Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628403
Xiang Wang, Haimeng Wu, V. Pickert
Silicon carbide (SiC) has seen tremendous advancement in high-efficiency, high-frequency, and high-temperature applications during recent years. However, the gate oxide of SiC MOSFET is reported to be less reliable compared with its Si counterpart, introducing the problem of threshold voltage (Vth) shift. Recent publications have investigated Vth shift which are mainly based on the long-time scale ranging from seconds to several days. However, the Vth shift in a shorter time scale has not been widely discussed and studied due to its high bandwidth requirement in measurement. This paper proposed an investigation into the short-time Vth shift using a developed current-controlled gate driver. The phenomenon of short-time Vth shift is captured and analyzed, which shows that it occurs within the first microsecond of the gate voltage being applied. Moreover, a modelling approach using the logarithm equation is proposed to describe the relationship between the short-time Vth shift and the gate stress time. Experiments are conducted under different temperatures, illustrating the temperature dependency of the short-time Vth shift process.
{"title":"Phenomenon of Short-Time Threshold Voltage Shift and Its Application in Junction Temperature Estimation","authors":"Xiang Wang, Haimeng Wu, V. Pickert","doi":"10.1109/peas53589.2021.9628403","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628403","url":null,"abstract":"Silicon carbide (SiC) has seen tremendous advancement in high-efficiency, high-frequency, and high-temperature applications during recent years. However, the gate oxide of SiC MOSFET is reported to be less reliable compared with its Si counterpart, introducing the problem of threshold voltage (Vth) shift. Recent publications have investigated Vth shift which are mainly based on the long-time scale ranging from seconds to several days. However, the Vth shift in a shorter time scale has not been widely discussed and studied due to its high bandwidth requirement in measurement. This paper proposed an investigation into the short-time Vth shift using a developed current-controlled gate driver. The phenomenon of short-time Vth shift is captured and analyzed, which shows that it occurs within the first microsecond of the gate voltage being applied. Moreover, a modelling approach using the logarithm equation is proposed to describe the relationship between the short-time Vth shift and the gate stress time. Experiments are conducted under different temperatures, illustrating the temperature dependency of the short-time Vth shift process.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133781182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628792
Sirun Zhu, Weijian Han
This paper proposes a closed-form modulation strategy for inductor current minimization of cascaded buck+boost converters (CBBCs). The minimum rms current trajectory (MCT) is analytically derived achieving low conduction and switching losses, and high efficiency. The proposed method does not rely on look-up tables that widely used in existing optimization method, significantly reducing the digital implementation effort. Moreover, instead of traditional instantaneous current detection, the average inductor current control is introduced to ensure the converter operated along MCT, eliminating the requirement for dc-to-MHz wide-bandwidth current sensing. High efficiency and easy implementation are achieved with the proposed method. The theoretical analysis is verified via computer simulation.
{"title":"Closed-Form Modulation Strategy for Current Minimization of Cascaded Buck+Boost Converters","authors":"Sirun Zhu, Weijian Han","doi":"10.1109/peas53589.2021.9628792","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628792","url":null,"abstract":"This paper proposes a closed-form modulation strategy for inductor current minimization of cascaded buck+boost converters (CBBCs). The minimum rms current trajectory (MCT) is analytically derived achieving low conduction and switching losses, and high efficiency. The proposed method does not rely on look-up tables that widely used in existing optimization method, significantly reducing the digital implementation effort. Moreover, instead of traditional instantaneous current detection, the average inductor current control is introduced to ensure the converter operated along MCT, eliminating the requirement for dc-to-MHz wide-bandwidth current sensing. High efficiency and easy implementation are achieved with the proposed method. The theoretical analysis is verified via computer simulation.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133962885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628813
Guangfu Ning, Bo Yuan, Liqing Liao, Guo Xu, M. Su
Various low dc voltage sources and energy storage devices are usually used in the industrial high voltage field, this paper introduces a high step-up pulse with modulation DC-DC converter based on the coupled inductor and resonant capacitor. The converter consists of an input-output in series boost unit and m (m > 1) expandable units, where each expandable unit includes two coupled-inductor-resonant-capacitor units. Meanwhile, due to the existence of resonant unit, all the diodes can realize soft switching.
