Pub Date : 2015-05-10DOI: 10.1109/IEMDC.2015.7409057
B. Anvari, Yongqi Li, H. Toliyat
Interest in using magnet-less switched reluctance generators for wind turbines applications continues to gain popularity. Mainly due to unstable price of the magnet raw material that is one of the main challenges for engineers to forecast the final cost of the wind turbine. This paper presents design of a direct drive switched reluctance generator (DDSRG) for wind turbine applications using Finite-Element Analysis (FEA) tools. The performance, weight, and cost of the proposed DDSRG is compared to a direct-drive permanent magnet generator (DDPMG). The FEA results demonstrate that for the same dimensions, the final cost of the proposed DDSRG is lower when compared to the conventional DDPMG for wind turbine applications. The main drawback of the DDSRG is that it has lower output power than DDPMG for the same dimensions. Also a DDSRG for the same output power as DDPMG has been designed in this paper.
{"title":"Comparison of outer rotor permanent magnet and magnet-less generators for direct-drive wind turbine applications","authors":"B. Anvari, Yongqi Li, H. Toliyat","doi":"10.1109/IEMDC.2015.7409057","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409057","url":null,"abstract":"Interest in using magnet-less switched reluctance generators for wind turbines applications continues to gain popularity. Mainly due to unstable price of the magnet raw material that is one of the main challenges for engineers to forecast the final cost of the wind turbine. This paper presents design of a direct drive switched reluctance generator (DDSRG) for wind turbine applications using Finite-Element Analysis (FEA) tools. The performance, weight, and cost of the proposed DDSRG is compared to a direct-drive permanent magnet generator (DDPMG). The FEA results demonstrate that for the same dimensions, the final cost of the proposed DDSRG is lower when compared to the conventional DDPMG for wind turbine applications. The main drawback of the DDSRG is that it has lower output power than DDPMG for the same dimensions. Also a DDSRG for the same output power as DDPMG has been designed in this paper.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"145 1","pages":"181-186"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74905699","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409163
Y. Iwaji, M. Hano, N. Okamoto, R. Takahata
A block commutation based position sensorless method for the low speed regions has previously been reported [8-10]. This method introduces "Induced Voltage caused by Magnetic Saturation (IVMS)". The IVMS is detected in the open phase of a Permanent Magnet Synchronous Motor (PMSM) driven by the block commutation. The commutating phases in this method are switched in accordance with the detected IVMS in the open phase. The detected IVMS is compared with the threshold voltage that was adjusted in advance. When the IVMS corresponds to the threshold voltage, the commutating phase is switched to the next phase. Therefore, the threshold voltages for the IVMS need to be correctly adjusted. However, several factors are involved in changing the threshold voltages, such as the motor characteristics, carrier frequency, and detection circuit. An automatic tuning technique for the threshold voltages of the IVMS-based position sensorless method is proposed in this paper. The principle for it and the experimental results are also presented.
{"title":"Automatic tuning technique for low speed position sensorless method based on block commutation drive","authors":"Y. Iwaji, M. Hano, N. Okamoto, R. Takahata","doi":"10.1109/IEMDC.2015.7409163","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409163","url":null,"abstract":"A block commutation based position sensorless method for the low speed regions has previously been reported [8-10]. This method introduces \"Induced Voltage caused by Magnetic Saturation (IVMS)\". The IVMS is detected in the open phase of a Permanent Magnet Synchronous Motor (PMSM) driven by the block commutation. The commutating phases in this method are switched in accordance with the detected IVMS in the open phase. The detected IVMS is compared with the threshold voltage that was adjusted in advance. When the IVMS corresponds to the threshold voltage, the commutating phase is switched to the next phase. Therefore, the threshold voltages for the IVMS need to be correctly adjusted. However, several factors are involved in changing the threshold voltages, such as the motor characteristics, carrier frequency, and detection circuit. An automatic tuning technique for the threshold voltages of the IVMS-based position sensorless method is proposed in this paper. The principle for it and the experimental results are also presented.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"204 1","pages":"872-877"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74393779","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409041
Adam Larson, S. Pekarek, Ron Wang, M. Bash, R. van Maaren
This paper highlights a magnetic equivalent circuit model for wound rotor synchronous machine design. The model includes provisions to calculate the performance of machines with an arbitrary number of damper windings in either the q- or d-axis. The computational cost of the model is considered on several modern computing platforms. Its use within design allows for a comprehensive, accurate exploration of a design space on a timeline that is consistent with most commercial product development.
