  
Severity Level ◽  
Content Type ◽  
Factors Affecting ◽  
Partial Proportional Odds Model ◽  
The Impact

Purpose The operation safety of the high-speed railway has been widely concerned. Due to the joint influence of the environment, equipment, personnel and other factors, accidents are inevitable in the operation process. However, few studies focused on identifying contributing factors affecting the severity of high-speed railway accidents because of the difficulty in obtaining field data. This study aims to investigate the impact factors affecting the severity of the general high-speed railway. Design/methodology/approach A total of 14 potential factors were examined from 475 data. The severity level is categorized into four levels by delay time and the number of subsequent trains that are affected by the accident. The partial proportional odds model was constructed to relax the constraint of the parallel line assumption. Findings The results show that 10 factors are found to significantly affect accident severity. Moreover, the factors including automation train protection (ATP) system fault, platform screen door and train door fault, traction converter fault and railway clearance intrusion by objects have an effect on reducing the severity level. On the contrary, the accidents caused by objects hanging on the catenary, pantograph fault, passenger misconducting or sudden illness, personnel intrusion of railway clearance, driving on heavy rain or snow and train collision against objects tend to be more severe. Originality/value The research results are very useful for mitigating the consequences of high-speed rail accidents.

scholarly journals Modeling and Experimental Investigation of Electromagnetic Interference (EMI) for SiC-Based Motor Drive

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5173
Author(s):  
Yingzhe Wu ◽  
Shan Yin ◽  
Hui Li ◽  
Minghai Dong
Keyword(s):  
Electromagnetic Interference ◽  
Semiconductor Device ◽  
Frequency Domain Analysis ◽  
Motor Drives ◽  
Motor Drive ◽  
Switching Frequency ◽  
Switching Speed ◽  
Fast Switching ◽  
Source Voltage ◽  
Switching Characteristics

The motor drive has been widely adopted in modern power applications. With the emergency of the next generation wide bandgap semiconductor device, such as silicon carbide (SiC) MOSFET, performance of the motor drive can be improved in terms of efficiency, power density, and reliability. However, the fast switching transient and serious switching ringing of the SiC MOSFET can cause unwanted high-frequency (HF) electromagnetic interference (EMI), which may significantly reduce the reliability of the motor drive in many aspects. In order to comprehensively reveal the mechanism of the EMI previously used in motor drives using SiC MOSFET, this paper plans to analyze the influences of both HF impedance of the motor and switching characteristics of the SiC MOSFET. A simulation model for motor drives has been proposed, which contains the HF circuit model of the motor as well as a semi-behavioral analytical model of the SiC MOSFET. Since the model shows a good agreement with the experimentally measured results on spectra of drain-source voltage of the SiC MOSFET (vds), phase to ground voltage of the motor (vphase), CM voltage (vcm), phase current of the motor (idm), and CM current (icm), it can be adopted to quantitatively investigate the influence of the motor impedance on EMI through frequency-domain analysis. Additionally, the impacts of switching characteristics of SiC MOSFET on EMI are also well studied according to relative experiment results in terms of switching speed, switching frequency, and switching ringing. Based on the analysis above, the relationship between motor impedance, switching characteristics of the SiC MOSFET, and HF EMI can be figured out, which is able to provide much helpful assistance for application of the motor drive.

Does opening high-speed railways affect the cost of debt financing? A quasi-natural experiment

2020 ◽  
Vol 10 (4) ◽  
pp. 473-496
Author(s):  
Hongling Guo ◽  
Keping Wu
Keyword(s):  
High Speed ◽  
Geographical Location ◽  
Debt Financing ◽  
Cost Of Debt ◽  
High Speed Railway ◽  
Content Type ◽  
Financing Cost ◽  
Debt Market ◽  
The Cost ◽  
The Impact

