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1
Amarasinghe, Kanishka A. "Resonance mode power supplies with power factor correction." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/23672.
Full textAbstract:
There is an increasing need for AC-DC converters to draw a pure sinusoidal current at near unity power factor from the AC mains. Most conventional power factor correcting systems employ PWM techniques to overcome the poor power factor being presented to the mains. However, the need for smaller and lighter power processing equipment has motivated the use of higher internal conversion frequencies in the past. In this context, resonant converters are becoming a viable alternative to the conventional PWM controlled power supplies. The thesis presents the implementation of active power factor correction in power supplies, using resonance mode techniques. It reviews the PWM power factor correction circuit topologies previously used. The possibility of converting these PWM topologies to resonant mode versions is discussed with a critical assessment as to the suitability of the semiconductor switching devices available today for deployment in these resonant mode supplies. The thesis also provides an overview of the methods used to model active semiconductor devices. The computer modelling is done using the PSpice microcomputer simulation program. The modifications that are needed to the built in MOSFET model in PSpice, when modeling high frequency circuits is discussed. A new two transistor model which replicates the action of a OTO thyristor is also presented. The new model enables the designer to estimate the device parameters with ease by adopting a short calculation and graphical design procedure, based on the manufacturer's data sheets. The need for a converter with a high efficiency, larger power/weight ratio, high input power factor with reduced line current distortion and reduced cost has led to the development of a new resonant mode converter topology, for power processing. The converter presents a near resistive load to the mains thus ensuring a high input power factor, while providing a stabilised de voltage at the output with a small lOOHz ripple. The supply is therefore ideal for preregulation applications. A description of the modes of operation and the analysis of the power circuit are included in the thesis. The possibility of using the converter for low output voltage applications is also discussed. The design of a 300W, 80kHz prototype model of this circuit is presented in the thesis. The design of the isolation transformer and other magnetic components are described in detail. The selection of circuit components and the design and implementation of the variable frequency control loop are also discussed. An evaluation of the experimental and computer simulated results obtained from the prototype model are included in the presentation. The thesis further presents a zero-current switching quasi-resonant flyback circuit topology with power factor correction. The reasons for using this topology for off-line power conversion applications are discussed. The use of a cascoded combination of a bipolar power transistor and two power MOSFETs i~ the configuration has enabled the circuit to process moderate levels of power while simultaneously switching at high frequencies. This fulfils the fundamental precondition for miniaturisation. It also provides a well regulated DC output voltage with a very small ripple while maintaining a high input power factor. The circuit is therefore ideal for use in mobile applications. A preliminary design of the above circuit, its analysis using PSpice, the design of the control circuit, current limiting and overcurrent protection circuitry and the implementation of closed-loop control are all included in the thesis. The experimental results obtained from a bread board model is also presented with an evaluation of the circuit performance. The power factor correction circuit is finally installed in this supply and the overall converter performance is assessed.
2
Xie, Manjing. "Digital Control for Power Factor Correction." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34258.
Full textAbstract:
This thesis focuses on the study, implementation and improvement of a digital controller for a power factor correction (PFC) converter.
The development of the telecommunications industry and the Internet demands reliable, cost-effective and intelligent power. Nowadays, the telecommunication power systems have output current of up to several kilo amperes, consisting of tens of modules. The high-end server system, which holds over 100 CPUs, consumes tens of kilowatts of power. For mission-critical applications, communication between modules and system controllers is critical for reliability. Information about temperature, current, and the total harmonic distortion (THD) of each module will enable the availability of functions such as dynamic temperature control, fault diagnosis and removal, and adaptive control, and will enhance functions such as current sharing and fault protection. The dominance of analog control at the modular level limits system-module communications. Digital control is well recognized for its communication ability. Digital control will provide the solution to system-module communication for the DC power supply.
The PFC converter is an important stage for the distributed power system (DPS). Its controller is among the most complex with its three-loop structure and multiplier/divider. This thesis studies the design method, implementation and cost effectiveness of digital control for both a PFC converter and for an advanced PFC converter. Also discussed is the influence of digital delay on PFC performance. A cost-effective solution that achieves good performance is provided. The effectiveness of the solution is verified by simulation.
The three level PFC with range switch is well recognized for its high efficiency. The range switch changes the circuit topology according to the input voltage level. Research literature has discussed the optimal control for both range-switch-off and range-switch-on topologies. Realizing optimal analog control requires a complex structure. Until now optimal control for the three-level PFC with analog control has not been achieved. Another disadvantage of the three-level PFC is the output capacitor voltage imbalance. This thesis proposes an active balancing solution to solve this problem.Master of Science
3
Yeh, Thomas. "Analysis of power factor correction converters /." Online version of thesis, 1992. http://hdl.handle.net/1850/11220.
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4
Williams, David. "Active power decoupling for a boost power factor correction circuit." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59145.
Full textAbstract:
During AC-DC conversion, the ripple power at the input of the converter must be filtered from the output. This filtering can be easily done by placing a capacitor on the DC bus. For systems with power output of hundreds of Watts or more, this capacitor must be quite high to effectively perform the filtering, and in order to be cost effective, an aluminum electrolytic capacitor (Al e-caps) needs to be used. The lifespan of Al e-caps is notoriously short, so for long lifespan systems, their use is not advisable. Film capacitors have longer lifespans than Al e-caps but are more expensive on a cost per Farad basis. Methods have been proposed to reduce the required capacitance so that film capacitors can be cost effectively used. One of these methods is to use a separate decoupling port in the circuit that can filter the ripple power without the limitation of being connected directly to the DC bus. The first contribution is a method of using an active power decoupling (APD) port with a buck-based circuit that does not require direct measurement of the AC input signal for controlling the ripple power to the port. This APD port requires only two extra switches and some simple signal processing circuitry to generate a reference signal and control the voltage to the APD port capacitor. The second contribution is a design guide for a sliding mode control (SMC) system for the APD port. SMC shows promise as a control system for power electronics circuits and has never been demonstrated on an APD port before. The proposed circuit and control system is used in a 700 Watt AC-DC converter with power factor correction and is compared in simulation to a benchmark converter using a passive capacitor on the DC bus. The capacitance is reduced from 300μF to a 35μF and a 75μF capacitor without any effect on performance as indicated by measures of the voltage ripple, power factor and total harmonic distortion. The capacitance reduction results in a cost savings of $175 on capacitors when using prices that were current at time of publication.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
5
Niezrecki, Christopher. "Power factor correction and power consumption characterization of piezoelectric actuators." Thesis, Virginia Tech, 1992. http://hdl.handle.net/10919/42619.
Full textAbstract:
A piezoceramic actuator used for structural control behaves electrically as a nearly pure capacitance. When conventional amplifiers are used to drive these actuators, the current and voltage is close to 90 degrees out of phase. This causes the power factor (PF) of the load to be close to zero and results in excessive power requirements. This thesis reports the results of a study of the following question: What effect does applying power factor correction methods to piezoceramic actuators have on their power consumption characteristics? A subproblem we explored was to detennine the qualitative relationship between the power consumption of a piezoceramic actuator and the damping that actuator added to a structure.