{"title":"An efficient circuit model for design of synchronous machines","authors":"Adam Larson, S. Pekarek, Ron Wang, M. Bash, R. van Maaren","doi":"10.1109/IEMDC.2015.7409041","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409041","url":null,"abstract":"This paper highlights a magnetic equivalent circuit model for wound rotor synchronous machine design. The model includes provisions to calculate the performance of machines with an arbitrary number of damper windings in either the q- or d-axis. The computational cost of the model is considered on several modern computing platforms. Its use within design allows for a comprehensive, accurate exploration of a design space on a timeline that is consistent with most commercial product development.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"7 1","pages":"84-89"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85362021","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409185
M. Diana, P. Guglielmi, Giovanni Piccoli, S. Rosu
The paper presents an SMPM multi-n-phase electric drive for traction application. The whole drive, motor structure, converter structure and a PWM control strategy is proposed. In particular the drive control and the DC-link advantage of a multi-phase structure is investigated in a specific machine design. The possibility to strongly reduce the DC-link capacitor stress is presented thanks to a phase shift in the PWM carriers of different converters. A comparison analysis is given for the same motor wounded and supplied in three different ways also considering fault conditions.
{"title":"Multi-N-phase SMPM drives","authors":"M. Diana, P. Guglielmi, Giovanni Piccoli, S. Rosu","doi":"10.1109/IEMDC.2015.7409185","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409185","url":null,"abstract":"The paper presents an SMPM multi-n-phase electric drive for traction application. The whole drive, motor structure, converter structure and a PWM control strategy is proposed. In particular the drive control and the DC-link advantage of a multi-phase structure is investigated in a specific machine design. The possibility to strongly reduce the DC-link capacitor stress is presented thanks to a phase shift in the PWM carriers of different converters. A comparison analysis is given for the same motor wounded and supplied in three different ways also considering fault conditions.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"2020 1","pages":"1011-1017"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81972790","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409246
A. Arafat, Seungdeog Choi
This paper presents a new approach for phase fault detection of a five-phase permanent magnet synchronous reluctance motor (PMa-SynRM). The proposed fault detection method has been developed through novel decomposition technique of sequential components of a five-phase electrical machine. Unlike conventional three phase machines, phase fault of five-phase machine shows different response under single phase fault, two adjacent phase fault, and two non-adjacent phase fault. A newly developed symmetrical component analysis is applied to identify those phase fault condition in five phase machines. The analysis has been further extended to detect the types of faults based on magnitude pattern of the fundamental frequencies of the symmetrical components in frequency domain. In this paper, open-phase fault detection analysis has been carried out through extensive simulation and experimental tests to validate the proposed method. A 5Kw dynamo system controlled by TI-DSP F28335 has been used.
{"title":"Fault detection of a five-phase permanent magnet synchronous reluctance motor based on symmetrical components theory","authors":"A. Arafat, Seungdeog Choi","doi":"10.1109/IEMDC.2015.7409246","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409246","url":null,"abstract":"This paper presents a new approach for phase fault detection of a five-phase permanent magnet synchronous reluctance motor (PMa-SynRM). The proposed fault detection method has been developed through novel decomposition technique of sequential components of a five-phase electrical machine. Unlike conventional three phase machines, phase fault of five-phase machine shows different response under single phase fault, two adjacent phase fault, and two non-adjacent phase fault. A newly developed symmetrical component analysis is applied to identify those phase fault condition in five phase machines. The analysis has been further extended to detect the types of faults based on magnitude pattern of the fundamental frequencies of the symmetrical components in frequency domain. In this paper, open-phase fault detection analysis has been carried out through extensive simulation and experimental tests to validate the proposed method. A 5Kw dynamo system controlled by TI-DSP F28335 has been used.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"21 1","pages":"1405-1411"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80339747","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409050
P. Sangha, T. Sawata, J. Yon, P. Mellor
For a permanent magnet (PM) motor used in an electro-hydrostatic actuation system, fluid drag loss in the air gap can be as high as 60% of motor internal losses and affects the motor efficiency; especially at low temperatures where the viscosity of the hydraulic fluid increases significantly. A PM motor has been designed and built to assess electromagnetic, fluid drag loss and dynamic performance. The design process utilised a theoretical equation for the fluid drag loss estimation which assumes a laminar flow. Assumption of the laminar flow has been validated by computational fluid dynamic analysis. A dummy motor was built and the fluid drag losses were measured for various speeds and temperatures. The test results show reasonable agreement with the theoretical calculation although the self-heating effect of the fluid made measurements at constant temperatures difficult.