PurposeThis study aims to investigate how opening high-speed railways affects the cost of debt financing based on China's background.Design/methodology/approachUsing panel data on Chinese listed firms from 2008 to 2017, this study constructs a quasi-natural experiment and adopts a difference-in-difference model with multiple time periods to empirically examine the relation between the high-speed railway openings and debt financing cost.FindingsOur results show that opening high-speed railways reduces the cost of debt financing, and this negative correlation is more significant in non-state firms, firms with weaker internal control, and firms that hire non-Big Four auditors. Besides, we explore the impact mechanisms and find that opening high-speed railways improves analyst attention, institutional investor participation, and information disclosure quality, which in turn lowers the cost of debt financing.Research limitations/implicationsThe results imply that the opening of high-speed railways helps to alleviate the information asymmetry and adverse selection between firms and creditors and ultimately reduces the cost of corporate debt financing.Practical implicationsThis paper can inform firms and stakeholders about the impact of opening high-speed railways on debt financing cost: it improves the information environment, reduces the geographical location restrictions of debt financing, ensures the reasonable pricing of corporate debt, and thus promotes the healthy and sound development of the debt market.Originality/valueThis paper provides theoretical support and empirical evidence for the impact of infrastructure construction on the information environment of the debt market in China, which enriches the research on the “high-speed railway economy.” In addition, as an exogenous event, the opening of high-speed railways instantly shortens the time distance between firms and external stakeholders, which gives us a natural environment to conduct empirical research, thus providing a new perspective for financial research on firms' geographical location.

An 8kW LLC resonant converter in plasma power supply based on SiC power devices for efficiency improvement

Circuit World ◽  
2019 ◽  
Vol 45 (4) ◽  
pp. 181-188
Author(s):  
Zhenmin Wang ◽  
Wenyan Fan ◽  
Fangxiang Xie ◽  
Chunxian Ye
Keyword(s):  
Silicon Carbide ◽  
Power Supply ◽  
High Frequency ◽  
Experimental Results ◽  
Switching Frequency ◽  
Resonant Converter ◽  
Plasma Power ◽  
Power Devices ◽  
Content Type ◽  
Llc Resonant Converter

Purpose This paper aims to present an 8 kW LLC resonant converter designed for plasma power supply with higher efficiency and lighter structure. It presents how to solve the problems of large volume and weight, low performance and low efficiency of traditional plasma power supply. Design/methodology/approach At present, conventional silicon (Si) power devices’ switching performance is close to the theoretical limit determined by its material properties; the next-generation silicon carbide (SiC) power devices with outstanding advantages can be used to optimal design. This 8 kW LLC resonant converter prototype with silicon carbide (SiC) power devices with a modulated switching frequency ranges from 100  to 400 kHz. Findings The experimental results show that the topology, switching loss, rectifier loss, transformer loss and drive circuit of the full-bridge LLC silicon carbide (SiC) plasma power supply can be optimized. Research limitations/implications Due to the selected research object (plasma power supply), this study may have limited universality. The authors encourage the study of high frequency resonant converters for other applications such as argon arc welding. Practical implications This study provides a practical application for users to improve the quality of plasma welding. Originality/value The experimental results show that the full-bridge LLC silicon carbide (SiC) plasma power supply is preferred in operation under conditions of high frequency and high voltage. And its efficiency can reach 98%, making it lighter, more compact and more efficient than previous designs.

The impact of order imbalance on returns, liquidity, and volatility in agricultural commodity markets

2018 ◽  
Vol 78 (5) ◽  
pp. 571-591 ◽  
Author(s):  
Steffen Volkenand ◽  
Guenther Filler ◽  
Martin Odening
Keyword(s):  
Trading Volume ◽  
High Speed ◽  
Price Volatility ◽  
Agricultural Commodity ◽  
Content Type ◽  
Order Imbalance ◽  
New Information ◽  
Agricultural Futures ◽  
Best Offer ◽  
The Impact

