Pub Date : 2021-06-14DOI: 10.1109/APEC42165.2021.9487179
Haleema Qamar, Hafsa Qamar, Deliang Wu, R. Ayyanar
DC link capacitor is one of the critical components in EV powertrain affecting the size, weight, and reliability. In a cascaded architecture (DC-DC stage followed by DC-AC stage), the size of DC link capacitor is dictated by the ripple current it has to support from both the stages. This work explores the benefits of relatively new PWM method called 240°-Clamped space vector PWM (240CPWM) in terms of reduced current stress on the DC link capacitor which corresponds to reduction in the DC link capacitor size. Detailed analysis of ripple current contribution from DC-DC and DC-AC stages is carried out leading to design methods for the DC link capacitor. It is shown that the current stress on the DC link capacitor for 240CPWM is 25% lower as compared to CSVPWM under same operating conditions. The analysis is validated by the experimental results from a 5 kW, 500 V (line to line voltage) hardware prototype.
{"title":"DC Link Capacitor Sizing for 240°-Clamped Space Vector PWM for EV Traction Inverters","authors":"Haleema Qamar, Hafsa Qamar, Deliang Wu, R. Ayyanar","doi":"10.1109/APEC42165.2021.9487179","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487179","url":null,"abstract":"DC link capacitor is one of the critical components in EV powertrain affecting the size, weight, and reliability. In a cascaded architecture (DC-DC stage followed by DC-AC stage), the size of DC link capacitor is dictated by the ripple current it has to support from both the stages. This work explores the benefits of relatively new PWM method called 240°-Clamped space vector PWM (240CPWM) in terms of reduced current stress on the DC link capacitor which corresponds to reduction in the DC link capacitor size. Detailed analysis of ripple current contribution from DC-DC and DC-AC stages is carried out leading to design methods for the DC link capacitor. It is shown that the current stress on the DC link capacitor for 240CPWM is 25% lower as compared to CSVPWM under same operating conditions. The analysis is validated by the experimental results from a 5 kW, 500 V (line to line voltage) hardware prototype.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79326340","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487368
Christian Rainer, Roberto Rizzolatti, S. Saggini, Mario Ursino
Several applications are migrating to a 48-V power-delivery architecture, including hyper-scale data-centers and artificial intelligence (AI) server-racks power distribution. High level trends of AI applications pushes computation aggressively towards sensors and actuators, opening considerable research and business development windows. Within the 48-V power-delivery architecture, new intermediate bus converter (IBC) solutions so called hybrid switched capacitor converter (HSC) [1] for high efficiency and high power density applications are becoming essential. To increase the IBC robustness and current sharing quality this paper is proposing a lossless current sensing method for an HSC converter with autotransformer. Experimental results on a 450 W 48-V to 6-V HSC module are showing the effectiveness of the proposed solution.
{"title":"Lossless Current Sensing Method for Hybrid Switched Capacitor Converter","authors":"Christian Rainer, Roberto Rizzolatti, S. Saggini, Mario Ursino","doi":"10.1109/APEC42165.2021.9487368","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487368","url":null,"abstract":"Several applications are migrating to a 48-V power-delivery architecture, including hyper-scale data-centers and artificial intelligence (AI) server-racks power distribution. High level trends of AI applications pushes computation aggressively towards sensors and actuators, opening considerable research and business development windows. Within the 48-V power-delivery architecture, new intermediate bus converter (IBC) solutions so called hybrid switched capacitor converter (HSC) [1] for high efficiency and high power density applications are becoming essential. To increase the IBC robustness and current sharing quality this paper is proposing a lossless current sensing method for an HSC converter with autotransformer. Experimental results on a 450 W 48-V to 6-V HSC module are showing the effectiveness of the proposed solution.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79328758","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487319
Fahad Alaql, Abdullah Alhatlani, I. Batarseh
When the input or output voltage range of the LLC converter is wide, the switching frequency must extend its range to cover the required voltage, and the magnetizing inductance needs to be reduced to increase the voltage gain. This leads to reduced efficiency due to increased conduction losses. Consequently, this paper proposes an LLC resonant converter with a wide voltage range based on a reconfigurable voltage rectifier for high-DC bus applications. Owing to the reconfiguration of the rectifier by two active switches, the rectifier can operate in three operation modes— voltage-doubler rectifier, a voltage-tripler rectifier, and a voltage-quadrupler rectifier. The proposed converter extends its voltage gain by changing the rectifier structure while the switching frequency operates near the resonant frequency. All MOSFET switches are turned on with zero-voltage switching, and all secondary diodes are turned off with zero-current switching. As a result, the performance efficiency is improved compared to that of the conventional LLC converter. A laboratory prototype was designed and experimentally tested to validate the operation and advantages of the proposed converter.