{"title":"An Expandable High Step-up Resonant DC-DC Converter","authors":"Guangfu Ning, Bo Yuan, Liqing Liao, Guo Xu, M. Su","doi":"10.1109/peas53589.2021.9628813","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628813","url":null,"abstract":"Various low dc voltage sources and energy storage devices are usually used in the industrial high voltage field, this paper introduces a high step-up pulse with modulation DC-DC converter based on the coupled inductor and resonant capacitor. The converter consists of an input-output in series boost unit and m (m > 1) expandable units, where each expandable unit includes two coupled-inductor-resonant-capacitor units. Meanwhile, due to the existence of resonant unit, all the diodes can realize soft switching.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134639827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628834
Shengyu Liu, Zishun Peng, Li Li, Zhenxing Zhao, Weng Zhou, Yuxing Dai
To improve the problem that the single power device inverter power supply cannot meet the requirements of power quality control under the new situation due to the poor high-frequency performance or high-cost limitation, this paper adopts the harmonic current frequency division control technology combined with the characteristics of Si IGBT and SiC MOSFET devices, and proposes a parallel multi-functional power supply scheme based on Si IGBT and SiC MOSFET inverters to compensate the harmonic current. The high-precision current tracking control is carried out through the fractional-order model predictive control, which improves the current control accuracy of the inverter power supply. The simulation and experimental results show that the scheme is safe, reliable and has various functions, and has a good ability of harmonic control and reactive power compensation.
{"title":"Parallel type based on Si-IGBT and SiC-MOSFET inverter Research on Multifunctional Power Supply","authors":"Shengyu Liu, Zishun Peng, Li Li, Zhenxing Zhao, Weng Zhou, Yuxing Dai","doi":"10.1109/peas53589.2021.9628834","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628834","url":null,"abstract":"To improve the problem that the single power device inverter power supply cannot meet the requirements of power quality control under the new situation due to the poor high-frequency performance or high-cost limitation, this paper adopts the harmonic current frequency division control technology combined with the characteristics of Si IGBT and SiC MOSFET devices, and proposes a parallel multi-functional power supply scheme based on Si IGBT and SiC MOSFET inverters to compensate the harmonic current. The high-precision current tracking control is carried out through the fractional-order model predictive control, which improves the current control accuracy of the inverter power supply. The simulation and experimental results show that the scheme is safe, reliable and has various functions, and has a good ability of harmonic control and reactive power compensation.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131021913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628500
Kang Hong, Guo Xu, Guangfu Ning, Yonglu Liu, M. Su
This paper proposes a dual-transformer-based phase-shifted PWM DC-DC converter with wide ZVZCS Range. The proposed converter realizes two full bridges in parallel by sharing a half bridge, which reduces the number of switches. The ZVS range of the lagging switches is extended by the leakage inductors of the two transformers, and the ZCS condition of the auxiliary half bridge is realized by phase shift control. Finally, simulation results have verified the wide ZVZCS range.
{"title":"Dual-Transformer-Based Phase-Shifted PWM DC-DC Converter with Wide ZVZCS Range","authors":"Kang Hong, Guo Xu, Guangfu Ning, Yonglu Liu, M. Su","doi":"10.1109/peas53589.2021.9628500","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628500","url":null,"abstract":"This paper proposes a dual-transformer-based phase-shifted PWM DC-DC converter with wide ZVZCS Range. The proposed converter realizes two full bridges in parallel by sharing a half bridge, which reduces the number of switches. The ZVS range of the lagging switches is extended by the leakage inductors of the two transformers, and the ZCS condition of the auxiliary half bridge is realized by phase shift control. Finally, simulation results have verified the wide ZVZCS range.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134143266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628822
Faheem Muhammad, Xinke Wu, Jinxu Yang, Yu Qi
This article discusses the operating performance of a four-switch resonance inverting bidirectional buck-boost DC/DC converter using a novel three-dimensional control variable scheme. This novel control scheme allows DC/DC converter to operates on wide-input to wide-output voltage range but also helps to achieve zero-voltage switching ZVS operation for all four switches. Additionally, the RMS value of resonance current is significant reduced, which is directly proportional to conduction loss.In the end, a four-switch resonance inverting buck-boost DC/DC converter is designed and experimentally tested, the prototype has recorded over 99% peak efficiency. The converter operates from -48Vdc to 28Vdc ~ 60Vdc Voltage.
