Pub Date : 2012-11-12DOI: 10.1109/ECCE.2012.6342398
T. Mishima, K. Akamatsu, M. Nakaoka
A new prototype of a secondary-side phase shifted (SPS) zero voltage and zero current soft switching PWM dc-dc converter with active rectifier is presented in this paper. The proposed dc-dc converter has no circulating current in the full-bridge circuits both of the primary and secondary sides, so that the related idling power can be minimized. Beside that, a wide-range soft switching can be attained from full load to no load by utilizing parasitic inductances of the high frequency (HF) transformer. The essential performance of a 1kW-50kHz prototype of the proposed dc-dc converter is originally demonstrated in experiments, and its effectiveness is discussed from the practical point of view.
{"title":"A zero voltage and zero current soft switching PWM dc-dc converter with secondary-side phase-shifting active rectifier","authors":"T. Mishima, K. Akamatsu, M. Nakaoka","doi":"10.1109/ECCE.2012.6342398","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342398","url":null,"abstract":"A new prototype of a secondary-side phase shifted (SPS) zero voltage and zero current soft switching PWM dc-dc converter with active rectifier is presented in this paper. The proposed dc-dc converter has no circulating current in the full-bridge circuits both of the primary and secondary sides, so that the related idling power can be minimized. Beside that, a wide-range soft switching can be attained from full load to no load by utilizing parasitic inductances of the high frequency (HF) transformer. The essential performance of a 1kW-50kHz prototype of the proposed dc-dc converter is originally demonstrated in experiments, and its effectiveness is discussed from the practical point of view.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"43 1","pages":"2544-2551"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85883983","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342439
F. Guo, Lixing Fu, Chien-Hui Lin, Cong Li, Jin Wang
This paper presents the small signal modeling and controller design of a bidirectional Quasi-Z-Source inverter (BQ-ZSI) for electric vehicle (EV) applications. The derived small signal model shows that the Quasi-Z-Source network (QZSN) is prone to oscillate when there is a disturbance from the dc input voltage. Since the battery pack voltage in an EV is easy to fluctuate because of the battery's internal impedance and rapid change of the load current, a dedicated voltage controller with feed forward compensation is designed to reject the disturbance and stabilize the dc-link voltage during non-shoot-through state. Simulation and experimental results are both presented to prove the effectiveness of the proposed controller.
{"title":"Small signal modeling and controller design of a bidirectional Quasi-Z-Source inverter for electric vehicle applications","authors":"F. Guo, Lixing Fu, Chien-Hui Lin, Cong Li, Jin Wang","doi":"10.1109/ECCE.2012.6342439","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342439","url":null,"abstract":"This paper presents the small signal modeling and controller design of a bidirectional Quasi-Z-Source inverter (BQ-ZSI) for electric vehicle (EV) applications. The derived small signal model shows that the Quasi-Z-Source network (QZSN) is prone to oscillate when there is a disturbance from the dc input voltage. Since the battery pack voltage in an EV is easy to fluctuate because of the battery's internal impedance and rapid change of the load current, a dedicated voltage controller with feed forward compensation is designed to reject the disturbance and stabilize the dc-link voltage during non-shoot-through state. Simulation and experimental results are both presented to prove the effectiveness of the proposed controller.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"16 1","pages":"2223-2228"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85899919","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342634
S. Sundaresan, Aye-Mya Soe, R. Singh
Silicon Carbide Anode Switched Thyristors (ASTs) overcome major limitations of conventional Si and SiC IGBT and GTO Thyristor solutions by providing robust, MOS-controlled, turn-off at high currents, current saturation in the output characteristics through series current controlled device turn-off. In this work, detailed static and switching characteristics of 6.5 kV-class SiC ASTs are reported, which include a low on-state voltage drop of 4 V at 100 A/cm2, slight positive temperature co-efficient of Von, current saturation at >; 100 A Cathode currents and fast turn-on and turn-off times of <; 2 μs while switching 3600 V and 14.5 A. The transient voltages seen by the Si MOSFETs during AST switching are examined to determine safe operating area limits for this circuit configuration.