{"title":"Improved LLC Resonant Converter with Rectifier Operating in Three Operation Modes for Wide Voltage Range Applications","authors":"Fahad Alaql, Abdullah Alhatlani, I. Batarseh","doi":"10.1109/APEC42165.2021.9487319","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487319","url":null,"abstract":"When the input or output voltage range of the LLC converter is wide, the switching frequency must extend its range to cover the required voltage, and the magnetizing inductance needs to be reduced to increase the voltage gain. This leads to reduced efficiency due to increased conduction losses. Consequently, this paper proposes an LLC resonant converter with a wide voltage range based on a reconfigurable voltage rectifier for high-DC bus applications. Owing to the reconfiguration of the rectifier by two active switches, the rectifier can operate in three operation modes— voltage-doubler rectifier, a voltage-tripler rectifier, and a voltage-quadrupler rectifier. The proposed converter extends its voltage gain by changing the rectifier structure while the switching frequency operates near the resonant frequency. All MOSFET switches are turned on with zero-voltage switching, and all secondary diodes are turned off with zero-current switching. As a result, the performance efficiency is improved compared to that of the conventional LLC converter. A laboratory prototype was designed and experimentally tested to validate the operation and advantages of the proposed converter.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81919784","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487247
Bowen Yang, Lulu Guo, Jin Ye
With the fast development of electric vehicles and vehicle onboard communication networks, modern electric vehicles suffer from potential threats from cyber networks. In order to secure vehicle safety and reliability, advanced attack detection techniques are in urgent need. In this paper, we propose a physics-based attack detection method using a random forest classifier. The key idea is to extract system features from the trustworthy and easy-to-get electric machine phase current signals, and use a random forest classifier to search a secure boundary to distinguish whether or not the powertrain system is under malicious cyber-attacks. The proposed method is tested and validated by simulation data generated from MATLAB Simulink. The results prove the feasibility of using electric machine phase current signals to represent multiple powertrain system features and accurately detect malicious attacks based on these extracted features.
{"title":"Physics-Based Attack Detection for Traction Motor Drives in Electric Vehicles Using Random Forest","authors":"Bowen Yang, Lulu Guo, Jin Ye","doi":"10.1109/APEC42165.2021.9487247","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487247","url":null,"abstract":"With the fast development of electric vehicles and vehicle onboard communication networks, modern electric vehicles suffer from potential threats from cyber networks. In order to secure vehicle safety and reliability, advanced attack detection techniques are in urgent need. In this paper, we propose a physics-based attack detection method using a random forest classifier. The key idea is to extract system features from the trustworthy and easy-to-get electric machine phase current signals, and use a random forest classifier to search a secure boundary to distinguish whether or not the powertrain system is under malicious cyber-attacks. The proposed method is tested and validated by simulation data generated from MATLAB Simulink. The results prove the feasibility of using electric machine phase current signals to represent multiple powertrain system features and accurately detect malicious attacks based on these extracted features.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84864367","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487170
Liang Wang, Haoyu Wang, Yu Liu, Junrui Liang, Minfan Fu
A novel dual-active-bridge based three-port converter (TPC) is proposed for islanded dc microgrids. The proposed converter can interface among three ports (PV source, battery, and dc-link) simultaneously with high integration. Rechargeable battery operates as an energy buffer to compensate for power mismatch between PV source and dc-link. Electric power can flow bi-directionally between the battery and dc-link. Pulse-width-modulation (PWM) on the primary side is utilized to realize the maximum power point tracking (MPPT) of PV panel. An optimized phase-shift-modulation (PSM) is introduced to regulate power flow, ensure ZVS among all MOSFETs and reduce circulating current over a wide range. To verify this concept, a 500 W rated prototype is designed. The designed prototype exhibits high efficiency in various operating modes. The experimental results agree well with the theoretical analysis.