{"title":"Assessment of fluid drag loss in a flooded rotor electro-hydrostatic actuator motor","authors":"P. Sangha, T. Sawata, J. Yon, P. Mellor","doi":"10.1109/IEMDC.2015.7409050","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409050","url":null,"abstract":"For a permanent magnet (PM) motor used in an electro-hydrostatic actuation system, fluid drag loss in the air gap can be as high as 60% of motor internal losses and affects the motor efficiency; especially at low temperatures where the viscosity of the hydraulic fluid increases significantly. A PM motor has been designed and built to assess electromagnetic, fluid drag loss and dynamic performance. The design process utilised a theoretical equation for the fluid drag loss estimation which assumes a laminar flow. Assumption of the laminar flow has been validated by computational fluid dynamic analysis. A dummy motor was built and the fluid drag losses were measured for various speeds and temperatures. The test results show reasonable agreement with the theoretical calculation although the self-heating effect of the fluid made measurements at constant temperatures difficult.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"42 167 1","pages":"139-142"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83270511","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409260
Markus Dirnberger, H. Herzog
Optimization of systems is a challenging task. During this process adjustments of the model and the optimization algorithm will influence its success. Therefore, this paper introduces an analytical approach to verify the results achieved by an optimization process. This is done by pushing the observed mild hybrid electric vehicle (HEV) into the recuperation mode and the generator mode of the electrical machine. Now physical equations enable a verification approach to calculate the additional CO2 emission due to a variation of the efficiency of the electrical machine used in the power train of the HEV. The efficiency variation of the electrical machine is done on a measured efficiency map by increasing and reducing it by ±10% for the optimization process. The analytical verification approach should be easy to implement and enable to verify the results of the optimization process therefore a mid efficiency of the electrical machine is used. Compared to other approaches only changes of the CO2 emission are considered. This enables to model the internal combustion engine (ICE) in an easy way. Finally, the results of the analytical verification approach are compared to the results achieved by the optimization process.
{"title":"A verification approach for the optimization of mild hybrid electric vehicles","authors":"Markus Dirnberger, H. Herzog","doi":"10.1109/IEMDC.2015.7409260","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409260","url":null,"abstract":"Optimization of systems is a challenging task. During this process adjustments of the model and the optimization algorithm will influence its success. Therefore, this paper introduces an analytical approach to verify the results achieved by an optimization process. This is done by pushing the observed mild hybrid electric vehicle (HEV) into the recuperation mode and the generator mode of the electrical machine. Now physical equations enable a verification approach to calculate the additional CO2 emission due to a variation of the efficiency of the electrical machine used in the power train of the HEV. The efficiency variation of the electrical machine is done on a measured efficiency map by increasing and reducing it by ±10% for the optimization process. The analytical verification approach should be easy to implement and enable to verify the results of the optimization process therefore a mid efficiency of the electrical machine is used. Compared to other approaches only changes of the CO2 emission are considered. This enables to model the internal combustion engine (ICE) in an easy way. Finally, the results of the analytical verification approach are compared to the results achieved by the optimization process.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"428 1","pages":"1494-1500"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75886342","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409053
Sung An Kim, Hyo-keun Jeon, S. Byun, Yunhyun Cho
This paper compares to investigate output characteristics according to a conventional and novel stator structure of axial flux permanent magnet (AFPM) motor for cooling fan drive system. Segmented core of stator has advantages such as easy winding and fast manufacture speed. However, a unit cost increase due to cutting off tooth tip to constant slot width. To solve the problem, this paper proposes a novel stator structure with three-step segmented core. The characteristics of AFPM were analyzed by time-stepping three dimensional finite element analysis (3D FEA) in two stator models, when stator cores are cutting off tooth tips from rectangular core and three step segmented core. Prototype motors were manufactured based on analysis results, and were tested as a motor.
