Pub Date : 2012-11-12DOI: 10.1109/ECCE.2012.6342748
Zhiming Lan, Yao-hua Li, Chongjian Li, Chunyi Zhu, Chengsheng Wang
Nowadays the medium and high voltage large power AC-DC-AC converters are widely used in various industrial fields. The integrated gate commutated thyristor (IGCT) is applied to these converters on a large scale due to its high rated voltage and current and other excellent characteristics. In this paper the investigation on IGCT-based NPC/H-bridge large power converter is proposed. The converter is composed of two IGCT-based five-level NPC/H-bridge converters and their outputs are in parallel connection. Each phase of the five-level NPC/H-bridge converter is composed of two IGCT-based three-level neutral point clamped (NPC) legs in an H-bridge form. The converter adopts modular design and the module of IGCT-based three-level NPC legs has been developed. The turn off characteristics of IGCT are investigated and tested. At last one type of carrier-based modified in-phase disposition (IPD) modulation scheme is simulated.
{"title":"Investigation on IGCT-based NPC/H-bridge large power converter","authors":"Zhiming Lan, Yao-hua Li, Chongjian Li, Chunyi Zhu, Chengsheng Wang","doi":"10.1109/ECCE.2012.6342748","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342748","url":null,"abstract":"Nowadays the medium and high voltage large power AC-DC-AC converters are widely used in various industrial fields. The integrated gate commutated thyristor (IGCT) is applied to these converters on a large scale due to its high rated voltage and current and other excellent characteristics. In this paper the investigation on IGCT-based NPC/H-bridge large power converter is proposed. The converter is composed of two IGCT-based five-level NPC/H-bridge converters and their outputs are in parallel connection. Each phase of the five-level NPC/H-bridge converter is composed of two IGCT-based three-level neutral point clamped (NPC) legs in an H-bridge form. The converter adopts modular design and the module of IGCT-based three-level NPC legs has been developed. The turn off characteristics of IGCT are investigated and tested. At last one type of carrier-based modified in-phase disposition (IPD) modulation scheme is simulated.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"40 1","pages":"726-730"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81596716","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.2012.6342608
F. Kurokawa, K. Kajiwara, Y. Shibata, Y. Yamabe, T. Tanaka, K. Hirose
This paper presents a new digital peak current mode dc-dc converter using a FPGA delay circuit and a simple A-D converter. The peak current detection circuit is only composed of RC integrator and field programmable gate array (FPGA) delay circuit. The sampling point of detected current is changed by the feedback value of output voltage. The RC integrator is performed as the A-D converter for the current. The proposed method can detect the peak point of current in real time and shows a superior transient response. As a result, the convergence time and undershoot of output voltage are suppressed to one third and one fourth, respectively.
{"title":"A new digital peak current mode DC-DC converter using FPGA delay circuit and simple A-D converter","authors":"F. Kurokawa, K. Kajiwara, Y. Shibata, Y. Yamabe, T. Tanaka, K. Hirose","doi":"10.1109/ECCE.2012.6342608","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342608","url":null,"abstract":"This paper presents a new digital peak current mode dc-dc converter using a FPGA delay circuit and a simple A-D converter. The peak current detection circuit is only composed of RC integrator and field programmable gate array (FPGA) delay circuit. The sampling point of detected current is changed by the feedback value of output voltage. The RC integrator is performed as the A-D converter for the current. The proposed method can detect the peak point of current in real time and shows a superior transient response. As a result, the convergence time and undershoot of output voltage are suppressed to one third and one fourth, respectively.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"19 1","pages":"1698-1702"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81700351","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.2012.6342757
Duong Tran, A. Khambadkone
In this paper, to ensure stable operation of a wind power plant augmented with energy storage, dynamic control for energy storage system (ESS) inside the wind power plant is investigated. Control structure and control parameters of ESS are selected based on proposed small-signal stability criterion and large-signal stability criterion. Simulation result shows that with proposed dynamic control scheme for the ESS, the wind power power plant is stabilized when grid behaves as a constant power load which becomes a destabilizing factor, or when there is failure of wind turbine.
