Pub Date : 2015-10-29DOI: 10.1109/ECCE.2015.7310161
Alan Wilson, S. Bernet
This paper compares 3-level and a 5-level ANPC-VSCs in terms of the power losses and the maximum output current given by the junction temperature of the most stressed device, in a wide range of operating points, by simulating theses converters with 4.5 kV, 120 A IGBT modules connected in series. The junction temperature of the most stressed semiconductors limits the maximum allowable output current, and in order to calculate these temperatures, power losses and thermal models are needed. The results show that the 3L-ANPC can deliver larger currents compared with the 5L-ANPC at the same average switching frequency, but with a comparable output harmonic quality, the performance of both converters are more comparable, although not similar.
{"title":"Comparative evaluation of losses in 3L and 5L ANPC converters using HV-IGBT modules","authors":"Alan Wilson, S. Bernet","doi":"10.1109/ECCE.2015.7310161","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310161","url":null,"abstract":"This paper compares 3-level and a 5-level ANPC-VSCs in terms of the power losses and the maximum output current given by the junction temperature of the most stressed device, in a wide range of operating points, by simulating theses converters with 4.5 kV, 120 A IGBT modules connected in series. The junction temperature of the most stressed semiconductors limits the maximum allowable output current, and in order to calculate these temperatures, power losses and thermal models are needed. The results show that the 3L-ANPC can deliver larger currents compared with the 5L-ANPC at the same average switching frequency, but with a comparable output harmonic quality, the performance of both converters are more comparable, although not similar.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"11 1","pages":"3542-3549"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91078441","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7310276
B. Weiss, R. Reiner, R. Quay, P. Waltereit, F. Benkhelifa, M. Mikulla, M. Schlechtweg, O. Ambacher
The effects on the EMI spectrum for various switching frequency modulation (SFM) scenarios in a high frequency boost converter are investigated in this paper. A GaN-device and a Si-device are compared with respect to their EMI behavior, which results from different gate charges and therefore different voltage gradients dv/dt on the power lines. First, the dynamic characteristics of the GaN-HEMT are demonstrated in detail. Then the behavior in the time domain and the frequency domain for switching operations at 300 kHz with various frequency modulation settings and an output power of 250 W are presented.
{"title":"Switching frequency modulation for GaN-based power converters","authors":"B. Weiss, R. Reiner, R. Quay, P. Waltereit, F. Benkhelifa, M. Mikulla, M. Schlechtweg, O. Ambacher","doi":"10.1109/ECCE.2015.7310276","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310276","url":null,"abstract":"The effects on the EMI spectrum for various switching frequency modulation (SFM) scenarios in a high frequency boost converter are investigated in this paper. A GaN-device and a Si-device are compared with respect to their EMI behavior, which results from different gate charges and therefore different voltage gradients dv/dt on the power lines. First, the dynamic characteristics of the GaN-HEMT are demonstrated in detail. Then the behavior in the time domain and the frequency domain for switching operations at 300 kHz with various frequency modulation settings and an output power of 250 W are presented.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"34 1","pages":"4361-4366"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91107628","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7310022
A. Trentin, P. Zanchetta, L. Empringham, L. de Lillo, P. Wheeler, J. Clare
This paper presents an experimental efficiency comparison study between two different AC-AC converter prototypes: the direct matrix converter (DMC) and indirect matrix converter (IMC). The evaluation is performed under different load conditions and using discrete IGBTs at a power level up to 9k[W]. The losses measurement is carried out by means of two power analyzers: one placed at the input and one at the output of the converters; to facilitate this measurement set-up the inclusion of an output filter was necessary in addition to the required input filter. Both converters implement the same traditional symmetrical space vector modulation and feature the same input/output filters design.