To address the subproblem, a feedback control experiment was built which used a ceramic piezoceramic actuator and a strain rate sensor configured to add damping to a cantilevered beam. A disturbance was provided by a shaker attached to the beam. The power consumption of the actuator was detennined by measuring the current and voltage of the signal to the actuator. The energy dissipated in the beam by the feedback control loop was assumed to be modeled by an ideal structural damping model. A model relating structural damping as a function of the apparent power consumed by the actuator was developed, qualitatively verified, and physically justified.
Power factor correction methods were employed by adding an inductor in both parallel to and in series with the piezoceramic actuator. The inductance values were chosen such that each inductor-capacitor (LC) circuit was in resonance at the second natural frequency of the beam.
Implementing the parallel LC circuit reduced the current consumption of the piezoceramic actuator by 75% when compared to the current consumption of the actuator used without an inductor. Implementing the series LC circuit produced a 300% increase in the voltage applied to the actuator compared to the case when no inductor was used. In both cases, employing power factor correction methods corrected the power factor to near unity and reduced the apparent power by 12 dB. A theoretical model of each circuit was developed.
The analytical and empirical results are virtually identical. The results of this study can be used to synthesize circuits to modify piezoceramic actuators, reducing the voltage or current requirements of the amplifiers used to drive those actuatorsMaster of Science
6
Qian, Jinrong. "Advanced Single-Stage Power Factor Correction Techniques." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30773.
Full textAbstract:
Five new single-stage power factor correction (PFC) techniques are developed for single-phase applications. These converters are: Integrated single-stage PFC converters, voltage source charge pump power factor correction (VS-CPPFC) converters, current source CPPFC converters, combined voltage source current source (VSCS) CPPFC converters, and continuous input current (CIC) CPPFC converters.
Integrated single-stage PFC converters are first developed, which combine the PFC converter with a DC/DC converter into a single-stage converter. DC bus voltage stress at light load for the single-stage PFC converters are analyzed. DC bus voltage feedback concept is proposed to reduce the DC bus voltage stress at light load. The principle of operations of proposed converters are presented, implemented and evaluated. The experimental results verify the theoretical analysis.
VS-CPPFC technique use a capacitor in series with a high frequency voltage source to achieve the PFC function. In this way, the input inductor is eliminated. VS-CPPFC AC/DC converters are developed, and their performance is evaluated. VS-CPPFC electronic ballasts with and without dimming function are also presented. The average lamp current control with duty ratio modulation is developed so that the lamp operates in constant power with a low crest factor over the line variation. The experimental results verify the CPPFC concept.
CS-CPPFC technique employs a capacitor in parallel with a high frequency current source to obtain the PFC function. The unity power factor condition and principle of operation are analyzed. By doing so, the switch has less switching current stress, and deals only with the resonant inductor current. Design considerations and experimental results of the CS-CPPFC electronic ballast are presented.
VSCS-CPPFC technique integrates the VS-CPPFC with the CS-CPPFC converters. The circuit derivation, unity power factor condition and design considerations are presented. The developed VSCS-CPPFC converters has constant lamp operation, low crest factor with a high power factor even without any feedback control.
CIC-CPPFC technique is developed by inserting a small inductor in series with the line rectifier for the conceptual VS-CPPFC, CS-CPPFC and VSCS-CPPFC circuits. The circuit derivation and its unity power factor condition are discussed. The input current can be designed to be continuous, and a small line input filter can be used. The circulating current in the resonant tank and the switching current stress are minimized. The average lamp current control with switching frequency modulation is developed, so the developed electronic ballast operates in constant power, low crest factor. The developed CIC-CPPFC electronic ballast has features of low line input current harmonics, constant lamp power, low crest factor, continuous input current, low DC bus voltage stress, small circulating current and switching current stress over a wide range of line input voltage.Ph. D.
7
Jiang, Yimin. "Development of advanced power factor correction techniques." Diss., Virginia Polytechnic Institute and State University, 1994. http://hdl.handle.net/10919/53609.
Full textAbstract:
Three novel power factor correction (PFC) techniques are developed for both single-phase and three-phase applications. These techniques have advantages over the conventional approaches with regard to the converter efficiency, power density, cost, and reliability for many applications.
The single-phase parallel PFC (PPFC) technique was established. Different from the conventional two-cascade-stage scheme, the PPFC technique allows 68% of input power to go to the output through only one time high frequency power conversion, but still achieves both unity power factor and tight output regulation. A family of PPFC converters were proposed for different power levels, which are simpler and more efficient than the conventional two-cascade-stage systems. Since isolated boost converters are adopted as the main power stage in some of the PPFC converters, a device based soft-switching technique was proposed for using IGBTs as the main power switches, which ensures the lower cost and higher efficiency benefits of the PPFC technique.
The single-ended boost converter is the most frequently used converter in the single-phase PFC applications. For high power and/or high voltage applications, the major concerns of the conventional boost converter are the inductor volume and weight, and Iosses on the power devices, which will affect converter efficiency, power density, and cost. In this dissertation, a novel three-level boost converter was developed, which can use a much smaller inductor and lower voltage devices than the conventional one, yielding higher power density, higher efficiency, and lower cost.
In three-phase applications, the three-phase boost rectifier is the most popular topology for the PFC purpose. A novel high performance boost PFC rectifier was developed, which provides several superior features than the conventional one with nearly no cost increase. lt inherently provides six-step PWM operation, which is the optimal PWM scheme with no circulating energy, minimum input ripple current, and minimum . switching events. It also greatly reduces the bridge diode reverse recovery loss, which is one of the major switching Iosses in the conventional three-phase boost rectifier. Furthermore, it can adopt very simple soft-switching techniques even with three independent analog controllers to further improve the performance. Several simple soft switched three-phase boost rectifiers have been developed. Besides, the bridge shoot-through problem is virtually eliminated. As a result, these new three-phase boost rectifiers have higher efficiency, higher power density, lower cost, and higher reliability compared with the conventional one.Ph. D.
8
Chan, Weng Hong. "Harmonic reduction and power factor correction in low power supply system." Thesis, University of Macau, 2002. http://umaclib3.umac.mo/record=b1445817.
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9
Tan, Benjamin H. "A Novel Arc Welding Power Supply with Improved Power Factor Correction." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2199.
Full textAbstract:
This paper presents the design and development of a novel Arc Welding Power Supply utilizing a modified two-switch forward converter topology. The proposed design improves the power quality by improving power factor to near unity and reducing total harmonic distortion. State space analysis of the proposed circuit showed that the circuit followed a boost-buck input output relationship. Simulation of the circuit was first implemented in LTspice to verify the functionality of the new topology. Hardware implementation of the proposed design was built on a scaled-down prototype for a proof-of-concept of the new topology. The prototype specifications were created for a 5A, 20V output with a 20-24V, 60Hz input. This project demonstrated that the proposed new topology was successful in obtaining a near unity power factor and a total harmonic distortion of less than 2%. Additionally, the prototype followed the simulation and calculations of a boost-buck function while varying duty cycle, and the final measurements aligned well with waveforms from the simulation.
10
Jones, Kevin David. "Harmonic distortion correction using active power line conditioners." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA300873.
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11
Zhang, Jindong. "Advanced Integrated Single-Stage Power Factor Correction Techniques." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/26480.
Full textAbstract:
This dissertation presents the in-depth study and innovative solutions of the advanced integrated single-stage power-factor-correction (S2PFC) techniques, which target at the low- to medium-level power supplies, for wide range of applications, from power adapters and computers to various communication equipment.
