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Search Results: 1 - 10 of 7851 matches for " DC Current Source "
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Complex subharmonic oscillation phenomenon of peak current controlled buck converter with current source load

Zhou Guo-Hu,Xu Jian-Ping,Bao Bo-Cheng,Wang Jin-Ping,Jin Yan-Yan,

物理学报 , 2011,
Abstract: Peak current controlled buck converter with current source load shows the complex phenomenon of fast-scale and slow-scale subharmonic oscillations. Its piecewise smooth switching model and discrete iterative map model are established in this paper. According to its discrete iterative map model, the effects of circuit parameters on the nonlinear dynamic behaviors of buck converter are analyzed by numerical simulation. It is found that attractive regions of fast-scale and slow-scale subharmonic oscillations and dual tori phenomena exist in the bifurcation diagram and Poincaré mapping, respectively. Time-domain simulation waveforms and phase portraits of buck converter are obtained by Runge-Kutta algorithm using the piecewise smooth switching model. The research results indicate that n-type subharmonic oscillation constituted by subharmonic oscillation and frequency-reduced subharmonic oscillation exists in the inductor current, and sine-type subharmonic oscillation constituted by fast scale and low scale exists in the output voltage, respectively. Analysis and simulation results are verified by experimental results.
Fine tuning of cascaded d-q axis controller for AC-DC-AC converter without DC link capacitor using artificial neural network
Padmanaban Sanjeevikumar,Balakrishnan GeethaLakshmi,Perumal Danajayan
Songklanakarin Journal of Science and Technology , 2008,
Abstract: This paper presents an artificial neural network (ANN) based approach to tune the parameters of the cascaded d-q axis controller for an AC-DC-AC converter without dc link capacitor. The proposed converter uses the cascaded d-q axis controller on the rectifier side and space vector pulse width modulation on the inverter side. The feed-forward ANN with the error back-propagation training is employed to tune the parameters of the cascaded d-q axis controller. The converter topology provides simple commutation procedure with reduced number of switches and has additional advantages such as good voltage transfer ratio, four quadrant operation, unity power factor, no DC link capacitor and less THD in both the line and load sides. Simulation results closely match with theoretical analysis.
Development of Monitoring System on Programmable High-Power DC Current Source

季三飞, 同向前, 黄金亮
Instrumentation and Equipments (IaE) , 2015, DOI: 10.12677/IaE.2015.34016
Abstract: 本文针对可编程直流电流源输出电流的幅值、频率、波形可设定的要求,设计了电流源的系统组成方案和电流参考波形的调制算法。可编程直流电流源由基于PC机的上位机监控系统和基于DSP控制的DC-DC变换器组成,两者通过RS485工业通信总线联系。基于LabVIEW的上位机监控系统的开发可实现对可编程直流电流源输出电流波形的调制和监控。实际装置的运行结果表明,上位机监控系统的设计满足装置的功能要求,操作简明,运行可靠。
According to the output current amplitude, frequency and waveform requirements of the pro-grammable DC current source, the structure scheme and the modulation algorithm were designed. The programmable DC current source is composed of PC monitoring system and DC-DC converter controlled by DSP. PC communicates with DSP by the industrial communication bus RS-485. The PC monitoring system based on LabVIEW is developed, which can achieve the modulation and monitoring on DC current source output. The operation results show that the PC monitoring system satisfies the requirements of device, with simple operation and high reliability.
电力系统自动化 , 2013, DOI: 10.7500/AEPS20130220008
Abstract: Acurrentsourceconverterbasedmulti-terminaldirectcurrent(DC)windenergyconversionsystem(WECS)isproposed.ThecurrentsourceDC/DCconverterisadoptedtoconnectawindturbinetoaninverterwithmaximumpowerpointcontrol.EachturbineisassociatedwithaDCsourcebyparallel-connectedtoacommonDClink.AfterDCpowercollection,acurrentsourceinverter(CSI)usinggateturn-offcomponentsisusedforthegridconnectionduetoitsflexiblereactivepowercontrolandshortcircuitprotectioncapabilities.Forsuchaparallelconnectionconfiguration,theCSIoperatesinaninputvoltagecontrolmode,whichmaintainstheDClinkvoltageconstant.Thedynamicresponsesofcombinedmechanicalandelectricalsystemsareinvestigatedwiththreedifferentoperationcases.SimulationandexperimentalresultsdemonstratethefeasibilityandstabilityofthecurrentsourceDC/DCconverterbasedmulti-terminalDCWECS.
Design of a Switched Capacitor Negative Feedback Circuit for a Very Low Level DC Current Amplifier  [PDF]
Hiroki Higa, Naoki Nakamura
Circuits and Systems (CS) , 2013, DOI: 10.4236/cs.2013.44048

To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.