{"title":"A Fully ZVS Dual-Active-Bridge Based Three-Port Converter with High Integration","authors":"Liang Wang, Haoyu Wang, Yu Liu, Junrui Liang, Minfan Fu","doi":"10.1109/APEC42165.2021.9487170","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487170","url":null,"abstract":"A novel dual-active-bridge based three-port converter (TPC) is proposed for islanded dc microgrids. The proposed converter can interface among three ports (PV source, battery, and dc-link) simultaneously with high integration. Rechargeable battery operates as an energy buffer to compensate for power mismatch between PV source and dc-link. Electric power can flow bi-directionally between the battery and dc-link. Pulse-width-modulation (PWM) on the primary side is utilized to realize the maximum power point tracking (MPPT) of PV panel. An optimized phase-shift-modulation (PSM) is introduced to regulate power flow, ensure ZVS among all MOSFETs and reduce circulating current over a wide range. To verify this concept, a 500 W rated prototype is designed. The designed prototype exhibits high efficiency in various operating modes. The experimental results agree well with the theoretical analysis.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84955017","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487186
Sandro Martin, Hui Li
A model predictive controller is proposed for an arm inductor-less MMC-based DC-DC solid-state transformer operating under interleaved phase-shifted square-wave modulation. The controller is based on an advanced dynamic model of the DC SST such that a closed-form solution of the underlying optimization problem is derived. The proposed converter achieves inductor-less current control and uses model-based linear regulators to generate current references. Simulation and experimental results are provided to validate the controller performance.
{"title":"Model Predictive Control of an Arm Inductor-less MMC-based DC SST","authors":"Sandro Martin, Hui Li","doi":"10.1109/APEC42165.2021.9487186","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487186","url":null,"abstract":"A model predictive controller is proposed for an arm inductor-less MMC-based DC-DC solid-state transformer operating under interleaved phase-shifted square-wave modulation. The controller is based on an advanced dynamic model of the DC SST such that a closed-form solution of the underlying optimization problem is derived. The proposed converter achieves inductor-less current control and uses model-based linear regulators to generate current references. Simulation and experimental results are provided to validate the controller performance.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84965506","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487051
Anran Wei, B. Lehman, W. Bowhers, M. Amirabadi
Non-inverting buck-boost converter is a classical topology that can provide wide range of voltage conversion and bidirectional power transfer; thus, it is frequently used in industrial applications. However, the conventional hard-switching configuration can only reach a high voltage conversion ratio at the expense of low efficiency due to switching loss. In this paper, a soft switching non-inverting buck-boost converter is proposed. This converter uses a small film capacitor in parallel with the link inductor to provide zero voltage switching (ZVS) by allowing the link capacitor and link inductor resonate between power transfer states. This paper presents the principles of the operation of this converter and verifies its performance through simulation and experiment.
{"title":"A soft-switching non-inverting buck-boost converter","authors":"Anran Wei, B. Lehman, W. Bowhers, M. Amirabadi","doi":"10.1109/APEC42165.2021.9487051","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487051","url":null,"abstract":"Non-inverting buck-boost converter is a classical topology that can provide wide range of voltage conversion and bidirectional power transfer; thus, it is frequently used in industrial applications. However, the conventional hard-switching configuration can only reach a high voltage conversion ratio at the expense of low efficiency due to switching loss. In this paper, a soft switching non-inverting buck-boost converter is proposed. This converter uses a small film capacitor in parallel with the link inductor to provide zero voltage switching (ZVS) by allowing the link capacitor and link inductor resonate between power transfer states. This paper presents the principles of the operation of this converter and verifies its performance through simulation and experiment.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85212636","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487463
Ramin Rahimi, Saeed Habibi, P. Shamsi, M. Ferdowsi
This paper presents a Z-source-based high step-up DC-DC converter that benefits from high voltage gain, low voltage stress on the semiconductor devices and the capacitors. The switched-capacitor cells are integrated with the conventional Z-source impedance network resulting in a new high step-up DC-DC converter. The proposed converter is suitable for photovoltaic (PV) applications where PV panels are linked to a 400 V DC bus in a DC microgrid. The proposed converter reduces the voltage stress on the diodes and the power switch to less than half the output voltage and achieves a high-voltage gain without imposing a limitation on the duty cycle and requiring a large number of components. The operating principles, the steady-state analysis, and a comparison with other similar high step-up DC-DC converters are presented. The simulation and experimental results validate the performance and the applicability of the proposed converter.