To limit the undesirable power converter input-current-harmonicâ s impact on the power line and other electronics equipment, stringent current harmonic regulations such as IEC 61000-3-2 have already been enforced. The S2PFC techniques have been proposed and intensively studied, in order to comply these regulations with minimal additional component count and cost.
This dissertation provides a systematic study of the S2PFC input-current-shaping (ICS) mechanism, circuit topology generalization and variation, bulk capacitor voltage stress and switch current stress, converter design and optimization, and evaluation of the state-of-the-art S2PFC techniques with universal-line input.
Besides, this presentation also presents the development of novel S2PFC techniques with a voltage-doubler-rectifier front end to both improve the performance and reduce the cost of S2PFC converters for (international voltage range) universal-line applications. The calculation and experimental results show that the proposed techniques offer a more cost-effective and efficient solution than industriesâ current practice, with universal-line input and converter power level up to 600 W. Finally, further improved technique is also presented with reduced filter inductor size and increased power density.Ph. D.
12
Clark, Colin William. "Digital control techniques for power quality improvements in power factor correction applications." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42799.
Full textAbstract:
The prevalence of standards and recommended practices to meet harmonic current limits has gained, and continues to gain, momentum over recent years. To meet these requirements, power electronic rectification devices are necessitated along with their specialized control techniques. A popular power electronic circuit to obtain low-harmonic input current is the boost power factor correction (PFC) converter, and with the advent of digital control, powerful control techniques to meet these harmonic current limits are possible.
The first contribution is a detailed guide to the conversion of an analog IC-controlled boost PFC converter to a digitally controlled equivalent. Design of the voltage and current sensing networks, compensator, overview of the critical interrupt service routines, and the control implementation in a digital signal processor (DSP) is presented. The existing boost PFC converter modified for digital control is successful, and provides a flexible prototyping test bench for further use.
The second contribution is a novel DSP-based discontinuous conduction mode (DCM) detection method for application to the boost PFC converter. The proposed detection method is computationally simple, and requires little or no modification to existing digitally controlled boost PFC converters using DSPs with on-board comparators. An experimental boost PFC converter verifies the effectiveness of the proposed detection method over traditional zero current detection and DCM detection techniques, enabling advanced control techniques for power quality improvements.
The final contribution is a new adaptive mixed conduction mode (MCM) control technique for the boost PFC converter. This MCM control technique applies the proposed DSP-based DCM detection method to realize higher power factor and decreased total harmonic distortion (THD) over a commercially available analog controller and a conventional digital controller. Using a boost PFC converter operating in MCM with the proposed adaptive control method, THD improvements of up to 4.55% at light loads and power factor improvements of up to 17.4% are provided over the analog and conventional digital controller.
13
Barbosa, Peter Mantovanelli. "Three-Phase Power Factor Correction Circuits for Low-Cost Distributed Power Systems." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/28651.
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Front-end converters with power factor correction (PFC) capability are widely used in distributed power systems (DPSs). Most of the front-end converters are implemented using a two-stage approach, which consists of a PFC stage followed by a DC/DC converter. The purpose of the front-end converter is to regulate the DC output voltage, supply all the load converters connected to the distributed bus, guarantee current sharing, and charge a bank of batteries to provide backup energy when the power grid breaks down.
One of the main concerns of the power supply industry is to obtain a front-end converter with a low-cost PFC stage, while still complying with required harmonic standards, especially for high-power three-phase applications. Having this statement in mind, the main objective of this dissertation is to study front-end converters for DPS applications with PFC to meet harmonic standards, while still maintaining low cost and performance indices.
To realize the many aforementioned objectives, this dissertation is divided into two main parts: (1) two-stage front-end converters suitable for telecom applications, and (2) single-stage low-cost AC/DC converters suitable for mainframe computers and server applications. The use of discontinuous conduction mode (DCM) boost rectifiers is extensively explored to achieve simplicity, while reducing the cost for DPS applications. Interleaving of DCM boost rectifiers is also explored as an alternative approach to further reduce the system cost by reducing the filtering requirements. All the solutions discussed are implemented for 3kW applications, while 6kW is obtained by interleaving two converters.Ph. D.
14
Gamboa, Gustavo. "REALIZATION OF POWER FACTOR CORRECTION AND MAXIMUM POWER POINT TRACKING FOR LOW POWER WIND TURBINES." Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4283.
Full textAbstract:
In recent years, wind energy technology has become one of the top areas of interest for energy harvesting in the power electronics world. This interest has especially peaked recently due to the increasing demand for a reliable source of renewable energy. In a recent study, the American Wind Energy Association (AWEA) ranked the U.S as the leading competitor in wind energy harvesting followed by Germany and Spain. Although the United States is the leading competitor in this area, no one has been able successfully develop an efficient, low-cost AC/DC convertor for low power turbines to be used by the average American consumer. There has been very little research in low power AC/DC converters for low to medium power wind energy turbines for battery charging applications. Due to the low power coefficient of wind turbines, power converters are required to transfer the maximum available power at the highest efficiency. Power factor correction (PFC) and maximum power point tracking (MPPT) algorithms have been proposed for high power wind turbines. These turbines are out of the price range of what a common household can afford. They also occupy a large amount of space, which is not practical for use in one's home. A low cost AC/DC converter with efficient power transfer is needed in order to promote the use of cheaper low power wind turbines. Only MPPT is implemented in most of these low power wind turbine power converters. The concept of power factor correction with MPPT has not been completely adapted just yet. The research conducted involved analyzing the effect of power factor correction and maximum power point tracking algorithm in AC/DC converters for wind turbine applications. Although maximum power to the load is always desired, most converters only take electrical efficiency into consideration. However, not only the electrical efficiency must be considered, but the mechanical energy as well. If the converter is designed to look like a purely resistive load and not a switched load, a wind turbine is able to supply the maximum power with lower conduction loss at the input side due to high current spikes. Two power converters, VIENNA with buck converter and a Buck-boost converter, were designed and experimentally analyzed. A unique approach of controlling the MPPT algorithm through a conductance G for PFC is proposed and applied in the VIENNA topology. On the other hand, the Buck-boost only operates MPPT. With the same wind profile applied for both converters, an increase in power drawn from the input increased when PFC was used even when the power level was low. Both topologies present their own unique advantages. The main advantage for the VIENNA converter is that PFC allowed more power extraction from the turbine, increasing both electrical and mechanical efficiency. The buck-boost converter, on the other hand, presents a very low component count which decreases the overall cost and volume. Therefore, a small, cost-effective converter that maximizes the power transfer from a small power wind turbine to a DC load, can motivate consumers to utilize the power available from the wind.M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE
15
Durrani, Yamin Qaisar. "Analysis of silicon carbide based semiconductor power devices and their application in power factor correction." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2573.
Full textAbstract:
Recent technological advances have allowed silicon (Si) semiconductor technology to
approach the theoretical limits of the Si material; however, power device requirements for
many applications are at a stage that the present Si-based power devices cannot handle.
