Pub Date : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449551
R. Steckel, Christian Köbler, A. Kremser, H. Herzog
This paper presents an analysis of the additional harmonic losses in a dual three-phase induction machine, conducted for several modulation techniques. The time and spatial harmonics due to inverter supply are analysed using symmetrical components to investigate the effects of magnetic coupling in multi-phase machines. The harmonic losses are measured and segregation of the two loss components (current heat and core) performed in post-processing. The results are then juxtaposed with the harmonic losses in a three-phase induction machine serving as a reference.
{"title":"Analysis of Harmonic Losses due to Inverter Supply in Dual Three-Phase Induction Machines","authors":"R. Steckel, Christian Köbler, A. Kremser, H. Herzog","doi":"10.1109/IEMDC47953.2021.9449551","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449551","url":null,"abstract":"This paper presents an analysis of the additional harmonic losses in a dual three-phase induction machine, conducted for several modulation techniques. The time and spatial harmonics due to inverter supply are analysed using symmetrical components to investigate the effects of magnetic coupling in multi-phase machines. The harmonic losses are measured and segregation of the two loss components (current heat and core) performed in post-processing. The results are then juxtaposed with the harmonic losses in a three-phase induction machine serving as a reference.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126451025","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449510
Hailin Huang, Dawei Li, X. Ren, R. Qu
This paper investigates the performances of dual PM split tooth vernier machines (DP-STVMs). It has been proved that by adjusting the distribution of stator auxiliary teeth, the flux modulation effect and no-load back EMF of DP-STVMs can be enhanced. However, this irregular structure also changes the periodicity and increases the amplitude of cogging torque. To investigate the source of cogging torque in DP-STVMs, an analytical method based on airgap fields and Maxwell stress tenser method is used, which can easily present the contribution of each airgap field component to the cogging torque. Based on the analysis, novel cogging torque reduction methods are proposed in this paper. Compared to regular rotor skewing method, the proposed methods can achieve better suppression effect on cogging torque and less reduction on noload back EMF.
{"title":"Analysis and Reduction of Cogging Torque in Dual PM Vernier Machine with Irregular Split Teeth","authors":"Hailin Huang, Dawei Li, X. Ren, R. Qu","doi":"10.1109/IEMDC47953.2021.9449510","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449510","url":null,"abstract":"This paper investigates the performances of dual PM split tooth vernier machines (DP-STVMs). It has been proved that by adjusting the distribution of stator auxiliary teeth, the flux modulation effect and no-load back EMF of DP-STVMs can be enhanced. However, this irregular structure also changes the periodicity and increases the amplitude of cogging torque. To investigate the source of cogging torque in DP-STVMs, an analytical method based on airgap fields and Maxwell stress tenser method is used, which can easily present the contribution of each airgap field component to the cogging torque. Based on the analysis, novel cogging torque reduction methods are proposed in this paper. Compared to regular rotor skewing method, the proposed methods can achieve better suppression effect on cogging torque and less reduction on noload back EMF.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"330 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116355571","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449569
V. Abramenko, C. Di, I. Petrov, J. Pyrhönen
The paper considers an idea of novel modular approach to a resolver design. The rotor of the resolver represents a simple piece of laminated steel with variable reluctance as in commercial resolvers. The stator part, however, is different. Each stator tooth is replaced with an H-core segment, which contains two windings: excitation and sensing. The design is unified in such a way that the same cores can be used in manufacturing resolvers of different sizes with different pole numbers. The size of the stator is significantly reduced because it can cover only about one saliency pitch of resolver. The solution is especially advantageous in electrical drives where the motor has a large number of poles. However, the side effect, which has a negative impact on the accuracy of a resolver with the proposed stator, should be considered during the design. The side effect is analyzed in the proposed resolver structure using the finite element method (FEM) and some approaches to reduce its negative effect are proposed.
