By analyzing the output voltage ripple of a buck-boost converter with large equivalent series resistance（ESR） of output capacitor, one valley voltage-mode controller for buck-boost converter is proposed. Considering...By analyzing the output voltage ripple of a buck-boost converter with large equivalent series resistance（ESR） of output capacitor, one valley voltage-mode controller for buck-boost converter is proposed. Considering the fact that the increasing and decreasing slopes of the inductor current are assumed to be constant during each switching cycle, an especial sampleddata model of valley voltage-mode controlled buck-boost converter is established. Based on this model, the dynamical effect of an output-capacitor time-constant on the valley voltage-mode controlled buck-boost converter is revealed and analyzed via the bifurcation diagrams, the movements of eigenvalues, the Lyapunov exponent spectra, the boundary equations,and the operating-state regions. It is found that with gradual reduction of output-capacitor time-constant, the buck-boost converter in continuous conduction mode（CCM） shows the evolutive dynamic behavior from period-1 to period-2, period-4, period-8, chaos, and invalid state. The stability boundary and the invalidated boundary are derived theoretically by stability analysis, where the stable state of valley voltage-mode controlled buck-boost converter can enter into an unstable state, and the converter can shift from the operation region to a forbidden region. These results verified by time-domain waveforms and phase portraits of both simulation and experiment indicate that the sampled-data model is correct and the time constant of the output capacitor is a critical factor for valley voltage-mode controlled buck-boost converter, which has a significant effect on the dynamics as well as control stability.展开更多
Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effe...Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effective digital data transmission, a power electronic converter referred as Modified Negative Luo Converter (MNLC) is proposed in this paper. MNLC is a high gain converter in which the output voltage increases in geometric progression. This paper portrays a novel concept of a 50 Hz pulse data transmission through RLCG (Resistance-inductance-capacitance with a shunt conductance) transmission line using MNLC. Signal frequency of 50 Hz to be transmitted is anded with a high frequency pulse that charges and discharges MNLC and produces the boosted negative output voltage. The boosted output is again transmitted through the RLCG transmission line from which 50 Hz data pulse is retrieved at the output of the transmission line by comparing with a comparator signal. This sort of MNLC aided data transmission not only introduces less loss in its transmitted data but also overcomes various health hazards of conventional radio frequency (RF) communication. This technique also proves that any data bit stream can be transmitted and retrieved using the proposed high gain DC-DC converter. The simulation model of the proposed system is implemented in MATLAB for various switching frequencies with its prototype of the converter developed and the results are verified.展开更多
在中小型永磁同步风力发电机中,桥式整流+DC/DC变换器拓扑具有结构简单的优点,其中DC/DC电路有Boost和Buck两种拓扑,探究两者的最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制性能区别是对其优化设计的关键,测控系统是性能分...在中小型永磁同步风力发电机中,桥式整流+DC/DC变换器拓扑具有结构简单的优点,其中DC/DC电路有Boost和Buck两种拓扑,探究两者的最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制性能区别是对其优化设计的关键,测控系统是性能分析的重要手段。通过系统总体方案设计,确认了系统参数及指标;分析了四桥臂DC/DC拓扑,并基于高端电流采样和隔离采样技术实现了系统电压、电流、功率和频率的采集,设计了功率驱动及单片机控制电路;探讨了适合单片机的MPPT爬坡搜索法软件;给出了基于LabVIEW的上位机操控系统的软件设计实现;搭建了测控系统,进行了MPPT和两种拓扑测控结果对比实验。实验结果表明测控系统达到了设计目标。展开更多
With the development of current electronic technology, numerous high-speed data acquisition systems provide a variety of potential benefits. This article describes a high-speed data acquisition system which consists o...With the development of current electronic technology, numerous high-speed data acquisition systems provide a variety of potential benefits. This article describes a high-speed data acquisition system which consists of ECL logic and TTL logic devices, samples and stores data with a 1 GHz clock. This system is accomplished easily and works stably. A performance test of this system has been undertaken and the results show that the effective number of bits （ENOB） is more than 6.5 bits.展开更多
Constraint pushing techniques have been developed for mining frequent patterns and association rules. How ever, multiple constraints cannot be handled with existing techniques in frequent pattern mining. In this paper...Constraint pushing techniques have been developed for mining frequent patterns and association rules. How ever, multiple constraints cannot be handled with existing techniques in frequent pattern mining. In this paper, a new algorithm MCFMC （mining complete set of frequent itemsets with multiple constraints） is introduced. The algorithm takes advantage of the fact that a convertible constraint can be pushed into mining algorithm to reduce mining research spaces. By using a sample database, the algorithm develops techniques which select an optimal method based on a sample database to convert multiple constraints into multiple convert ible constraints, disjoined by conjunction and/or, and then partition these constraints into two parts. One part is pushed deep inside the mining process to reduce the research spaces for frequent itemsets, the other part that cannot be pushed in algorithm is used to filter the complete set of frequent itemsets and get the final result. Results from our detailed experi ment show the feasibility and effectiveness of the algorithm.展开更多
The correlations have been developed with the flash data to predict the multiphase flow and mass transfer in the oil wells designs. Therefore, the laboratory pressure/volume/temperature (PVT) reports require calculati...The correlations have been developed with the flash data to predict the multiphase flow and mass transfer in the oil wells designs. Therefore, the laboratory pressure/volume/temperature (PVT) reports require calculation of the flash Oil Formation Volume Factor and the flash Solution Gas/Oil Ratio data starting from Differential Liberation tested data. Once these parameters are known, the oil density and other thermophysical properties can be determined by a complete model for the different states of pressure and temperature in the well during its production life and initial design. The subject of this paper is how to read and make proper use of information contained in the IMP laboratory PVT reports, for the oil wells designs. The discussion is focused on the laboratory report for the well number 407 located in the Maloob field in Mexico.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61371033 and 51407054)the Foundation for the Author of National Excellent Doctoral Dissertation of China(Grant No.201442)the Fundamental Research Funds for the Central Universities of China(Grant No.2682016CX035)