The requirements include higher blocking voltages, switching frequencies, efficiency, and
reliability. Material technologies superior to Si are needed for future power device
developments. Silicon Carbide (SiC) based semiconductor devices offer one such
alternative. SiC based power devices exhibit superior properties such as very low
switching losses, fast switching behavior, improved reliability and high temperature
operation capabilities. Power factor correction stage of power supplies is identified as an
area where application of these devices would prove advantageous. In this thesis a high
performance, high efficiency, SiC based power factor correction stage is discussed. The
proposed topology takes advantage of the superior properties of SiC semiconductor based
devices and the reduced number of devices that the dual boost power factor correction
topology requires to achieve high efficiency, small size and better performance at high
temperature. In addition to this analysis of SiC based power devices is carried out to study
their characteristics and performance.
16
Lord, Edward Michael. "Single-stage power factor correction converter topologies for low power off-line applications." Thesis, University of Edinburgh, 2004. http://hdl.handle.net/1842/15234.
Full textAbstract:
Since January 2001 it has been necessary for equipment connected to the low voltage public distribution network in Europe and Japan to comply with IEC 61000-3-2. The regulation IEC 61000-3-2 specifies the level of current that can be drawn for particular harmonics. Much equipment today is fitted with a Switch Mode Power Supply (SMPS) at its input to interface between the line voltage and internal low voltage electronics. This SMPS must not only convert the line voltage, but also ensure that the input current to the device meets the IEC regulations. To meet these regulations two methods are normally used, passive filtering using a large filter inductor or a boost converter cascaded with the main DC/DC SMPS converter with isolation. To try and reduce component count, cost and increase efficiency many new single-stage Power Factor Correction (PFC) topologies have been proposed. In a single-stage topology the output voltage regulation and meeting IEC 61000-3-2 are combined into a single power stage. Unfortunately very little is known about the behaviour or performance of these single-stage topologies. In this thesis two of the more promising single-stage topologies, the bi-forward and CS S2PFC converters are investigated further. A new topology using a low frequency switch (LFSPFC) is introduced. The topologies are analysed investigating input current shape and harmonic content, voltage variation on bulk capacitance and component stresses. Simulation in PSpice is used to confirm circuit operation. Four 150W output power experimental circuits were built: bi-forward converter, CS S2PFC converter, passive filtering cascaded with a forward converter and a boost pre-regulator cascaded with a forward converter. The converters operate from universal input voltage and have outputs at 5V and 12V. A 100W test circuit was built for the LFSPFC operating from 230V input voltage and with an output of 5V. Experimental results are presented showing circuit behaviour and performance of the bi-forward, CS S2PFC and LFSPFC converters. The bi-forward and CS S2PFC converters are compared to the passive filter and boost converter cascaded with a forward converter. It is demonstrated that neither of these single-stage topologies is at present a viable replacement for either present method, but the LFSPFC could be a lighter weight and less bulky alternative to passive filtering.
17
Saasaa, Raed. "A single-stage interleaved resonant power factor correction converter." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59199.
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Applications requiring DC voltages vary widely, from low power, such as LED lighting, to high power, as in industrial motor drives and battery chargers. Accordingly, a unified power architecture for all applications is not practical for efficiency, size and cost optimization. The use of LED lighting system became popular due to its many advantages. The new outdoor applications such as street and flood lighting require high power (i.e. >200 W) in contrast to the low power existing LED drivers. Generally, the conventional architecture of AC/DC converters consists of two main stages; The first is current-shaping stage to improve PF and the second is to provide isolation and tight regulation over the output voltage. Recently, the research on AC/DC converters has focused on optimizing the converter design to be more reliable and efficient for low and medium power applications. Specifically, techniques have been proposed to eliminate the DC output bus electrolytic capacitor by introducing auxiliary DC/DC converter. On the other hand, the integrated converters were deployed by many researchers to decrease the number of switches, facilitate the controller design, and improve the efficiency. This thesis presents a novel single-stage AC/DC converter that can achieve high power factor with reduced switching losses for semiconductor devices. The topology is derived by integrating the interleaved boost-type PFC and full bridge LLC resonant converters. Due to interleaving at the input, the converter exhibits less input current ripple compared to the existing topologies. Therefore, it is suitable for applications up to approximately 500 W. A detailed analysis of the operation modes is presented. Also, a 350–W prototype is designed to verify the effectiveness of the topology.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
18
Mathew, Jimson. "Design techniques for low power on-chip error correction." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492442.
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As integrated circuit density increases, digital circuits characterized by high operating frequencies and low voltage levels will be increasingly susceptible to faults. Furthermore, it has recently been shown that for many digital signature and identification schemes an attacker can inject faults into the hardware and the resulting incorrect outputs may completely expose their secrets. On-chip error masking techniques such as error correction could be one of the options to mitigate the above problems. To this end, this thesis presents a framework of techniques to design error circuits.
19
George, Mark S. "Power factor correction using a boost quasi-resonant converter." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41901.
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A steady-state analysis of a quasi-resonant zero current boost converter is performed in its application to a single-phase power factor correction circuit. The known closed-form expressions are used to design the boost converter and the multiloop control circuit. The operating characteristics are simulated by using PSPICE and are experimentally verified. Considerations for a practical design are based upon hardware operating at a maximum of 1 megahertz, with a 115 VRMS input, 200 VDC and 100 watt output.
Master of Science
20
Wall, Simon Robert. "Control of switched-mode power converters." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362966.
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Zhao, Yiqing. "Single Phase Power Factor Correction Circuit with Wide Output Voltage Range." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35764.
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The conventional power factor correction circuit has a fixed output voltage. However, in some applications, a PFC circuit with a wide output voltage range is needed. A single phase power factor correction circuit with wide output voltage range is developed in this work.
After a comparison of two main power stage candidates (Buck+Boost and Sepic) in terms of efficiency, complexity, cost and device rating, the buck+boost converter is employed as the variable output PFC power stage. From the loss analysis, this topology has a high efficiency from light load to heavy load.
The control system of the variable output PFC circuit is analyzed and designed. Charge average current sensing scheme has been adopted to sense the input current. The problem of high input harmonic currents at low output voltage is discussed. It is found that the current loop gain and cross over frequency will change greatly when the output voltage changes. To solve this problem, an automatic gain control scheme is proposed and a detailed circuit is designed and added to the current loop.
A modified input current sensing scheme is presented to overcome the problem of an insufficient phase margin of the PFC circuit near the maximum output voltage. The charge average current sensing circuit will be bypassed automatically by a logical circuit when the output voltage is higher than the peak line voltage. Instead, a resistor is used to sense the input current at that condition. Therefore, the phase delay caused by the charge average current sensing circuit is avoided.
The design and analysis are based on a novel air conditioner motor system application. Some detailed design issues are discussed. The experimental results show that the variable output PFC circuit has good performance in the wide output voltage range, under both the Boost mode when the output voltage is high and the Buck+Boost mode when the output voltage is low.Master of Science
22
Landin, Per. "Digital Baseband Modeling and Correction of Radio Frequency Power Amplifiers." Doctoral thesis, KTH, Signalbehandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94762.