{"title":"Novel modular design of a position-sensing resolver","authors":"V. Abramenko, C. Di, I. Petrov, J. Pyrhönen","doi":"10.1109/IEMDC47953.2021.9449569","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449569","url":null,"abstract":"The paper considers an idea of novel modular approach to a resolver design. The rotor of the resolver represents a simple piece of laminated steel with variable reluctance as in commercial resolvers. The stator part, however, is different. Each stator tooth is replaced with an H-core segment, which contains two windings: excitation and sensing. The design is unified in such a way that the same cores can be used in manufacturing resolvers of different sizes with different pole numbers. The size of the stator is significantly reduced because it can cover only about one saliency pitch of resolver. The solution is especially advantageous in electrical drives where the motor has a large number of poles. However, the side effect, which has a negative impact on the accuracy of a resolver with the proposed stator, should be considered during the design. The side effect is analyzed in the proposed resolver structure using the finite element method (FEM) and some approaches to reduce its negative effect are proposed.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"295 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124276908","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449559
W. Gruber, Wolfgang Stallinger
This work deals with a compact and efficient permanent magnet excited synchronous machine to be used as paraglider towing winch. A battery supply with a voltage of only 48V is chosen for mobility and safety reasons. A rough machine design is first carried out analytically. After predesign, the final machine geometry is genetically optimized by 2D finite element method simulation using the software tool SyMSpace. After manufacture, the drive is commissioned with field-oriented control and the expected machine characteristics are compared with measurement results. Finally, also two self-sensing rotor angle estimation methods (one for the lower and one for upper speed range) are implemented and evaluated as back-up system to the installed rotor angle encoder.
{"title":"Design and Implementation of a 12.5kW PMSM as Paraglider Towing Winch","authors":"W. Gruber, Wolfgang Stallinger","doi":"10.1109/IEMDC47953.2021.9449559","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449559","url":null,"abstract":"This work deals with a compact and efficient permanent magnet excited synchronous machine to be used as paraglider towing winch. A battery supply with a voltage of only 48V is chosen for mobility and safety reasons. A rough machine design is first carried out analytically. After predesign, the final machine geometry is genetically optimized by 2D finite element method simulation using the software tool SyMSpace. After manufacture, the drive is commissioned with field-oriented control and the expected machine characteristics are compared with measurement results. Finally, also two self-sensing rotor angle estimation methods (one for the lower and one for upper speed range) are implemented and evaluated as back-up system to the installed rotor angle encoder.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129852123","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449491
H. Won, Yang-Ki Hong, Jonathan Platt, Minyeong Choi, Briana Bryant, Seungdeog Choi
This paper presents a novel stator-shifted six-phase fractional-slot concentrated winding ferrite spoke-type permanent magnet synchronous machine for an electric truck application. The proposed motor consists of a stator with dual three-phase windings that are 75 degrees apart and a rotor with a ferrite permanent magnet in spoke configuration. To further reduce the torque ripple, one circular void and notch are introduced on the stator and rotor, respectively. The simulation results show that the proposed motor exhibits 138% lower torque ripple, 108% lower back-EMF at 3000 rpm, and 95.5% higher maximum speed with a maximum torque of 2150 Nm and no demagnetization, compared to three-phase integrated-slot distributed winding NdFeB V-type PMSM of Prius 2010.
{"title":"Six-phase Fractional-slot Concentrated Winding Ferrite Spoke-type Permanent Magnet Synchronous Motor for Electric Truck","authors":"H. Won, Yang-Ki Hong, Jonathan Platt, Minyeong Choi, Briana Bryant, Seungdeog Choi","doi":"10.1109/IEMDC47953.2021.9449491","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449491","url":null,"abstract":"This paper presents a novel stator-shifted six-phase fractional-slot concentrated winding ferrite spoke-type permanent magnet synchronous machine for an electric truck application. The proposed motor consists of a stator with dual three-phase windings that are 75 degrees apart and a rotor with a ferrite permanent magnet in spoke configuration. To further reduce the torque ripple, one circular void and notch are introduced on the stator and rotor, respectively. The simulation results show that the proposed motor exhibits 138% lower torque ripple, 108% lower back-EMF at 3000 rpm, and 95.5% higher maximum speed with a maximum torque of 2150 Nm and no demagnetization, compared to three-phase integrated-slot distributed winding NdFeB V-type PMSM of Prius 2010.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130938009","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449588
Xuliang Yao, Shengqi Huang, Jingfang Wang, Feiyang Zhang, Yujian Wang, He Ma
Due to low cost and high reliability, the Hall-effect sensor is adopted as an alternative to the encoder. This paper presents a pseudo sensorless deadbeat predictive current control (PSDBPCC) method to improve the estimation accuracy of the rotor speed and position with Hall-effect sensors. In this method the output signals of the Hall-effect sensors are transformed to the Hall vector which contains high order harmonics by Clark transformation. The adaptive vectorial filter (AVF) is introduced to extract the fundamental waves of the Hall vector. The rotor speed and position are estimated from the fundamental waves with an improved phase locked loop (PLL) structure. Compared with the conventional method, the proposed method has higher estimation accuracy in steady state and better dynamic tracking performance. The experimental results verify the effectiveness of the proposed method.