{"title":"Dynamic control of energy storage system for stable operation of wind power plant","authors":"Duong Tran, A. Khambadkone","doi":"10.1109/ECCE.2012.6342757","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342757","url":null,"abstract":"In this paper, to ensure stable operation of a wind power plant augmented with energy storage, dynamic control for energy storage system (ESS) inside the wind power plant is investigated. Control structure and control parameters of ESS are selected based on proposed small-signal stability criterion and large-signal stability criterion. Simulation result shows that with proposed dynamic control scheme for the ESS, the wind power power plant is stabilized when grid behaves as a constant power load which becomes a destabilizing factor, or when there is failure of wind turbine.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"12 1","pages":"666-671"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81836121","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.2012.6342487
Xiaogao Xie, Z. Lan, Chen Zhao
A new primary side controlled high power factor single-stage flyback LED driver with self-adjusted current reference proposed in this paper. The self-adjusted current reference is realized by a negative feedback circuit to achieve output current regulation and suitable for discontinuous conduction mode (DCM) or boundary conduction mode (BCM). The output of the self-adjusted current reference is a half-sine waveform and followed by the primary current, hence high power factor can be achieved. A DCM single-stage flyback LED driver with self-adjusted current reference is analyzed in this paper and detailed design considerations are presented. Finally, a DCM laboratory prototype for LED driver with 360mA/25V output based on the theoretical analyses was built up. Experimental results show that good output current regulation and high PF can be achieved.
{"title":"A new primary side controlled high power factor single-stage flyback LED driver","authors":"Xiaogao Xie, Z. Lan, Chen Zhao","doi":"10.1109/ECCE.2012.6342487","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342487","url":null,"abstract":"A new primary side controlled high power factor single-stage flyback LED driver with self-adjusted current reference proposed in this paper. The self-adjusted current reference is realized by a negative feedback circuit to achieve output current regulation and suitable for discontinuous conduction mode (DCM) or boundary conduction mode (BCM). The output of the self-adjusted current reference is a half-sine waveform and followed by the primary current, hence high power factor can be achieved. A DCM single-stage flyback LED driver with self-adjusted current reference is analyzed in this paper and detailed design considerations are presented. Finally, a DCM laboratory prototype for LED driver with 360mA/25V output based on the theoretical analyses was built up. Experimental results show that good output current regulation and high PF can be achieved.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"16 1","pages":"3575-3580"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84306580","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.2012.6342448
J. Miller, C. Ayers, L. Seiber, D. Smith
The capacitor industry requires fast and accurate characterization of component equivalent series resistance (ESR) and capacitance (C). In a manufacturing setting the measurements must be very fast, repeatable and high quality for use in process control, data collection and monitoring, plus for printing on the component SKU label. The fastest characterization testing is done electronically using pulse techniques and these must provide accurate assessment of the true parameter values. In this work a calorimeter method was developed to corroborate ESR values obtained using a recently developed electronic ESR characterization method at ORNL. Calorimeter measurements are very slow, tedious and subject to error if chamber inlet air is not properly conditioned. It was found that the provisional coplanar bus plate used for mounting a power ring high current capacitor introduced frequency dependence in ESR results that electronic measurement techniques did not incur. The calorimeter method lends itself well to parameter characterization under real world application conditions at rated current, frequency and wave shape.
{"title":"Calorimeter evaluation of inverter grade metalized film capacitor ESR","authors":"J. Miller, C. Ayers, L. Seiber, D. Smith","doi":"10.1109/ECCE.2012.6342448","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342448","url":null,"abstract":"The capacitor industry requires fast and accurate characterization of component equivalent series resistance (ESR) and capacitance (C). In a manufacturing setting the measurements must be very fast, repeatable and high quality for use in process control, data collection and monitoring, plus for printing on the component SKU label. The fastest characterization testing is done electronically using pulse techniques and these must provide accurate assessment of the true parameter values. In this work a calorimeter method was developed to corroborate ESR values obtained using a recently developed electronic ESR characterization method at ORNL. Calorimeter measurements are very slow, tedious and subject to error if chamber inlet air is not properly conditioned. It was found that the provisional coplanar bus plate used for mounting a power ring high current capacitor introduced frequency dependence in ESR results that electronic measurement techniques did not incur. The calorimeter method lends itself well to parameter characterization under real world application conditions at rated current, frequency and wave shape.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"65 1","pages":"2157-2163"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85279175","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.2012.6342173
Y. Lobsiger, J. Kolar
In this paper, a closed-loop active IGBT gate drive providing highly dynamic diC/dt and dvCE/dt control is proposed. By means of using only simple passive measurement circuits for the generation of the feedback signals and a single operational amplifier as PI-controller, high analog control bandwidth is achieved enabling the application even for switching times in the sub-microsecond range. Therewith, contrary to state of the art gate drives, the parameter dependencies and nonlinearities of the IGBT are compensated enabling accurately specified and constant diC/dt and dvCE/dt values of the IGBT for the entire load and temperature range. This ensures the operation of an IGBT in the safe operating area (SOA), i.e. with limited turn-on peak reverse recovery current and turn-off overvoltage, and permits the restriction of electromagnetic interference (EMI). A hardware prototype is built to experimentally verify the proposed closed-loop active gate drive concept.