Full textAbstract:
Aspects related to behavioral modeling and correction of distortions for radio frequency (RF) power amplifiers (PAs) are treated in the thesis. When evaluating the performance of a behavioral model it is important to, first of all, use an evaluation criterion, and second, make sure that the criterion actually tells something about the behavior one wishes to describe. This is used in the weighted error spectral power ratio (WESPR) criterion by means of a frequency dependent weighting function. When the parameters of the models are estimated a suitable error criterion should likewise be used. The frequency weighting function in the WESPR is used in the extraction of the parameters. It is shown on two types of PAs that the model performance measured as WESPR can be improved while the model complexity is reduced compared to the standard frequency neutral criterion. When building a model of a system it is advantageous to take account of the physical structure and incorporate this knowledge into the model. It can improve model performance and possibly reduce the number of parameters. By starting from a physically motivated nonlinear model of a RF PA, the commonly used memory polynomial (MP) models are derived. Additionally, three novel MP model structures are derived. Using data measured on a PA it is found that two of these model structures have lower model errors while using fewer parameters than models previously published in the literature. Methods to increase the power efficiency and the linearity of RF PAs have been investigated. One of these methods is digital predistortion (DPD) which improves the linearity, thus facilitating operation at higher power levels which improves power efficiency. The other method is a signal shaping method that makes the signal more favorable to the PA by reducing the highest peaks to lower values. It is experimentally shown that the combination of DPD and signal shaping results in an increase of power efficiency in the order of 2-4 times. An instability in the feedback loop that updates the parameters of the DPD was also identified and two solutions were proposed. One solution changes the parameters of the DPD in such a way that the instability is avoided and the other changes the signal to avoid high amplitudes. The nonlinear effects of class-D outphasing amplifiers are considered. Four model structures are proposed and evaluated on data measured from two amplifiers. In order to reduce the distortions in the output signal from the amplifiers an algorithm using constant envelope amplitude (purely phase-modulated) signals is proposed. The DPD is evaluated and found to reduce the distortions in a state-of-the-art 32 dBm class-D outphasing PA to make it fulfill the linearity requirements for downlink signals used in the universal mobile telecommunications system (UMTS).Denna avhandling behandlar ett antal aspekter av digital beteendemodellering och korrektion av effektförstärkare för radiofrekvensapplikationer. När prestandan hos en beteendemodell skall bedömas är det för det första viktigt att ha ett utvärderingskriterium och för det andra är det viktigt att detta kriterium fokuserar på de relevanta delarna av beteendet man är intresserad av. Detta används i kriteriet weighted error spectral power ratio (WESPR) genom att en viktning införs. Denna viktning används för att fokusera på de aspekter av beteendet som är viktiga att beskriva. På samma sätt är det viktigt att fokusera på att minimera de relevanta delarna av modellfelet. Genom att använda viktningen från WESPR när parametrarna i beteendemodellen skall estimeras visas det på två olika typer av PA att modellprestandan kan förbättras och modellkomplexiteten reduceras när ett relevant felkriterium används. När en modell av ett system byggs är det fördelaktigt att använda den kunskap man har om det fysikaliska systemet. Det kan förbättra modellprestandan samtidigt som antalet parametrar kan reduceras. Genom att börja med en fysikaliskt motiverad modell av en effektförstärkare och införa antaganden härleds de populära minnespolynomen. Dessa har tidigare inte haft någon fysikalisk förklaring. Dessutom härleds tre nya minnespolynom. Av dessa visar två av strukturerna lägre modellfel samtidigt som färre parametrar används än i de tidigare publicerade minnespolynomen. Metoder för att förbättra energieffektiviteten och linjariteten i effektförstärkare har undersökts. En av dessa metoder är digital predistorsion (DPD) vilken förbättrar linjariteten och möjliggör på så vis högre uteffekter, vilket i sin tur förbättrar energieffektiviteten. Den andra testade metoden går ut på att förändra signalen genom att reducera effekttopparna så att signalen blir lämpligare för förstärkaren. Det visas experimentellt att kombinationen av dessa metoder kan resultera i förbättringar av energieffektiviteten på 2-4 gånger. En instabilitet i återkopplingsslingan för parameteruppdateringen av DPD identifieras och två förslag på lösningar ges. Det första förslaget modifierar parametrarna så att instabiliteten undviks. Det andra förslaget förändrar signalen så att de höga amplituderna undviks och systemet stabiliseras på detta sätt. Slutligen studeras de ickelinjära effekterna i klass-D utfasningsförstärkare. Tre modellstrukturer föreslås och utvärderas på uppmätta data från två olika förstärkare. För att reducera störningarna i utsignalen från förstärkarna föreslås en DPD-algoritm som använder signaler med konstant amplitud (rent fasmodulerade signaler). Denna DPD utvärderas och det visas att den kan reducera störningar i utsignalen hos en modern 32 dBm klass-D utfasande förstärkare så att den uppfyller linjaritetskraven för signaler som används i nedlänken (från basstation till mobil enhet) i telekommunikationssystemet universal mobile telecommunications system (UMTS).
QC 20120514
23
Ahmed, Saeed. "Controlled on-time power factor correction circuit with input filter." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-11072008-063637/.
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Kalpaktsoglou, Dimitrios. "Power factor correction for stand-alone wave energy conversion buoys." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519591.
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Zhang, Yaping. "High-power, high-brightness laser diodes with distributed phase correction." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246369.
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Zhang, Jindong. "Study and Improvement of Single-Stage Power Factor Correction Techniques." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36938.
Full textAbstract:
This thesis work focuses on the study and improvement of single-stage power factor correction techniques.
The generalized structures of the present pulse-width-modulation (PWM) integrated single-stage power factor correction (PFC) converters are presented. The typical PFC cells in the single-stage PFC converter are identified. After that, the necessary PFC condition is derived and verified to understand the principle of the single-stage PFC converters.
As an example, the continuous current mode (CCM) current source single-stage PFC converter is studied. The circuit intuitions and design consideration of this converter are presented. Also, an improved current source single-stage PFC converter with a low-frequency auxiliary switch is proposed to overcome the problem of the previous converter. Experimental verification shows the improvement is effective.
To evaluate single-stage PFC technique, a comparison study between the current source single-stage and the boost two-stage PFC converters is done in this thesis. It shows that for universal line application, due to the wide bus-capacitor voltage range, single-stage PFC converters have higher component ratings than two-stage PFC converters. This limits the application of single-stage PFC converter. Therefore, an interesting future work will be how to reduce the bus voltage range of single-stage PFC converters.Master of Science
27
Zhou, Chen. "Design and analysis of an active power factor correction circuit." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53729.
Full textAbstract:
The design of an active-unity power factor correction circuit with variable-hysteresis
control for off-line dc-to-dc switching power supplies is described. Design
equations relating the boost inductor current ripple to the circuit components selection
and circuit performance arc discussed. A computer-aided design program (CADO) is
developed to give the optimal circuit components selection. A 500 watt, 300 volt experimental
circuit is built to verify the simulation and analysis results.
The control-to-output response of the power factor circuit is verified with the experimental
results. Design guidelines for the low-frequency feedback network are presented.
Small-signal closed-loop responses are measured with an experimental power
factor circuit.Master of Science
28
Rustom, Khalid. "STEADY STATE AND DYNAMIC ANALYSIS AND OPTIMIZATION OF SINGLE-STAGE POWER FACTOR CORRECTION CONVERTERS." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2216.