PurposeThe purpose of this paper is to investigate and compare the impact of order imbalance on returns, liquidity and price volatility in agricultural futures markets on an intraday basis. The authors examine whether order imbalance is more powerful to explain variations in asset prices compared to other indicators of trading activity, particularly trading volume.Design/methodology/approachUsing Chicago Mercantile Exchange best bid best offer data, the impact of order imbalance is analyzed via regression analyses. The analyses are carried out for corn, wheat, soy, live cattle and lean hogs in March 2008 and March 2016.FindingsResults confirm the positive relation between order imbalance and returns as well as between order imbalance and price volatility as suggested by market microstructure models. Order imbalance, however, does not generally outperform trading volume as an explanatory variable.Practical implicationsFor some contracts, returns can be predicted using lagged order imbalance. This offers the opportunity to derive profitable trading strategies.Originality/valueThis paper is one of the first attempts to explore the relationship between order imbalance and returns, liquidity and volatility for agricultural commodity futures on an intraday basis, accounting for the increased trading volume and for the high speed at which new information enters the market in an electronic trading environment.

Traders and time: who moves the market?

2015 ◽  
Vol 32 (1) ◽  
pp. 74-97 ◽  
Author(s):  
Fabrizio Ferriani
Keyword(s):  
High Frequency ◽  
Dominant Role ◽  
Market Liquidity ◽  
Content Type ◽  
Market Activity ◽  
Information Models ◽  
Informed Traders ◽  
Transaction Level ◽  
Instantaneous Volatility ◽  
The Impact

Purpose – This paper is aimed to investigate the impact of different categories of traders on price and volume durations at Euronext Paris. The two series are respectively related to the instantaneous volatility and the market liquidity; hence, they are particularly suited to test microstructure hypotheses. Design/methodology/approach – A Log-autoregressive conditional duration model was adopted to include the information on the traders’ identity at the transaction level. High-frequency data were used and how the informed traders and the liquidity provider affect the arrival of market events was studied. The robustness of our results was also checked by testing different distributions and controlling for microstructure effects. Findings – It was found that informed traders and the liquidity provider exert a dominant role in accelerating the market activity. This result depends on the state of the market, i.e. it is effective only during periods of high frequency of transactions. The estimates for price durations show that a high instantaneous volatility can be mainly ascribed to a great concentration of informed traders. Informed traders are also found to shorten volume durations by clustering small-size orders to disguise their private signal. For both durations, the liquidity provider is also found to foster the market activity, likely because of his contractual duties. Originality/value – The article is of interest for researchers in the field of market microstructure, as well as for specialists in the high-frequency trading. Results provide an empirical confirmation of information models which theorize an accelerating effect for informed trading. To the best of the authors’ knowledge, this is the first contribution to study the impact of traders’categories at the transaction level and with different definitions of durations.

scholarly journals Modeling and simulation of intersection quasi-moving block speed guidance based on connected vehicles

2020 ◽  
Vol 3 (2) ◽  
pp. 67-78
Author(s):  
Qing Xu ◽  
Jiangfeng Wang ◽  
Botong Wang ◽  
Xuedong Yan
Keyword(s):  
Traffic Congestion ◽  
High Speed ◽  
Connected Vehicles ◽  
Content Type ◽  
Communication Range ◽  
Proposed Model ◽  
Simulation Results ◽  
The Impact ◽  
Block Section ◽  
Guidance Model

