Pub Date : 2018-03-04DOI: 10.1109/APEC.2018.8341256
M. Luol, D. Dujić, J. Allmeling
Magnetic hysteresis together with eddy current effects are typically present in metal based core materials and contribute significantly to the nonlinearity and power loss of the magnetic components operating in power electronic converters. In order to investigate their influence on the system's behavior in time domain, model which is accurate and simple enough to be integrated into circuit simulation environment, is desired. This work proposes a modeling's approach using permeance-capacitance based magnetic circuit, which combines the hysteresis and eddy current effect of the magnetic components in system-level time domain simulation.
{"title":"Permeance based modeling of magnetic hysteresis with inclusion of eddy current effect","authors":"M. Luol, D. Dujić, J. Allmeling","doi":"10.1109/APEC.2018.8341256","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341256","url":null,"abstract":"Magnetic hysteresis together with eddy current effects are typically present in metal based core materials and contribute significantly to the nonlinearity and power loss of the magnetic components operating in power electronic converters. In order to investigate their influence on the system's behavior in time domain, model which is accurate and simple enough to be integrated into circuit simulation environment, is desired. This work proposes a modeling's approach using permeance-capacitance based magnetic circuit, which combines the hysteresis and eddy current effect of the magnetic components in system-level time domain simulation.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131576408","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341391
Andy Schroedermeier, D. Ludois
A dv/dt filter is useful to mitigate the deleterious effects of voltage pulses with high edge rates, such as voltage overshoot in motor drive systems, which can cause premature motor failure. With the introduction of wide-bandgap semiconductor drives, these issues will become more pronounced. This paper introduces a new type of dv/dt filter where the inductor, capacitor, and damping resistor are integrated into the output bus bar or cable of the inverter. This integrated filter may be smaller, lighter, and cheaper to construct than filters built from discrete components. An analytical model of the integrated dv/dt filter is developed, and this model is used to design output filters for a 460 V AC, 3-phase silicon carbide motor drive that meet the NEMA MG 1 Part 31 requirements for inverter-rated motors. Prototype filters are constructed and tested with a silicon carbide inverter connected to a 460 Vrms induction motor, and experimental results demonstrate output waveforms that match the analytical model and meet the NEMA requirements.
{"title":"Integrated inductors, capacitors, and damping in bus bars for dv/dt filter applications","authors":"Andy Schroedermeier, D. Ludois","doi":"10.1109/APEC.2018.8341391","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341391","url":null,"abstract":"A dv/dt filter is useful to mitigate the deleterious effects of voltage pulses with high edge rates, such as voltage overshoot in motor drive systems, which can cause premature motor failure. With the introduction of wide-bandgap semiconductor drives, these issues will become more pronounced. This paper introduces a new type of dv/dt filter where the inductor, capacitor, and damping resistor are integrated into the output bus bar or cable of the inverter. This integrated filter may be smaller, lighter, and cheaper to construct than filters built from discrete components. An analytical model of the integrated dv/dt filter is developed, and this model is used to design output filters for a 460 V AC, 3-phase silicon carbide motor drive that meet the NEMA MG 1 Part 31 requirements for inverter-rated motors. Prototype filters are constructed and tested with a silicon carbide inverter connected to a 460 Vrms induction motor, and experimental results demonstrate output waveforms that match the analytical model and meet the NEMA requirements.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124570542","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341079
A. Moeini, Shuo Wang
In this paper, two state-of-charge (SOC) balancing techniques are proposed for an electrical vehicle charging station which is based on a grid-tied cascaded H-bridge (CHB) multilevel converter. The first proposed technique uses the redundant states of the CHB converter to generate different AC voltages to balance the SOCs of the CHB cells. For the first proposed technique, the active power injected to the CHB converter is calculated and the optimal switching state that can regulate the SOCs of batteries is designed before switching transitions. In the second proposed technique, the information of AC input current is employed to design the switching states at each quarter of the period. As shown in this paper, the two proposed techniques can regulate the SOCs of the multilevel converter much faster than two conventional techniques in literature without increasing cost or complexity of the converter. This can increase the battery charging speed on the grid-tied converter. The experiments are conducted on a 7-level CHB converter to validate the two proposed techniques.