{"title":"Experimental comparison between direct matrix converter and indirect matrix converter based on efficiency","authors":"A. Trentin, P. Zanchetta, L. Empringham, L. de Lillo, P. Wheeler, J. Clare","doi":"10.1109/ECCE.2015.7310022","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310022","url":null,"abstract":"This paper presents an experimental efficiency comparison study between two different AC-AC converter prototypes: the direct matrix converter (DMC) and indirect matrix converter (IMC). The evaluation is performed under different load conditions and using discrete IGBTs at a power level up to 9k[W]. The losses measurement is carried out by means of two power analyzers: one placed at the input and one at the output of the converters; to facilitate this measurement set-up the inclusion of an output filter was necessary in addition to the required input filter. Both converters implement the same traditional symmetrical space vector modulation and feature the same input/output filters design.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"2009 1","pages":"2580-2587"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89513190","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7309777
O. Ojo, M. Ramezani, A. Gautam
This paper presents a sensor-less vector control method which estimates the rotor angle and speed of a nine-phase, Interior Permanent Magnet (IPM) machine with concentrated stator winding, especially for use at starting, zero and low speed operations. The injection of unique high frequency voltage signals into a non-torque producing third sequence circuit of the machine provides current information for the estimation of the rotor angle and speed without generating any high frequency torque ripple. The fundamental voltage component impressed on the motor by the converter, with the estimated rotor angle and rotor speed are used for the speed control of the motor drive under minimum stator copper loss operation. In order to computer simulate the complete controlled drive, including both the fundamental and high frequency components a full order model of the motor is utilized. The control and estimation strategies proposed have been implemented on a 2 hp, 36 slots, 4-pole concentrated stator wound interior permanent magnet motor drive. Some simulation based on a full order coupled machine model and experimental results validate the proposed vector control scheme for operation at both low and high speed operations.
{"title":"Sensor-less vector control of the nine-phase concentrated wound interior permanent magnet motor drive using a unique third sequence high frequency injection into the stator windings","authors":"O. Ojo, M. Ramezani, A. Gautam","doi":"10.1109/ECCE.2015.7309777","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7309777","url":null,"abstract":"This paper presents a sensor-less vector control method which estimates the rotor angle and speed of a nine-phase, Interior Permanent Magnet (IPM) machine with concentrated stator winding, especially for use at starting, zero and low speed operations. The injection of unique high frequency voltage signals into a non-torque producing third sequence circuit of the machine provides current information for the estimation of the rotor angle and speed without generating any high frequency torque ripple. The fundamental voltage component impressed on the motor by the converter, with the estimated rotor angle and rotor speed are used for the speed control of the motor drive under minimum stator copper loss operation. In order to computer simulate the complete controlled drive, including both the fundamental and high frequency components a full order model of the motor is utilized. The control and estimation strategies proposed have been implemented on a 2 hp, 36 slots, 4-pole concentrated stator wound interior permanent magnet motor drive. Some simulation based on a full order coupled machine model and experimental results validate the proposed vector control scheme for operation at both low and high speed operations.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"1 1","pages":"853-859"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89881659","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7310267
Jiefeng Hu, Qishuang Ma, Chuanqi Ren, D. Dorrell
The development of distributed generation (DG) systems has led to the increasing use of voltage source inverters. However, step-changes in the modulated voltage can produce dangerous peak common-mode currents (CMCs), which can interfere with the power system ground and cause detrimental effects on other equipment. In this paper, the root cause of CMCs is explored and analyzed. After this, a new method which combines of a modified inverter topology and a predictive current control scheme is developed. The test results show that the proposed method effectively controls the load current while the CMCs can be reduced significantly.
{"title":"A predictive current control of voltage source inverters for common-mode current attenuation","authors":"Jiefeng Hu, Qishuang Ma, Chuanqi Ren, D. Dorrell","doi":"10.1109/ECCE.2015.7310267","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310267","url":null,"abstract":"The development of distributed generation (DG) systems has led to the increasing use of voltage source inverters. However, step-changes in the modulated voltage can produce dangerous peak common-mode currents (CMCs), which can interfere with the power system ground and cause detrimental effects on other equipment. In this paper, the root cause of CMCs is explored and analyzed. After this, a new method which combines of a modified inverter topology and a predictive current control scheme is developed. The test results show that the proposed method effectively controls the load current while the CMCs can be reduced significantly.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"8 1","pages":"4295-4300"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73548708","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7310204
A. Gilson, S. Tavernier, M. Gerber, C. Espanet, F. Dubas, D. Depernet
This paper presents a high-speed 3 kW 80 krpm surface-mounted permanent magnet (SMPM) motor for compressor applications. The design procedure using finite element analysis (FEA) is presented with a particular focus on the efficiency calculation. The paper also aims to give general indications to provide a cost-efficient solution. A prototype is built and experimental results are given and compared to the simulations.