Purpose This study aims to propose a speed guidance model of the CV environment to alleviate traffic congestion at intersections and improve traffic efficiency. By introducing the theory of moving block section for high-speed train control, a speed guidance model based on the quasi-moving block speed guidance (QMBSG) is proposed to direct platoon including human-driven vehicles and connected vehicles (CV) through the intersection coordinately. Design/methodology/approach In this model, the green time of the intersection is divided into multiple block intervals according to the minimal safety headway. Connected vehicles can pass through the intersection by following the block interval using the QMBSG model. The block interval is assigned dynamically according to the traveling relation of HV and CV, when entering the communication range of the intersection. To validate the comprehensive guidance effect of the proposed model, a general evaluation function (GEF) is established. Compared to CVs without speed guidance, the simulation results show that the GEF of QMBSG model has an obvious improvement. Findings Compared to CVs without speed guidance, the simulation results show that the GEF of QMBSG model has an obvious improvement. Also, compared to the single intersection speed guidance model, the GEF value of the QMBSG model improves over 17.1%. To further explore the guidance effect, the impact of sensitivity factors of the CVs’ environment, such as intersection environment, communication range and penetration rate (PR) is analyzed. When the PR reaches 75.0%, the GEF value will change suddenly and the model guidance effect will be significantly improved. This paper also analyzes the impact of the length of block interval under different PR and traffic demands. It is found that the proposed model has a better guidance effect when the length of the block section is 2 s, which facilitates traffic congestion alleviation of the intersection in practice. Originality/value Based on the aforementioned discussion, the contributions of this paper are three-fold. Based on the traveling information of HV/CV and the signal phase and timing plans, the QMBSG model is proposed to direct platoon consisting of HV and CV through the intersection coordinately, by following the block interval assigned dynamically. Considering comprehensively the indexes of mobility, safety and environment, a GEF is provided to evaluate the guidance effect of vehicles through the intersection. Sensitivity analysis is carried out on the QMBSG model. The key communication and traffic parameters of the CV environment are analyzed, such as path attenuation, PR, etc. Finally, the effect of the length of block interval is explored.

scholarly journals Leadership and performance in intermunicipal networks

2020 ◽  
Vol 32 (2) ◽  
pp. 177-196
Author(s):  
Denita Cepiku ◽  
Marco Mastrodascio
Keyword(s):  
Local Government ◽  
High Frequency ◽  
High Performance ◽  
Network Performance ◽  
Leadership Behaviors ◽  
Content Type ◽  
Specific Category ◽  
And Performance ◽  
Integrative Leadership ◽  
The Impact

PurposeThe purpose of this research is to highlight the impact of integrative leadership behaviors on network performance in local government networks.Design/methodology/approachThe data were retrieved from a survey conducted on 362 local government network leaders in Italy. Their leadership behaviors were compared with the level of network performance anonymously self-reported.FindingsThe findings show that high frequency in the usage of a specific category of behavior does not always lead to high performance in local government networks. Moreover, leadership behaviors leading to highly performing networks are not always engaged most frequently by networks' leaders.Originality/valueThis research gives an empirical contribution to a neglected topic: network leadership. Moreover, the authors attempt to highlight how it is able to influence network performance.

EFFECT OF A HIGH-FREQUENCY VIBRATION BOUNDARY ON RBC

2018 ◽  
Vol 18 (08) ◽  
pp. 1840032
Author(s):  
ZHONG YUN ◽  
CHUANG XIANG ◽  
LIANG WANG
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Blood Pump ◽  
Vibration Velocity ◽  
Immersed Boundary ◽  
High Frequency Vibration ◽  
Rbc Membrane ◽  
Spring Network Model ◽  
Boltzmann Method ◽  
The Impact

The vibrations in blood pumps were often caused by high speed, suspension structure, viscoelastic implantation environment and other factors in practical application. Red blood cell (RBC) was modeled using a nonlinear spring network model. The immersed boundary-lattice Boltzmann method (IB-LBM) was used to investigate the impact of high-frequency vibration boundary on RBC. To confirm the RBC model, the simulation results of RBC stretching were compared with experimental results. We examined the force acting on RBC membrane nodes; moreover, we determined whether RBC energy was affected by different frequencies, amplitudes, and vibration models of the boundary. Furthermore, we examined whether RBC energy was affected by the distance between the top and bottom boundaries. The energy of RBCs in shear flow disturbed by the vibration boundary was also investigated. The results indicate that larger amplitude (Am), frequency (Fr), and opposite vibration velocity of top and bottom boundary produced a larger force that acted on RBC membrane nodes and larger energy changes in RBCs. The vibration boundary may cause turbulence and alter RBC energy. When the blood pump was designed and optimized, the vibration frequency and amplitude of the blood pump body and impeller should be reduced, the phase of the blood pump body and impeller vibration velocity should be close. To alleviate the free energy of RBCs and to reduce RBC injury in the blood pump, the distance between RBCs and the boundary should not be less than 20[Formula: see text][Formula: see text]m.

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