{"title":"The state of charge balancing techniques for electrical vehicle charging stations with cascaded H-bridge multilevel converters","authors":"A. Moeini, Shuo Wang","doi":"10.1109/APEC.2018.8341079","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341079","url":null,"abstract":"In this paper, two state-of-charge (SOC) balancing techniques are proposed for an electrical vehicle charging station which is based on a grid-tied cascaded H-bridge (CHB) multilevel converter. The first proposed technique uses the redundant states of the CHB converter to generate different AC voltages to balance the SOCs of the CHB cells. For the first proposed technique, the active power injected to the CHB converter is calculated and the optimal switching state that can regulate the SOCs of batteries is designed before switching transitions. In the second proposed technique, the information of AC input current is employed to design the switching states at each quarter of the period. As shown in this paper, the two proposed techniques can regulate the SOCs of the multilevel converter much faster than two conventional techniques in literature without increasing cost or complexity of the converter. This can increase the battery charging speed on the grid-tied converter. The experiments are conducted on a 7-level CHB converter to validate the two proposed techniques.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124046572","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 : 2018-03-04DOI: 10.1109/APEC.2018.8340985
J. Afsharian, D. Xu, Bin Wu, B. Gong, Z. Yang
In this paper, the one phase loss operation of the three-phase isolated buck matrix-type rectifier with integrated boost output stage is analyzed. During normal operation (three-phase operation) the boost switch is disabled and during one phase loss is enabled. The analysis of one phase loss with combination of buck and boost (buck+boost) operation shows that the converter is able to deliver two-third of rated power and regulate the output voltage with maximum output voltage drop less than 4 % of nominal output voltage with significantly smaller output capacitor comparing with conventional buck matrix-type rectifier. The performance of the converter in buck and buck+boost operation is evaluated and verified by simulations and experiments on a 5 kW prototype.
{"title":"Analysis of one phase loss operation of three-phase isolated buck matrix-type rectifier with a boost switch","authors":"J. Afsharian, D. Xu, Bin Wu, B. Gong, Z. Yang","doi":"10.1109/APEC.2018.8340985","DOIUrl":"https://doi.org/10.1109/APEC.2018.8340985","url":null,"abstract":"In this paper, the one phase loss operation of the three-phase isolated buck matrix-type rectifier with integrated boost output stage is analyzed. During normal operation (three-phase operation) the boost switch is disabled and during one phase loss is enabled. The analysis of one phase loss with combination of buck and boost (buck+boost) operation shows that the converter is able to deliver two-third of rated power and regulate the output voltage with maximum output voltage drop less than 4 % of nominal output voltage with significantly smaller output capacitor comparing with conventional buck matrix-type rectifier. The performance of the converter in buck and buck+boost operation is evaluated and verified by simulations and experiments on a 5 kW prototype.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129451698","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341027
Rabisankar Roy, S. Kapat
Stability of a distributed power architecture (DPA) still remains a major concern, even though individual stand-alone DC-DC converters are designed with sufficient (small-signal) stability margins. In such architectures, a tightly regulated point-of-load (PoL) converter resembles a constant power load (CPL) which introduces a negative-impedance effect to the source converter. This effect may introduce limit cycle oscillation (LCO) and may eventually destabilize the overall DPA. In this paper, a source buck converter is considered under digital current-mode control (DCMC) with a proportional-integral (PI) voltage controller, which is driving a CPL buck converter. During a power step-transient in the CPL, stable controller gain ranges under DCMC are computed for the source converter for individual operating conditions. Thereafter, a phase-plane based geometric framework is proposed to compute the optimal proportional gain for the source converter to achieve near time optimal recovery. A hardware prototype is made with 50 W nominal power ratings for individual converters. Analytical predictions and improved performance are validated experimentally.