{"title":"Static and switching characteristics of 6500 V Silicon Carbide Anode Switched Thyristor modules","authors":"S. Sundaresan, Aye-Mya Soe, R. Singh","doi":"10.1109/ECCE.2012.6342634","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342634","url":null,"abstract":"Silicon Carbide Anode Switched Thyristors (ASTs) overcome major limitations of conventional Si and SiC IGBT and GTO Thyristor solutions by providing robust, MOS-controlled, turn-off at high currents, current saturation in the output characteristics through series current controlled device turn-off. In this work, detailed static and switching characteristics of 6.5 kV-class SiC ASTs are reported, which include a low on-state voltage drop of 4 V at 100 A/cm2, slight positive temperature co-efficient of Von, current saturation at >; 100 A Cathode currents and fast turn-on and turn-off times of <; 2 μs while switching 3600 V and 14.5 A. The transient voltages seen by the Si MOSFETs during AST switching are examined to determine safe operating area limits for this circuit configuration.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"111 1","pages":"1515-1519"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86789945","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342687
M. Sprenger, R. Álvarez, S. Bernet
The neutral-point balancing of 3L-NPC converter has been studied in many works in the past [1], [2], [3], [4]. Nevertheless, the literature shows a theoretical focus neglecting issues like the requirements of the energy flow information for the implementation of the majority of the proposed methods. This paper presents a new dc-link neutral-point balancing method that directly controls the converter dead-times to balance the dc-link. An analytic model is derived to describe the neutral-point voltage dependent on the dead-times. Simulation results are given to verify the model and the new balancing scheme.
{"title":"Direct dead-time control - a novel dc-link neutral-point balancing method for the three-level neutral-point-clamped voltage source inverter","authors":"M. Sprenger, R. Álvarez, S. Bernet","doi":"10.1109/ECCE.2012.6342687","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342687","url":null,"abstract":"The neutral-point balancing of 3L-NPC converter has been studied in many works in the past [1], [2], [3], [4]. Nevertheless, the literature shows a theoretical focus neglecting issues like the requirements of the energy flow information for the implementation of the majority of the proposed methods. This paper presents a new dc-link neutral-point balancing method that directly controls the converter dead-times to balance the dc-link. An analytic model is derived to describe the neutral-point voltage dependent on the dead-times. Simulation results are given to verify the model and the new balancing scheme.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"3 1","pages":"1157-1163"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87395766","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342795
Qian Sun, S. Patil, S. Stoute, N. Sun, B. Lehman
The design of a new-type of inductive magnetic energy harvesting system with high permeability magnetic material combined with a dual polarity boost converter is presented. By using the strong magnetostatic interaction between the coils and permanent magnets, the output power and power density of the energy harvester is enhanced compared to conventional air cored inductive harvesters. In the proposed dual polarity boost converter, the coil leakage inductor of the harvester is utilized to form the input inductor of the boost converter to minimize the converter size. Therefore, the magnetic energy harvester and the power converter share the same magnetic core. Optimum system design becomes a balance of core size, required leakage inductance and required magnetizing inductance in order to extract maximum energy.
{"title":"Optimum design of magnetic inductive energy harvester and its AC-DC converter","authors":"Qian Sun, S. Patil, S. Stoute, N. Sun, B. Lehman","doi":"10.1109/ECCE.2012.6342795","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342795","url":null,"abstract":"The design of a new-type of inductive magnetic energy harvesting system with high permeability magnetic material combined with a dual polarity boost converter is presented. By using the strong magnetostatic interaction between the coils and permanent magnets, the output power and power density of the energy harvester is enhanced compared to conventional air cored inductive harvesters. In the proposed dual polarity boost converter, the coil leakage inductor of the harvester is utilized to form the input inductor of the boost converter to minimize the converter size. Therefore, the magnetic energy harvester and the power converter share the same magnetic core. Optimum system design becomes a balance of core size, required leakage inductance and required magnetizing inductance in order to extract maximum energy.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"19 1","pages":"394-400"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87396090","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342412
S. Parker, B. Mcgrath, D. G. Holmes
The control of a grid connected voltage source inverter (VSI) with an LCL filter is a very challenging task, since the LCL network causes a resonance phenomenon near to the control stability boundary. While many active damping methods have been proposed to overcome this issue, the role that PWM transport delay plays in the effectiveness of these strategies is still not fully resolved. This paper presents a theoretical discrete time analysis frame work that identifies three distinct regions of LCL filter resonance - a high resonant frequency region where active damping isn't required; a critical resonant frequency where a controller cannot stabilise the system; and a low resonant frequency region where active damping is essential. Suitable controllers are then proposed for the two stable regions, with gain calculations that allow for the greatest system bandwidth and damping. Simulation and experimental results verify the presented analysis.