{"title":"Pseudo Sensorless Deadbeat Predictive Current Control for PMSM Drives With Hall-Effect Sensors","authors":"Xuliang Yao, Shengqi Huang, Jingfang Wang, Feiyang Zhang, Yujian Wang, He Ma","doi":"10.1109/IEMDC47953.2021.9449588","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449588","url":null,"abstract":"Due to low cost and high reliability, the Hall-effect sensor is adopted as an alternative to the encoder. This paper presents a pseudo sensorless deadbeat predictive current control (PSDBPCC) method to improve the estimation accuracy of the rotor speed and position with Hall-effect sensors. In this method the output signals of the Hall-effect sensors are transformed to the Hall vector which contains high order harmonics by Clark transformation. The adaptive vectorial filter (AVF) is introduced to extract the fundamental waves of the Hall vector. The rotor speed and position are estimated from the fundamental waves with an improved phase locked loop (PLL) structure. Compared with the conventional method, the proposed method has higher estimation accuracy in steady state and better dynamic tracking performance. The experimental results verify the effectiveness of the proposed method.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130840393","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449571
Timothy Slininger, W. Chan, E. Severson, B. Jawdat
Magnetic bearings are an area of interest for high speed applications, such as flywheel energy storage systems, to remove friction losses. Stable levitation cannot be achieved through a static passive magnetic bearing system, as indicated by Earnshaw's Theorem. Solutions using active magnetic bearings have been presented which achieve stable levitation, but induce losses in the current used to actively stabilize one or more degrees of freedom. To overcome these losses while retaining stable operation a fully passive architecture can be created utilizing superconducting magnetic bearings. This paper will review the key passive magnetic and superconducting technologies, their design and optimizations methods for different topologies, and existing work done to combine both into a functional stable system.
{"title":"An Overview on Passive Magnetic Bearings","authors":"Timothy Slininger, W. Chan, E. Severson, B. Jawdat","doi":"10.1109/IEMDC47953.2021.9449571","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449571","url":null,"abstract":"Magnetic bearings are an area of interest for high speed applications, such as flywheel energy storage systems, to remove friction losses. Stable levitation cannot be achieved through a static passive magnetic bearing system, as indicated by Earnshaw's Theorem. Solutions using active magnetic bearings have been presented which achieve stable levitation, but induce losses in the current used to actively stabilize one or more degrees of freedom. To overcome these losses while retaining stable operation a fully passive architecture can be created utilizing superconducting magnetic bearings. This paper will review the key passive magnetic and superconducting technologies, their design and optimizations methods for different topologies, and existing work done to combine both into a functional stable system.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126919515","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449574
Zihang Chen, Feiyu Chen, Xiaoyan Huang, Zhaokai Li, Min Wu
Aiming at the phenomenon of integral drift in the rotor position observed by the Luenberger Observer, a sliding mode term is added to the original Luenberger term to enhance the robustness of the system. Meanwhile, in order to simplify the complexity of the observer, this paper reduces the order of the original state equation. The Differential Evolution Algorithm (DEA) is used to optimize the observer gain coefficient globally, which reduces the contingency and randomness of manual tuning.