{"title":"A noval ZVS Control Scheme for Four-Switch Resonance Inverting bidirectional buck-boost DC/DC Converter for 5G-RF Power Amplifier","authors":"Faheem Muhammad, Xinke Wu, Jinxu Yang, Yu Qi","doi":"10.1109/peas53589.2021.9628822","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628822","url":null,"abstract":"This article discusses the operating performance of a four-switch resonance inverting bidirectional buck-boost DC/DC converter using a novel three-dimensional control variable scheme. This novel control scheme allows DC/DC converter to operates on wide-input to wide-output voltage range but also helps to achieve zero-voltage switching ZVS operation for all four switches. Additionally, the RMS value of resonance current is significant reduced, which is directly proportional to conduction loss.In the end, a four-switch resonance inverting buck-boost DC/DC converter is designed and experimentally tested, the prototype has recorded over 99% peak efficiency. The converter operates from -48Vdc to 28Vdc ~ 60Vdc Voltage.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133611912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628458
Pengyuan Jiang, F. Deng, Q. Yu, Jifeng Zhao
The main challenge of the medium-voltage drive with modular multilevel converters (MMCs) is the capacitor voltage ripple, and the existing suppression method inevitably injects high-frequency common-mode voltage and circulating current into MMCs. However, circulating current errors occur with the increase of common-mode voltage frequency and lead to failure of high-frequency injection methods. This paper proposes an improved high-frequency injection method, which can suppress the capacitor voltage ripple under circulating current errors through compensating the circulating current reference. The proposed improved high-frequency injection method can reduce the peak value of arm current and regulate the compensation parameter automatically. Simulation studies with the professional tool PLECS are conducted and results confirm the effectiveness of the proposed improved high-frequency injection method.
{"title":"Capacitor Voltage Ripple Suppression of Modular Multilevel Converters Based on Improved High-Frequency Injection Method","authors":"Pengyuan Jiang, F. Deng, Q. Yu, Jifeng Zhao","doi":"10.1109/peas53589.2021.9628458","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628458","url":null,"abstract":"The main challenge of the medium-voltage drive with modular multilevel converters (MMCs) is the capacitor voltage ripple, and the existing suppression method inevitably injects high-frequency common-mode voltage and circulating current into MMCs. However, circulating current errors occur with the increase of common-mode voltage frequency and lead to failure of high-frequency injection methods. This paper proposes an improved high-frequency injection method, which can suppress the capacitor voltage ripple under circulating current errors through compensating the circulating current reference. The proposed improved high-frequency injection method can reduce the peak value of arm current and regulate the compensation parameter automatically. Simulation studies with the professional tool PLECS are conducted and results confirm the effectiveness of the proposed improved high-frequency injection method.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"44 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132153969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628632
Qingyu Song, Feifan Ji, Yanjun Li
The actual torque of PMSM may discrepant from the expected torque due to the non-linear characteristics and inconsistency during mass production of PMSM. Meanwhile, achieving high-precision torque control is vital to the safety performance of electric vehicles. A proposed multi-closed-loop algorithm is introduced in this paper. In order to reduce cost and save space, no torque sensors are used. A look-up table model is established by analyzing the data of the calibration experiments, which realizes the high-precision observation of the torque. Under the control of the voltage and current double closed-loop, the proposed power closed-loop further improves the accuracy. The stability of the whole system is analyzed by small signal model, via which, design instructions of proper PI controller parameters are given out. The strategy is verified through the simulation and experimental results.