{"title":"Closed-loop IGBT gate drive featuring highly dynamic di/dt and dv/dt control","authors":"Y. Lobsiger, J. Kolar","doi":"10.1109/ECCE.2012.6342173","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342173","url":null,"abstract":"In this paper, a closed-loop active IGBT gate drive providing highly dynamic diC/dt and dvCE/dt control is proposed. By means of using only simple passive measurement circuits for the generation of the feedback signals and a single operational amplifier as PI-controller, high analog control bandwidth is achieved enabling the application even for switching times in the sub-microsecond range. Therewith, contrary to state of the art gate drives, the parameter dependencies and nonlinearities of the IGBT are compensated enabling accurately specified and constant diC/dt and dvCE/dt values of the IGBT for the entire load and temperature range. This ensures the operation of an IGBT in the safe operating area (SOA), i.e. with limited turn-on peak reverse recovery current and turn-off overvoltage, and permits the restriction of electromagnetic interference (EMI). A hardware prototype is built to experimentally verify the proposed closed-loop active gate drive concept.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"73 1","pages":"4754-4761"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85615793","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.2012.6342532
K. M. Huq, M. Baran, S. Lukić, O. Nare
This paper considers the operational issues related to community level micro-grids which uses PV systems as the main local power generation. To facilitate the operation of such systems, the paper investigates the use of local storage, and proposes an Energy Management System (EMS) for this purpose. The paper shows that the proposed EMS can address the main operational issues, such as reducing energy consumption during peak loading conditions and limiting excess reverse power flow back to the utility.
{"title":"An Energy Management System for a community energy storage system","authors":"K. M. Huq, M. Baran, S. Lukić, O. Nare","doi":"10.1109/ECCE.2012.6342532","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342532","url":null,"abstract":"This paper considers the operational issues related to community level micro-grids which uses PV systems as the main local power generation. To facilitate the operation of such systems, the paper investigates the use of local storage, and proposes an Energy Management System (EMS) for this purpose. The paper shows that the proposed EMS can address the main operational issues, such as reducing energy consumption during peak loading conditions and limiting excess reverse power flow back to the utility.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"179 1","pages":"2759-2763"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76720888","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.2012.6342461
S. Ani, H. Polinder, J. A. Ferreira
This paper presents the design, manufacture and performance results of a low cost permanent magnet generator for small wind application. PM generators are able to achieve high efficiency compared with other generator types, but they also cost more than other generators. To make PM generators a low cost option, the generator configuration and materials have to be carefully selected. The paper highlights why the selected generator is designed, the choices made and the effect of used materials and manufacturing process on efficiency and energy yield. Results show that the annual energy yield of the system with prototype axial flux PM generator is comparable to that of commercially available systems.
{"title":"Low cost axial flux PM generator for small wind turbines","authors":"S. Ani, H. Polinder, J. A. Ferreira","doi":"10.1109/ECCE.2012.6342461","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342461","url":null,"abstract":"This paper presents the design, manufacture and performance results of a low cost permanent magnet generator for small wind application. PM generators are able to achieve high efficiency compared with other generator types, but they also cost more than other generators. To make PM generators a low cost option, the generator configuration and materials have to be carefully selected. The paper highlights why the selected generator is designed, the choices made and the effect of used materials and manufacturing process on efficiency and energy yield. Results show that the annual energy yield of the system with prototype axial flux PM generator is comparable to that of commercially available systems.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"160 1","pages":"2350-2357"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76979072","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.2012.6342406
Shengfang Fan, Yaosuo Xue, Kai Zhang
Conventional single-phase inverters exhibit double line frequency power pulsating, which affects dc sources such as photovoltaic performance and battery lifetime. Bulky dc-link electrolytic capacitors are typically employed as transient energy buffer to decouple the pulsating ac power from constant dc power, but such passive components suffer from temperature and aging concerns. For high reliability and high power density, active power decoupling approach is preferred. This paper presents a novel active power decoupling method by using a six-switch single-phase inverter topology. A small film capacitor is used as pulsating energy buffer in ac side, which not only improves the reliability but also the efficiency. A novel vector PWM for this topology is also proposed to maximize the dc voltage utilization, and to achieve the independent controls of the inverter output power and power decoupling. The simulation results have verified the proposed power decoupling method.