{"title":"Regions of active damping control for LCL filters","authors":"S. Parker, B. Mcgrath, D. G. Holmes","doi":"10.1109/ECCE.2012.6342412","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342412","url":null,"abstract":"The control of a grid connected voltage source inverter (VSI) with an LCL filter is a very challenging task, since the LCL network causes a resonance phenomenon near to the control stability boundary. While many active damping methods have been proposed to overcome this issue, the role that PWM transport delay plays in the effectiveness of these strategies is still not fully resolved. This paper presents a theoretical discrete time analysis frame work that identifies three distinct regions of LCL filter resonance - a high resonant frequency region where active damping isn't required; a critical resonant frequency where a controller cannot stabilise the system; and a low resonant frequency region where active damping is essential. Suitable controllers are then proposed for the two stable regions, with gain calculations that allow for the greatest system bandwidth and damping. Simulation and experimental results verify the presented analysis.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"89 1","pages":"53-60"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89018527","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342389
F. Alonge, M. Cirrincione, F. D’Ippolito, M. Pucci, A. Sferlazza
This paper proposes a technique for the estimation of the electrical parameters of the equivalent circuit of LIMs, taking into consideration the end effects, and focuses on the application of an algorithm based on the minimization of a suitable cost function. It proposes also a set of tests to be made in order to estimate the variation of the magnetic parameters of the LIM versus the magnetizing current as well as the magnetizing curve of the machine. The proposed methodology has been verified experimentally on suitably developed test setup.
{"title":"Parameter identification of linear induction motor model in extended range of operation by means of input-output data","authors":"F. Alonge, M. Cirrincione, F. D’Ippolito, M. Pucci, A. Sferlazza","doi":"10.1109/ECCE.2012.6342389","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342389","url":null,"abstract":"This paper proposes a technique for the estimation of the electrical parameters of the equivalent circuit of LIMs, taking into consideration the end effects, and focuses on the application of an algorithm based on the minimization of a suitable cost function. It proposes also a set of tests to be made in order to estimate the variation of the magnetic parameters of the LIM versus the magnetizing current as well as the magnetizing curve of the machine. The proposed methodology has been verified experimentally on suitably developed test setup.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"21 1","pages":"2670-2675"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78983266","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342799
R. Singh, S. Mishra
In the modern point-of-load applications, a number of low and medium power converters are used very close to the actual load. These applications require superior dynamic response and better power processing density to save space on the motherboard. Hysteretic modulators are one of the obvious choices for these applications because of their superior dynamic response with minimal number of filter capacitors. This paper presents a novel carrier generation based fully digital hysteretic modulator for point-of-load (POL) converters. The proposed structure creates a piece-wise linear synthetic ripple using sensed converter voltages, without the need of direct inductor current sensing. The artificial synthetic ripple is then added to the output voltage and fed as a carrier to the hysteretic comparator, which helps in natural load current feed-forward. This proposed digital modulator helps in reduction of the output capacitors and exhibits superior large-signal dynamics for a Point-of-Load Converter. It is a low cost solution and gives immediate fault detection (within one switching cycle) in case of the top switch (main switch) failure of the converter, thus providing adequate protection to the microprocessor load. Analysis, simulation, and experimental results on a 2 V/ 10 A single phase prototype are presented to verify the properties of the proposed algorithm.