{"title":"A High-accuracy Torque Control Strategy of PMSM for Electric Vehicles","authors":"Qingyu Song, Feifan Ji, Yanjun Li","doi":"10.1109/peas53589.2021.9628632","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628632","url":null,"abstract":"The actual torque of PMSM may discrepant from the expected torque due to the non-linear characteristics and inconsistency during mass production of PMSM. Meanwhile, achieving high-precision torque control is vital to the safety performance of electric vehicles. A proposed multi-closed-loop algorithm is introduced in this paper. In order to reduce cost and save space, no torque sensors are used. A look-up table model is established by analyzing the data of the calibration experiments, which realizes the high-precision observation of the torque. Under the control of the voltage and current double closed-loop, the proposed power closed-loop further improves the accuracy. The stability of the whole system is analyzed by small signal model, via which, design instructions of proper PI controller parameters are given out. The strategy is verified through the simulation and experimental results.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134445737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628459
Yujie Ding, Haimeng Wu, Zhiwei Gao, Hailong Zhang
With the increasing deployment of the electric vehicles, the study of advanced battery charging strategy has become of great significance to improve charging performance with reduced loss. This paper presents an optimized adaptive charging strategy for EV battery packs based on a developed system loss model. An electrical model integrated with thermal properties for the lithium-ion battery with cooling as well as a full loss model for the power converter have been included in this complete model. To reduce the overall loss of the charging system, the influence of temperature and varying internal resistance at different state of charge (SOC) have been considered to obtain an objective function. Moreover, an enhanced particle swarm optimization (PSO) algorithm is proposed and applied to speed up convergence time as well as enhance the precision of the solution. The results show that this proposed strategy can reduce the total loss by 4.01% and a 7.48% decrease of the charging time compared with the classical approach without applying this optimization.
{"title":"An Adaptive Charging Strategy of Lithium-ion Battery for Loss Reduction with Thermal Effect Consideration","authors":"Yujie Ding, Haimeng Wu, Zhiwei Gao, Hailong Zhang","doi":"10.1109/peas53589.2021.9628459","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628459","url":null,"abstract":"With the increasing deployment of the electric vehicles, the study of advanced battery charging strategy has become of great significance to improve charging performance with reduced loss. This paper presents an optimized adaptive charging strategy for EV battery packs based on a developed system loss model. An electrical model integrated with thermal properties for the lithium-ion battery with cooling as well as a full loss model for the power converter have been included in this complete model. To reduce the overall loss of the charging system, the influence of temperature and varying internal resistance at different state of charge (SOC) have been considered to obtain an objective function. Moreover, an enhanced particle swarm optimization (PSO) algorithm is proposed and applied to speed up convergence time as well as enhance the precision of the solution. The results show that this proposed strategy can reduce the total loss by 4.01% and a 7.48% decrease of the charging time compared with the classical approach without applying this optimization.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"325 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133208141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-13DOI: 10.1109/peas53589.2021.9628634
L. Sang, Yang Zhou, J. Wu, X. Niu, Zechen Du, Hao Shi, Jialin Li, Fei Yang
We study the electrical and reliability characteristics of 6500V/25A SiC diode module. The diode module consists of the active metal bonding (AMB) AlN substrates mounted on an AlSiC base plate. Each AMB is assembled with one 6500V/25A SiC diode single chip. We mainly study the typical static characteristics of 6500V/25A SiC diode module measured at room temperature and high temperature. The measurement results show that the on-resistance increases when the module works at higher temperature and the reverse characteristics have good high temperature stability. The switching experiments show very low reverse recovery time and reverse recovery charge. At the same time, the 6500V/25A SiC diode module has passed the 1000h HTRB, H3TRB, temperature cycling, high temperature and high humidity reliability assessments. This means that the 6500V/25A SiC diode module has good high temperature reliability and can be used for subsequent devices applications.
{"title":"The electrical and reliability characteristics of 6500V/25A SiC diode module","authors":"L. Sang, Yang Zhou, J. Wu, X. Niu, Zechen Du, Hao Shi, Jialin Li, Fei Yang","doi":"10.1109/peas53589.2021.9628634","DOIUrl":"https://doi.org/10.1109/peas53589.2021.9628634","url":null,"abstract":"We study the electrical and reliability characteristics of 6500V/25A SiC diode module. The diode module consists of the active metal bonding (AMB) AlN substrates mounted on an AlSiC base plate. Each AMB is assembled with one 6500V/25A SiC diode single chip. We mainly study the typical static characteristics of 6500V/25A SiC diode module measured at room temperature and high temperature. The measurement results show that the on-resistance increases when the module works at higher temperature and the reverse characteristics have good high temperature stability. The switching experiments show very low reverse recovery time and reverse recovery charge. At the same time, the 6500V/25A SiC diode module has passed the 1000h HTRB, H3TRB, temperature cycling, high temperature and high humidity reliability assessments. This means that the 6500V/25A SiC diode module has good high temperature reliability and can be used for subsequent devices applications.","PeriodicalId":268264,"journal":{"name":"2021 IEEE 1st International Power Electronics and Application Symposium (PEAS)","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121784339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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