{"title":"Design of a cost-efficient high-speed high-efficiency PM machine for compressor applications","authors":"A. Gilson, S. Tavernier, M. Gerber, C. Espanet, F. Dubas, D. Depernet","doi":"10.1109/ECCE.2015.7310204","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310204","url":null,"abstract":"This paper presents a high-speed 3 kW 80 krpm surface-mounted permanent magnet (SMPM) motor for compressor applications. The design procedure using finite element analysis (FEA) is presented with a particular focus on the efficiency calculation. The paper also aims to give general indications to provide a cost-efficient solution. A prototype is built and experimental results are given and compared to the simulations.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"2 1","pages":"3852-3856"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76614992","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7309702
Junyeong Jung, Yonghyun Park, Sang Bin Lee, Changhee Cho, Kwonhee Kim, E. Wiedenbrug, M. Teska
Most of the failures in oil-lubricated journal bearings are associated with mechanical instabilities produced by lubrication system problems or bearing wear, and result in increased shaft vibration. Therefore, monitoring of the journal bearing condition in the field mainly relies on analysis of proximity probe or accelerometer signals. However, not all motors with journal bearings are equipped with such mechanical sensors due to cost or environmental restrictions. In this paper, the feasibility of applying motor current signature analysis (MCSA) for remote monitoring of mechanical instabilities in journal bearings produced by oil whirl and bearing clearance problems, is evaluated. In addition, a small-scale journal bearing test setup that can be implemented in low voltage motors for testing journal bearing faults under controlled conditions, is presented. An experimental study on a sealless fuel pump motor operating in the field, and on the custom-built journal bearing motor test setup shows that MCSA is capable of providing remote monitoring of journal bearing oil whirl and increased clearance for potentially preventing motor failure. The results of vibration analysis are also presented for comparative evaluation.
{"title":"Monitoring of journal bearing faults based on motor current signature analysis for induction motors","authors":"Junyeong Jung, Yonghyun Park, Sang Bin Lee, Changhee Cho, Kwonhee Kim, E. Wiedenbrug, M. Teska","doi":"10.1109/ECCE.2015.7309702","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7309702","url":null,"abstract":"Most of the failures in oil-lubricated journal bearings are associated with mechanical instabilities produced by lubrication system problems or bearing wear, and result in increased shaft vibration. Therefore, monitoring of the journal bearing condition in the field mainly relies on analysis of proximity probe or accelerometer signals. However, not all motors with journal bearings are equipped with such mechanical sensors due to cost or environmental restrictions. In this paper, the feasibility of applying motor current signature analysis (MCSA) for remote monitoring of mechanical instabilities in journal bearings produced by oil whirl and bearing clearance problems, is evaluated. In addition, a small-scale journal bearing test setup that can be implemented in low voltage motors for testing journal bearing faults under controlled conditions, is presented. An experimental study on a sealless fuel pump motor operating in the field, and on the custom-built journal bearing motor test setup shows that MCSA is capable of providing remote monitoring of journal bearing oil whirl and increased clearance for potentially preventing motor failure. The results of vibration analysis are also presented for comparative evaluation.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"1 1","pages":"300-307"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78583748","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}
Virtual synchronous generator (VSG) is a control scheme applied to the inverter of a distributed generating unit in order to support power system stability by imitating the behavior of a synchronous generator. A lot of effort has been dedicated to investigating the power stage control of VSG, but the waveform quality of VSG is not fully discussed. This paper analyses a VSG with an inner voltage loop to attenuate waveform distortion influenced by dead-time effect. And main parts of the voltage loop are voltage regulator and active damping of the LCL filter. Generally speaking, the voltage regulator attenuates the influence of dead-time effect, and the active damping suppresses the resonance peak caused by the LCL filter and makes it easier to stabilize the whole system. Based on the proportional-resonant (PR) compensator together with capacitor-current-feedback active damping which is widely used for their effectiveness and simple implementations, a step-by-step design method of the controller parameters for voltage loop is proposed. By carefully dealing with the interaction between the voltage regulator and active damping, the satisfactory regions of the controller parameters for meeting the system specifications are obtained, from which the controller parameters can be easily picked out. Simulation results verify the effectiveness of inner voltage loop.