{"title":"Near time optimal recovery in a digitally current mode controlled buck converter driving a CPL","authors":"Rabisankar Roy, S. Kapat","doi":"10.1109/APEC.2018.8341027","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341027","url":null,"abstract":"Stability of a distributed power architecture (DPA) still remains a major concern, even though individual stand-alone DC-DC converters are designed with sufficient (small-signal) stability margins. In such architectures, a tightly regulated point-of-load (PoL) converter resembles a constant power load (CPL) which introduces a negative-impedance effect to the source converter. This effect may introduce limit cycle oscillation (LCO) and may eventually destabilize the overall DPA. In this paper, a source buck converter is considered under digital current-mode control (DCMC) with a proportional-integral (PI) voltage controller, which is driving a CPL buck converter. During a power step-transient in the CPL, stable controller gain ranges under DCMC are computed for the source converter for individual operating conditions. Thereafter, a phase-plane based geometric framework is proposed to compute the optimal proportional gain for the source converter to achieve near time optimal recovery. A hardware prototype is made with 50 W nominal power ratings for individual converters. Analytical predictions and improved performance are validated experimentally.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127151356","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341033
J. Qahouq, Yuan Cao
The paper introduces the concept of a battery system or pack architecture that is divided into several battery modules that share the load power wirelessly and are controlled wirelessly. Each of the wireless battery modules includes its own power electronics for DC-AC power conversion for Wireless Power Transfer (WPT), regulation of voltage and State-Of-Charge (SOC), and wireless communication link with an on-board unit. The on-board unit combines the power received wirelessly from all of the battery modules (AC-DC or AC-AC conversion) and its master controller uses the voltage, current, and other information received wirelessly from the battery modules to wirelessly send back control commands in order to regulate the discharge (or charge) rate of each battery module. For example, in the Electric Vehicles (EVs) application this wirelessly controlled and distributed battery system or pack can potentially allow for exchanging or swapping the wireless battery modules in a safer, easier, and faster manner. This can potentially contribute to significantly reduced “Range Anxiety” phenomenon that is associated with EVs.
{"title":"Distributed battery system with wireless control and power transfer — A concept introduction","authors":"J. Qahouq, Yuan Cao","doi":"10.1109/APEC.2018.8341033","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341033","url":null,"abstract":"The paper introduces the concept of a battery system or pack architecture that is divided into several battery modules that share the load power wirelessly and are controlled wirelessly. Each of the wireless battery modules includes its own power electronics for DC-AC power conversion for Wireless Power Transfer (WPT), regulation of voltage and State-Of-Charge (SOC), and wireless communication link with an on-board unit. The on-board unit combines the power received wirelessly from all of the battery modules (AC-DC or AC-AC conversion) and its master controller uses the voltage, current, and other information received wirelessly from the battery modules to wirelessly send back control commands in order to regulate the discharge (or charge) rate of each battery module. For example, in the Electric Vehicles (EVs) application this wirelessly controlled and distributed battery system or pack can potentially allow for exchanging or swapping the wireless battery modules in a safer, easier, and faster manner. This can potentially contribute to significantly reduced “Range Anxiety” phenomenon that is associated with EVs.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130563925","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341327
Sanghyeon Park, Lei Gu, J. Rivas-Davila
This paper presents a high-voltage dc-dc converter that includes inductively-isolated rectifiers. Previous work on multi-stage class-DE rectifiers only included capacitive dc isolation, limiting the output voltage to twice of the capacitor voltage rating. By adding an air-core transformer before the rectifier for inductive isolation, the maximum output voltage can be twice the breakdown voltage of the insulation between the transformer's primary and secondary windings, thus allowing the implementation of a small, lightweight, and fast transient high-voltage dc-dc converter. We experimentally demonstrate a multi-modular converter design with 60 V input voltage and 35 kV output voltage with 73 % efficiency.
{"title":"60 V-to-35 kV input-parallel output-series DC-DC converter using multi-level class-DE rectifiers","authors":"Sanghyeon Park, Lei Gu, J. Rivas-Davila","doi":"10.1109/APEC.2018.8341327","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341327","url":null,"abstract":"This paper presents a high-voltage dc-dc converter that includes inductively-isolated rectifiers. Previous work on multi-stage class-DE rectifiers only included capacitive dc isolation, limiting the output voltage to twice of the capacitor voltage rating. By adding an air-core transformer before the rectifier for inductive isolation, the maximum output voltage can be twice the breakdown voltage of the insulation between the transformer's primary and secondary windings, thus allowing the implementation of a small, lightweight, and fast transient high-voltage dc-dc converter. We experimentally demonstrate a multi-modular converter design with 60 V input voltage and 35 kV output voltage with 73 % efficiency.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127885663","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}
This paper proposes a torque ripple reduction method for the aircraft wound-rotor synchronous starter/generator in the starting mode. The high-frequency injection method which is commonly used in sensorless control and parameter identification algorithms yields significant torque ripple on the main generator (MG). Since the main exciter (ME) and the MG are mounted on the same shaft, in this paper, the torque of the ME is controlled to compensate the torque ripple of the MG, so that the ripple on the output torque can be reduced. A method which integrates the open-loop control of the field current of the MG into the closed-loop control of the torque of the ME is proposed. The effectiveness of this method is verified by experimental results.