A High Dynamic Range GMI Current Sensor  [PDF]
Aktham Asfour, Jean-Paul Yonnet, Manel Zidi
Journal of Sensor Technology (JST) , 2012, DOI: 10.4236/jst.2012.24023
Abstract: The design and performances of a high dynamic range DC-AC current sensor utilizing Giant Magneto-Impedance (GMI) are presented. The sensor is based on a GMI element with negative feedback. The sensing element is a 30 μm diameter GMI Co-based amorphous wire. It is curled to a toroidal core of 2 cm diameter. A bias magnetic field of about 650 A/m is applied to the GMI element to obtain an asymmetric GMI effect. A strong negative feedback is introduced to ensure linearity in a wide dynamic range. Analog conditioning electronics was fully developed. This includes a square wave oscillator based on an inverter trigger; a peak detector and a high gain amplifier with zero adjust. The GMI element is driven at a 3 MHz frequency and 5 mA peak-to-peak current. The closed-loop operations are investigated and the performances of the sensor are presented. DC current measurements are performed. The sensor exhibits good sensitivity and very good linearity, free from hysteresis, in a wide dynamic range of ±40 A. The sensitivity is about 0.24 V/A and the linearity error is about 0.02% of the full scale (FS). The hysteresis error is smaller than the measurement accuracy. AC current measurements using the developed sensor have also been successfully achieved. The sensor bandwidth in closed-loop was about 1.7 kHz.
Fault Ride-through Capability Enhancement of VSC-HVDC-connected Offshore Wind Power Plants
电力系统自动化 , 2015, DOI: 10.7500/AEPS20140119001
Abstract: ToachieveactivecontroloftheACvoltagemagnitudeofwindpowerplant(WPP)collectornetworkandimprovethefaultride-through(FRT)capability,anFRTschemebasedonfeedforwardDCvoltagecontrolispresentedforvoltagesourceconverter-highvoltagedirectcurrent(VSC-HVDC)connectedoffshoreWPPs.Duringsteadystateoperation,anopenloopACvoltagecontrolisimplementedattheWPP-sideVSCoftheHVDCsystemsothatanypossiblecontrolinteractionsbetweenWPP-sideVSCandVSCofwindturbineareminimized.Whereasduringanygridfault,adynamicACvoltagereferenceismadeaccordingtoboththeDCvoltageerrorandACactivecurrentfromtheWPPcollectorsystem,thusensuringfastandrobustFRToftheVSC-HVDC-connectedoffshoreWPPs.Undertheunbalancedfaultconditioninthehostpowersystem,theresultingoscillatoryDCvoltageisdirectlyusedintheVSCACvoltagecontrollerattheWPPsidesothattheWPPcollectorsystemvoltagealsoreflectstheunbalanceinthemaingrid.TimedomainsimulationsareperformedtoverifytheefficacyoftheFRTschemebasedontheproposedfeedforwardDCvoltagecontrol.SimulationresultsshowsatisfactoryFRTresponsesoftheVSC-HVDC-connectedoffshoreWPPunderbalancedandunbalancedfaultsinthehostpowersystem,asisshownunderaseriousfaultintheWPPcollectornetwork.
A Novel Over-Current Protection Technique Applied to Peak-Current Type DC-DC Converter  [PDF]
Yu Fang, Tengfei Wei, Liang He, Yong Xie, Yan Xing
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.26045
Abstract: The change of the over-current protection point of the power switches, caused by slope compensation, is analyzed in detail. It is discovered that the peak current protecting value increases as the duty cycle decreases. As a result, the safety operation of the switches is damaged greatly. A novel solution to improve over-current protection with constant peak current limitation is proposed by inducing synchronous slope compensation into the current limit function instead of the original constant voltage. The design principle and method of the protection circuit based on a UC3846 PWM controller for the interleaved dual-forward converter is presented. Experimental results are given to verify the analysis.
A Single Phase Current Source PFC Converter Based on UC3854  [PDF]
Jianbo Yang, Weiping Zhang, Faris Al-Naemi, Xiaoping Chen
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B164

A novel high-power-factor Buck type converter with average current control based on UC 3854 is proposed. The input current is directly controlled by average current control scheme to deliver sinusoidal input current and to gain a high power factor. The practical results, which illustrate the proposed control philosophy, were obtained from a 120 W AC/DC Buck type converter. The power factor can reach 0.97.

Simulation and Analysis on Winding Deformation of a Power Transformer in Current Transformer Connecting Manner  [PDF]
Lanqin Geng, Ning Zhang
Journal of Power and Energy Engineering (JPEE) , 2015, DOI: 10.4236/jpee.2015.34001

Transformer winding deformation?is one of the main types of transformer faults. To check if a power transformer is being under winding deformation, the transformer can be connected in a current transformer during its testing. A transformer winding simulating model is set up under this connecting manner. Then the simulation has been performed with?current source which is the frequency sweep power. The simulation results show that the winding deformation can be reflected effectively with current source method.?This method lays the foundation for the realization of on-line monitoring and diagnosis of the transformer neutral directly grounded side winding.

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