Full textAbstract:
With the increased interest in applying Power Factor Correction (PFC) to off-line AC-DC converters, the field of integrated, single-stage PFC converter development has attracted wide attention. Considering the tens of millions of low-to-medium power supplies manufactured each year for today's rechargeable equipment, the expected reduction in cost by utilizing advanced technologies is significant. To date, only a few single-stage topologies have made it to the market due to the inherit limitations in this structure. The high voltage and current stresses on the components led to reduced efficiency and an increased failure rate. In addition, the component prices tend to increase with increased electrical and thermal requirements, jeopardizing the overarching goal of price reduction. The absence of dedicated control circuitry for each stage complicates the power balance in these converters, often resulting in an oversized bus capacitance. These factors have impeded widespread acceptance of these new techniques by manufacturers, and as such single stage PFC has remained largely a drawing board concept. This dissertation will present an in-depth study of innovative solutions that address these problems directly, rather than proposing more topologies with the same type of issues. The direct energy transfer concept is analyzed and presented as a promising solution for the majority of the single-stage PFC converter limitations. Three topologies are presented and analyzed based on this innovative structure. To complete the picture, the dynamics of a variety of single-stage converters can be analyzed using a proposed switched transformer model.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD
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Pal, Subarna. "Simulation of current mode control schemes for power factor correction circuits." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0008/MQ36162.pdf.
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Monjardin-Lopez, Jesus Fernando. "Wavefront characterisation and beam correction for high power diode laser arrays." Thesis, Heriot-Watt University, 2006. http://hdl.handle.net/10399/2014.
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Dinsdale, Michael J. "The scheme-dependence of power correction fits to event shape observables." Thesis, Durham University, 2005. http://etheses.dur.ac.uk/3011/.
Full textAbstract:
A recent analysis by the DELPHI collaboration showed that if one uses an "optimised" choice of renormalization scale, some e+e(^-) event shape means can be described without significant power corrections. Motivated by this, in this thesis optimised scales (and schemes) are applied to similar observables. First, abrief review of QCD and scale/scheme optimisation is given. Then, the distributions of the e+e(^-) event shapes l-thrust and heavy-jet mass are studied within the Method of Effective Charges, including performing a next-to-leading log resummation of the effective charge beta function. There is some reduction in the apparent size of power corrections, but the resummed results behave pathologically in the 2-jet limit. Next, the Principle of Minimal Sensitivity is applied to the choice of renormalization and factorization scales for event shape means defined in the Breit frame of ep BIS. This has little effect on the perturbative predictions and large power corrections are still required. However, if one introduces separate renormalization scales for the qγ* and gγ* sub-processes, a substantial reduction in the size of the power corrections is seen for most observables.
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Wu, Tung-Mao, and 吳東懋. "Power Quality Correction." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/12656614688368513651.
Full textAbstract:
碩士國立臺灣海洋大學
電機工程學系
98
Due to the fast improvements of the technologies of electric power, all types of electric facilities can satisfy the needs of end users on electricity usage either in livehood or industry. However, power quality is getting worse because of diversified loading which has impacted on power system and electrical facilities. Furthermore, it has caused many problems on electricity usage and extra unnecessary power consumption which have reflected on the increasing maintenance fee and running cost. This thesis will have a series of analyses and examinations on power quality, voltage variation, flash voltage, power frequency, power harmonic waves, power impulse, and in-equivalent system. Moreover, the thesis will propose a reliable solution and dependable suggestion based on existing power saving solutions and web manager power SCADA.
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Huang, Kuan-Ju, and 黃冠儒. "Development of a Digital Meter with Power Factor Correction Correction Capability." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/d8q927.
Full textAbstract:
碩士國立臺北科技大學
自動化科技研究所
105
The thesis proposed a digital meter with power factor correction capability when the measured signal contains harmonic components. By using resistor voltage divider circuit and current clamp, the input voltage and current are transferred to small voltage signals which can be processed by the microprocessor. These voltage and current waveform are digitized through an analog-to-digital convertor (ADC). Fast Fourier Transform (FFT) is applied. The Hanning Window and frequency interpolation algorithm is used to correct the voltage and current signals. As the front-end circuit may introduce phase shift, phase compensation calculation is required. Accurate RMS voltage, RMS current, active power, reactive power, apparent power, power factor and frequency can be calculated. When measured signal contains harmonic components, the THD is calculated and is used to correct the power factor calculation. The final measurement results are displayed on the LCD and transmitted through the UART. Calibration procedure is also developed to simplify the calibration process. All of the calibration parameters are stored in nonvolatile memory.
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Aydonat, Meric. "Power Grid Correction Using Sensitivity Analysis." Thesis, 2010. http://hdl.handle.net/1807/25415.
Full textAbstract:
Power grid voltage integrity verification requires checking if all the voltage drops on
the grid are less than a certain threshold that guarantees proper circuit operation.
This thesis addresses the problem of correcting the grid when some voltage drops
exceed this threshold by making minor modifications to the existing design. The
method uses current constraints that capture the uncertainty about the underlying
circuit behavior to find the maximum voltage drop on the grid, and then to estimate
the voltage drop as a function of the metal widths on the grid. It formulates a nonlinear
optimization problem and finds the required change in widths that reduces the
maximum voltage drop on the grid below the threshold while keeping the total area
cost at a minimum.
35
Gau, Yu-Jun, and 高鈺鈞. "Low Cost Simple Power Factor Correction." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5uw96v.
Full textAbstract:
碩士遠東科技大學
電機工程研究所
107
This thesis proposes a low-cost simple power factor correction converter architecture. Since the commercially available power factor correctors are upgraded to 400V without lower voltage, considering the low-voltage equipment can be used, it is proposed to achieve high-efficiency circuits at low cost. This article uses the IC ICE2PCS02 in continuous conduction mode as the correction IC for this power factor corrector. This circuit simulates the boost converter simulation in the case of input 70-130Vac boost to output 200V for three different load cases. At half load, the efficiency can reach 94-95% or more. When it is fully loaded, its efficiency can reach 98-99%, effectively achieving a low-cost and high-efficiency structure.
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Fan, Yang-Dian, and 范揚典. "Comparator Implemented Digital Power Factor Correction Rectifier." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/fe7tu6.
Full textAbstract:
碩士國立高雄科技大學
電機工程系
107
Power factor correction rectifier (PFC) is the front end of most computer power supplies. Due to the climate change, high efficiency over wide load range is highly demanded in PFCs. This drives digital controller to replace analog controller. Analog to digital converters (ADC) are the essential parts for all digital powers. Some previous researches replace the ADC with a comparator and a counter for measuring the DC value of a rippled signal. Comparator based control does not only reduces system cost, but also eliminates the sampling error of the ADC. For those signals with small ripple, the comparator based digital controller injects extra analog ripple on signal feedback for signal sensing. However, in digital PFC, system operation point varies along the line voltage. The fixed analog ripple injection can only be optimized for one operating point. Therefore, a digital ripple injection is introduced in this paper. Instead of using analog circuits to generate analog ripple, a digital to analog converter (DAC) and a low pass filter can generate filtered digital ripple signal as the ripple inject. Based on digital ripple injection, a 500 watt digital PFC is implemented experimentally.