{"title":"A torque ripple reduction method for the aircraft wound-rotor synchronous starter/generator in the starting mode","authors":"Shuai Mao, Weiguo Liu, Zan Zhang, Ningfei Jiao, Dongdong Zhao","doi":"10.1109/APEC.2018.8341065","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341065","url":null,"abstract":"This paper proposes a torque ripple reduction method for the aircraft wound-rotor synchronous starter/generator in the starting mode. The high-frequency injection method which is commonly used in sensorless control and parameter identification algorithms yields significant torque ripple on the main generator (MG). Since the main exciter (ME) and the MG are mounted on the same shaft, in this paper, the torque of the ME is controlled to compensate the torque ripple of the MG, so that the ripple on the output torque can be reduced. A method which integrates the open-loop control of the field current of the MG into the closed-loop control of the torque of the ME is proposed. The effectiveness of this method is verified by experimental results.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129228792","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341422
Y. Mukunoki, Takeshi Horiguchi, A. Nishizawa, Kentaro Konno, T. Matsuo, M. Kuzumoto, M. Hagiwara, H. Akagi
This paper describes electro-thermal co-simulation of two parallel-connected SiC-MOSFETs using a temperature-dependent compact model for a discrete SiC-MOSFET. The temperature-dependent compact model is constructed on the basis of the previous model with appropriate-modification of output characteristics and threshold voltage. This compact model also gives the accurate reproducibility of the transient waveforms in a high region of drain current. The current sharing simulation between the parallel-connected SiC-MOSFETs under thermally-imbalanced conditions is experimentally verified. Based on the above verification, the electro-thermal co-simulation in a boost chopper is conducted, which successfully shows the junction temperature distribution between the two SiC-MOSFETs.
{"title":"Electro-thermal co-simulation of two parallel-connected SiC-MOSFETs under thermally-imbalanced conditions","authors":"Y. Mukunoki, Takeshi Horiguchi, A. Nishizawa, Kentaro Konno, T. Matsuo, M. Kuzumoto, M. Hagiwara, H. Akagi","doi":"10.1109/APEC.2018.8341422","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341422","url":null,"abstract":"This paper describes electro-thermal co-simulation of two parallel-connected SiC-MOSFETs using a temperature-dependent compact model for a discrete SiC-MOSFET. The temperature-dependent compact model is constructed on the basis of the previous model with appropriate-modification of output characteristics and threshold voltage. This compact model also gives the accurate reproducibility of the transient waveforms in a high region of drain current. The current sharing simulation between the parallel-connected SiC-MOSFETs under thermally-imbalanced conditions is experimentally verified. Based on the above verification, the electro-thermal co-simulation in a boost chopper is conducted, which successfully shows the junction temperature distribution between the two SiC-MOSFETs.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125370250","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 : 2018-03-04DOI: 10.1109/APEC.2018.8341240
Bogdan Džonlaga, D. R. Joca, L. Quéval, J. Vannier
The influence of the coupling of the arm inductors of a modular multilevel converter has been investigated through transient simulations. In particular, positive, negative and zero coupling coefficient were considered for both steady-state and transient operating conditions. The effect of the coupling on the transient response, the capacitor voltage ripple, the circulating current, the DC short-circuit current and the switch power losses has been closely examined. The possibility to reduce either the circulating current or the DC short-circuit current has been demonstrated, opening the door to improved performances of modular multilevel converter with only minor modifications.
{"title":"Transient analysis of a modular multilevel converter with coupled arm inductors","authors":"Bogdan Džonlaga, D. R. Joca, L. Quéval, J. Vannier","doi":"10.1109/APEC.2018.8341240","DOIUrl":"https://doi.org/10.1109/APEC.2018.8341240","url":null,"abstract":"The influence of the coupling of the arm inductors of a modular multilevel converter has been investigated through transient simulations. In particular, positive, negative and zero coupling coefficient were considered for both steady-state and transient operating conditions. The effect of the coupling on the transient response, the capacitor voltage ripple, the circulating current, the DC short-circuit current and the switch power losses has been closely examined. The possibility to reduce either the circulating current or the DC short-circuit current has been demonstrated, opening the door to improved performances of modular multilevel converter with only minor modifications.","PeriodicalId":113756,"journal":{"name":"2018 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122975008","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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