文摘By analyzing the output voltage ripple of a buck-boost converter with large equivalent series resistance（ESR） of output capacitor, one valley voltage-mode controller for buck-boost converter is proposed. Considering the fact that the increasing and decreasing slopes of the inductor current are assumed to be constant during each switching cycle, an especial sampleddata model of valley voltage-mode controlled buck-boost converter is established. Based on this model, the dynamical effect of an output-capacitor time-constant on the valley voltage-mode controlled buck-boost converter is revealed and analyzed via the bifurcation diagrams, the movements of eigenvalues, the Lyapunov exponent spectra, the boundary equations,and the operating-state regions. It is found that with gradual reduction of output-capacitor time-constant, the buck-boost converter in continuous conduction mode（CCM） shows the evolutive dynamic behavior from period-1 to period-2, period-4, period-8, chaos, and invalid state. The stability boundary and the invalidated boundary are derived theoretically by stability analysis, where the stable state of valley voltage-mode controlled buck-boost converter can enter into an unstable state, and the converter can shift from the operation region to a forbidden region. These results verified by time-domain waveforms and phase portraits of both simulation and experiment indicate that the sampled-data model is correct and the time constant of the output capacitor is a critical factor for valley voltage-mode controlled buck-boost converter, which has a significant effect on the dynamics as well as control stability.
文摘Telecom sectors generally operate at negative voltages to reduce the effect of corrosion caused in the metallic wire due to electrochemical reaction while communicating signals. To feed those lines and to have an effective digital data transmission, a power electronic converter referred as Modified Negative Luo Converter (MNLC) is proposed in this paper. MNLC is a high gain converter in which the output voltage increases in geometric progression. This paper portrays a novel concept of a 50 Hz pulse data transmission through RLCG (Resistance-inductance-capacitance with a shunt conductance) transmission line using MNLC. Signal frequency of 50 Hz to be transmitted is anded with a high frequency pulse that charges and discharges MNLC and produces the boosted negative output voltage. The boosted output is again transmitted through the RLCG transmission line from which 50 Hz data pulse is retrieved at the output of the transmission line by comparing with a comparator signal. This sort of MNLC aided data transmission not only introduces less loss in its transmitted data but also overcomes various health hazards of conventional radio frequency (RF) communication. This technique also proves that any data bit stream can be transmitted and retrieved using the proposed high gain DC-DC converter. The simulation model of the proposed system is implemented in MATLAB for various switching frequencies with its prototype of the converter developed and the results are verified.
文摘在中小型永磁同步风力发电机中,桥式整流+DC/DC变换器拓扑具有结构简单的优点,其中DC/DC电路有Boost和Buck两种拓扑,探究两者的最大功率点跟踪(Maximum Power Point Tracking,MPPT)控制性能区别是对其优化设计的关键,测控系统是性能分析的重要手段。通过系统总体方案设计,确认了系统参数及指标;分析了四桥臂DC/DC拓扑,并基于高端电流采样和隔离采样技术实现了系统电压、电流、功率和频率的采集,设计了功率驱动及单片机控制电路;探讨了适合单片机的MPPT爬坡搜索法软件;给出了基于LabVIEW的上位机操控系统的软件设计实现;搭建了测控系统,进行了MPPT和两种拓扑测控结果对比实验。实验结果表明测控系统达到了设计目标。
文摘With the development of current electronic technology, numerous high-speed data acquisition systems provide a variety of potential benefits. This article describes a high-speed data acquisition system which consists of ECL logic and TTL logic devices, samples and stores data with a 1 GHz clock. This system is accomplished easily and works stably. A performance test of this system has been undertaken and the results show that the effective number of bits （ENOB） is more than 6.5 bits.
基金Supported by the National Natural Science Foun-dation of China(60542004)
文摘Constraint pushing techniques have been developed for mining frequent patterns and association rules. How ever, multiple constraints cannot be handled with existing techniques in frequent pattern mining. In this paper, a new algorithm MCFMC （mining complete set of frequent itemsets with multiple constraints） is introduced. The algorithm takes advantage of the fact that a convertible constraint can be pushed into mining algorithm to reduce mining research spaces. By using a sample database, the algorithm develops techniques which select an optimal method based on a sample database to convert multiple constraints into multiple convert ible constraints, disjoined by conjunction and/or, and then partition these constraints into two parts. One part is pushed deep inside the mining process to reduce the research spaces for frequent itemsets, the other part that cannot be pushed in algorithm is used to filter the complete set of frequent itemsets and get the final result. Results from our detailed experi ment show the feasibility and effectiveness of the algorithm.
文摘The correlations have been developed with the flash data to predict the multiphase flow and mass transfer in the oil wells designs. Therefore, the laboratory pressure/volume/temperature (PVT) reports require calculation of the flash Oil Formation Volume Factor and the flash Solution Gas/Oil Ratio data starting from Differential Liberation tested data. Once these parameters are known, the oil density and other thermophysical properties can be determined by a complete model for the different states of pressure and temperature in the well during its production life and initial design. The subject of this paper is how to read and make proper use of information contained in the IMP laboratory PVT reports, for the oil wells designs. The discussion is focused on the laboratory report for the well number 407 located in the Maloob field in Mexico.