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Hsu, Yu-chun, and 許毓群. "Implementation of a Digital DC Power Supply with Power Factor Correction." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/44114013949569299375.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
96
The thesis implements a digital DC power supply with power factor correction. The hardware circuit includes a power factor correction circuit and a phase-shift full-bridge circuit. In the thesis, a UC3854 is used to control the power factor of the input source. In addition, a TMS320LF2407A is used to execute the closed loop control algorithms. The detailed principles and design methods are included. Finally, a DC power supply with 48V/864W, 0.99 power factor, satisfactory EN-61000-3-2 Standards is implemented. Experimental results can validate the theoretical analysis to show the feasibility and correctness of the thesis.
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Ku, Chen-wei, and 顧振維. "Design of Robust SEPIC Power Factor Correction Circuits." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/x6phvx.
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碩士國立中山大學
電機工程學系研究所
95
This thesis mainly studies the active power factor correction circuit using a new AC/DC Single Ended Primary Inductance Converter (SEPIC). For power factor correction, inductor current is operated in the continuous conduction mode. First of all, the converter is analyzed by state space averaging method. Furthermore, the operational principle of PFC circuit with PI control law is analyzed. A good power factor system is then developed by time-domain and frequency-domain analysis. A classical PFC circuit with PI control law has low power factor when light load. In order to overcome problem, the thesis proposes a SEPIC circuit with robust performance. Compared with circuits using classical PI controller and PFC IC, the proposed system obtains higher power factor under the condition of the same light load.
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Wu, Chen-chia, and 吳振嘉. "Study of Active Power-Factor Correction Controller Circuits." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/74243596431118058324.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
93
This thesis aims at investigating the technologies of the active power-factor correction (PFC) circuit. The system originally in the article is based on a boost converter circuit as the structure, the control method is to adopt the average current mode. We doesn’t only narrate the circuit principle of the systematic circuit in the article but also use the OrCAD PSpice A/D software to simulation. Finally, we implemented make a prototype circuit and verified the proposed method. The experimental result shows that it can reach the goal for the power-factor correction.
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Cheng, Kai-fang, and 鄭凱方. "Design and Modeling of Power Factor Correction Circuits." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/16884200876201526098.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
93
This thesis aims to investigate an active power factor correction (PFC) circuit and its mathematical model, in order to develop a reliable and efficient simulation platform. By using the PI controller, we can control the inductor current and the output voltage of the boost converter. Finally, we constructed the circuit and analyzed the results to verify that our mathematical model is valid.
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Lan, Yi-Meng, and 藍義孟. "CCM Single-Stage Power Factor Correction Electronic Ballast." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/99552950824506979014.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
92
This thesis presents a continuous-current-mode (CCM) single-stage power factor correction (PFC) electronic ballast, which is a combination of a boost-type PFC network and a DC/AC inverter to allow CCM operation for the PFC inductor in the boost-type PFC network. Among the PFC techniques proposed in recent years, in general, the discontinuous-current-mode (DCM) single-stage PFC electronic ballasts have such drawbacks as high electromagnetic interference (EMI), high current stress, and high switching and conduction losses. The PFC capacitor of the developed boost-type PFC network can help the PFC inductor to achieve CCM, thus shaping the input current of the proposed electronic ballast to achieve high power factor (PF). Finally, a 36W rated power electronic ballast prototype circuit is designed and implemented. Experimental results verify the advantages of the proposed ballast; these include the following: the input current harmonics meet the IEC 61000-3-2 Class C Standard, and the ballast offers lower conducted EMI and lower current stress on switches and diodes.
42
Ikriannikov, Alexandr. "New Developments in Single Phase Power Factor Correction." Thesis, 2000. https://thesis.library.caltech.edu/6104/1/Ikriannikov_a_2000.pdf.
Full textAbstract:
Power Factor Correction (PFC) is a necessary feature of many AC/DC Power Electronics products. The issues of increasing the value of the Power Factor (PF) and increasing efficiency of transferring the power in such applications motivated this thesis.
Input rectification is needed for the most topologies in AC/DC applications for these topologies to perform however, it is pretty much one of the main causes of distortions and power losses. Diode bridge is also one the hottest components of PFC, which is an important issue in terms of thermal management.
New approach for Power Factor Correction is introduced in the first part. Topologies with bipolar gain characteristics are proposed to be used, naturally providing constant DC output from non-rectified AC input. Practical design of such converter is presented and analyzed, theoretical predictions are confirmed by experimental data; proposed idea of Power Factor Correction is verified.
Another new general approach of Power Factor Correction improvement is introduced in second part. Idea of shifting input line rectification to switching elements of the power stage is proposed for certain topologies and verified on practical example. Key features are analyzed and illustrated by experimental data. This class of converters presents an opportunity for accurate comparison with related conventional topologies, which is included to show the advantages of the new approach.
General advantages and improvements of Power Factor value in bridge-less topologies in comparison to conventional converters are analyzed and illustrated experimentally in the third part of the thesis.
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Wu, Hsiang-Yu, and 伍翔榆. "Battery Balancing Charger with Interleaved Power Factor Correction." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/68157200208396427624.
Full textAbstract:
碩士國立彰化師範大學
電機工程學系
104
An interleaved battery balancing charger with power factor correction for two series-connected batteries is proposed in this thesis. The developed balancing charger is composed of a two-phase interleaved buckboost converter and a dual-output balancing charging circuit. The interleaved buckboost converter is operated in discontinuous conduction mode for power factor correction. The voltage and current of each battery are sampled and fed back to a micro-controller unit. The dual-output balancing charging circuit would be controlled with constant-current / constant-voltage charging algorithm and according to the state of each battery. Finally, a hardware with rated power 200W and ac input 110V for charging two 12V/22Ah series-connected batteries is constructed. Additionally, a hardware with single phase buckboost converter is also constructed for comparison. From the experimental results, it is seen that the performance of the interleaved topology is better. The efficiency of the proposed converter is up to 93% and each of the two batteries can be well balancing charged.
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Wu, Rong-hui, and 吳榮輝. "DESIGN OF TWO-STAGE BOOST POWER FACTOR CORRECTION." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/84559969850444277906.
Full textAbstract:
碩士大同大學
電機工程學系(所)
97
ABSTRACT This thesis presents the problem with respect to the dual boost technique of the power factor correction ( PFC ) application. In the PFC a series problem will occur when the PFC is worked in single boost ( only one section_PFC bus is 400V ) even in low mains input, it will then generate a low mains voltage of switching loss on the PFC MOSFET to reduce the efficiency in low mains input . Therefore, In order to prevent this issue happened, we need to change the design concept from single boost to two-stage boost which can improve the efficiency when the input is in low mains voltage for EPA standard application. We knew that if we want to improve the efficiency in low mains voltage that is also passed EPA standard requirement which have to change the design concept to increase low mains voltage efficiency that means as below : Low mains input_90Vac~160Vac : PFC voltage is setting in 250Vdc High mains input_170Vac~264Vac : PFC voltage is setting in 400Vdc
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Che, Lin-Wei, and 林維哲. "Intelligent energy-saving clothes dryerwith power factor correction." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/49166780854980985719.