{"title":"A novel active power decoupling method for single-phase photovoltaic or energy storage applications","authors":"Shengfang Fan, Yaosuo Xue, Kai Zhang","doi":"10.1109/ECCE.2012.6342406","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342406","url":null,"abstract":"Conventional single-phase inverters exhibit double line frequency power pulsating, which affects dc sources such as photovoltaic performance and battery lifetime. Bulky dc-link electrolytic capacitors are typically employed as transient energy buffer to decouple the pulsating ac power from constant dc power, but such passive components suffer from temperature and aging concerns. For high reliability and high power density, active power decoupling approach is preferred. This paper presents a novel active power decoupling method by using a six-switch single-phase inverter topology. A small film capacitor is used as pulsating energy buffer in ac side, which not only improves the reliability but also the efficiency. A novel vector PWM for this topology is also proposed to maximize the dc voltage utilization, and to achieve the independent controls of the inverter output power and power decoupling. The simulation results have verified the proposed power decoupling method.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"5 1","pages":"2439-2446"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80880389","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.2012.6342683
X. Zhang, D. Vilathgamuwa, K. Tseng, B. Bhangu, G. Chandana
In recent years, electric propulsion systems have increasingly been used in land, sea and air vehicles. The vehicular power systems are usually loaded with tightly regulated power electronic converters which tend to draw constant power. Since the constant power loads (CPLs) impose negative incremental resistance characteristics on the feeder system, they pose a potential threat to the stability of vehicular power systems. This effect becomes more significant in the presence of distribution lines between source and load in large vehicular power systems such as electric ships and more electric aircrafts. System transients such as sudden drop of converter side loads or increase of constant power requirement can cause complete system instability. Most of the existing research work focuses on the modeling and stabilization of DC vehicular power systems with CPLs. Only a few solutions are proposed to stabilize AC vehicular power systems with non-negligible distribution lines and CPLs. Therefore, this paper proposes a novel loop cancellation technique to eliminate constant power instability in AC vehicular power systems with a theoretically unbounded system stability region. Analysis is carried out on system stability with the proposed method and simulation results are presented to validate its effectiveness.
{"title":"A loop cancellation based active damping solution for constant power instability in vehicular power systems","authors":"X. Zhang, D. Vilathgamuwa, K. Tseng, B. Bhangu, G. Chandana","doi":"10.1109/ECCE.2012.6342683","DOIUrl":"https://doi.org/10.1109/ECCE.2012.6342683","url":null,"abstract":"In recent years, electric propulsion systems have increasingly been used in land, sea and air vehicles. The vehicular power systems are usually loaded with tightly regulated power electronic converters which tend to draw constant power. Since the constant power loads (CPLs) impose negative incremental resistance characteristics on the feeder system, they pose a potential threat to the stability of vehicular power systems. This effect becomes more significant in the presence of distribution lines between source and load in large vehicular power systems such as electric ships and more electric aircrafts. System transients such as sudden drop of converter side loads or increase of constant power requirement can cause complete system instability. Most of the existing research work focuses on the modeling and stabilization of DC vehicular power systems with CPLs. Only a few solutions are proposed to stabilize AC vehicular power systems with non-negligible distribution lines and CPLs. Therefore, this paper proposes a novel loop cancellation technique to eliminate constant power instability in AC vehicular power systems with a theoretically unbounded system stability region. Analysis is carried out on system stability with the proposed method and simulation results are presented to validate its effectiveness.","PeriodicalId":6401,"journal":{"name":"2012 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"39 1","pages":"1182-1187"},"PeriodicalIF":0.0,"publicationDate":"2012-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85778130","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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