{"title":"Characteristics comparison of a conventional and novel stator structure of axial flux permanent magnet motor for cooling fan drive system","authors":"Sung An Kim, Hyo-keun Jeon, S. Byun, Yunhyun Cho","doi":"10.1109/IEMDC.2015.7409053","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409053","url":null,"abstract":"This paper compares to investigate output characteristics according to a conventional and novel stator structure of axial flux permanent magnet (AFPM) motor for cooling fan drive system. Segmented core of stator has advantages such as easy winding and fast manufacture speed. However, a unit cost increase due to cutting off tooth tip to constant slot width. To solve the problem, this paper proposes a novel stator structure with three-step segmented core. The characteristics of AFPM were analyzed by time-stepping three dimensional finite element analysis (3D FEA) in two stator models, when stator cores are cutting off tooth tips from rectangular core and three step segmented core. Prototype motors were manufactured based on analysis results, and were tested as a motor.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"77 1","pages":"154-159"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78766161","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409154
Y. Sangsefidi, S. Ziaeinejad, A. Mehrizi‐Sani
A multi-motor drive, which independently controls multiple motors by a single microcontroller and converter, reduces the system cost by reducing the drive system parts count. This paper proposes direct torque control (DTC) of a two-phase induction motor (as the main motor) and hysteresis-based current control of a permanent magnet DC motor (as the auxiliary motor) using a four-leg converter. An augmented switching table is proposed to control both motors. Analytical equations are also proposed to assess the current ripple and controllability of the DC motor. The proposed drive system and presented theories are validated by simulation case studies in MATLAB/Simulink.
{"title":"A new two-motor drive to control a two-phase induction motor and a DC motor","authors":"Y. Sangsefidi, S. Ziaeinejad, A. Mehrizi‐Sani","doi":"10.1109/IEMDC.2015.7409154","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409154","url":null,"abstract":"A multi-motor drive, which independently controls multiple motors by a single microcontroller and converter, reduces the system cost by reducing the drive system parts count. This paper proposes direct torque control (DTC) of a two-phase induction motor (as the main motor) and hysteresis-based current control of a permanent magnet DC motor (as the auxiliary motor) using a four-leg converter. An augmented switching table is proposed to control both motors. Analytical equations are also proposed to assess the current ripple and controllability of the DC motor. The proposed drive system and presented theories are validated by simulation case studies in MATLAB/Simulink.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"30 1","pages":"818-822"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91238776","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 : 2015-05-10DOI: 10.1109/IEMDC.2015.7409111
Shaohua Lin, Xiao Li, Thomas Wu, L. Chow, Z. Tang, S. Stanton
The interior permanent magnet motor is the central component of modern high performance hybrid electric vehicles. During the vehicle's normal operation, demagnetization can occur in the magnets due to temperature rise and high current loading, which could change the IPM's electrical and mechanical characteristic and the overall system performance significantly. To study these effects on the system level, in this paper, we propose a reduced order motor model based on FEA solution that takes into account the permanent magnet's temperature dependency, current loading and nonlinear saturation effects. The proposed model runs at circuit simulation speed which is suitable for system level simulation and while having the accuracy of FEA. Using this model, we are able to quantify the current consumption during a standard drive cycle simulation due to temperature and current loading variations.
{"title":"Temperature dependent reduced order IPM motor model based on finite element analysis","authors":"Shaohua Lin, Xiao Li, Thomas Wu, L. Chow, Z. Tang, S. Stanton","doi":"10.1109/IEMDC.2015.7409111","DOIUrl":"https://doi.org/10.1109/IEMDC.2015.7409111","url":null,"abstract":"The interior permanent magnet motor is the central component of modern high performance hybrid electric vehicles. During the vehicle's normal operation, demagnetization can occur in the magnets due to temperature rise and high current loading, which could change the IPM's electrical and mechanical characteristic and the overall system performance significantly. To study these effects on the system level, in this paper, we propose a reduced order motor model based on FEA solution that takes into account the permanent magnet's temperature dependency, current loading and nonlinear saturation effects. The proposed model runs at circuit simulation speed which is suitable for system level simulation and while having the accuracy of FEA. Using this model, we are able to quantify the current consumption during a standard drive cycle simulation due to temperature and current loading variations.","PeriodicalId":6477,"journal":{"name":"2015 IEEE International Electric Machines & Drives Conference (IEMDC)","volume":"1 1","pages":"543-549"},"PeriodicalIF":0.0,"publicationDate":"2015-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89662266","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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