Full textAbstract:
碩士崑山科技大學
電機工程研究所
100
The core of this paper is based on intelligent energy-saving clothes dryer with power factor correction. And design the boost power factor correction converters, BLDC motor speed control drive system and temperature control of the drive system. The power supply uses the boost converter structure and adopts average current control method to complete the active power calibration purposes. It meets the regulations of international current harmonics wave. In drying technology, a new energy-saving automatic drying control methods improved from original patent is designed.The microprocessor is used to detect the exhaust temperature gradient for controlling the shutdown of the heater and the motor speed. When the small change of the exhaust temperature gradient is reached, it represents that no more water inside clothes can be evaporated and the clothes has been dry enough, the heater is automatically shut down and steps to end the dryer. At this moment, the motor, which is used to drive the drum and fan, keeps operating, and the fan speed is controlled to drive more the cooler outside air to cool down hot clothes faster. It can also obtain less-wrinkle of clothes and less static electricity on clothes. While the exhaust temperature is close to that of outside air, the dryer will be completely shut down, the clothes will be less-wrinkle because of fast and enough cooling. Thus, the user will not feel hurt taking clothes even right after the dryer stop.And this dryer can obtain energy-saving and carbon-reducing effect,and the above user friendly designs make user more convenient using.While this dryer is used, it does only need to one-touch on the power and without any set-up process. More than that, the user does not worry the wrong time setup resulting in over drying or not-enough drying. It is proved from experiments that the energy-saving effect of this innovative method is 20% high than those of other dryers.
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Wu, Yi-Wei, and 吳亦瑋. "Study of Digital Controller for Power Factor Correction." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/28346693759425565290.
Full textAbstract:
碩士中原大學
電機工程研究所
100
【Abstract】 Power supply is still based on analog control IC as the main controller, the advantage of a low cost. The circuit is relatively simple. Fast response; but usually only to provide specific control functions, simple user interface, not suitable for operation in the complex power system integration, and control loop compensation is not easy to adjust. In recent years, with the rapid development of digital signal controllers, the digitization of the power system is the trend of the future development of power design, power management, and multi-functional power supply requirements, an increase of more switching power driver IC demand also changed the power supply power supply architecture. Digital power technology has the flexibility of the parameters, programmable, you can use the firmware control mode, the complex power control and management strategies, from the accurate numerical computation of the impact of environmental change, the integration of modular applications in the development of timing, the key is that the demand for power management-oriented integration. In the commercialization of the product development process, the first digitization of the power supply interface, the development of system-oriented power management mechanism, and then gradually internalized to the power supply control IC with in the process control, and finally developed into going digital type loop control. As the power requirements of the new generation of high performance microprocessors, power supply control IC from the traditional single analog control, toward a multi-functional integrated control IC development, such as TI and Infineon launched at the same time with a power factor correction and pulse-width modulation control of the multi-function control IC. I believe in the near future, the application of digital analog IC design technology in the power supply control IC development, will become the development trend of the power supply control IC, power supply control IC toward a digital, programmable, intelligent direction.
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Tsai, Hsien-Yi, and 蔡憲逸. "Novel Soft-Switching Bridgeless Power Factor Correction Circuits." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/84640922552273594209.
Full textAbstract:
博士國立臺灣大學
電機工程學研究所
99
Power factor correction (PFC) has become almost a must for off-line power applications nowadays. Despite intensive research in the past decade, this is still a hot-research topic among power electronic field because of the “green” push for the future electric power applications. About ten years ago, there was a PFC power-stage configuration named” Bridgeless” reported. In this configuration, the diode bridge conventionally used PFC applications can be removed and therefore resulting in lower conduction power loss for the applications. The main focus of this dissertation is about soft-switching “Bridgeless” PFC (BPFC) circuits which feature improved efficiency. In the dissertation, three classes of soft-switching BPFC circuits are proposed. The first class is a zero-voltage transition BPFC in which an assistant circuit is used to achieve soft switching in the main power switches. However, the assistant switch is still turned off by hard switching. The second class is a zero-voltage zero-current BPFC circuit in which soft switching is achieved not only for the main switches but also for the assistant switch. And the third class is an extension of the first class to a three-phase PFC circuit. Different circuit variations are also proposed to the above three classes. Computer simulations and experimental results are presented in the dissertation. Design guidance is also included. Improvements of efficiencies, compared to conventional hard-switching circuits are in the range of one to two percentage points which is a significant improvement.
48
Guo, Jia-Lin, and 郭家菱. "Bridgeless Interleaved Buck Converter for Power Factor Correction." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/6yy57v.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
106
This thesis studies the active power factor correction. In terms of converters, this thesis proposes a novel bridgeless interleaved buck converter for power factor correction, and uses digitalized average current control method to control the AC input voltage in positive half-cycle and negative half-cycle to achieve power factor correction. The interleaved architecture not only controls simplicity, but also can effectively reduce the component current stress at high output power, improve the high current resistance of the power components, the overlarge volume of the inductors, and the overlarge of output capacitors. This thesis actually produces a 480W bridgeless interleaved buck converter to verify whether the analysis and design considerations are reasonable. Unlike most power factor correction converters, which are used in the boost architecture, the bridgeless interleaved buck converter proposed in this thesis can be used in lower voltage applications, can reduce the values of output electrolytic capacitor and reduce the cost, and also because of the interleaved buck architecture, it can be applied to applications with high output power. The feasibility of the proposed architecture is verified by the experimental results in this thesis, and the total harmonic distortion and power factor of the input current can meet the international specifications.
49
Hsu, ChihChieh, and 徐志杰. "Implementation of a Digital Power Factor Correction Controller for Power Supply Applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19763637135407822958.
Full textAbstract:
碩士國立臺北大學
電機工程研究所
99
This thesis focuses on the study of digitally programmable control concepts as well as on the design and implementation of a power factor correction(PFC)circuit for high power applications. It uses a 110VAC mains voltage as input and then step-up input voltage to the PFC converter by the autotransformer.The output voltage and load power are 400V and 200W respectively. Digital signal controller(DSC) system control core uses dsPIC30F4011 produced by Microchip. The algorithms of the PFC utilizes the average current control method which allows the inductance current and voltage be in phase to achieve low harmonic distortion, low ripple output voltage and high efficiency A DSC-based fully digital control of PFC can achieve programmable, fewer components and greater flexibility design. The circuit can be realized through scaling input voltage, inductor current, and output voltage by ADC module. Then compensates and obtains the error signal by comparing the set reference voltage in the digital PI compensation. The down-scaled signal will be sent to the DAC to do the steps and control the duty signal for PWM with a complete cycle of the control loop. Finally, the desired output regulation and current in-phase with voltage waveform are achieved. Behavioral simulation of the power factor correction stage is verified by using Matlab/Simulink software and full model of PFC is obtained by reference waveform parameters adjustment and compensation.
50
Liu, Chih-Wen, and 劉誌文. "The Design and Implementation of a Two-Quadrant Active Clamp Forward Converter with Power-Factor-Correction Converter with Power-Factor-Correction." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/98688362522878433226.
Full textAbstract:
碩士國立高雄應用科技大學
電機工程系
97
This thesis focuses on the analysis and design of a two-quadrant active clamp forward converter with active power factor correction. First, the characteristics of the power factor correction and conventional active clamp forward converter will be analyzed in this thesis, and then an improved two-quadrant active clamp forward converter topology is proposed. The topology will focus on solving the problems that when the main power switch of conventional active clamp forward converter is turned off, it will need to afford higher voltage stress, and that the zero voltage switching conditions between the main switch and auxiliary switch has big difference. Finally, the theory is verified by IsSpice software and a 100W AC-DC power converter is implemented. The maximum efficiency of the two-stage converter is 83%.