{"title":"A High Step-Up Z-Source DC-DC Converter for Integration of Photovoltaic Panels into DC Microgrid","authors":"Ramin Rahimi, Saeed Habibi, P. Shamsi, M. Ferdowsi","doi":"10.1109/APEC42165.2021.9487463","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487463","url":null,"abstract":"This paper presents a Z-source-based high step-up DC-DC converter that benefits from high voltage gain, low voltage stress on the semiconductor devices and the capacitors. The switched-capacitor cells are integrated with the conventional Z-source impedance network resulting in a new high step-up DC-DC converter. The proposed converter is suitable for photovoltaic (PV) applications where PV panels are linked to a 400 V DC bus in a DC microgrid. The proposed converter reduces the voltage stress on the diodes and the power switch to less than half the output voltage and achieves a high-voltage gain without imposing a limitation on the duty cycle and requiring a large number of components. The operating principles, the steady-state analysis, and a comparison with other similar high step-up DC-DC converters are presented. The simulation and experimental results validate the performance and the applicability of the proposed converter.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85240761","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487169
David Bamgboje, W. Harmon, T. Hu
In this work, a blocking-diode self-oscillating buck converter (SOBuC) is proposed to meet the demand for high performance LED drivers. For robustness and tight LED current regulation, multiple closed loop controls such as indirect inductor current reconstruction using offline PWM controller and peak current control using a common comparator were proposed and implemented. To cater for the lost signal during indirect inductor current reconstruction, control adjustments were made, and other strategies were proposed. The desired transient/steady state performance verified via simulation yielded a maximum efficiency of 94.8% and 2.7% LED current ripple factor.
{"title":"Self-oscillating Buck Converter LED Driver with Indirect Inductor Current Reconstruction","authors":"David Bamgboje, W. Harmon, T. Hu","doi":"10.1109/APEC42165.2021.9487169","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487169","url":null,"abstract":"In this work, a blocking-diode self-oscillating buck converter (SOBuC) is proposed to meet the demand for high performance LED drivers. For robustness and tight LED current regulation, multiple closed loop controls such as indirect inductor current reconstruction using offline PWM controller and peak current control using a common comparator were proposed and implemented. To cater for the lost signal during indirect inductor current reconstruction, control adjustments were made, and other strategies were proposed. The desired transient/steady state performance verified via simulation yielded a maximum efficiency of 94.8% and 2.7% LED current ripple factor.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76618285","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 : 2021-06-14DOI: 10.1109/APEC42165.2021.9487266
Zhongting Tang, Yongheng Yang, F. Blaabjerg
The unbalanced power losses of the semiconductor switches affect the thermal loading, and thus, the reliability of power converters is challenged. In this paper, the unbalance loss distribution of power devices has been analyzed in a full-bridge (FB) PV inverter, which employs the traditional hybrid unipolar pulse width modulation (UPWM) for reactive power injection. This analysis serves to improve the design and control of the FB inverter to enhance its reliability. More importantly, a new modulation method is proposed to balance the power losses, resulting in good thermal performance and increase lifetime. The proposed method periodically changes the switching operation modes at the grid frequency to ensure equal power losses, and thus, the almost identical junction temperature of each power switch. Simulation and experimental results have validated the effectiveness of the loss analysis and the proposed modulation scheme.
{"title":"Loss Unbalance Issue of the Full-bridge Inverter with Reactive Power Injection","authors":"Zhongting Tang, Yongheng Yang, F. Blaabjerg","doi":"10.1109/APEC42165.2021.9487266","DOIUrl":"https://doi.org/10.1109/APEC42165.2021.9487266","url":null,"abstract":"The unbalanced power losses of the semiconductor switches affect the thermal loading, and thus, the reliability of power converters is challenged. In this paper, the unbalance loss distribution of power devices has been analyzed in a full-bridge (FB) PV inverter, which employs the traditional hybrid unipolar pulse width modulation (UPWM) for reactive power injection. This analysis serves to improve the design and control of the FB inverter to enhance its reliability. More importantly, a new modulation method is proposed to balance the power losses, resulting in good thermal performance and increase lifetime. The proposed method periodically changes the switching operation modes at the grid frequency to ensure equal power losses, and thus, the almost identical junction temperature of each power switch. Simulation and experimental results have validated the effectiveness of the loss analysis and the proposed modulation scheme.","PeriodicalId":7050,"journal":{"name":"2021 IEEE Applied Power Electronics Conference and Exposition (APEC)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77057558","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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