{"title":"A novel carrier generation based fully digital hysteretic modulator for point-of-load converters","authors":"R. Singh, S. Mishra","doi":"10.1109/ECCE.2012.6342799","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342799","url":null,"abstract":"In the modern point-of-load applications, a number of low and medium power converters are used very close to the actual load. These applications require superior dynamic response and better power processing density to save space on the motherboard. Hysteretic modulators are one of the obvious choices for these applications because of their superior dynamic response with minimal number of filter capacitors. This paper presents a novel carrier generation based fully digital hysteretic modulator for point-of-load (POL) converters. The proposed structure creates a piece-wise linear synthetic ripple using sensed converter voltages, without the need of direct inductor current sensing. The artificial synthetic ripple is then added to the output voltage and fed as a carrier to the hysteretic comparator, which helps in natural load current feed-forward. This proposed digital modulator helps in reduction of the output capacitors and exhibits superior large-signal dynamics for a Point-of-Load Converter. It is a low cost solution and gives immediate fault detection (within one switching cycle) in case of the top switch (main switch) failure of the converter, thus providing adequate protection to the microprocessor load. Analysis, simulation, and experimental results on a 2 V/ 10 A single phase prototype are presented to verify the properties of the proposed algorithm.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"2019 1","pages":"364-371"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79195372","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342279
Goh Teck Chiang, J. Itoh, J. Lee, R. Lorenz
This paper discusses the performance of an interior permanent magnet synchronous machine by using deadbeat-direct torque flux control (DB-DTFC) in a hybrid power circuit structure, which consists of an indirect matrix converter (IMC) and a reactor free boost converter (RFBC). The first section of this paper documents the performance of DB-DTFC when carrier comparison PWM and space vector modulation (SVM) are used as modulation techniques. Corresponding Volt-sec solutions for each modulation technique are shown via simulation and experiments. The second section discusses DB-DTFC properties in the proposed IMC/RFBC circuit. The results demonstrate that DB-DTFC is capable of delivering fast dynamic torque response in one sample period even when (i) variable switching frequency is applied in the inverter of the IMC and (ii) DC offset current occurs in the output current of the IMC.
{"title":"Performance evaluation of interior permanent magnet synchronous machines using deadbeat-direct torque flux control in an indirect matrix converter with a reactor free boost converter","authors":"Goh Teck Chiang, J. Itoh, J. Lee, R. Lorenz","doi":"10.1109/ECCE.2012.6342279","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342279","url":null,"abstract":"This paper discusses the performance of an interior permanent magnet synchronous machine by using deadbeat-direct torque flux control (DB-DTFC) in a hybrid power circuit structure, which consists of an indirect matrix converter (IMC) and a reactor free boost converter (RFBC). The first section of this paper documents the performance of DB-DTFC when carrier comparison PWM and space vector modulation (SVM) are used as modulation techniques. Corresponding Volt-sec solutions for each modulation technique are shown via simulation and experiments. The second section discusses DB-DTFC properties in the proposed IMC/RFBC circuit. The results demonstrate that DB-DTFC is capable of delivering fast dynamic torque response in one sample period even when (i) variable switching frequency is applied in the inverter of the IMC and (ii) DC offset current occurs in the output current of the IMC.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"2 1","pages":"4008-4014"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77109567","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 : 2012-11-12DOI: 10.1109/ECCE.2012.6342712
S. Dasgupta, S. N. Mohan, S. K. Sahoo, S. K. Panda
In this paper, a novel grid voltage sensor-less operation of the generalized three-phase grid connected distributed generating source based inverter operation is proposed. The method also takes into consideration the presence of a local load at the point of common coupling (PCC). In the proposed method, the same inverter current controller is used to estimate the grid voltages and to control the inverter to achieve the control on grid active and reactive power flow along with the sinusoidal grid currents. The proposed system is implemented directly in the a-b-c frame and Spatial Repetitive Controller (SRC) is used as the main control algorithm of the proposed scheme. Experimental results are provided to show the efficacy of the proposed sensorless control methodology.
{"title":"A grid voltage sensor-less operational approach of interconnecting distributed generating source based inverter to unbalanced generalized three-phase grid together with local load at PCC","authors":"S. Dasgupta, S. N. Mohan, S. K. Sahoo, S. K. Panda","doi":"10.1109/ECCE.2012.6342712","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342712","url":null,"abstract":"In this paper, a novel grid voltage sensor-less operation of the generalized three-phase grid connected distributed generating source based inverter operation is proposed. The method also takes into consideration the presence of a local load at the point of common coupling (PCC). In the proposed method, the same inverter current controller is used to estimate the grid voltages and to control the inverter to achieve the control on grid active and reactive power flow along with the sinusoidal grid currents. The proposed system is implemented directly in the a-b-c frame and Spatial Repetitive Controller (SRC) is used as the main control algorithm of the proposed scheme. Experimental results are provided to show the efficacy of the proposed sensorless control methodology.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"113 1","pages":"982-987"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76545704","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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