{"title":"DEA-tuning of Reduced-order Extended Luenberger Sliding Mode Observers(ELSMO) for Sensorless Control of High-speed SPMSM","authors":"Zihang Chen, Feiyu Chen, Xiaoyan Huang, Zhaokai Li, Min Wu","doi":"10.1109/IEMDC47953.2021.9449574","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449574","url":null,"abstract":"Aiming at the phenomenon of integral drift in the rotor position observed by the Luenberger Observer, a sliding mode term is added to the original Luenberger term to enhance the robustness of the system. Meanwhile, in order to simplify the complexity of the observer, this paper reduces the order of the original state equation. The Differential Evolution Algorithm (DEA) is used to optimize the observer gain coefficient globally, which reduces the contingency and randomness of manual tuning.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124204095","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449526
E. Kurvinen, T. Choudhury, Juuso Narsakka, Iikka Martikainen, J. Sopanen, R. Jastrzebski
Design of High Speed (HS) electric machines is an iterative process that requires a multidisciplinary design team to accomplish the required performance. In this study, a design space method (DSM) is developed to streamline conceptual designing of a high-speed and high-power electric machine. The method uses analytical equations and a rotordynamic model to determine geometrical dimensions based on the application requirements. These dimensions create a feasible baseline design for the particular application. However, considering the dimensions as design variables and using the baseline design as a starting point, a multidimensional combination and interaction of the design variables and the correlated output for the particular topology of motor and performance range can be further studied for design exploration and optimization purposes. The study includes a test case where the baseline dimensions are determined and compared to an existing machine from literature, and then further explored to identify the sensitivity of different outputs with respect to different design variables. The method enables rapid design iterations, rotordynamics and rotor mass optimization. The baseline design can be also used as a starting point for the detailed design.
{"title":"Design Space Method for Conceptual Design Exploration of High Speed Slitted Solid Induction Motor","authors":"E. Kurvinen, T. Choudhury, Juuso Narsakka, Iikka Martikainen, J. Sopanen, R. Jastrzebski","doi":"10.1109/IEMDC47953.2021.9449526","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449526","url":null,"abstract":"Design of High Speed (HS) electric machines is an iterative process that requires a multidisciplinary design team to accomplish the required performance. In this study, a design space method (DSM) is developed to streamline conceptual designing of a high-speed and high-power electric machine. The method uses analytical equations and a rotordynamic model to determine geometrical dimensions based on the application requirements. These dimensions create a feasible baseline design for the particular application. However, considering the dimensions as design variables and using the baseline design as a starting point, a multidimensional combination and interaction of the design variables and the correlated output for the particular topology of motor and performance range can be further studied for design exploration and optimization purposes. The study includes a test case where the baseline dimensions are determined and compared to an existing machine from literature, and then further explored to identify the sensitivity of different outputs with respect to different design variables. The method enables rapid design iterations, rotordynamics and rotor mass optimization. The baseline design can be also used as a starting point for the detailed design.","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123710283","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 : 2021-05-17DOI: 10.1109/IEMDC47953.2021.9449579
T. Balachandran, John D. Reband, Max Lewis, K. Haran
A co-design of an electric aircraft powertrain optimization is investigated in this paper. Number of propulsors, gear ratio, propeller and motor geometry are considered as system design variables. Optimization of the system design for high overall system efficiency and low mass is attempted with considerations for winding temperature, current density, iron flux density, and machine aspect ratio. The powertrain was sized to deliver thrust according to a simple set of mission requirements at desired flight speed for a representative passenger aircraft. The results suggested that small propulsor counts are optimal for low weight and high efficiency, and that an ideal propeller speed exists for a given co-design problem
{"title":"Co-Design of Integrated Propeller and Inner Rotor PMSM for Electric Aircraft Application","authors":"T. Balachandran, John D. Reband, Max Lewis, K. Haran","doi":"10.1109/IEMDC47953.2021.9449579","DOIUrl":"https://doi.org/10.1109/IEMDC47953.2021.9449579","url":null,"abstract":"A co-design of an electric aircraft powertrain optimization is investigated in this paper. Number of propulsors, gear ratio, propeller and motor geometry are considered as system design variables. Optimization of the system design for high overall system efficiency and low mass is attempted with considerations for winding temperature, current density, iron flux density, and machine aspect ratio. The powertrain was sized to deliver thrust according to a simple set of mission requirements at desired flight speed for a representative passenger aircraft. The results suggested that small propulsor counts are optimal for low weight and high efficiency, and that an ideal propeller speed exists for a given co-design problem","PeriodicalId":106489,"journal":{"name":"2021 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129491406","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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