{"title":"Step-by-step controller design of voltage closed-loop control for virtual synchronous generator","authors":"Xinran Chen, X. Ruan, Dongsheng Yang, Heng Wu, Wenxin Zhao","doi":"10.1109/ECCE.2015.7310191","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310191","url":null,"abstract":"Virtual synchronous generator (VSG) is a control scheme applied to the inverter of a distributed generating unit in order to support power system stability by imitating the behavior of a synchronous generator. A lot of effort has been dedicated to investigating the power stage control of VSG, but the waveform quality of VSG is not fully discussed. This paper analyses a VSG with an inner voltage loop to attenuate waveform distortion influenced by dead-time effect. And main parts of the voltage loop are voltage regulator and active damping of the LCL filter. Generally speaking, the voltage regulator attenuates the influence of dead-time effect, and the active damping suppresses the resonance peak caused by the LCL filter and makes it easier to stabilize the whole system. Based on the proportional-resonant (PR) compensator together with capacitor-current-feedback active damping which is widely used for their effectiveness and simple implementations, a step-by-step design method of the controller parameters for voltage loop is proposed. By carefully dealing with the interaction between the voltage regulator and active damping, the satisfactory regions of the controller parameters for meeting the system specifications are obtained, from which the controller parameters can be easily picked out. Simulation results verify the effectiveness of inner voltage loop.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"9 1","pages":"3760-3765"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75163495","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7310252
Jinwei He, Y. Li
To satisfy the requirement of operating DG units in both grid-tied and islanding microgrids, relatively large shunt capacitors are often selected for the output LCL filters of power converters. This modification can bring a few challenges, such as harmonic distortions and steady-state tracking errors, to the line current regulation during power converter grid-tied operation. In addition, the line current control problems can be more severe when the model-based one-step deadbeat current control scheme is used to reduce the computational load of DG unit controller and to enhance the dynamic current response. To overcome these limitations, a resonance dampened control method is developed utilizing the concept of the recently proposed weighted average current control with two current measurements. First, the weighted average current is accurately controlled via a modified deadbeat control scheme based on a virtual filter plant. To reduce the line current tracking errors caused by weighted average current approximation, a simple feed-forward term using existing grid voltage measurement is added to the line current reference of the proposed deadbeat control. Simulated and experimental results validate the effectiveness of the proposed method.
{"title":"An accurate deadbeat control method for grid-tied converter using weighted average current sensing","authors":"Jinwei He, Y. Li","doi":"10.1109/ECCE.2015.7310252","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7310252","url":null,"abstract":"To satisfy the requirement of operating DG units in both grid-tied and islanding microgrids, relatively large shunt capacitors are often selected for the output LCL filters of power converters. This modification can bring a few challenges, such as harmonic distortions and steady-state tracking errors, to the line current regulation during power converter grid-tied operation. In addition, the line current control problems can be more severe when the model-based one-step deadbeat current control scheme is used to reduce the computational load of DG unit controller and to enhance the dynamic current response. To overcome these limitations, a resonance dampened control method is developed utilizing the concept of the recently proposed weighted average current control with two current measurements. First, the weighted average current is accurately controlled via a modified deadbeat control scheme based on a virtual filter plant. To reduce the line current tracking errors caused by weighted average current approximation, a simple feed-forward term using existing grid voltage measurement is added to the line current reference of the proposed deadbeat control. Simulated and experimental results validate the effectiveness of the proposed method.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"18 1","pages":"4194-4201"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75336794","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 : 2015-10-29DOI: 10.1109/ECCE.2015.7309941
A. Safayet, P. Fajri, I. Husain
In this paper, a new approach for reactive power management based on inverter's capacity and sensitivity to the critical bus has been presented. The approach addresses the voltage rise and reverse power flow issue when residential renewable energy sources such as rooftop solar panels produce more energy than the local load demand. The overvoltage issues are controlled by active management of reactive power flow. This method improves the voltage regulation of distributed system with high penetration of renewable energy sources while utilizing the inverters' reactive power capacity.
{"title":"Reactive power management for overvoltage prevention at high PV penetration in low voltage distribution system","authors":"A. Safayet, P. Fajri, I. Husain","doi":"10.1109/ECCE.2015.7309941","DOIUrl":"https://doi.org/10.1109/ECCE.2015.7309941","url":null,"abstract":"In this paper, a new approach for reactive power management based on inverter's capacity and sensitivity to the critical bus has been presented. The approach addresses the voltage rise and reverse power flow issue when residential renewable energy sources such as rooftop solar panels produce more energy than the local load demand. The overvoltage issues are controlled by active management of reactive power flow. This method improves the voltage regulation of distributed system with high penetration of renewable energy sources while utilizing the inverters' reactive power capacity.","PeriodicalId":6654,"journal":{"name":"2015 IEEE Energy Conversion Congress and Exposition (ECCE)","volume":"77 1","pages":"1988-1994"},"PeriodicalIF":0.0,"publicationDate":"2015-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75283433","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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